newfuturevintage Posted November 29, 2007 Report Share Posted November 29, 2007 OK, I got around to posting some pics. These are of the first driver I built, it's a welding bar steel base, a brass top and 4x40 SAE (about M3) screws holding the two together to form a bobbin. The screws also behave as pole pieces, and each have two washers to serve as spacers. I tapped threads into the steel base for the screws. The coil is potted in wax. I only had 30awg/ .25mm wire, so it's only ~100 turns and is ~4ohms. Nice thing about this arrangement is it can't banana. If I rewind this, I may omit the washers in the center 4 poles to keep the windings thinner Side View of the driver. The magnets in this pic were replaced with bar magnets: Bottom of the driver without magnets. The holes on the ends were to be for the mounting screws: Hooked up to a 386 amp test setup. The plug in the pic has a pair of alligator / croc clips hanging off it, & a guitar jack on it: The test amp interior layout: Link to comment Share on other sites More sharing options...
col Posted November 29, 2007 Report Share Posted November 29, 2007 (edited) That's a crazy circuit! Thanks for posting the links to it. I'm going to try the optical route for the time being. I've ordered a few Vactrols from allied electronics and will start playing with them. The idea is to start with a variation of craig anderton's optical compressor circuit in Electronic Projects for Musicians book as it's simple enough for me to understand, and will also take care of the buffering in one fell swoop. Will post details if it's successful. It seems complicated, but it breaks down into pretty basic sections, none of which are very complex: input buffer, power supply, harmonic modes, agc, power-amp... if you were to ditch e.g. the harmonic mode section, it would get much smaller... same goes for the AGC. As far as Vactrols... I haven't been able to source any locally, so haven't tried that route. One thing to watch out for is that they vary dramatically in response rate, so make sure you get the fast ones - that will make a big difference in this application Another issue that may not be obvious to you is the importance of the topology of the AGC - for our purposes, a feed-forward design _may_ be significantly better than a feedback design ! If you can have a feedforward design with similar distortion characteristics and response time, then it will certainly be a better bet than one based on feedback. The problem is that the feedback version takes it's control signal from the output of the amp, before the driver/strings/pickup. This means that the signal is leveled before it reaches the part where there is an imbalance in the frequency response of the system. This means that there will be a bigger variation in drive depending on the string and fret being played. A feedforward circuit on the other hand controls the gain based on the output of the pickup, so any difference in levels caused by which string, or fret is being played will be processed by the AGC. There is still some variation even with a feed-forward AGC, but at least it is minimized. A feedback AGC will still work a lot better than no AGC, and if the feedback version can be lower distortion, faster response and simpler circuit, then it may still be a good compromise. The important thing is to be aware that there is a notable difference. ...the ideal would be a 1 chip limiter / class-d amp. this makes a lot of sense to me. Given the unavailability of DIY - appropriate class-D chips, I wonder about finding small off the shelf amps and hacking them. Unfortunately, as far as I can tell, all the off the shelf amps in class-d seem to be high power jobs - that's what folks want for car audio systems etc. The low power stuff is mostly used in miniaturized electronic goods, so mobile phones, mp3 players etc. You can't buy off the shelf 2 watt class-d amps (yet). I guess we'll have to wait for the diy mp3 player craze to kick off cheers Col Edited November 29, 2007 by col Link to comment Share on other sites More sharing options...
col Posted November 29, 2007 Report Share Posted November 29, 2007 OK, I got around to posting some pics. Cool - it's always great to see more sustainer porn These are of the first driver I built, it's a welding bar steel base, a brass top and 4x40 SAE (about M3) screws holding the two together to form a bobbin. The screws also behave as pole pieces, and each have two washers to serve as spacers. I tapped threads into the steel base for the screws. The coil is potted in wax. I only had 30awg/ .25mm wire, so it's only ~100 turns and is ~4ohms. Nice thing about this arrangement is it can't banana. If I rewind this, I may omit the washers in the center 4 poles to keep the windings thinner One thing I would suggest is that If you are going to use that hefty steel bar as a base, you must have the magnets on the inside of if - having the bar between the magnets and the rest of the driver basically shields the driver from the the magnets - not what you want to do I think it would be fine to have the magnets under the pole pieces, then the steel bar as the base on the very bottom (only with a single coil driver though)... alternatively, use some non-magnetic material like wood, plastic, brass, aluminium or some non- magnetic alloy. Other than that - great first effort, congrats Col Link to comment Share on other sites More sharing options...
mrjstudios Posted November 29, 2007 Report Share Posted November 29, 2007 jamforthelamb- I am also in the US.... I got some of my wire from ebay -- most US dealers that sell there sell 100meter rolls (yes, even the US dealers use Meter measurements -- even though they also use AWG instead of mm!!) of magnet wire, for around US$14. I had to buy 1 roll from some dealer's website though -- I think it was the .2mm (32AWG) coil. Sometimes there aren't all gauges on sale at any given time on ebay. newfuturevintage- That driver looks really good -- especially the coil. You should see mine (total mess, though they usually work...). However, Col is right about the welding bar. I actually used that same type of barstock (3mm thick) as the CORE of my driver -- but using it like you did might block some power coming from the magnets. Try it anyway though, like it is, because it might still be powerful enough to work just fine. Also, the brass 'cover' also bothers me... I remember a large discussion a while back about using shielding, and I'm pretty sure it was discovered that any conductive material near the driver would mess with the electromagnetic functions of it. Plus, if your coil's insulation rubs off in 2 spots, the brass could short it where the plastic would not. Being a trumpet player too (yes, there is more to life than guitar ), I like the look of the brass though! Good work. -MRJ Link to comment Share on other sites More sharing options...
newfuturevintage Posted November 30, 2007 Report Share Posted November 30, 2007 Col-- Thanks for the thoughts on AGC design. Will take them into consideration when breadboarding (yep, I'll get one) the Vactrol based design. MRJ & Col -- Thanks for the kind words, and the thoughts on the Steel / Brass. As ugly as the driver is, it seems to work pretty well. Better than the design I ended up putting in the guitar itself (pics to follow, naturally). Not sure if it's because the magnets make contact with the poles themselves or some other reason. Unfortunately, I have no base for comparison, so I have no idea how an efficient driver should behave. Brass was selected for its non-magnetic properties (and it's very easy to work with). I may disassemble this to rewind with thinner wire. If I do, I'll try to try it without the brass top and see if there's any difference in efficiency. Point well taken about the shorting potential. That did occur to me, but this was more my proof-of-concept attempt, ie: if this doesn't work, I'm not going any further . My thought was if I build another of this design I'd cover the metal with electrical tape prior to winding. I'm also terrible at working with plastic, and have a bit better handle on metal. If I redesign this with the magnets on the other side of the steel, I'm gonna have to rethink it a bit as the pole pieces themselves hold this together. maybe small magnets between the pieces? Any thoughts would be appreciated. Thanks! Link to comment Share on other sites More sharing options...
psw Posted November 30, 2007 Author Report Share Posted November 30, 2007 Hey there.... Great to see so many new people interested and thanks to Col and everyone else for replying while I am otherwise distracted... Here's one for col... I call this anti-K.I.S.S. Wiring As usual things get a little out of hand....hmmm I am working on this project and it is taking an inordinate amount of time and is very complex. More will be revealed about all that is going on with this thing and it will have brought together a number of interesting side projects from the sustainer thread, as well as being the guitar the next generation sustainer is fully installed in... I did have this wired up for sound with 10 very good usable sounds...typical strat and a collection of series sounds and it sounds great and was very quiet. A lot of point to point wiring though and when I tried implementing a second set of more complex tone selections (yes Col, I agree, caps and stuff are a great option...the idea is a kind of super switchable varitone kind of effect plus 10 more different combinations and some interaction (like phasing) between the two 4pdt and one dpdt switch pots. Of course, if that isn't enough, you can just see the circuit (wrapped in yellow) next to the middle control that completely activates all the sustainer functions (twist switch for on-off-bypass, push pull for harmonic function, turn knob for drive control)...wiring any sustainer type device is tricky, sustainiac have a lot of reservations about custom wiring schemes with sustainer technology and fernandes don't offer it at all... But wait, there's more... I have been working on my piezo system and it is coming along. Several failed attempts, but I am getting a sound out of it. I have designed a new circuit for it and you can see that has been just fitted here next to the volume control and above the super switch selector...umm...and under the wires...ok...you can just see a trim pot that varies the amount of internal gain to the circuit... The pot controls are a curious beast...they need to be reverse mounted as they can't screw in like conventional pots, thos aluminium struts are there to hold them securely in place yet still allow easy switch functions. These pots are designed and built by me for this project (for the newer guys) and are pots with dual switching functions...push pull and twist 4pdt and I have three in there!!! Also a super switch selector...so a lot of switching power... But don't cringe too soon, there are no visible switches on the outside of the guitar and the selections are grouped into banks that are selected by a conventional 5 way selector... I think it is a unique approach, but as I say, the complexity was getting a bit much and the whole cavity was looking like a dish of spaghetti...not good. So...I am using pretty rainbow coloured ribbon cables from the various control functions and preamps (there is an optional active buffer also, and perhaps remote power option down the track...this stuff is in the jack plate cavity). The idea is to take a line from each control, pot, switch, pickup, etc and run them all to a central buss. For testing and trouble shooting and eventual modification and evolution, these wires can be brought out and switches about without having to mess with the internal and difficult to reach components. I have even wired in things that may not be used (like coil taps to the noise canceling coils of the single coils, etc). So...I am working towards rewiring it back to the 10 sounds that impressed me before and sorting out the piezo and sustainer into this...I will then have a go at other "novelty" selections for the two switches associated with the tone control. Just how the piezos will be integrated is up for grabs...one idea is that they can be added to any mag selection, but I also have an idea that I could have the option of running them direct when on so that when you turn the guitar down with the piezos on, you are left with the acoustic sound and a kind of blend control...just a thought... Anyway...too many options and features elsewhere in the guitar, but will be exploring it in a future thread in the main area when it is all up and running... Meanwhile...need to get back to more of the sustainer project proper... pete Link to comment Share on other sites More sharing options...
Chip Posted November 30, 2007 Report Share Posted November 30, 2007 Hi, havn't been here in a while just wondering if there was an ETA for your sustainers psw, no chance before x-mas i suppose? Link to comment Share on other sites More sharing options...
newfuturevintage Posted December 1, 2007 Report Share Posted December 1, 2007 (edited) Some pics of the second driver I built and the guitar where it's currently residing. The coil is wound on the original neck PU that I sacrificed to the cause. (it was really horrible anyhow). This is the guitar, pre-mod. I didn't do the dice, though I wish I could claim them as my work. Vegas! Telly says, "who loves ya baby?" The gutted pickup. The bobbin is a bit too tall (maybe a mm or two), but works. Sorry for the lack of scale on the pic. I'd guess the bobbin is 4 or 5mm tall. The wound driver (180 winds of .25mm wire, 8.9ohms). The vice holds the bobbin in place for winding. The tape holds everything together while it gets potted in wax. Here's the driver on the test amp, post-dip. I sense a lot of folks are leery of using wax. I like it as a coil can be tested very quickly after it's potted, and the coil is neater and easier to wind dry. Disclaimer: HOT WAX IS DANGEROUS -- it's a drag to get on you, and more importantly, it is flammable. As cool as this project is, it's not worth torching your home, so be very careful if you use wax. Getting the guitar ready for the install. Nothing like tequila to help this sort of thing. See warning about hot wax above. Tequila and hot wax don't mix. The Switchcraft #13 in action. I'm using this and the SPST switch next to it on the (+) battery lead to power up the 386. Doing this instead of using a stereo jack on circuit / guitar ground maintains only one path between the 386 and the guitar's ground to prevent the nasty ground (earth) loop I was getting. The plastic nub brings the two blades of the switch together when a cable is inserted for insulated switching. All signal & driver leads are shielded. The very simple driver circuit. It's more or less the smokey amp schematic. There is indeed a pronounced loading effect on the pickup, so a buffer would be better (as would AGC). The pickup in there is quite bright, so it balances out OK tonally. The trimmer is between pins 1 & 8 on the 386 to adjust gain. I may wire this to the tone knob instead. As it is, it's at the full 10k, putting the gain at the low end of the 386's range in an effort to reduce the fizz factor. The initial driver install. The screws added go to the core inside the pickup, which was already threaded for pole pieces. They hold the base to the cover, and I'm hoping extend the magnetic field up a bit, but I'll be the first to admit I haven't the foggiest idea if they do. That said, adjusting the poles up or down does seem to influence the performance of the driver. I was getting nasty feedback when the driver was installed. The original PU was the most poorly made, microphonic POS I've seen, so I swapped this for a HB; the feedback went away, unless the HB was coil-tapped. Switches: the switch above the driver is a DPDT switch selecting fundamental / harmonic modes via the driver leads from the amp. The switch above the HB selects HB or single coil mode. In SC mode, it also shunts the input to the 386 to ground & disconnects the PU from the 386 input to get rid of loading and keep the SC from feeding back. So yep, in sustain mode, only the humbucker works. Usability of the device is good. All strings react well, except the high E, which seems to be common. In fundamental mode it rings a bit longer. In harmonic mode it rings for less time. The low E reacts almost instantaneously above the 10th fret -- tap a note and it immediately rings LOUDLY. Response seems best for things in the key of E minor. Perhaps because the driver's right around where the 24th fret would be? Battery life is as of yet unknown. I estimate I've used this for three hours in testing / playing and it's still going strong (386 amps I've used in the past seem to last between 10 and 20 hours on a 9v alkaline when used with 8ohm drivers, depending on volume). I'll likely end up putting a battery access plate on the rear of the guitar at some point. As it is now, I've got to lift the pickguard. Not convenient. Unfortunately, after getting everything together, (and also changing the tuners & bridge) I wanted to tighten the truss rod to even out the action (and hopefully sustainer performance). Turns out the truss rod is swinging freely inside the neck! D'oh! So I may either swap the neck or move onto a different guitar for my next victim. It does play OK as-is, so it's not fatal, but man! Aw, what do you expect from a $75 guitar? Again, thanks everybody for all the help & ideas! Ron Edited December 1, 2007 by newfuturevintage Link to comment Share on other sites More sharing options...
jamforthelamb Posted December 4, 2007 Report Share Posted December 4, 2007 Hey Everyone, Tore apart my donor single coil, and I've glued spacer in for the recommended 3mm coil size. I found 32g (.2mm) wire at Fry's Electronics locally. I had a couple of quick question while I'm waiting for the glue to dry. #1 has anyone tried using a thicker gauge strings on their "sustainer" guitar. I thought that the thicker B and E strings might help to get them sustaining longer. The guitar I'm using for this is going to strictly be setup for the sustainer, so if putting thicker strings on there is beneficial then I'm going to go for it. #2 I assume that whammy bars are well suited for use with the sustainer? My "sustainer" guitar is a hardtail, but I may consider putting a bigsby type trem on there if it seems like it will make it more "playable". I noticed a lot of whammy work in PSW's sound samples, that's why I'm asking. God bless, Kevin Link to comment Share on other sites More sharing options...
psw Posted December 5, 2007 Author Report Share Posted December 5, 2007 Hi Kevin/jamforthelamb...welcome to sustainer land! You know...I wrote a typically long reply, love the pics there Ron/newfuturevintage, especially the details like that "curiously strong" tin, are you sure you should be using that with Tequila? Also, well said about the wax... Disclaimer: HOT WAX IS DANGEROUS -- it's a drag to get on you, and more importantly, it is flammable. As cool as this project is, it's not worth torching your home, so be very careful if you use wax. Yes hot wax and a lot of other tempting strategies are very dangerous (like attempting to pot in super glue...very bad idea...also do not try and break magnets or machine to size) I use and recomend PVA/woodworking glue. I put this into the bobbin before winding and it squeezes through as it's wound for absolute coverage...it might be a little messy but at least it is safe and washes off with water. My new coils are epoxy wound but this is not recommended and I spent $100 on different products before I found one that was suitable for making my new coils. These use epoxy as an essential structural element as there are no bobbins holding it together...not really suitable to DIY and not reversible if things go wrong. Ok...oh...and Chip... Hi, havn't been here in a while just wondering if there was an ETA for your sustainers psw, no chance before x-mas i suppose? Sorry, not before this christmas....only days away. However, I have been working countless hours lately wiring up the prototype and preparing one for a guitar to be custom made for a major artist and debut in January in the US. There may even be an opportunity to see the thing soon, maybe even hear it on record (here is a hint, though this artist does not do endorsements and this is very much "undercover", not a product launch...slave audio/machine rage) There are, as always, some unexpected quirks in any new design and this new "product" is turning out a little different to these conventional approaches and available products...a good thing, but taking a lot of work and some trouble shooting and redesign along the way. I have one working now (after last nights marathon wiring (all day till 2am ) and it is simply amazing...still a bit to go on the rest of the guitar...the artists guitar will be a lot more straight forward. So...back on topic...Kevin... #1 has anyone tried using a thicker gauge strings on their "sustainer" guitar. Thicker strings do work better, but are harder to bend, etc. All sustainers recommend 10's, which is what I use. My new system has fantastic high string response, so the 09's may work out with this system as a lot of people really want to stay light for their style. Bass strings respond well, it is to do with the amount of magnetic material in the strings that the device has to work with. Be careful though, thicker strings will put a lot more pressure on the neck and may be damaging to the guitar and take a lot of getting used to. #2 I assume that whammy bars are well suited for use with the sustainer? My "sustainer" guitar is a hardtail, but I may consider putting a bigsby type trem on there if it seems like it will make it more "playable". I noticed a lot of whammy work in PSW's sound samples, that's why I'm asking. I think so, but it depends a lot on your personal style. I really like players like Jeff Beck who use the trem extensively...a trem allows the manipulation of the sustainers long notes, even to play melodies with it. I played a Les Paul exclusively for years and years (say 20!) including all my bands, but in more recent times, have switched to modified custom cheapo strat copies...now I am hooked. Bigsby's are notoriously hard to keep in tune and are quite different, only really suitable to a little wobble on notes. I'd say, leave it for now, if you really like this device, then do it again with a cheap strat to get proper trem action. One of the reasons that I like the trem is that it allows for detuning of notes. With bending, it is difficult to get notes to go flat (need to pre-bend and release). This is a much more natural, sweeter effect than the typical vibrato or sharp bend that only raises the pitch. A violin vibrato for instance moves up and down around the note. singer's blue notes are typically slightly flat major thirds and perfect fifths, not sharp minors and flat fives. It may seem a little pedantic, but there is a big difference in the detail. A trem allows for this effect, as well as the typical sharp bends. I have my trem set up to be floating and use a few different strategies to keep it stable with the standard trem on a strat. My new guitar has staggered locking tuners, roller trees and a trem-setter, and seems to be very stable, but there are other methods too if people are interested without going to this extreme and expense in new hardware. This guitar is way over the top!!! The guitar I am working on is a showpiece for all the experimental work I have been doing for some time now, including the sustainer, packaged in such a way as to be practical and simple in use, but extreme in it's features and sounds. It also has a number of aesthetic and philisophical "themes" that I hope will, in the end, make it seem "right" and not just gimicky. To do this I have actually had to build some of the electronic hardware and develop new ways of wiring to accommodate it. The guitar is a natural mahogany strat type high end squier with a HB in the neck and two noiseless single coils. There is the natural, organic feel of the satin finished timber and smooth curves of the design and looks like a fairly classy top loaded contemporary strat. All the screws have been replaced with small black allen key bolts, giving a subtle machine look to the thing. There is a fair bit of chrome involved too, but also leather and tortoise shell that gives a kind of industrial revolution kind of retro feel to it. Inside, it looks like a computer! I have custom made three switch pots that not only push pull, but also have a base that twists to operate 4pdt switches. On the outside they look like typical chrome (tele-style knobs), but each pot has two separate hidden switching functions to them. In addition to the pots, these switches have 18 connection points, each, so a lot of wires. To work it all out I have been using color coded ribbon cable for everything. In addition, there are three circuits, the new sustainer, a preamp for a piezo set up, and a buffer for optional "active" mode. I even have provisions for remote power via a stereo lead, or recharging of the battery via the same, but that will come later. I have done some testing, the basic sounds so far are two banks of 5 sounds via the selector (a superswitch, so there is another 24 connection points on this alone). The volume knob lower twist switch, changes the selector from a typical strat, single coil parallel mode, to a series mode with a more gibson like flavor and full bodied range of sounds. I am planning on another switch to change these to another bank of sounds with phasing and various filters and pickup combinations for a more unique range. So, there are 20 sounds right there. Add a piezo system and you get 40 different possibilities, plus an active mode on all these...then there will be some interaction between the modes, so that the tone switch in one position may result in a funky phasing of some positions on the first bank. So...right there we are looking at 40 plus tones in what would appear to be a normal five position strat setup on the surface. But wait, there is more...the sustainer system. This is entirely operated by the middle control knob and switches. It is completely hidden with no outward modifications or pickup changes. When switched on it goes directly to a full HB mode, so is also a bit like a solo switch, and will return to whatever setting selected when turned off. The harmonic function is operated by pulling up on the push pull knob. So...without any obvious additional switches, you get 20 different selections (4 banks of five), plus all of those with piezo addition and some variations within them from interaction between switching. Plus, two sustainer modes and all the variations between with the variable drive control in sustainer mode. Plus, an option to have the entire guitar "active" for more zing. If this turns out to be a "profitable" adventure, then this one off, never to be repeated wiring catastrophe, may be adapted to some kind of active electronic switching for a similar result. It would be super cool if all of this wiring and selecting could be done electronically with a programed chip, it may even allow for chip replacement or re-programming, so that these selections could be customized, or the guitar "rewired" without wires... This could also make for simpler switching and other options (like digital encoder pots) to be used. The could also be the possibility of control signals being sent to outboard gear to add effects to different selections or control them from the guitar. All of this is way outside my experience and technical ability, but it is a very interesting scenario. The sustainer itself is worth the price of admission, and I can equally see a viable dedicated instrument that is pure sustainer guitar with a single bridge pickup over my swiss army like approach on this one. The trick is to have these features hidden in appearance and use and for myself, an instrument that constantly surprises, amuses and inspires. Kind of a mix between a fav guitar and the inspiration that comes from trying out something different down the local music shop...if you know what I mean. So...have tried to post a few things but seem to be having some problem with my connections, hope this makes up for it and encourages people to keep experimenting and exploring this and other projects...and dreaming up new ideas and variations... pete Link to comment Share on other sites More sharing options...
jamforthelamb Posted December 5, 2007 Report Share Posted December 5, 2007 Thanks PSW on both accounts. Yeah, I've played with a Bigsby before, and I'm aware of the short comings. I love rockabilly music so I like their subtleness, but I think I will take your suggestion and just hold off until I get my first one working. Another thought I had was using a slide on the sustainer guitar Got my driver "wired" last night. Took me three or four tries (wire breaks, to many wraps, etc...). When measured it measures 12 ohms, but on my meter if you touch the two test leads together it measures 4 ohms, so I compensated. Hope that's correct. I wired it up to a little "smokey" amp I gutted (runs on a 386 chip). I tested it by plugging the circuit input into a guitar, and the driver wired to the output of the circuit. I held the driver near the strings, but they didn't "seem" to sustain much more then normal, however if I put the driver near the bridge pickup the driver would make a squeal. I'm hoping that means at the least that my driver works (but probably needs potted better), and I just need to build a better circuit. I used wood working glue as suggested for the driver, but I'm going to go back over it with some hot glue to seal it/pot it in real good. I didn't get to test it real good because when I finished it was after midnight. Any advise on what to do next ? Thanks! Kevin Link to comment Share on other sites More sharing options...
newfuturevintage Posted December 7, 2007 Report Share Posted December 7, 2007 ...When measured it measures 12 ohms, but on my meter if you touch the two test leads together it measures 4 ohms, so I compensated. Hope that's correct. You should have a dial labeled "ohms adjust" on your meter. Use this to get rid of the 4 ohm offest you're seeing. If you don't have it, you're probably still in the ballpark by your compensation method. I wired it up to a little "smokey" amp I gutted (runs on a 386 chip). I tested it by plugging the circuit input into a guitar, and the driver wired to the output of the circuit. I held the driver near the strings, but they didn't "seem" to sustain much more then normal, however if I put the driver near the bridge pickup the driver would make a squeal. I'm hoping that means at the least that my driver works (but probably needs potted better), and I just need to build a better circuit. I used wood working glue as suggested for the driver, but I'm going to go back over it with some hot glue to seal it/pot it in real good. I didn't get to test it real good because when I finished it was after midnight. Any advise on what to do next ? Hi Kevin-- it does sound like your coil is working. If you put it too close to the pickup you're using to drive the smokey it will squeal. I've noticed you do need to get the coil quite close to the strings to acoustically notice that it's working. Also, on mine, if I roll off the tone at the guitar it reduces the efficacy of the sustainer. When you're testing, have the controls full open, only use the bridge pickup, and test near the neck PU, or around the 12th fret. Also, use a fresh battery in the smokey. If you reverse the leads to the coil, you alternate between harmonic and fundamental modes, and they behave differently. For me, harmonic mode is very dramatic on the low E and A strings, and less so on the higher strings. Fundamental mode is more even across the board. You may not get response from the hi -E. Good luck~ ron Link to comment Share on other sites More sharing options...
jamforthelamb Posted December 7, 2007 Report Share Posted December 7, 2007 Hi Kevin-- it does sound like your coil is working. If you put it too close to the pickup you're using to drive the smokey it will squeal. I've noticed you do need to get the coil quite close to the strings to acoustically notice that it's working. Also, on mine, if I roll off the tone at the guitar it reduces the efficacy of the sustainer. When you're testing, have the controls full open, only use the bridge pickup, and test near the neck PU, or around the 12th fret. Also, use a fresh battery in the smokey. If you reverse the leads to the coil, you alternate between harmonic and fundamental modes, and they behave differently. For me, harmonic mode is very dramatic on the low E and A strings, and less so on the higher strings. Fundamental mode is more even across the board. You may not get response from the hi -E. Good luck~ ron Hi Ron, Thanks for the tips man. I actually have now built a Fetzer/Ruby. I'm in the dubbing stages now (had a bad pot). I played around a lot more with the Smokey+driver on the guitar the sustainer is going in. It's only wound with a G string right now, but I could get it to work with both "modes". God bless, Kevin Link to comment Share on other sites More sharing options...
newfuturevintage Posted December 8, 2007 Report Share Posted December 8, 2007 Hi Ron, Thanks for the tips man. I actually have now built a Fetzer/Ruby. I'm in the dubbing stages now (had a bad pot). I played around a lot more with the Smokey+driver on the guitar the sustainer is going in. It's only wound with a G string right now, but I could get it to work with both "modes". Right on Kevin! If you've got it working like this, you're in very good shape. Posting also to update my progress on the optical compressor for the 386. I'm still playing around with it, but I've been able to clean up the output of the 386 substantially. I'm using a Vactrol as a balance pot between the inverting and non-inverting inputs on the 386, and driving its LED (for the time being, this will probably need to change) directly from the speaker output of the 386. Taking a look at the output of the 386 on an oscilloscope, I have been successful in keeping the 386 from hitting the clipping point, while still getting it to have full output consistently. One weird thing though is that there is what (might be?) looks like crossover distortion (with or without the Vactrol)... it shows up as a flat, vertical interruption of the test sine wave, at the zero crossing, and it gets more pronounced as the input signal gets smaller. I suspect this is the fizz one hears on a smokey amp as its input signal decays. This is present on both a low 9V battery (testing at 8vdc under load), and on an unregulated 9vdc wall wart (testing 11vdc under load). More later as I figure out what's going on. Raulk on, Ron Link to comment Share on other sites More sharing options...
col Posted December 9, 2007 Report Share Posted December 9, 2007 (edited) Posting also to update my progress on the optical compressor for the 386. I'm still playing around with it, but I've been able to clean up the output of the 386 substantially. I'm using a Vactrol as a balance pot between the inverting and non-inverting inputs on the 386, and driving its LED (for the time being, this will probably need to change) directly from the speaker output of the 386. Taking a look at the output of the 386 on an oscilloscope, I have been successful in keeping the 386 from hitting the clipping point, while still getting it to have full output consistently. That sounds promising. A few things to consider while developing your circuit: The different ways you could set up your vactrol will have a big impact on the 'feel' of your sustainer. The difference between feedforward and feedback topologies I've already explained so I'll give you a summary of the other stuff (that I can remember right now) The level of compression is significant ways to set it up: #1 compressor: some basic compression: as the input rises, the output also rises, but the 'slope' is less steep. #2 brick wall limiter: The signal level is limited at some chosen threshold any signal higher than this will produce an output at the same level. #3 'dynamic range inversion': this setup mean that when the signal is large, the output will be very low - ideally anything above about 1 V would produce almost no output, while a low level signal maybe ~60mV would give a strong output. #1 would give some benefit, helping to even out the sustainer response. #2 would have a bigger impact giving a much more even response. #3 creates a much more responsive 'alive' but very controlled almost 'synthetic' system, gentle hammer-ons swell quickly into loud even sustain. This mode also helps to conserve battery usage - when playing hard rhythm stuff, the drain will be low as the signal into the circuit will always be high - also when a sustained note has reached its equilibrium, the drain will be reduced particularly on the more responsive strings and higher up the neck. Basically, you need lots of drive/power to bring the sustain up to the desired level quickly, after which you want to only use just enough juice to keep it at that level. One potential problem with this setup is the need for an 'expander' effect below a certain input level to prevent low level noise from driving the circuit. My first circuit was a #3 and it was extremely responsive and superb fun to play. The downside is that it was definitely an 'effect' the swell was so fast that it was quite obvious - similar to but not the same as extreme compressor settings. Unfortunately there were also other problems with that circuit. My current circuit is about half way between #2 and #3. The maximum output happens with the input signal at around 100 - 200 mV, above that the output becomes significantly reduced, although it never gets near zero, also, the gain at very low input levels is nothing like as high as it was in my first circuit. This gives a much more natural 'transparent' effect, although it means that the 'swell' takes much longer to develop as does harmonic bloom. Another issue with a slow response envelope is that the initial attack of a note is very 'loud' which pushes the circuit into heavy compression, but the signal drops off quickly after the initial attack. If the 'decay' of the circuits response envelope is slower than the natural decay of the guitar after a hard strum, there will be a dip in volume after the strum before the sustainer kicks in. Unfortunately, the circuit I used as a base for mine limits the decay time to at least 10 times the attack time, so this issue is evident (not too bad though) There are also advantages to #1! With heavy compression, there is less drive from the circuit during the attack and initial decay parts of a note/chord. Reducing or removing the compression would allow the sustainer to have more of an effect in this initial part of the sound which should lead to a more organic 'wild' response similar to what you get from a basic fetzer/ruby. For some things, this raw uneven instant response will give the best feel and sound. If I was forced to choose, I would go for something similar to my current circuit but with a slightly faster swell/bloom.. I think I can achieve this through a more efficient driver. My ideal circuit would have a compression control (or switch) that could vary from no compression through #1 & #2 to extreme 3# it would also have a threshold control (maybe as a trimmer on the board). This would give a great range of effects and feels for all situations, and would definitely be more useful than having multiple harmonic modes. So to recap its: feed-forward topology compression control with extremely wide range minimal distortion (both amplitude and phase) variable attack and decay threshold control response drops off for very low input levels (either naturally or through some expander functionality) Some simple 'harmonic mode' switch. One weird thing though is that there is what (might be?) looks like crossover distortion (with or without the Vactrol)... it shows up as a flat, vertical interruption of the test sine wave, at the zero crossing, and it gets more pronounced as the input signal gets smaller. I suspect this is the fizz one hears on a smokey amp as its input signal decays. Many transistor based amps/FX seem to have this sort of low level fizz on decayed notes, not sure if it's to do with not having enough signal to turn on the transistors/diodes or what... I think that with circuits based on discrete components, it can be minimized with careful biasing, but I'm not sure about how to deal with it when its inside a 'black box'. Have you tried different LM386 chips to see if they all exhibit the same characteristics? Also the fact that an LM386 is class AB means that there will always be some crossover distortion. We definitely do NOT want to use a class A amp for this application because efficiency is a priority. Maybe a good low power class-d would be better, then again maybe not. fwiw, I get no audible distortion/fizz/fuzz from my setup, although I don't have access to a scope to probe the circuit . Seem like you have the knowledge and the kit to take this stuff on another stage which is great news. If you have any more ideas and/or questions, I can tell you most of the stuff that has been discussed/tried in the past, e.g. different ideas for implementing harmonic modes etc. cheers and good luck Col Edited December 9, 2007 by col Link to comment Share on other sites More sharing options...
psw Posted December 11, 2007 Author Report Share Posted December 11, 2007 Ohhh...I've missed some stuff, I wonder why I wasn't given a notification. Will have to read up a little...been very busy with my own circuit which also has some AGC. Still looking for an appropriate name, have a few. Mean while, have built a dedicated test guitar and hope to have this finished circuit and rig sent off this week for fitting into the real thing in the next month or so...some really exciting stuff. I have been having some trouble with the usual sustain mode. Used in my strat type guitar, phase reversing the driver actually killed sustain and harmonics giving the thing a very dead sound, and not is some quirky good way...I built an anti-sustain device...hmmm I have been doing a little experimenting and found that there are other sustain mode possibilities to be had, though the phase reverse harmonic effect is sorely missed. The switching in complicated guitars like mine is confusing (3 pickups and trick wiring) and have yet to find a conclusive solution with my guitar. Have put it a side and am putting the test rig into a two pickup guitar and rejigged a more satisfactory on-off-bypass for such a scheme. I am planning on getting into some digital switching experiments to see how difficult it is and the possibilities there, not just for the sustainer. It may well be that this kind of thing is required for my particular switching requirements on this unique guitar. Still, there may be a solution and if anyone has any clever wiring for this switch, let me know... got to run, 2am now...but will read up and glad to see some things are working and a bit more new blood and discusssion continuing in my absence...best wishes and keep on keeping on... pete Link to comment Share on other sites More sharing options...
collie_doggy Posted December 15, 2007 Report Share Posted December 15, 2007 Hi, I'm new to this sustainer topic. I actually have the Fernandes 401 kit in front of me and I am trying to figure out how it works. Does anyone know what the transformer is doing in the circuit on the underside of the board? Does anyone know the function performed by the circuit portion on the riser board? This portion is covered in black paint and looks to have four SMC DIL chips amongst other things on it. Now, I know that some of you have the answer to the following, as trawling through the thread I find some of you have already made working circuits with the harmonic mode : How is the harmonic mode produced please? Thanks James Link to comment Share on other sites More sharing options...
psw Posted December 16, 2007 Author Report Share Posted December 16, 2007 Hi There collie_doggy / James Some interesting questions that I'd like the answers to to...although I have never seen a sustainer guitar, other than my own.... I actually have the Fernandes 401 kit in front of me and I am trying to figure out how it works. Do you mean in principle...as in how does a "sustainer" do what it does...or technically...give me a hint!!! If you have the kit, I assume you are not planning on building one based on the work here, but the basic idea is the same. Essentially, you have a driver with a coil in it that is operating just like a speaker coil, and the strings like a speaker cone. The circuit is an amplifier that takes the guitar signal as it's source and so the strings are in a feedback vibrating in response to their own sound...hence they won't stop till the signal stops. Technically, it is not so easy, the driver and amp need to be matched...you can't have just any coil of wire, like a guitar's pickup for instance, as for one thing, there would be a massive impedance mismatch. You While the fernandes may have a dedicated driver, it may be using a tiny transformer to address an impedance mismatch. The transformer could also be there to isolate the signal...all sorts of things. I really don't know, they keep these detaily things pretty guarded. Does anyone know the function performed by the circuit portion on the riser board? This portion is covered in black paint and looks to have four SMC DIL chips amongst other things on it. I don't know what a riser board is...not sure...but the circuit or some part of it is probably protected by an epoxy coating...mainly from prying eyes like your and mine. These are likely to simply be op amp and amps, but even SMD cap chips and such can appear like this under epoxy. I doubt they'd bother, but it is not unknown to insert "fake" not connected components into circuits to throw of reverse-engineers...no point making it easy for anyone... Another important feature of the commercial systems, a feature that member col here has explored quite a bit, is AGC...automatic gain control. This adjusts the drive in response to the string signal so that the thing doesn't drive harder than it needs or you want it to, and avoiding a complete runaway effect and smoothing out the variations between note and string response. Now, I know that some of you have the answer to the following, as trawling through the thread I find some of you have already made working circuits with the harmonic mode : How is the harmonic mode produced please? Ok...so beyond the basic idea...there are problems with "phase", in the tiny amount of time it takes for the signal to be "hear by the pickup, amplified and (mainly) the electromagnetic driver respond (what I call the speed of the driver) the string may have moved...i.e, instead of physically moving up, as when it was "picked up", it maybe on a down swing. The higher the note, the faster the strings physically vibrate, the greater the problem. There are most likely chips to control the phase of the signal in depending on the frequency to compensate for the driver's inbuilt inefficiencies. (in my work I have sought to address this with faster, more responsive drivers rather than electronic compensation) Now....if you reverse the phase, the signal will be on the up string while the string is physically moving down. So, you would expect to have created an "anti-sustainer"...instead of driving the string it would be fighting against the string's vibration and dampening it down. But a guitar string does not move in a simple sign wave pattern (otherwise it would sound more like a flute or computer generated tone), behind the main vibaration frequency are multiples of the vibration, the harmonics that give the guitar tone character and richness. The result is, a drive signal in reverse, 180 degrees out of phase, will dampen the lowest, strongest fundamental frequency...the E in a low e string for instance. Magically though, it will still drive the upper harmonics behind it...the one driven next is most likely be a natural octave or fifth or octave or fifth above the note...notes from the natural harmonic series. When you create a harmonic on an open string by lightly touching the twelfth fret, this is exactly what you are doing, dampening the main string vibration and revealing the octave harmonic behind it. The 9th fret, the fifth above that, the 7th, two octaves above and as you move towards the string ends, you will find ever more from the harmonic series. The driver does the same thing, but it can not move along the string like you move your finger. The result is an inconsistency of harmonic response depending on how far the fretted note is from the location of the driver and the phase of these constituent harmonic vibrations to the signal it is driving at. Fortunately, there are lots of harmonics, and these "notes" are inherently "in tune" as they were always a part of the original note...the effect then is typically musical, though the note and how high it is may be surprising and not entirely logical at first. One reason that the ear likes some distortion and can make judgements on what kind of distortions it likes is because this raises the level of these background harmonics within a note at the same time as it clips the tops off the wave form. Hence the difference between the throaty rich sound of a saxophone compared to the pure tone on a flute and the lifelessness of a computer generated sine wave. One reason I am obsessed with this technology is that we are dealing with the physical actual organic vibration of sound, not a synthesized or analogue manipulation of the guitar's electronic signal, but the actual vibration of the strings that produces this signal...this above the fact that it will sustain a note forever, or even that it can generate harmonics automatically. I love the fact for instance, that it can reveal these hidden tones and drive the strings in way's other than simple plucking. ---- Obviously, I am hooked but, as I say...have no experience with the commercial units. This thread has explored the principles and various ways you can make your own. explore solutions to some of it's technical problems and simply enjoy a chat about the whole thing and anything else that comes along. For long term follower's of the thread, you will have noticed an inconsistency in my presence here. Never fear, I am doing more work on this than ever before. I even had to get another guitar to make a test bed for this and all future developments of my own personal system. The first "commercial" prototype is essentially built and working and will be winging it's way to the USA next week. Although not built yet, I believe that it will be going into a custom high end "Jackson" like guitar made of black limba and have additional features, some very new from yours truly in the electronics department. I have a stripped out strat here now and have the thing set up in that and it's great. The problem is toning down my natural desire to complicate and add more to something. "the artist" likes a straight ahead simple "tool" and has a very physical stage presence and guitar technique. He is also very innovative in his approach so building something that will provide the features that he needs (kill switching for instance) and things he may feel could be useful (I am working on "maim switching"...it doesn't kill the signal, but seriously f#$%k$k) it up...hehehehe) that will be unique to this guitar. Have been so busy, that I have had little chance to take photo's or to post here generally, but once finished, will be rejoining the brains trust with more details and adventures in sustainland, and of course, some questions of my own. Still looking for a "name" for this thing....tossing about a few ideas, but in need of more input...post here, PM or email me with suggestions. As for the "technology"...the circuit and driver are working really well, installation is as ever a b!t)h, but I think it will impress a few here. The range is pretty wide so you can get a controlled, clean effect like col prefers right up to a "fizzy" full on sound. Also, more powerful and responsive in many way's than the original which is a few years old now and pretty much retired. I am preferring a simple toggle for the on/off/bypass function and a drive control with push/pull for the harmonic function...neat and clean and easy to use. As I say, welcome to James and all the other's and season's greetings, better get back to it... pete Link to comment Share on other sites More sharing options...
col Posted December 17, 2007 Report Share Posted December 17, 2007 Now, I know that some of you have the answer to the following, as trawling through the thread I find some of you have already made working circuits with the harmonic mode : How is the harmonic mode produced please? Now....if you reverse the phase, the signal will be on the up string while the string is physically moving down. So, you would expect to have created an "anti-sustainer"...instead of driving the string it would be fighting against the string's vibration and dampening it down. But a guitar string does not move in a simple sign wave pattern (otherwise it would sound more like a flute or computer generated tone), behind the main vibaration frequency are multiples of the vibration, the harmonics that give the guitar tone character and richness. The result is, a drive signal in reverse, 180 degrees out of phase, will dampen the lowest, strongest fundamental frequency...the E in a low e string for instance. Magically though, it will still drive the upper harmonics behind it...the one driven next is most likely be a natural octave or fifth or octave or fifth above the note...notes from the natural harmonic series. Inverting the signal is certainly the simplest way of creating a 'harmonic mode' type of effect. unfortunately, it is not a particularly pleasant sound and it is not a controllable one either... it has a tendancy to choke the tone out of the guitar. Think about what is happening... The initial signal is flipped so, as Pete states, the fundamental note is canceled and the first harmonic is accentuated... but that is nothing like the end of the story... as the harmonic takes over as the main note coming from the string, that note becomes the one that is canceled by the circuit and in this way, it iteratively works it's way up the harmonics until it gets to where it is limited by the frequency response of the sustainer system (driver + circuit) at this point you either get a fairly quiet dead sound or some level of shrill harmonic as the circuit settles between canceling the note and not being able to drive a higher note. Of course, because the sound of this inversion based harmonic mode is so closely tied to the response of the rest of the system, it will sound ok on some setups, do not much at all on others, and on those 'better' circuits with good frequency range, it will produce piercing un-musical sounds I am sure there are numerous better ways to generate harmonic modes. The best I have come up with so far is using an all pass filter to change the phase of the signal but only over a limited band of frequencies - this means that you can chose where the effect begins (on my setup, the lowest notes don't get inverted so I get a full bottom end to the sound). you can also choose where the upper limit is (this is not independant of the lower notes on my setup) so you don't get the runaway effect limited only by the systems frequency response as on the simple signal inversion effect... basically this means that you have some control over how high pitched the harmonics will be and over where on the neck the start kicking in, and you keep the guts of the guitars tone as well. I am sure that the most useful and variable harmonic effect will come from using a 2nd or 3rd order band-pass filter - this will drive only a small band of frequencies within the input signal and will be controllable using a knob, so you should be able to sweep through different harmonics as you play... this mode will certainly cancel a lot of notes too, but it will add that interactive element that is missing from the other approaches. A higher order high pass filter may also generate a good more 'natural' harmonic effect. I tried using a first order high pass filter which worked but was not good enough, and I didn't have enough space on my board to implement a higher order filter, so Ive not fully explored the possibilities here yet. Definitely try using an all-pass filter for harmonic effect - for me it's the best so far. Who knows maybe someone with better electronics skills than me can create a more controllable higher order all pass that can be tweaked via a knob in a useful way. One reason that the ear likes some distortion and can make judgements on what kind of distortions it likes is because this raises the level of these background harmonics within a note at the same time as it clips the tops off the wave form. Hence the difference between the throaty rich sound of a saxophone compared to the pure tone on a flute and the lifelessness of a computer generated sine wave. This is kind of off topic in this post because harmonics in distortion as a subject is not particularly relevant to 'harmonic mode' in a sustainer... anyway: there are some well studied reasons why some distortions sound good and others don't, and its nothing to do with the level or number of background harmonics. It is to do with which harmonics are there and which are missing. One effect is that certain types of harmonics mimic the ones that occur naturally in our ears when they are exposed to very loud sounds - hearing these will raise the level of 'excitement', the sound is perceived as louder than it is and our bodies produce more adrenaline... a distortion that produces these harmonics will be exciting to listen to... it's part of the wider field of psychoacoustics. Another consideration is that some harmonics will have a more consonant harmonic relationship to the fundamental note than others these tend to produce a more musical 'warm' sound than harmonics that are more dissonant... this is one reason why valve amps have a naturally 'warm' sound, they naturally produce more 'in-tune' harmonics and fewer 'out of tune ones' (although it is possible for non-valve circuits to produce these 'better' harmonics, and there are plenty of other reasons why valve amps often sound 'better' than tranny amps) btw, as we're already way off topic, Pete, the reason that a Sax has such an expressive 'throaty' less 'pure' sound is because - unlike most wind instruments that are cylindrical tubes with a bell on the end, a sax is a cone - this makes it vibrate in a more chaotic (in a mathematical sense) way, and its sound is far more reactive to what the player is doing. ---- For long term follower's of the thread, you will have noticed an inconsistency in my presence here. Never fear, I am doing more work on this than ever before. I even had to get another guitar to make a test bed for this and all future developments of my own personal system. Well, actually, you're not doing more work on 'this' than ever before - you are doing lots of work on a commerical kit that you are developing, which grew out of this thread, but it is not part of this thread - unless you plan to publish your driver specs, diagrams and circuit schematics here ? This is the 'sustainer ideas thread', not the 'sustainer secrets that I'm not telling you' thread Maybe it's time that you started a new thread for your commercial kit, or ideally created a separate website/blog for that project ? I'm really interested to hear how its going and what the developments are etc., but I don't think this is the place for that kind of news. Glad to hear that things are moving forward though. (btw, I've got some great names for my system, but I can't tell you unless you sign a NDA - I think you will be amazed when you hear them though!) cheers Col Link to comment Share on other sites More sharing options...
newfuturevintage Posted December 17, 2007 Report Share Posted December 17, 2007 OK, so as mentioned a couple weeks ago, I've been playing with optically limiting the 386 chip. I'm using a Vactrol VTC5C2 (about $4us from Allied Electronics). It's a combo LED / Photoresistor assembly. Full disclosure: I'm quite lazy, and I've just enough electronics knowledge to be dangerous. With this in mind, I've got the LED section of the Vactrol in parallel with the driver, and the resistor section across the inverting and non-inverting inputs to the 386. As output level rises, resistance between the two inputs to the 386 drops, and signal into the 386 begins to even out between the inputs, partially canceling. The goal is twofold: to keep the 386 from going into distortion in an effort to reduce the fizz effect, and to smooth out the response of the system by backing off output level as the level of the sustainer-induced feedback increases. I've yet to install the thing into my testbed guitar, but here are a couple oscilloscope shots of sin waves going into the circuit. These shots are from a dummy load (just an 8 ohm load made of resistors). When I hooked it up to a speaker, there was some extraneous HF junk that was removed by adding a 100nF cap in parallel with the output. I suspect this was due to the speaker's movement as physically restraining the speaker shifts the phase of the junk. I still have to put a sustainer coil on the scope to see if that cap will be needed or not. Hmmmm, what else, oh, my design thought was to frequency limit the amp to between about 80Hz and ~2kHz figuring that's where it's going to be most effective. These shots are polarity reversed as I'm using the inverting input (mistake carried through to execution ) for the main input. No biggie as I'll be putting the coil on a polarity reversal switch anyhow for harmonic / fundamental mode. The remainder of the phase shift should be coming from the input filter cap and the DC blocking output cap? Both shots are ~110Hz (approx. open A string's fundamental @ A = 440Hz). Peak to peak, input signal is ~0.5Vac, output signal is ~3.2Vac, with the battery reading around 8Vdc under load. This is a shot with the Vactrol switched out of the circuit. The bottom trace is the input signal, the top is the amplified signal. This is a shot with the Vactrol in the circuit. Believe it or not, that little bit of brightness at the top and bottom of the trace is audible as distortion on a sin wave. Nothing nearly as bad as that super-jagged trace in the first pic. Pins 1 & 8 on the 386 are disconnected for gain of 20. You should see what the trace looks like with the gain set to 200 -- totally squared off! I'm anxious to see how well (if at all) this works in practice. A friend has given me a victim, newly christened "the DisasterCaster", that I'm hoping to have done by the new year. Will keep you posted. Link to comment Share on other sites More sharing options...
col Posted December 17, 2007 Report Share Posted December 17, 2007 (edited) Believe it or not, that little bit of brightness at the top and bottom of the trace is audible as distortion on a sin wave. I believe it hehe, first thing I though when I glanced at the pic was... hmm, a little bit of distortion there, but shouldn't be bad enough to worry about... Seems good. A few things to think about: what happens to the output level of the limited signal when you change the frequency (82hz to 2kHz)? what happens to the amount of distortion when you change the frequency ? how fast can the attack and decay of the limiter be before you get significant distortion in the low frequencies ? a question: Is it a brick wall limiter, a compressor or an 'extreme' dynamic range inverting limiter ? BTW, is there somewhere in the UK where I can get a few of these vactrols ? I've tried Maplin and my local independant electronics store with no luck. cheers Col Edited December 17, 2007 by col Link to comment Share on other sites More sharing options...
newfuturevintage Posted December 18, 2007 Report Share Posted December 18, 2007 what happens to the output level of the limited signal when you change the frequency (82hz to 2kHz)? I don't have the frequency range dialed in at the moment (not enough variety of caps to play with right now), and I still have to put it on a coil and measure that. The differences between testing an 8-ohm speaker and an 8-ohm resistor load are quite different. Ballpark though, between ~120 and 1.5k hertz, the level with a resistor load is fairly constant. I'm guessing outside these values, the response is falling off at 6dB/Oct (just using single caps to do this). With a speaker, it's all over the map. Further, if I push the speaker in, response flattens out. I know there's something fundamental that's causing this, I'm just ignorant of it. Folks that know more, please help! what happens to the amount of distortion when you change the frequency ? This appears to my ear on the speaker (and on the O'scope with the resistor) to not be affected by frequency much. Much greater effect is caused by signal level. how fast can the attack and decay of the limiter be before you get significant distortion in the low frequencies ? I have no provision for attack nor decay times in the circuit. I chose the VTL5C2 based on its slow attack and release times, 7ms attack and 150ms release under on/off conditions. Playing a bass guitar into a modified circuit (much larger input capacitor, much smaller HF filter cap), the attack feels very "pumpy". Subjectively, I've noticed this happens at much longer attack times than 7ms on compressors I'm familiar with. As for distortion, even with the circuit heavily clamping the bass guitar signal, fuzzy distortion wasn't pronounced. Datasheets & pics of the Vactrol can be found at the manufacturer's site: http://optoelectronics.perkinelmer.com/cat...me=VTL5C+Series a question: Is it a brick wall limiter, a compressor or an 'extreme' dynamic range inverting limiter ? It's a compressor I'm attempting to make behave as a brick wall. There's a resistor in series with the photoresistor that sets the maximum gain reduction. I don't really know if it's controlling threshold or ratio though . I suspect it's controlling ratio; threshold would be controlled by adjusting the "on" level of the LED. Again, I really only know enough to be dangerous to myself. BTW, is there somewhere in the UK where I can get a few of these vactrols ? I've tried Maplin and my local independant electronics store with no luck. They're actually kind of difficult to find in the US. Your best bet may be to either contact Allied (as they're the most reasonably priced) and see if they export, or to hack one from a LED and a photoresistor in close proximity. Totally worth playing with though, a lot of fun. Thanks for the input, Col, Ron Link to comment Share on other sites More sharing options...
psw Posted December 18, 2007 Author Report Share Posted December 18, 2007 Well, I am a little bit surprised at this attitude, but it is one that has been raised elsewhere in the forum...but in this case, there are some additional ironies... Firstly, I congratulate new members here and others who have stuck with it to keep the thing alive and interesting. I am very proud of this thread and all that it has achieved... I take it that the winking smiley was that I should take it in jest... Yes...I am attempting to make a commercial, very small scale venture from it, but I have litterally spent thousands of dollars on this "hobby"/obsession and countless hours, much of it here, not only discussing and documenting ideas, but encouraging people with their own... The debate elsewhere has been over things like whether commercial professional builders, like Rhoades56/Perry Ormsby...should be allowed to enter GOTM. There was total agreement that they should...very many of the people here, virtually all the moderators, Kevin's Trem-no thingy and others have commercial ventures, are in fact full time luthiers, and many more aspire to be or sell their "projects" or even build one off's for commissions. It is no different for me except that I am only concentrating my efforts on this one component, by and large... The fact that I have done so much work and spent so much time and money on this, and that I am now stepping up with a even more developed "product" should not preclude me from contributing to the discussion, surely... Anyway...I have had my rant on this...last time the result was that I should not disclose anything about the commercial product development (like schematics and other details) at all in public...hence the secrecy. Again, this secrecy should not preclude me from participating... To me, this argument would preclude collie_doggie from participating due to having investing in a commercial unit himself...but seeking to know more about how it works. We have explored the ebow various times...even pedal compressor, sampler infinite sustainers have been raised way back when... For a long time, the thread was largely a blog for my own experiments...pretty much exclusively. While the title is "sustainer ideas" (which I think what I am doing is a further development of those things)...there is a subtitle you know..."Ideas, links, projects on DIY sustainers"...and even then, only because there wasn't room to list everything, and no one knew that 5 years later it would still be going...it seems to be a unique achievement... The really ironic thing is that, as long as my name is on it as the thread starter, it is my thread and frankly...it can go wherever I want it to, short of actually selling my devices in this part of the forum. Promoting them is alright though...but really, all I was doing is trying to contribute to a question and to update my progress... A lot more on this will be revealed and I am prepared to personally shed more light on this work by email...as at the time it was suggested that I not only stop posting but remove work pertaining to it, I didn't hear anyone say...no stay and tell us all the details...as I recall, the response was that this was the right thing to do... This thread is great and these "digressions" are really useful... One effect is that certain types of harmonics mimic the ones that occur naturally in our ears when they are exposed to very loud sounds - hearing these will raise the level of 'excitement', the sound is perceived as louder than it is and our bodies produce more adrenaline... a distortion that produces these harmonics will be exciting to listen to... it's part of the wider field of psychoacoustics. I found this to be particularly insightful in relation to the "loud" effect of the sustainer on the same guitar...great contribution and I don't think so far off topic, except for the present discussion on limiters perhaps, but then this is a perenial topic that was raised over 200 pages ago... A little digression into distortions is also not off topic...a compressor is essentially a distortion of the signal...and distortion in the form of fizz would be very much on topic...so the reasons some are bad and other's (like our fizz) sound "bad" is relevant...certainly to me... Similarly the very true observations about the sax and the chaotic and reactive nature of it is something of what I'd like for this device to develop...I really do think there is potential to have a similar rich and reactive sound (not a fake sax, but something different but equally expressive) So thanks for those, I really mean it...more please... I also think that a lot of people do want to know a bit about what I am doing and would probably get a bit shirty if I made a success of it and stopped contributing or developing new stuff here because of it...plus I would miss you guys... Also, I am learning a great deal in recent times about an important but little explored area of this project....the installation process and other things of that ilk... Anyone who has done this project, or even installed a commercial unit will know the difficulties of installation. The switching a wiring can be a nightmare, the marrying of the instrument and the sustainer device problematic and complex...and, it is only when you get to this stage really, that things like fizz and pops reveal themselves... So while design and theory and circuits are important, they are only stage one... Stage two is making these things to a standard to which they can be tested without having to factor in inconsistencies of construction...everyones approach does seem to be a little different...even quality control can have a major impact. Stage three is getting the thing actually into the guitar...this I find to be the most difficult to do. It is also something that no one does a lot of, so the experience bank is a little low... Now...I have spent weeks recently on this very important issue, and this will increasingly be a focus of mine. I will even be doing some work with digital switching and maybe even pic programming...not just for the sustainer but for a more complete switching system, possibly programmable, and most likely running off a button cell watch battery and that lasting for a year or so for the switching function...But that is a bit further down the track... What I have been doing is two guitars that are very different and one in particular that, due to the commercial nature and the profile of the "commission", cant accept compromises like pops and such... I have learn't so much...and none of this is secret...I just haven't had time to explore that here lately...and no0 one seems to be installing these things in guitars at the moment...so perhaps that is off topic. If anyone wants to know a little more about what I am doing in commercially sensitive areas, drop me a line. Otherwise, a lot more will be revealed... What I can say is that there is no "perfect" sustainer...but what I have been working on is a significant improvement...at least on my previous stuff. This will be tested shortly as I have a contact now who is in fact a sustainiac installer and will be testing this out and making some comparisons for me. There is a nod towards so many people who have contributed over the years with a lot of features, a few of my own...but mainly a lot of work. The design I am using now is not really practical for a one off do DIY project. Technically, there will be distortions and stuff in there I am sure...but the proof is in the palying and it does seem to be performing well. So...for those who have come in recently...I have an ultra thin coil that mounts onto a pickup...a small circuit based on the LM386 but with some simple AGC backwards fed and coupled by capacitors. The design seems to also vary the zobel improving phase angles, even as it controls gain. It has a single trim pot to set the maximum range (just below squealing) and a "drive" pot that is not simply a sensitivity control (it will vary the gain through the AGC, at extreme settings allowing that full on slightly fizzy (if the trim pot is set to allow that in the drive range), and the runaway effect that was a feature of the original guitar...now three years old and retired...RIP). I am still using a 4pdt switch to activate and bypass and select the bridge pickup...I suspect though I will be wanting even more for a three pickup guitar (hence the electronic switching interest)...It does though, on lower setting give a very controlled and clean sustain. The reverse phase strategy is a little problematic...nothing like as consistent as my original...but very good on the low strings. I also suspect that this thing will drive 9 gauge high e's in standard mode...a first in my experience... It is also extremely reactive to various tone controls setups. As the tone control affects both the output and the input to the circuit, it seems to be able to be used to draw out harmonics in the standard mode. This is much in line with the recent comments on filters as a means to create a better harmonic effect. This is also something I wish to explorer...and is very much true and worth doing. The patents suggest though that reversing the phase is the way it is done too. There is no getting around the fact that if the string is playing a harmonic...it is feeding back that harmonic and trying to drive it higher...even with filters I would presume... I have been experimenting with a whole bunch of stuff and am pleased to say that I have finished it tonight and will be winging it's way to the USA tomorrow and it is exciting to think that this will feature in a very high end specialized guitar and fall into the hands of someone who can exploit it's potential. The "project" became more than just a supply of this device, but a whole purpose built wired "harness type affair. It was tricky for me because I do tend to throw everything into such things...but this guitar is not for me, or the builder so some moderation needed to be applied. It will be a showcase not only for my stuff, but for this guitar maker and the idea is to make something that meets all the players needs and be of quality even if a little striped down in both apearance and function. There are some interesting "easter eggs" thrown in of course. I believe the guitar...not yet fully built...will be a black limba jackson-esque type guitar...quality without ornamentation. This "artist" is known for being very physical in his style and manipulating sound with unusual dj style approach. Important to him is a toggle "kill switch" (as well as extensive use of a "whammy" pedal). He is not known to use sustainer guitars, so it will be interesting to see what he does with this feature. Some of the easter eggs I have included is dual killer switches of unique style and design. One that I hope will be include is a push button conventional shorting kill...it is quite large and stainless steel with a great positive action and incredibly well built and sturdy...it sits pretty much flush with the surface of the guitar. The other is a "missile launching switch! This is a 2 way momentary oversized toggle switch...it always switches back out of the dead zone...again very strong. I modified this switch with a dremel so that it will do both normally open and normally closed. On the back is a trim pot and a carefully selected cap (I took days working on the values) so that, unlike a kill switch that turns off (hence kill's) the sound, by pulling up on the tone control push pull, the toggle will switch to a "maim" switch. It doesn't kill it, but ^%$%#$ it up. Actually, it is a similar effect as instantly moving from one extreme fo the tone control to the other...the selection of cap was crucial to get the desired wah like effect I was looking for. There are other features and hopefully when it is finished, I will be able to show more...I may even be able to get the builder on to give us some detail here, or elsewhere in the forum. The harmonic switch is a push pull too, so there will be a minimum of switches and stuff on it and those innovations that are unique to it, are largely hidden. Already there are plans for further collaborations, but I am still no where near the stage of "production" though that now seems inevitable as I have had a few inquiries based on word of mouth alone...even a few offers. Hopefully something will come from all this and I can feed back some of what I am learning to the forum as I am working on some fundamental practical issues and working with a few people who have a very critical eye and a vested interest in this being a very reliable and practical device. So...I hope no one is offended by my typically digressive and long thread...I do tend to over react, but I do think there is more to this yet to be discovered and a lot of the "sustainer ideas" being discussed of late will bear fruit. One limitation of doing anything commercial is the need to commit yourself to a particular design, by doing this it does stiffle some creativity and innovation. I doubt that I will be working on new and improved driver designs in the near future...not because this is the be all and end all, but simply because I have to commit myself to a design and process for it at some point. I do think that it is an improvement of what is available now with a broader range and more features. More could be done, and if the coil production side of things gets a boost, then I may well be able to supply these to people who may wish to experiment further with circuits, filters or compression technology with a consistency of driver that will help in guaging results between experimenters...perhaps even developing add on or replacement versions and improvements that can piggy back on my success if all goes well... Anyway, will leave it there for now...the details here should be enough for a lot of people, but I will entertain convincing arguments to say more (or perhaps less ) on request... Sustain on for Christmas...btw, I have a working title, but it seems to change every week... cheers... pete Link to comment Share on other sites More sharing options...
col Posted December 18, 2007 Report Share Posted December 18, 2007 ...Also, I am learning a great deal in recent times about an important but little explored area of this project....the installation process and other things of that ilk... Anyone who has done this project, or even installed a commercial unit will know the difficulties of installation. The switching a wiring can be a nightmare, the marrying of the instrument and the sustainer device problematic and complex...and, it is only when you get to this stage really, that things like fizz and pops reveal themselves... that's why I said KISS So while design and theory and circuits are important, they are only stage one... Stage two is making these things to a standard to which they can be tested without having to factor in inconsistencies of construction...everyones approach does seem to be a little different...even quality control can have a major impact. yep, if you want a comercially viable system, you need to have one that is designed to cope with the inconsistencies rather than one that tries to remove them! Look inside most gadgets (at least those from more than a decade ago) and you will find that they have lots of little trimpots. On the production line, there would have been someone with a custom setup to probe and adjust those trimmers on each circuit in an efficient way... that gets around manufacturing inconsistencies and component tolerances. Modern gadgets are more likely to do something similar in software (or firmware), but they are still designed to cope with the inconsistencies rather than to avoid them. One of the reasons digital technology has all but taken over in most areas is that as long as the gadgets stays within the tolerances, the user experience is always the same - no subtle differences... it either works completely, or not at all. That makes it cheaper to produce.. no need for that guy/robot on the production-line with a probe and screwdriver. An example would be that for a sustainer, you would have your system designed so that if the driver is optimal, the amp will need to be turned down... the maximum amp gain would tuned to match whatever you considered the minimum acceptable driver 'quality' to be... Another area where one might need trimmers is in the AGC. FETs are notoriously variable as are MOSFETS (not quite so bad iirc) and also Vactrol type devices. So a good design would probably have a circuit designed to work with a broad range of devices and trimmers to tune the circuit so all the units could function equally. I'm not suggesting this would be easy, just that it is possible and good designers tend to build this kind of flexibility into their systems. cheers Col Link to comment Share on other sites More sharing options...
curtisa Posted December 18, 2007 Report Share Posted December 18, 2007 (edited) Another area where one might need trimmers is in the AGC. FETs are notoriously variable as are MOSFETS (not quite so bad iirc) and also Vactrol type devices. So a good design would probably have a circuit designed to work with a broad range of devices and trimmers to tune the circuit so all the units could function equally. I'm not suggesting this would be easy, just that it is possible and good designers tend to build this kind of flexibility into their systems. 'Course, you could make the AGC circuitry more repeatable and universal by utilising the more specialised VCA chips, thus doing away with the multiplicity of trimmers required just to get the system working. Mind you the trade off in that case is cost - would you rather spend time and money tweaking the circuit once it's built, or spend more money at the outset and buy a dedicated $10 chip to do it all for you? I should really re-explore the AGC system on my setup. I have a bunch of spare THAT2181 VCA's kicking around at home doing nothing... Edited December 18, 2007 by curtisa Link to comment Share on other sites More sharing options...
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