onelastgoodbye Posted October 21, 2006 Report Share Posted October 21, 2006 Has anyone got any improvements to the driver design? I think there may still be some work to be done there, if not the design, the construction at least! Perhaps there is a way to make it more efficient. I have another variation on the split blade bilateral design I posted earlier, half bladed, half adjustable poles!...and I think a stacked coil may also hold some posibilities, especially as a stand alone unit with some kind of internal magnets, more thought required there still... I just wound a coil using the latest incarnation of the jig. Broke the wire when removing the core..again. I still think I can make it work though. Link to comment Share on other sites More sharing options...
col Posted October 21, 2006 Report Share Posted October 21, 2006 (edited) Ok, so I've just been fiddling with my (still handheld at this stage) pickup/driver sustainer, and I was running it through a limiter that was built from a kit published in an Australian electronics magazine (Silicon Chip if anyone is interested). The kit is sadly out of production now, but it featured the SSM2018 VCA chip at it's heart and also a very similar precision rectifier circuit as the THATcorp appnote. And it's a feed-forward design. AND it makes a helluva difference! Why is there no self-satisfied smug 'I told you so' smiley ? I can get plenty of sustain on every string in just about every position. What's more is I can get the same performance at a greater distance from the strings than just using the plain old LM386 circuit, which means we don't necessarily need to have super-low action anymore. Yep, its nice isn't it... an even response all over the neck makes the thing feel much more professional. still gotta watch the distance between driver and strings - too much, and the battery will drain much faster. For some reason I'm getting better low string performance too, not sure why. Beforehand I could only go down to the note "E" on the 5th string/7th fret before it started sustaining harmonically instead of fundamentally. Now I can get fundamental sustain almost all the way down to low "G", 6th string, 3rd fret. Could be that I'm now no longer pushing the LM386 into clipping and accentuating the upper harmonics of the note? Another possibility is that it is phase related... on the simple fetzer ruby it has been noted that switching the output cap from a 220u to a 100u changes the response to favour the high strings - at the same time it causes the low strings to jump quickly to harmonics... the change in caps causes a not insignificant increase in phase distortion at 82hz. My next trick will be trying to tailor the response of the sidechain to emphasise the high-note drive. I've been having more trouble getting the response quick enough while keeping enough low frequency response to drive the lower stings at their fundamental frequency. So...can you extend you analogy or mix some metaphors to explain why we need to take the reference for the compressor from the input, not the output, as is commonly the case? Back to my old faithfull car analogy... Two drivers are asked to drive their car at a steady pace along a country road. Driver A is in a race car with no speedometer, just a revometer that tells him how fast the engine is going, he decides to keep it in 4th gear and use his revometer to keep the engine working at the same power assuming that this will keep him going at the same speed. He does fine until he gets to a steep uphill - where he almost comes to a standstill (high E string 1st fret).... Then, coming down the other side, he gets arrested by the police for speeding (G string rattling against 14th fret) Driver B has a speedometer in his car that measures the speed of the car in relation to the road - irrespective of the power train. Using that to keep a steady pace he can adjust for environmental effects like hills, wind resistance etc by adjusting the throttle to keep the speed reading steady... So: Driver A is the feedback compressor that only takes into account its own output level when deciding whether to adjust its 'throttle' - engine speed = circuit output level Driver B is the 'feedforward' (a misleading term in this context) compressor that uses the overall output of the system to make adjustments - road speed = guitar output level With feedback compression (eg, Col's original schematic, the Aussie comp etc) .... [nitpicking mode] my original schematic wasn't the same as a normal feedback compressor - it was a feedback&forward™ compressor in that it fed its midpoint signal back to its first stage and forward to its second... I realised early on that a standard feedback compressor would not work, but didn't re-discover the (obvious now) solution of the feed forward topology until a little later [/nitpicking mode] I also feel that the feedforward compressor topology could be altered in order to give even better performance for our somewhat unusual application some 'dynamic range invertion' for the lignals whos levels are under the compressors threshold would still be benificial... although I've not thought of a simple way to achieve this yet - I guess the easiest way from a design POV would be to have two compressors running together, one as a limiter, and the other set with a gentle compression level - both would use the same sidechain control signal, but their VCAs would be connected in series with each other. If we got this right, we could get a nice tailored compound response curve.... @Curtis: I'm using electronics workbench to simulate stuff - it allows me to do loads of iterative trial and error hacking (otherwise I wouldn't even be attempting to 'design' circuits). cheers Col Edited October 21, 2006 by col Link to comment Share on other sites More sharing options...
psw Posted October 21, 2006 Author Report Share Posted October 21, 2006 Ok, ok...you got me... You do realize of course we appear to be moving inextricably toward the conclusions and solutions that the commercial units have adopted... Why is there no self-satisfied smug 'I told you so' smiley ? maybe this is it... .... Good analogy there too...so now we understand more about the AGC required and are stepping back into the phase correction territory that I used to fret over in the early part of the thread. It was with my Hex designs that I sought to correct some of these effects and while they may have attempted to address the string to string response, they wouldn't have addressed the, "action" related issues, the fretting (length of string) or phase related issues...other than to provide more speed, that is, a more efficient transfer of the signal to the string to minimise phase differences between the circuit's output and the actions of the driver/s. The Floyd Rose Patent offered a solution with a number of capacitors that were switched in according to the frequency of the signal...is this the direction we are headed also? I am getting a better understanding of the effect and reasoning behind such strategies now that I have a working basic sustainer guitar to play with. Of course another easier response is to compress the **** out of the guitar's signal so as to compensate for the different responses of the string to the driver...that is probably why it is better and easier to get a good sound from a distorted, compressed signal that adds back harmonics through distortion. It also may be that our "fizz" is not so much EMI related but a phase related issue in which the driver is somehow suppressing certain frequencies of the strings actual vibration and altering the "tone" in some way...or perhaps EMI travels further at different frequencies (hence it is worse in harmonic mode)... I wonder too the effect of moving the driver to the mid position. I get a very powerful response from the driver in the higher frets...while in part it is because the strings are being pushed right down to the driver...but, it has always been inferred (though I debated it) that the positioning of the driver around the 24th fret position was because in the centre of the string it would be easier to drive them (more physical swing in the centre of vibration) The fact that a very powerful drive is achieved wasy up at the 24th fret indicates however the contrary. At this freting position the driver is at the end of the strings length, yet is still able to give a very powerful response. This is why for a while, I was trying to drive the string from the bridge end. The driver could at all times be close to the strings with little variation caused by fretting action and there are plenty of harmonics at this point and closer together... However...at the bridge is the bridge pickup, and we would have to be extremely clever to be able to avoid an EMI interaction with a driver right next to a pickup! Perhaps a bridge driver, neck pickup (a reverse of the present arrangment) should be tried, if only to see how it would go. In the end we may simply be reinvienting the wheel and gradually working our way towards acknowledging the need not only for a round object, but for the axle to be as near to the centre of it as possible! rats... Unless we were able to develop a driver that was fast enough (as the thin driver coil is designed to address), perhaps even creative AGC control is not enough. Still...a basic DIY sustainer is possible, even if the response is a little skew-wiff, by very simple means, and that it'self is an achievement and worth doing...it is still a valid instrument and project... pete PS...I wonder what the effect of a BTL amp, with no output caps, would have on phase issues. Link to comment Share on other sites More sharing options...
curtisa Posted October 21, 2006 Report Share Posted October 21, 2006 Hey...that sounds like the one I built...is it a 4 knob compressor/limiter? DSE and others used to sell it as a kit, right? I built mine and included a LM386 module so I could optionally use the driver direct from it...same idea, proof of concept... Nah, not the same, though I do know of the one you're talking about. Mine is the 5-knob jobbie produced by Jaycar for all of about 6 months in 2000 or so. I don't have the design notes and original magazine article anymore though, so I'm going to have to reverse engineer it to find out how it works. It's feed forward though, anything in the circuit schematics of use, or does it rely on this chip? It's more the topology used, not so much the chips used. Pretty much just proving Col's idea of using feed-forward as a control method, and my insistence of using the precision rectifier (ala THAT corp) as the control voltage generator. The SSM2018 is pricey but not unattainable, but the main drawback is that it's minimum supply voltage is +/- 5V, which pretty much eliminates it's use for us in battery operated systems, unless we want to consider phantom powering or perhaps dual 9V batteries. I'm sure there are other options out there that will work. We've just got to find them. Meanwhile...holding the pickup above the strings is ok, but it is hard to guage the EMI problem as it is spraying EMI towards the guitar whereas when in the guitar it is level with the pickup... With this preamp, are you able to get the device closer to the pickup do you think? That's something I am working on at the moment, but it will take some time before I can get a hands-free sustainer going. The pickup/driver is currently removed from a guitar that I'm building that will eventually have the sustainer permanently installed. I don't have any other guitars that I can install a single coil pickup in to try it out in situ, so until I've got the guitar built I have to continue experimenting by holding the driver in my hands Ebow-style. I don't think the compressor will help the driver in terms of proximity to the guitars' pickups. If anything I'm expecting to be worse simply because the system has to incorporate makeup gain for the quieter strings/notes - there's more gain present (and more risk of feedback) when there's no signal passing through it. Perhaps this is a good excuse to incorporate downward expansion or noise gating into the driver system? Getting too complicated...I'd vote for minimising the potential for feedback at the driver-end of things - more development of the self-cancelling-humbucker-bilateral-dual-rail-super-duper driver. You do realize of course we appear to be moving inextricably toward the conclusions and solutions that the commercial units have adopted... Well, there probably is a reason why they're using these systems, and I'm sure we're just discovering the same pitfalls that they went through during the R&D of their products. PS...I wonder what the effect of a BTL amp, with no output caps, would have on phase issues. Might be time to order one in and try it out Why is there no self-satisfied smug 'I told you so' smiley ? Haha! How's this: Thankyou, Col Yep, its nice isn't it... an even response all over the neck makes the thing feel much more professional. still gotta watch the distance between driver and strings - too much, and the battery will drain much faster. I haven't checked this yet, so I have no idea what, if any improvements or reduction in battery performance has been achieved by incorporating the limiter into the design. Besides, the limiter is currently running off +/- 12V on a separate supply to the 9V LM386. I don't really have any way of getting the whole shebang running on the same battery at this stage. Another possibility is that it is phase related... on the simple fetzer ruby it has been noted that switching the output cap from a 220u to a 100u changes the response to favour the high strings - at the same time it causes the low strings to jump quickly to harmonics... the change in caps causes a not insignificant increase in phase distortion at 82hz. This is probably more in relation to changing the resonant frequency of the driver, and hence the best band of frequencies at which the driver works. That's not to say that phase differences aren't a factor, but I suspect it's not the largest variable, particularly at the lower strings @Curtis: I'm using electronics workbench to simulate stuff - it allows me to do loads of iterative trial and error hacking (otherwise I wouldn't even be attempting to 'design' circuits). Yeah, that's what I'm using too, but my version must be a few revisions older than yours as I don't have a LM13700 model. Cheers, Curtis. Link to comment Share on other sites More sharing options...
col Posted October 21, 2006 Report Share Posted October 21, 2006 ...so now we understand more about the AGC required and are stepping back into the phase correction territory that I used to fret over in the early part of the thread. It was with my Hex designs that I sought to correct some of these effects and while they may have attempted to address the string to string response, they wouldn't have addressed the, "action" related issues, the fretting (length of string) or phase related issues...other than to provide more speed, that is, a more efficient transfer of the signal to the string to minimise phase differences between the circuit's output and the actions of the driver/s. The Floyd Rose Patent offered a solution with a number of capacitors that were switched in according to the frequency of the signal...is this the direction we are headed also? Nah I just brought it up because its always there, and is something we need to bear in mind whenever we get results that are slightly unexpected... So far it seems probable that we won't need complex phase correction... just careful circuit design that doesn't introduce too much phase distortion. ...or perhaps EMI travels further at different frequencies (hence it is worse in harmonic mode)... that sounds interesting - certainly would be useful to know, might help us get a better understanding of how it all fits together... which is never a bad thing Perhaps a bridge driver, neck pickup (a reverse of the present arrangment) should be tried, if only to see how it would go. Yes, that would be a useful test, if it worked and was as good but different, a system could be setup where there was a driver/pickup pair at bridge and neck - you could switch between neckDriver/bridgePickup and bridgeDriver/neckPickup btw, I found a simple and well discribed compressor circuit that features switchable feedforward/back topology - it is based on the 'orange squeezer' and could be simplified to use maybe a dual op-amp, LM386, two JFET transistors and a handfull of caps and resistors... its called 'tangerine peeler' there's plenty of info on Mark Hammers site and on diystompboxes - enough to help us simplify this and tailor it to the sustainer project. Before I found this, I read a post from mark hammer where he first suggested hop to switch the Orange Squeezer to feed forward - so I tried that out, and it works pretty well, even without the extra controls in his heavily modified circuit... cheers Col Link to comment Share on other sites More sharing options...
psw Posted October 22, 2006 Author Report Share Posted October 22, 2006 col btw, I found a simple and well discribed compressor circuit that features switchable feedforward/back topology - it is based on the 'orange squeezer' and could be simplified to use maybe a dual op-amp, LM386, two JFET transistors and a handfull of caps and resistors... its called 'tangerine peeler' Hey...that tangerine peeler seems to be using my buffer thingy idea...kinda... psw Ok...so following on from this, could we use a compressor circuit with a dual op amp. One set up as a buffer or adjustable preamp, the other as a standard compressor that varies the adjustment, not by the effect on it's own adjusted output, but the unaltered signal of the first? Does this make any sense, or am I off the track with this? So far it seems probable that we won't need complex phase correction... just careful circuit design that doesn't introduce too much phase distortion. Well that is a relief...these circuits are getting way to complex to be really practical...I am sure eventually we will find a better way... Yes, that would be a useful test, if it worked and was as good but different, a system could be setup where there was a driver/pickup pair at bridge and neck - you could switch between neckDriver/bridgePickup and bridgeDriver/neckPickup But you could never have both together with sustain and the switching would be a nightmare... What might be interesting is to try and develop some kind of active pickup/driver in the size of a humbucker that not only drove from the bridge but collected the signal. That home made ebow, and the ebow itself has it's driver and pickup only an inch from eachother. I did get a hex coil to work pretty close to the single coil bridge pickup (about 2cm) so a combination of pickup and driver could concievably be possible in that format using low impedance coils, appropriate preamping, magnetic shielding and drive elements on a different plane for the pickup coils...but perhaps another day...I digress...frequently tim I just wound a coil using the latest incarnation of the jig. Broke the wire when removing the core..again. I still think I can make it work though. That's a shame...did you do the paper thing? Perhaps the core needs to be slightly wedge shaped to get it out, or be of some kind of rubber or perhaps come apart... How did the side clamps go...neat, more compact? Nah, not the same, though I do know of the one you're talking about. Mine is the 5-knob jobbie produced by Jaycar for all of about 6 months in 2000 or so. I don't have the design notes and original magazine article anymore though, so I'm going to have to reverse engineer it to find out how it works. Silicon chip do great stuff... You know, if you can find a tafe that does electronics, you can find the mag and get a copy of the circuit...there are indexes in some issues every year that stretch back I think, perhaps on line even...I used to go down and get stuff where I used to live. Also, the State Libraries have to keep copies...if you are keen, perhaps on interlibrary loan (ex-librarian here!) curtis I don't have any other guitars that I can install a single coil pickup in to try it out in situ, so until I've got the guitar built I have to continue experimenting by holding the driver in my hands Ebow-style. I understand...always a problem. Still a purpose built guitar is the way to go in many respects... People who do this testing should be aware that there can be some interaction between the driver and the neck pickups magnetics and that a good installation may well improve an already good thing...certainly EMI issues may lessen. As something really fun and interesting to try out, it is a fantastic and very cheap proposition...don't really need switches, just a coil and the amplifier circuit...$20 bucks maybe. Might be time to order one in and try it out yes, well I that ex-wife of mine has one....and I intend to get this stuff back sooner than later. Slightly off topic...It has been a very trying week...I lost access to my children on a whim in a most distressing manner for both me and my children...must have cost about $1k to get them back, this week alone, plus a day off work and a lot of sleepless nights. Have spent over $20k in the last 3 months...it is shocking, but that is how it goes...and I still don't have anything from the house...grrr 18 months of hell!!! grrr...still, on the upside, found a house that looks promising and when that happens, there will be a short break in my transmissions, then a lot of stuff will return and I can do something with my hands to distract me...like try out some of this stuff... The Virtual Sustainer Corp is on to something with the compressor thing and I think there are some major clues in that circuit col. We need to keep this thing as simple as possible, small and with easily obtainable parts. I still like the modular idea and the possibility of combining the amp and driver into a single unit...so make sure there is provision for the phase reversal and keep in mind the eventual switching required. The only reservations there is the need to take the preamped signal right up to the driver and avoiding interferance...worse comes to worse, It may have to hide in the trem cavity out back! Anyway...keep up the good work and live well... pete PS...I think I need to take up a different hobby...perhaps I should play the guitar more... Link to comment Share on other sites More sharing options...
bancika Posted October 22, 2006 Report Share Posted October 22, 2006 Hello, I've stripped one old single coil pickup for driver. Now is the time to wind it. one question: how should I determine when is enough with winding. Wire is lacquered so I can't measure resistance with DMM without stripping lacquer from it. Any suggestions? Tnx Link to comment Share on other sites More sharing options...
col Posted October 22, 2006 Report Share Posted October 22, 2006 Hello, I've stripped one old single coil pickup for driver. Now is the time to wind it. one question: how should I determine when is enough with winding. Wire is lacquered so I can't measure resistance with DMM without stripping lacquer from it. Any suggestions? Tnx Two ways you can go: #1 every so often (say, at 80 turns then every 20 after that?) you use a bit of wet&dry to rub off the insulation and test with a multimeter. #2 use the pickup winding calculator to work out how many turns you will need based on your wire guage, insulation and the dimensions of your core. I've used both methods with success - although the second is less hassle, you do need to be sure that you know the specs of the wire you're using. Col Link to comment Share on other sites More sharing options...
psw Posted October 22, 2006 Author Report Share Posted October 22, 2006 It doesn't need to be exact...I used the first method, attached the first lead wire to make it esier, and make sure you do make a good connection (push probe hard on to wire) to read the value. See the pictorial...there will be between 100-200 winds...the resistance will increase rapidly as you get above 100! Make sure you pot with glue (I used PVA/woodglue) as you go...this will heal over where you read anyway...the glue is important....again see the pictorial... pete Link to comment Share on other sites More sharing options...
bancika Posted October 22, 2006 Report Share Posted October 22, 2006 Thanks for replies. Can someone help with winding calculator. I'm not sure what are core dimensions and what are bobin dimensions? Also, what should I put for insulation diam? Here's pic of old pickup I cannibalized for the purpose I glued two L profiles on sides to make coil 3mm high. Link to photo Can I use universal transparent glue for potting coil? It's the only one I have here at the moment (except for super glue), it adheres to both metal and plastic. Link to comment Share on other sites More sharing options...
psw Posted October 22, 2006 Author Report Share Posted October 22, 2006 Got to run to work...5am here... I would still wind and measure but because the core is significantly thicker than mine, you will probably find that you need to fill up this 3mm space (try to keep it neat and compact) and have some tape handy to hold in the sides and push them in as you go. Any glue should probably be ok as long as you can work with it...superglue would be avoided then. Great photo by the way and neat construction so far. Can someone help with winding calculator. I'm not sure what are core dimensions and what are bobin dimensions? Also, what should I put for insulation diam? I've not used this program but it does look useful. the core is the width of the part you are winding on, you could set the bobbin to zero if you are measuring the coil space as 3mm I guess. Insulation is just the enamel coating...tiny... It is because of these variables that I would simply measure it. I made one driver on this model rated at 8 ohms exactly...while the one in my guitar is rated more like 7 and still works fine...so I wouldn't be too concerned. You may find that after the first go and testing you decide that you could have done a better job on the coil and end up doing it again...many people have found this and you will not find it takes long, is expensive in wire or difficult to do with a little practice... good luck... pete PS...you could try a stacked coil with a similar approach, but as this is untested, probably best to continue as you are doing and get something that works to start with... p Link to comment Share on other sites More sharing options...
col Posted October 22, 2006 Report Share Posted October 22, 2006 Thanks for replies. Can someone help with winding calculator. I'm not sure what are core dimensions and what are bobin dimensions? Also, what should I put for insulation diam? Here's pic of old pickup I cannibalized for the purpose I glued two L profiles on sides to make coil 3mm high. Link to photo Can I use universal transparent glue for potting coil? It's the only one I have here at the moment (except for super glue), it adheres to both metal and plastic. the important measurements for getting the correct impedance (8ohm, or 2x4 ohm for dual core) are the wire guage, the length of the core and the width of the core. just set the insulation of a few 10ths of a milimeter more than the wire diameter e.g. wire diam. 0.23 insulation diam. 0.26... The bobbin width just gives you a visual indication of whether your bobbin is going to be big enough to take your coil... and it's not that accurate in my experience (unless you were using a mechanical winding machine...) As far as getting the correct turns for the Ohms you want, you can ignore the bobbin width setting, and if you take a good guess at the insulation diameter, the error will not be significant.... e.g. if you say wire diam 0.25, insulation diam 0.8 (which would be daft), then the result will be way out, but if you guess at insulation 0.26 or 0.28, it wont make much difference (two turns as a matter of fact) - just try those settings in the calculater to get a feel for it Col Link to comment Share on other sites More sharing options...
bancika Posted October 22, 2006 Report Share Posted October 22, 2006 thanks guys I tried calculating it and get 113 windings...core is 60x6x3mm tweaking wire thickness for one 1/100th doesn't change anything important. It shouldn't make much of a difference anyway, speakers have always lower resistance than impedance (when I measured 8 ohm speaker it showed 7.2) Tomorrow I'll try to find some wire in local stores and get back to work. Cheers Link to comment Share on other sites More sharing options...
psw Posted October 23, 2006 Author Report Share Posted October 23, 2006 It shouldn't make much of a difference anyway, speakers have always lower resistance than impedance (when I measured 8 ohm speaker it showed 7.2) That's right, the ability to make a neat coil that is immune to vibration and is roughly the impedance we want is what is most important...you have made a good start, 10 minutes winding is all it should take. I pushed the side windings in as I went with a stick and cut some electricians tape down to 3mm to bind it all up neatly and keep it in place as the glue dried. Even if it takes a long time to completely dry, the glue and the neat coil should be enough to use it, so don't fret over it not being dry. This is crucial for a bobbinless coil to hold it all together of course, but not so much in your case. Remember if worse comes to worse, you could simply take it apart and reuse the bobbin, just as you did with the pickup windings. Good luck on the 0.2mm wire...I found a roll last week at the local shops....odd how some have trouble locating it! Ok...here is another variation on the split blade idea... This has the same bladed driver but screw poles for the pickup. These poles, like the previous blade version are of the opposite magnetic polarity of the driver opposite (in typical HB configuration) so attract and help contain the magnetic field and hopefully EMI. Changes in EMI will in part be between the two bilateral drivers, from side to side and have more of the thin core theory effects too. The poles could be adjusted for pickup response and/or for the adjusting of the driver's sheild or driving window...similar to the shunts in the sustainiac patent. I have also slightly overlapped the driver blades...this is between the g and d strings but may avoid a dead spot or opening for EMI to escape. You will see that in the sustainiac, the actual cores under the metal plate on top feature a quite sizable gap between them to accomodate the coils. As my idea staggers the cores, I do not have this problem. Also, note how small the thin driver is in the bilateral format compared to the sustainiac driver. I am quite please with this concept and would suit both a rail pickup conversion, possibly a humbucker conversion, or a stand alone driver...what do you think? ... pete Link to comment Share on other sites More sharing options...
spazzyone Posted October 23, 2006 Report Share Posted October 23, 2006 I think if you get some time this weekend you will be telling us how good it works Link to comment Share on other sites More sharing options...
bancika Posted October 23, 2006 Report Share Posted October 23, 2006 I tried today in local electronic stores but without luck, they don't have lacquered wire at all. Later I'll go out and check electric supply stores, maybe they have it Link to comment Share on other sites More sharing options...
col Posted October 23, 2006 Report Share Posted October 23, 2006 I tried today in local electronic stores but without luck, they don't have lacquered wire at all. Later I'll go out and check electric supply stores, maybe they have it Did you try asking for 'magnet wire' or 'winding wire' ? If the shop assistant is of the usual standard, they may not know that these are all equivalent. Col Link to comment Share on other sites More sharing options...
bancika Posted October 23, 2006 Report Share Posted October 23, 2006 yeah, I was asking for 0.2mm copper wire used for coils/transformers/windings...they seemed like they hear about it for the first time in life Link to comment Share on other sites More sharing options...
bancika Posted October 23, 2006 Report Share Posted October 23, 2006 (edited) Got back from search and nothing. Anyone knows where can I order it online. Most shops do not want to ship to Serbia. Anyone wants to sell/trade wire sufficient for 2-3 drivers? Cheers Edited October 23, 2006 by bancika Link to comment Share on other sites More sharing options...
curtisa Posted October 23, 2006 Report Share Posted October 23, 2006 Got back from search and nothing. Anyone knows where can I order it online. Most shops do not want to ship to Serbia. Anyone wants to sell/trade wire sufficient for 2-3 drivers? Cheers Farnell and RS Components will stock it, though it may be a bit more expensive than over-the-counter sales. Cheers, Curtis. Link to comment Share on other sites More sharing options...
Hasa Posted October 24, 2006 Report Share Posted October 24, 2006 Hi, I've been loosely following this thread since about page 70, and this morning in the shower I had an idea that might just work. I did a quick bit of reading, and from my limited knowledge of electronics, I guess that it could work. It has been mentioned a few times that there is a 'pop' sound that is made when the device is turned on and off. It has also been noted that with reduced power, the 'pop' is quieter (the LP sustainer comes to mind). The idea is to use a blend pot or variable resistance pot between the battery and the circuit to reduce the amount of power going to the sustainer circuit. In theory, this could enable the circuit to be always on, but only drawing a fraction of the amount from the battery, and it could possibly remove the 'pop' sound altogether by having it so quiet that it can't be heard. It's just an idea, and I don't have the time at the moment to build a sustainer (final Year 12 exams start on Friday), but when that's all over, I reckon I'll have a go myself to make one of these things. Please let me know if it is at all possible. Link to comment Share on other sites More sharing options...
curtisa Posted October 24, 2006 Report Share Posted October 24, 2006 No, I don't think that will work. Placing a variable resistance in series with the battery supply (or even wired as a voltage divider) to reduce the pop may work for a bit, but you're likely to burn out the pot if you leave it positioned just shy of full rotation. You may also find there's some instability in the sustainer circuit as you start winding the pot back, as you're introducing unnecessary and excess impedance in the power supply. I've just had another look at the LM386 datasheet and it seems that you can force the chip to mute by either connecting pin 7 to the supply line, or shorting pin 1 to ground. I reckon there's a possibility there for making popless on/off switching by somehow sequencing the power supplies around the chip - say when turning off the sustainer, pin 1 is shorted to ground and a moment later the power supply shuts off (or drains slowly, over a few hundred milli seconds or so). Yet more things to try out... Cheers, Curtis. Link to comment Share on other sites More sharing options...
psw Posted October 24, 2006 Author Report Share Posted October 24, 2006 Hi Hasa... Welcome to the sustainer thread and thanks for contributing. I am aware that there are a lot of people who share an interest in what we are doing even if they don't intend to do it themselves...a lot of "guests" are with us...and welcome to you to...Like hasa, if you have thoughts or comments, questions or whatever, feel free to contribute. Case in point...although Hasa's idea may not be practical, by examining such things new thoughts arise...as curtis has made in response...every contribution ios valuable even, and perhaps especially, encouragement! Got back from search and nothing. Anyone knows where can I order it online. Most shops do not want to ship to Serbia. Anyone wants to sell/trade wire sufficient for 2-3 drivers? OK...I am feeling generous, but please everyone don't contact me to supply materials. In appreciation of your work and distribution of the DIY Layout Designer program and the work that this has contributed to guitar experimentation (here and at arons stompbox forum) I'd be prepared to send you a small reel. Please email or PM me with details and I'll see what I can work out for you... Plus..you know I couldn't inport something similar from Canada, what's with that...Australia may be far away but my money is surely as good as anyone elses isn't it? I'd love to be able to supply some kind of kit of materials as it appears that even in the states people have trouble finding things...but I think there does need to be some agreement as to the circuitry and driver design for this to be possible. Hopefully my situation will change in the near future and next year such a scheme could be possible...any input into this would be appreciated. Eventually I kinda dream that if a sure fire design could be created with minimal and easy installation, something like a mid-driver for strat's for instance...I could build such things. But, we are talking hand crafted here and it would be hard to compete with the commercial units and justify not simply buying a proven and professionally made and sophisticated product unless there were significant benefits and a price difference...and that would be a little difficult to conceive at this point. Anyway...time will tell... pete Link to comment Share on other sites More sharing options...
col Posted October 24, 2006 Report Share Posted October 24, 2006 (edited) I've just had another look at the LM386 datasheet and it seems that you can force the chip to mute by either connecting pin 7 to the supply line, or shorting pin 1 to ground. I reckon there's a possibility there for making popless on/off switching by somehow sequencing the power supplies around the chip - say when turning off the sustainer, pin 1 is shorted to ground and a moment later the power supply shuts off (or drains slowly, over a few hundred milli seconds or so). Many guitar amps produce a thump when switched off - others don't. I imagine that there will be some circutry for this that we could borrow - assuming that the pop is still an issue when using a dual core driver. I've been playing some more with FET based compressors converted to feed-forward topology. The orange squeezer is ok, however its frequency response isn't really good enough for our purposes - particularly when you try to reduce the attack and decay times. one circuit I have found works exceptionally well as a feedback limiter - can have amazingly quick attack and decay, and has a very stable frequency response. Unfortunately it doesn't work so well as a feedforward design (I imagine the Orange Squeezer has the same issue, but its not as obvious). The problem is that the feedforward version limits the signal asymetrically - in the feedback circuit, the negative feedback removes most of this asymetry. What this means (I think) is that there will always be lots of harmonic content an less fundamental for the low notes, which menas no nice stable fundamental mode for the sustainer. The only fix I can see that might work is using the fet attenuator in the negative feedback loop of an op-amp gain stage - could this fix the asymetry ? I have tried to set this up, but so far unsuccessfully. Edit: here is a doc with a FET attenuator something like I'm thinking of Another possible option would be the LA Light compressor, this is a feedforward design based on an LED/LDR combo - which makes it difficult to simulate, so I've not tried it yet. EDIT: at last I found a link to the LA-Light schem HERE oops - gotta go cheers Col Edited October 24, 2006 by col Link to comment Share on other sites More sharing options...
onelastgoodbye Posted October 24, 2006 Report Share Posted October 24, 2006 Finally, succes on the coreless bobbinless driver front! I've managed to build a 4 ohm coil; 2mm high 7mm wide; this time utilizing a temporary core out of hard rubber (kudos to psw). I can get the width down to 6 mm, but that's as small as it goes (which is really tiny btw). Still need to wind an inverse coil for a humbucking driver. The whole dual rail driver won't be more than 13-14 mm wide. The temporary rubber bobbin just made building the jig even easier than it was (at first it had an aluminium core which was a bit tricky), I hope other people are willing to give it a try now, I'll have some pictures and details up tomorrow.It's really not that hard and winding one coil doesn't take more than 5 minutes (hey, it's 5 minute epoxy so I had to be quick ) In return you get a nice clean coil that's as small as it can physically be, and as it's a coreless driver, it's now possible to experiment with various core materials without the need to wind new coils. Link to comment Share on other sites More sharing options...
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