Sustainer Ideas

[G_urr_A]

You mentioned that it'd need tweaking whenever something changes in the signal path. To me, it feels like it'd really be a good idea to implement several "settable" presets. Of course, these could be used both for having several different "sustainer based" effects, or for having one effect but different settings for use with different pups.

How you'd implement that electrically I don't really know though... And it's kind of difficult to say much about what controls I'd want when I don't know how it feels to play around with it.

About mounting the sustainer-thingy at the bridge or somewhere else, I wouldn't really be bothered (I'd get the thing if I wanted it, regardless of it's demands for position), but I guess it's easier to keep it clean looking if it's near the bridge, especially on rear routed guitars. So I think it's worth some time exploring the bridge positions. I personally wouldn't be concerned right now, since all my guitars are black (and black cables should match neatly), but if you've got a nice flamed maple top with an oil finnish, it'll be difficult to have the cable(s) there without them being noticed.

Keep it up!

[psw]

Well the cables would either go into the guitar through a hole under the driver, probably 2.5mm hole on either end of the driver with this prototype, or through the pickup cavity so the wires wont show at all.

The bridge mounted guitar (or at least near the bridge) has another benifit...the necessity for a super low action is not so critical and, having the driver close to the strings (1mm) is far less obtrusive. Overall it is much neater but difficult to implement. Nevertheless, I'll give it a bit of a go, started a modified driver design for the purpose this morning. Each time I try this I also alter the driver component values to test for optimum efficiency. It is getting a bit expensive, and as each driver has been different, it's hardly a scientific test.

I'm of the impression that the device could probably retail for about half the cost of current systems, or about the cost of a replacement pickup. Development though is expensive and I'm always destroying some components (as I did this morning) which means pulling it apart to extract and replace the part.

This does not mean that it would be difficult to manufacture (if anyone's interested) as once the design is settled proper jigs and systems could speed up the process and ensure everything goes together ok. The circuitry would no doubt be sent out for manufactur and probably uses surface mount components.

Has anyone seen suitable switches (dpdt). Perhaps something small enough to be incorporated in a surface mounted control "pad", thin pots for same or ideas for perhaps digital switching or control...let me know. The best I've found lately are subminiture slide switches but they aren't really player friendly IMHO.

psw

[Steve Vai]

I'm probably going to get a Strat style guitar with one bridge humbucker and a pickguard, so the mounting I'd want is the same as what you've done before. I don't mind very much where it goes as long as it works; next to the bridge would be cool.

[psw]

Fair enough Mr Vai

Now, every now and then, I look in my failure box (there's about fifty different prototypes in there!) and try out some old design or idea. Sometimes new developments in circuitry or understanding make a difference and I get a new direction to explore.

Anyhow, dug up something that I gave up on a while back. Fiddled about with it a little and the idea was good after all...seems to be more powerful, efficient, requires less current and produces less interferance with the other pickups. It uses a new magnetic structure, a development of the last driver's ideas. It does cost twice as much to produce and a little more work but compared to the cost of switches it's not that significant to eventual overall production costs.

Now it seems to work ok in just about any position (near the bridge is fine) but it will need to be a little wider (this width increase may be part of it's success anyway). The dimensions are 1cm between each driver so just over 6cm long, still about 4-5mm thick and about 9mm wide. This width is the significant difference. The last one was 5mm wide.

Also, cause I cant help myself, I thought of a cool way of indicating when the thing is on...5 LED's, one between each string so the whole thing glows. If you sand the tops off and paint them black, the light will still show through but when off will appear black. I'm still fond of the chrome cover so perhaps a black stripe down the middle that lights when in operation.

I'm sure people will think these types of things (packaging, etc) aren't important but there needs to be something to set the thing aside from other devices in the marketplace, especially with something so small. I guess I want people to say, what the hell has that guy using there. Still, it's a matter of taste...I could put LED's on the ends of the device so one would be pointing up at the player or have none and have the indicator near the controls.

The inclusion of these lights wont effect the dimensions of the device as the space is there to allow the magnetic field to "circulate" correctly.

Anyway, looking out for switch options. Got some sub-miniture toggles for the prototype when I get to making up the controls. One idea is to make a new type of jack socket that includes the circuitry, controls and allows space for the battery in the jack socket hole. I could extend it up so that the sensitivity pot is at about the same level as the volume and just under the bridge. Another easy thing would be to make a "tailpiece" that goes behind the bridge and holds the circuitry, battery and controls. With this type of implementation it would be possible to use a slider pot for the sensitivity and I had a thought to mount the switches on their side or slightly angled up. Slide switches (which can be quite small and cheap could also be used.

Anyway...feel free to comment critisize or suggest some alternatives

psw

[Daniel Sorbera]

I think the 5 LED's would make for an awesome looking device

How many controls will it require?

Edited January 21, 2005 by Godin SD

[psw]

I'm not sure yet how many controls...I'd love some suggestions

My test circuit has an on/off switch and a phase reversal (dpdt) switch, plus a sensitivity control and an LED.

I need to find room for the circuit, the above controls and a 9volt battery. My test guitar is practically hollow under the scratch plate so not really a problem but I don't think people will want to cut too many holes in the guitar and the battery will need changing/charging quite often.

There will also be some tweaking trim pots to "tune" the system to the guitar. Pickup power and placement of driver and it's relation to other pickups are the main issues that will need to be adjusted for any given guitar.

Now for controls, as discussed above, I could have like a three way switch replacing the sensitivity knob with sounds set with trimpots from the circuit, but I'm going off this idea.

In line with my "synth" idea the driving signal could be effected to produce a different texture to the sound. Distortion (perhaps some diodes in the feedback circuit) is an obvious one. Tremolo would sound effective too as the intensity of the drive could fluctuate like orchestral strings perhaps. Auto wah would be another interesting one too as it could sweep through harmonics but it does this anyway so I might forget about this.

So perhaps another switch to switch the distortion/tremolo in and out and trimpots somewhere for speed, etc. These ideas will be explored at another time.

Basically intensity on/off and harmonic switch are the minimum. The main problem with an externally mounted control is the depth of the pots and switches and where best to place them. Perhaps there's someone out there who knows about digital switching (4066 chip perhaps) to miniturize this stuff with tiny surface mount push button switches.

Anyway, slow progress, but progress all the same. I have an idea that if the driver is significantly refined, and each one is getting better, the performance will take care of itself and the circuit will be relatively straight forward.

Bye for now

psw

Anyone else have an opinion on LED lit driver...not too much?

[thomasteven]

I personally think it would look kind of odd on a nice Les Paul or something, it would just bring too much attention to itself. Now if it were on some guitar just to fool around with it's not a big deal. Just my honest opinion.

[lovekraft]

No, it's a great idea (anything that glows makes marketing easier!), but add a power switch so the LEDs can be turned off to save current. That glowing strip could easily become your brand image!

As for fancy configuration switching, etc., you could always use cheap DIP switches driving analog switching chips to handle several parameters - it's a convenient way to add programmable "preset" patches that involve changing several different settings with a single switch. It's not MIDI, but it's easy to implement, and simple to troubleshoot and program (a caveman could do it! ). A 16-pin DIP switch and a couple of CD4016 CMOS quad bilateral switches is a complete "preset" package - add another DIP switch for each "preset" patch. You could program several settings, and activate them sequentially with a simple rotary switch (like a varitone switch).

[psw]

thomasteven...yeah, had the same concern, of course you could turn them off. With digital switching you could even have them light up to show you which mode your in...outside 2 for fundumental 3 for harmonic and five for beserk boost mode. Or, you could wire them to the signal which carrys a lot of current so that they light when you play. As I say, when off they just look black. They would also help in installation too. The alignment of the drivers with the stings is important. I build the a cm apart, having lights 1cm apart, between the strings may help DIY's get this right...of course a ruler would work just as well!

Basically digital switching is attractive because I figure you could use momentary surface mount spst switches to activate as many poles as would be required. Now, finding some kind of pot or something that could be mounted with them might be a little tricky....any ideas?

Anyway...after wasting a whole day and about $20 worth of hard to get components on my last idea....I'm back to the silver driver. Still learn't some valuable information from the experiment.

LK, glad to see your back to contributing publically on this . I think I've found out where the high frequency noise is comming from....the driver cables....doh! So, any thoughts on how to address this problem. You'll see from the photo that I'm using quite thick (2mm perhaps) cables as I thought they'd impede the current less. They are however reasonably long. Basically thin speaker cables. They are also separate, coming out at either end.

Now, if I get the wires well away from the guitar's electronics the thing seems to work perfectly. I mentioned that the tone control helped control the high frequency oscillation. It turns out that it isn't affecting the signal into the driver's circuitry so much (I've spent quite a bit of effort filtering highs out of the circuitry) but attenuating the highs in the guitars output to cope with this interferance. It also explains why sometimes the thing works and then when I come back with the same settings, the wires have moved and the thing goes beserk! This makes a mockery of a lot of my results so that success with the bridge driver say is hard to replicate. The fact that it has worked indicates that it's possible but something as simple as this dramatically effects progress in this direction.

So how do I solve the problem. Shorter leads I guess. ferrite beads on the line? Power amp circuit as close as possible to the driver? Non metalic cover for the driver array? Better internal shielding? Some kind of noise cancelling inverted signal perhaps?

Solving this could make all the difference and I could move straight on to the issue of control....or at least build this thing into this guitar.

One good thing is that I think I have established that the silver driver works perfectly well to produce a result that surpasses the current sustainer technology. This is pleasing because this design is easier and cheaper to make than some others with less chance of me superglueing my fingures together again!

thanks

psw

[thomasteven]

It also explains why sometimes the thing works and then when I come back with the same settings, the wires have moved and the thing goes beserk!

Excuse me if I'm wrong, but somewhere I read that if power wires come near wires carrying audio signals there can be a lot of feedback/fuzz/noise/whatever you'd like to call it. Now this may be only for AC or only DC, I'm not completely sure, just thought I'd offer my advice to help with some of the problems.

[lovekraft]

Well, I don't think that your 9 volt supply is going to tax the current-handling capabilities of any kind of decent audio wire. It might be worth trying shielded cable with only the control box end grounded - That might get you enough isolation to cut the oscillation. The other obvious possibility is to twist the driver wires tightly together like the heater wires in a good tube amp. You might even try a shielded, twisted-pair mic cable, and make sure your LED and amp power supply connections are bypassed to ground with a big cap for each. Sorry, that's all I got unless you can tell me the approximate frequency, and then we can discourage it with a notch filter.

[psw]

OK...well I guess I should have mentioned that the effect is not as bad with the battery versus the regulated power supply which I guess allows it to draw as much current as it likes.

The frequency changes under different conditions, even moving the wire around, so I don't think filtering it out is the solution.

So, shielding it could help? OK, thats easy enough...I had this idea that the noise would transfer into the ground and on into the guitars electronics. Should the circuitry not be connected to the guitar's main ground somehow? It picks it up from the bridge pickups signal into the device.

Changing the phase of the pickups (which reverses the signal) changes the harmonic just like the harmonic switch (which reverses the driver wires) with different noise. It particularly doesn't like both neck and bridge pickups on. But this is a complcated situation with the induction boost, the original and the transferring pickups.

I get the feeling that distortion in the driving signal is also detrimental to efficient drive. The pre-amp has a 40db boost and the signal is attenuated through (I think) a 10k (or is it 1k) pot. Would I get more control with a larger pot after the preamp?

I should still probably round off the highs in the preamp. I'm thinking of putting together a preamp from a 074 quad op-amp chip. Probably a unity gain buffer for isolation, trimming volume, a say x10 preamp stage with some kind of high frequency timing and midrange boost, then on to the poweramp stage. I'd then have two spare op-amps for signal modification or some other preamp functions (say piezo amp, booster) separate from the driver. Or they could be used to adjust for the different pickup volumes. Electronics are not my strong point.

How about those push buttons / digital switching ideas? You got any ideas for an alternative control than a pot...something thin that could surface mount to the outside of the guitar.

Also, probably will split the pre-amp and driver amp sections to limit the driver cable length. Idealy the power amp would be built in to the driver, which I had thought of before but I don't have space for even SMD electrolytic capacitors. Are there alternatives to those larger output caps in the power amp. What would happen without them and just coupling caps or chip capacitors? If it's just that it would loose bass and I cut all the highs off we might get something of the midrange signal I'm after. The lower strings, being thicker and having more mass, and moving at a slower speed, are far easier to drive. The A string is always the first to drive. Powerful signals like these swamp the others in chord work in general, or so it seems.

Anyway, back to real life

psw

oh, and LK...I think there is already bypass in the poweramp section, and possibly the preamp also...how big a cap were you thinking? As for the LED's, I don't think that's going to be a problem.

I built half of the 5 light model, it looks pretty cool. I could do something similar with the slimline version...I'm making another slightly shorter version with an LED on either end. I might take the wires from the centre but with shielded cable there is going to have to be a little drillin' to be done.

and, thomasteven...I think your thinking of mains AC causing noise. It gives of a 50hz signal. I think what I'm getting is similar but the amplification and compound regeneration of very high frequencies, probably normal background noise and weird resonant frequenciese in the drivers and pickups,

thanks for the prompt replys, guys

[lovekraft]

Yes, I'm talking large bypass caps, a couple hundred microfarads or more, especially if you're using a wall-wart. You could also use a 6dB/octave lowpass filter at the amp's output to roll off the highs above 1.5KHz to help control it (maybe a series 470ohm resistor and .22uF cap shunted to ground?).

[psw]

Is that the...errr..Zobel network? I don't think I've got a resistor that large in it, I'll perhaps try some different values, maybe a trim pot

Here's another question out of left field. If you shine an LED through a fishing line or clear sheet...will it glow...perhaps a little sanding to deflect the light along it's length...if you get what I mean?

Edited January 23, 2005 by psw

[lovekraft]

Dude, a 470 ohm resistor is very small, just in case that wasn't what you really meant to say. Yeah, that's right, a Zobel network, that's the ticket!

If you can find some fluorescent tinted acrylic sheet, backlight it, and roughen the top surface, you can almost make it look like neon! Is that kinda what you had in mind? Blue LEDs will make red fluorescent acrylic light up like Vegas!!

[psw]

Well yes something like that...perhaps not quite as gaudy. I could expose the magnet array, their nickel plated and light up around them...you can get tiny SMD LED's and wire up a strip also. But then, perhaps I don't want people to be able to see anything of the driver's guts for a while. I thought perhaps some thick fishing line, sanded a little with a hidden LED on each end across the line. I could use bi color LED's so that it would change color with the mode. Anyhow...that can wait a while!

Great News LK....twisting the wires really, really helped. Still works best with the guitars tone down but we are talking the cheapest quality single coil ceramics here and considering this, the performance is great.

Now switching is going to be another issue. Digital is probably be the way to go simply for the number of simutaneous switching that may be required and some kind of gain control. That means I could (I assume) use surface mount momentary push button switches on a thin (say 4mm) control panel mounted wherever you want. Unless somone has some better ideas and know where to get them. I take it that trim pots couldn't take the constant use? Small slider pot may make more sense as it's a little thinner but most people like a knob to wrap their finger around so I'm looking for suggestions.

Inside, I'd suggest a preamp/control circuit. A power amp circuit nearer to the driver, the driver and this control panel. I'm thinking a direct line from the bridge pickup but I'm not sure if I should somehow use the pickup selector or bypass it and have a mode selector from the control panel and disable it when the sustainer is in use. The gain has to be greately diminished when using the neck pickup so, by bypassing the selector, this could be tailored to taste with a trim pot.

By the way guys, I've worked out a way to make the pickup ring version...it requires a different magnet array and is so deeper (perhaps 6mm) but is only about 3mm thick. It probably means a little carving out of the top of a les paul (or any other guitar) under the pickup ring (so it wont be seen) but where only talking a couple of mm so I guess thats the price you pay. I've tested it and in principle it works. Still don't know how humbuckers will react but I don't forsee a problem...could even be better.

So, I'm making a new driver (halfway through it), and working on the circuit. But fitting to the guitar will probably have to wait till I have a better ideal of how to set up the controls. If anyone has knowledge of, or can point me in the direction of digital switching (IC's 4016 or 4066 typically) this could help. Looking at an on/off switch, a fundamental harmonic switch and probably a 2-3 position selector switch.

If I go on to add some simple effects say volume swell, tremolo, distortion then I'd need at least another. Any simple ways of implementing these types of effects would be appreciated. I was thinking of switching in some back to back diodes for clipping and I've got 2 spare LM071 opamps for other stuff not used for the sustainer.

Anyway, looking better all the time.

If I can decide on a suitable final design for the driver I'll set up the jigs to replicate it easily. Once the circuitry is finalized perhaps I'll be able to roll some out for testing by others...at least I'll get an idea of cost. I have the feeling it will be very competative with current systems and perhaps not much more than a replacement pickup.

see ya

psw

[lovekraft]

The digital switching part is easy - use CMOS multiplexers:

http://www.fairchildsemi.com/ds/CD%2FCD4053BC.pdf

You can try using a VSR drill to twist those wires extremely tight, and cover them with heatshrink - it works really well in tube stuff. And since both your driver and the string are acting as lowpass filters, I doubt that you're losing much drive from harmonic distortion, so I wouldn't worry about that. The real limitation is of course headroom, since there's no way for your signal to swing further than +/-4.5volts, but that's a limitation you should be able to work around.

Unless you have a compelling reason to do otherwise, I would hardwire the preamp to the bridge pickup, and isolate its input from the others. That way, you'll have a consistent signal coming in regardless of which pickups are selected at the switch. Of course, you'd know better than anyone about that, but at the very least, it should only use one pickup at a time to source the sustainer driver. Keep the sustainer loop and the output signal completely segregated.

I also think that adding effects is gilding the lily - this thing's going to be complicated enough to set up and use without adding tiny stompbox equivalents to it, and the likelyhood of your distortion sounding anywhere near as good as f'ristance a TS-808 without using up a lot of real estate and being quite costly is pretty slim ( ditto for a tremolo, and if you get me real infinite sustain, I'll do my own controlled volume swells with the volume knob or a volume pedal!!). Why compete with proven poducts that are readily available at extremely low prices, especially if they sound as good or better than yours? Don't bury the strong points of your device with a bunch of dubious "features".

If you can consistently drive the string and still let the user choose whichever pickup selection(s) he wants for the output, you are golden!! Hell, if you can just make the equivalent of a 6 string Ebow, I'll buy the first one at full retail plus VAT, and pay shipping to the US!! If you make a sustainer that simply sustains, no bells and whistles, but will work in any guitar, with any pickup choice, not only will you be head and shoulders above what's currently available, but people will figure out how to use it, especially if you can keep the cost down. You can always release a Limited Edition feature overkill version later, at ten times the price!

OK, I'm done.

[Steve Vai]

Yeah, I'd agree about the effects. I guess it would make it more versatile with the built in effects, but I'd prefer to have the effects come from pedals, and they could turn away some people because it could get too complicated.

Would a driver mounted under a pickguard be too far from the strings to be effective?

[psw]

Hmmm....have we forgotten my hairbrained "natural synthesiser idea?

Firstly...no you can't hide it anywhere...perhaps you could paint it the color of your pickguard but why bother, eventually I'll get it down to something tasteful, I promise! Actually I thought the crome one was quite good, would you prefer black, by chance? Seriously, the thing has to be about 1mm from the string when fretted at the highest string and a low action so the string is reasonably close to it when fretted anywhere along the string. By reasonably I mean very close, OK!

Now...The effects don't compete with others...the idea is not to process the guitar signal like some lame brained sears guitar of yore...no, no, no! The idea is to "effect" the driving signal, thus effecting the way in which the string vibrates. The effect would go between the preamp and the poweramp of the driver circuitry...not the guitar's signal. A tremolo I expect would bring in and out the drive and in harmonic mode cycle the harmonic while the momentum of the string would carry the fundumental through the inbetween cycles. The clipper idea would probably produce a grainier sound, perhaps a bit reedy. Some kind of attack modifier (slow gear) would bring the drive signal in only as a notes natural decay begins so that the the note would die away then come back, perhaps as a harmonic, like a kind of repeat effect. I tried a flanger and it swept up and down sounding the strings harmonics as it touched upon them...very weird.

The sound quality of the effects aren't really that important to the concept as it is the effect they have on the strings vibration that is really being heard. The exception to this is in the "induction drive" mode (which is the boost effect) where the neck pickup sounds the driver's interpretation of the bridge pickup as sensed by the neck! This is a unique feature of my driver that hasn't been put forward as a possibility before...and it's really good. I didn't expect that it would work at all but I think that the size and magnetic structure allows for it in my design.

But yes, perhaps a bit much.....so I'll take that on board!

Now here's a great little article on electronic switching for effects or anything...pretty much what I was getting at:

Tone God's Wicked Switches Article

But you know...perhaps two knobs and a switch are the go. One for gain/or sensitivity...the other a rotary selector. A switch for the on off.

I'm still kind of attracted to a surface mount control and the idea of a stylish box behind the bridge with battery and everything pretty much in it...I need more ideas on how to implement this thing.

Now "hardwire the bridge pickup to the preamp" is exactly what I've done. I don't quite follow the rest, but there are two main modes of operation....bridge pickup, driven from the neck...a clean precise drive sound. The other mode is the neck pickup on which is that above mentioned "induction drive"...aggressive with an enormous boost (like 300%) available (silly really) which needs to be calmed down as the two are ridiculously different in volume.

Ok, so I need on/off, harmonic mode, and drive mode switches (dpdt's) and a gain control. personally I like toggle switches but I'm just not sure how people think about drilling and incorporating that much switchware on their guitar, plus finding room for the 9v battery. This configuration will require the total bypass of pickup selection. On a strat you loose the mid pickup options too that also yield interesting sounds.

So, thanks for your kind words of encouragement, and perhaps I should stick to the core idea. Having got this close, I really want to install it into the guitar but the player/device interface will likely be crucial to it's success. So help me out by putting your minds to what you would want sticking on or out of your guitar and how much your prepared to drill and/or cut into your guitar.

peace, brothers in sustain (still no thoughts on a name by the way?)

psw

[x189player]

I'll drill anything, install anything. Any guitar this thing goes in is a total hotrod, no pretending to be a 57 tele or anything.

I'd suggest looking at switched pots, you know, like a radio volume knob with an off switch. Not sure the value you need for gain, i think generic radio volumes are what, 10k? That would combine two of the most important controls together.

In that case I'd suggest using pull-switch DPDT's for the harmonic mode and drive modes. I like having seperate switches rather than a rotary of combinations- who can remember them?

On a three- knob strat a nice way to install it would be to convert to master volume and tone, and make the third knob the off/gain knob. Swap the other two pots for pull-switch pots and you have a completely stock-looking knob arrangement.

So forgive me for being to the point, but do you have any idea when you might make these available? wild guess? (this year?) I'm really dying of suspense here. sorry if you're sick of hearing the question...

Edited January 24, 2005 by x189player

[psw]

welcome x189 player

yeah I like your idea but your still looking at replacing all the pots in the guitar. I know no one seems to like push buttons or rotary controls or sliding pots. I found some switched pots but I think I'd prefer a switch so that the gain is preset, you don't want to be messing around with the gain when you launch into that super sustain solo.

Perhaps an on-off-on mini toggle could select between normal and "induction drive" and off and another for harmonic selection plus the gain knob. As you say, replacing the tone on a Strat or even Les Paul or adding a knob to others. hat way we're down to two switches and a knob just like the current sustainers but with the addition of the induction drive feature.

As for your other question. When I look at all the time and money that's gone into this thing I better get something out of it. Once the grind of perfecting the system and trying all the alternatives, the solution I'm sure will seem so easy. That's when you get ripped off. I've disclosed too much already I'm sure and there are probably others trying to work out the secrets of the driver. As soon as I let one get out of my hands, someones going to crack it open and go running straight down to the patent office.

Now patents are expensive. Perhaps someone would buy the idea from me, or maybe I'll just go crazy and sell as many as I can before it gets into the wrong hands.

There is still a bit of work to be done. At the moment it's this control issue. I tend to make things too complicated so I need your help here to keep it to basics. The driver is working and my next one will be perhaps a little more universal as it will be thinner and shorter but a bit deeper. I'm anticipatind attaching it to the neck pickup's side so that it will serve as height adjustment. That means probably increasing the pickup slot and cavity width by about 3mm and cutting a section out of the pickup ring on HB guitars.

I haven't really thought about height adjustment for the driver before but I'd appreciate some ideas. The closeness to the strings is rather vital.

anyway, late for work....got to go

psw

[lovekraft]

The clipper idea would probably produce a grainier sound, perhaps a bit reedy. Some kind of attack modifier (slow gear) would bring the drive signal in only as a notes natural decay begins so that the the note would die away then come back, perhaps as a harmonic, like a kind of repeat effect. I tried a flanger and it swept up and down sounding the strings harmonics as it touched upon them...very weird.

What I think you're going to find is that F/X that work in the the frequency/time/phase domain will make obvious changes in the string's timbre (and that of the oscillation that you're fighting ), but amplitude F/X (compression, clipping, tremolo) are only going to change the driver's effectiveness. Tremolo (amplitude modulation) is going to sweep the driver in and out of the "sweet spot" where it drives the string without overdriving it, and clipping harmonics are going to be rolled off by the lowpass filtering that you're using to fight oscillations, especially on the higher notes, leaving basically some compression of the fundamental, and 3rd, 5th and 7th harmonics on the lower notes (since symmetrical clipping adds only odd order harmonics). Just keep in mind that it will also compress the noise in the drive signal, making it even easier to start oscillations.

It's just me, and we all know about my arch-conservative design approach , but I would concentrate on making the system bulletproof, stable and reliable across platforms (eg, LP, PRS, Strat, Tele, etc.), and only then start doing the circuit-bending to get the system to scream like a Yeti or bark like a dog. Substance, then style, but like I said, that's just me.

[Biohazard]

Hi, fantastic stuff psw. LED idea is great, asthetics is something that catches my eye with a product.

I agree that you shouldnt go and build effects into the device though. Keep it at what it was first intended to do, otherwise you concentrate on the side project, then maybe side-side projects and thats why the main project ends up failing.

When you ask what people would like from it in terms of whether they would modify their instrument, I think you may also need to ask further afield than this forum. On here, there are people building instruments from scratch, and putting different electronics in etc, so they are perfectly willing to route extra. Then you get some people like me wiht built in fuzz, aluminium cladded guitar who obviously have no problem routing out extra. However, those guys who have factory guitars of decent quality, those are the ones who dont want to harm their pride and joy, but might love to try a device like this.

[psw]

Very good points both LK and Bio

If effects were to be of use then perhaps later in some kind of add on module. Perhaps I just have a problem finishing anything...always looking for distractions.

So, no effects and no to digital switching for now. In fact, I've just come back from the electronics store and have the parts for another driver (that makes two and the current working prototype). Also I got a really small pot (about 10mm cube plus shaft) that's completely sealed (going to try a A10k after the preamp) and some subminiture dpdt toggle switches.

I'm proposing an external box (stylish I hope) that will accomodate 3 switches, pot, preamp and battery. This will be mounted behind or just below the bridge. A direct line from the bridge pickup and the guitar's output will need to hook up. Possibly a signal line and power to the driver amp. The driver amp will be an internal tiny device in the neck pickup's cavity hard wired to the driver just above it. This will ensure the least interferance and max efficiency for the power amp.

For the external box, with a little effort I hope to make something about the size of two 9v batteries lying side by side, flat. If I shape the enclosure so that the switches and pot are at a 45 degree angle they should fit in ok and the protruding knob and switch toggles wont stick out too much. When you think about it, your standard knob ( ) sticks out more than this.

Now, of course all this stuff could be mounted internally if you wish, but as a demonstration, or potential product, it would show how small the device really is and be usable without too much internal wiring.

I might be able to use those spare opamps to buffer the guitar's output with one and to reduce the output (adjustable) for the "induction drive" when activated.

So:

Switch one is simply on/off but it needs to re-route the guitar's output, bypassing the pickup selector, light an LED and turn on the power.

Switch two, selects between normal (bridge pickup) or "induction drive" (neck pickup) with associated signal reduction on the output for the later.

Switch three, reverses the signal (phase switch) to create the harmonic drive effect.

Sustain pot, adjusts the gain between the preamp and poweramp stages.

Now, if I could find a small on-off-on switch, I could reduce the switches to just two as I said in my last post, but there may be advantages in the three.

Each switch is dpdt...are the above functions possible do you think?

What do you guys think of this proposal?

I'm going to put together the even slimmer driver and muck around with the amp ideas, thanks for your input...I hear you

psw

just two late additions...is there anyway do you think of automatically limiting the induction drive to the level of the bridge pickup...or an adjustable level above...say with a compator or opamp. The tone of the drive is quite different.

and, in this the pickup selector is inactive (just as in present systems I assume) although you get to keep all your pickups as is and get two distict drive modes plus harmonics and variable sensitivity. No one has a problem with that?

Edited January 25, 2005 by psw

[lovekraft]

Why are you eliminating the selector switch? Isn't it easier to simply pick a driver source independent of the selector switch, and leave the user his choice of output sources? It's just so much simpler, more robust, and it doesn't require near as much "surgery" to implement. Am I missing something - is there a reason for not making the other pickups available independent of the drive source?

I'm also unsure of what you mean by "...automatically limiting the induction drive to the level of the bridge pickup..." - do you mean gain control, as in a limiter?

Sorry, you know I'm kinda thick sometimes...