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Post by ms on Dec 20, 2016 6:53:24 GMT -5
When computing the response of, for example, a pickup from the impedance, you have to correctly locate the source in the circuit in order to get the correct response. This is not so difficult with a pickup, but I always get a bit confused when considering eddy currents as well as the more obvious components. Speaking of eddy currents and how to understand them, here is the beginnings of a theory, something I started a few years ago, but have not done much wth since. MutualInductanceLoading.pdf (65.82 KB)
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Post by stratotarts on Dec 20, 2016 6:58:56 GMT -5
Our threads here have definately taken the science of guitar and pickup electronics further than has been presented anywhere before on a public site. On the modelling, the derivation and use of impedance curves is promising so long as it also comes with a voltage vs frequency curve. You need real and complex impedance plus voltage vs frequency to capture it. An impedance curve that varies with frequency will still give a flat-line response into a high impedance input unless voltage change is also modelled. The method of making a 6-part model, although it works quite well, is tricky to form an algorythm for, since there are 6 variables and the result is a close fit rather than an exact match. Ive been using 3 resistors, 2 inductors and 1 cap. To find 6 values you need 6 pieces of info, which are usually highly interactive. The easiest one to get right is to match the measured dcr. So i make the main coil resistance a function of tbe other two and tbe dcr. This then leaves 5x variables. These varaibles cant be fully seperated but each has a more primary effect on certain aspects of the response. It takes many interations to home in. In our loaded and unloaded models, the single cap most directly affects the frequency ratio of the two peaks, in combination with the cable capacitance. Tbe load resistor (in parallel with the whole model) is most effective in changing the height of the unloaded peak. The main inductance gets the peak frequencies where they should be. The second inductor with its series resistor shapes the curves, getting the width of tbe peaks and any mid dips modelled. These are the trickiest ones to select and equally reasonable modells can have a range of values here and still be a good (though not perfect) match. I'm still not sure what the "eddy current" resistor and inductor actually do. I understand inductive/capacitance resonance, but I'm not sure how the parallel resistor and inductor manage to create a second low pass filter that somehow leaves the original inductive/capacitance resonance mostly untouched, as opposed to, say, a resistor by itself, which purely dampens the original resonance, or just an inductor by itself, which acts as a high pass filter. Put the two together in series, and it does neither of those things that they do by themselves. AFAIK, actual eddy current attenuation is external to the pickup circuit; it's within the "AC source" black box. In LTSpice I have to live with the fixed voltage for the AC sweep, but can you just model the eddy currents as an attenuation of the "AC source" with GuitarFreak? Lastly, I don't quite understand how the impedance curve differs from the voltage by frequency bode plots. The impedence is reactance and resistance, we know the resistance is whatever it is, so if you drive the pickups with a constant voltage in, the voltage curve that comes back out must owe to the variable impedance with frequency. So, how is an impedance curve different from what we're doing now? Well, I think the first questions are still open for more research and head banging. To the last question, the impedance curve that we're measuring now doesn't capture phase information, only amplitude. We can see phase on the plots, but because it doesn't convey much more information than the amplitude by just eye-balling it, it isn't of much interest. But when modeling, a precise phase measurement would capture the effect of all the L's and C's in the pickup across the entire spectrum. Here is a document I'm finding useful to understand impedance measurements: Agilent Impedance Measurement Handbook
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Post by reTrEaD on Dec 20, 2016 8:28:24 GMT -5
I personally have held the idea, for decades, that any guitar's tone can be improved by playing loudly, and preferably directly in front of the speaker(s). One might be surprised at just how good a $50 Teisco Del Rey can sound, given the right stage and amp/speaker arrangement. I reckon a Teisco might sound similar to a decent guitar when you get the volume up to the point where blood begins to leak from your ears. Other than that, not-so-much.
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Post by reTrEaD on Dec 20, 2016 8:37:16 GMT -5
Case in point: A few years ago, Guitar Center bought Eric Clapton's "Blackie" for just pennies short of One - Million - Dollars (US). That's enough to feed lunch to everyone, not just the poor kids, in a city the size of Los Angeles for a week, perhaps longer. And why did the price rise so high, at least a thousand times over its intrinsic value? The old "It was good enough for E.C., so it must be worth more. Just look at all that tone he got out of it!" mindset.* There might be another answer to the "why?". bit.ly/2hVsSI6
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Post by blademaster2 on Dec 20, 2016 12:33:56 GMT -5
stratotarts said:
"John's 6-component pickup circuit model does manage to track measured results to fractions of a decibel. There are also some interesting models in Zoeller's work, yet untranslated to English. So there is a lot more hope for it than you suggest...."
I feel like I was misinterpreted here. I am indeed impressed at how well we can match the measured response in simulation using these models and it certainly is useful. My point was that the complexity of the full end-to-end system would only include that response as a part of it, and that the louder you go starts to lessen its dominance. It also seems evident that other parasitics like eddy currents and distributed capacitance versus lumped capacitance might not play a huge role in this response (and since currents are low, this seems reasonable).
sumgai: I have a Teisco that has its own voice, and as you said it can sound beautiful especially when cranked through a nice amplifier like my VOX. In some ways I feel like I was influenced more by marketing than my own ears when I concluded as a teenager that it was a 'bad sounding' guitar, and I am glad I kept it. To the point I think we both have made, when the amplified volume begins to excite the body material of any guitar to become part of the overall tone we get the benefit of that material's own resonant properties added to the intrinsic sound that we had from the guitar before the amplification.
Louder is better, and not only for the amplifier itself but also the guitar.
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Post by reTrEaD on Dec 20, 2016 12:49:02 GMT -5
when the amplified volume begins to excite the body material of any guitar to become part of the overall tone we get the benefit of that material's own resonant properties added to the intrinsic sound that we had from the guitar before the amplification. Louder is better, and not only for the amplifier itself but also the guitar. But as you mentioned earlier, not so good for your better half. I suppose you could get "excite" the body material without exciting the missus. www.parts-express.com/dayton-audio-daex13ct-8-coin-type-13mm-exciter-3w-8-ohm--295-216
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Post by blademaster2 on Dec 20, 2016 13:26:36 GMT -5
Thanks for the link!
That exciter, or a product like it, has been on my mind for years. I would be interested to fasten it somewhere on the guitar body material (within the electronics cavity) and drive it with an amplifier. I do not know how its structural impedance would be best matched to the wood, possibly using a wooden protrusion in the cavity to absorb and pass along the vibrations.
Maybe it would only be annoying, but imagine if it could introduce that 'woody' tone to the guitar even at low volumes, or improve sustain? I would love to hear how it would work even if only as an experiment.
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Post by reTrEaD on Dec 20, 2016 14:20:23 GMT -5
I would be interested to fasten it somewhere on the guitar body material (within the electronics cavity) and drive it with an amplifier. I do not know how its structural impedance would be best matched to the wood, possibly using a wooden protrusion in the cavity to absorb and pass along the vibrations. Rather than further derail this thread with a tangent, it might be more polite to throw some ideas back and forth in a new thread.
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Post by sumgai on Dec 21, 2016 2:01:10 GMT -5
Rather than further derail this thread with a tangent, it might be more polite to throw some ideas back and forth in a new thread. Technically speaking....
The very title of this thread is "Modeling an electic guitar with LTSpice", not just modeling a pickup, or any one other part of the guitar. So perhaps this whole thing should've been moved awhile ago, but since antigua started it, and since the sub-Forum is his domain, I'm gonna make an Executive Decision and leave it right where it is.
But beyond that, the suggestion is actually quite good. I'd probably locate such a new thread right next to newey's Wooden "Stompbox" project, 'cause it's gonna be the same try-and-try-again method of finding the correct (sounding) spot to install the device onto/into the guitar body.
reTrEaD, you have the guide-on, lead the way!
sumgai
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col
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Post by col on Dec 21, 2016 13:43:02 GMT -5
But beyond that, the suggestion is actually quite good. I'd probably locate such a new thread right next to newey's Wooden "Stompbox" project, 'cause it's gonna be the same try-and-try-again method of finding the correct (sounding) spot to install the device onto/into the guitar body.
reTrEaD, you have the guide-on, lead the way!
sumgai
Hmmmm. What about sprinkling a fine powder over the body of the guitar and blasting it with a speaker from beneath? If loud enough, the powder should migrate to the nodes. The exciter would then be placed in the largest void between nodes. My guess is that this would be the best location for the device. Though, of course, the location would vary between guitar body designs and (maybe to a small degree) materials utilised in their construction. Just a thought.
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Post by antigua on Dec 21, 2016 15:14:48 GMT -5
One of the benefits of modelling that I haven't got into yet, but which stratotarts has in the past, is say you have hot pickups and you want them to have the same EQ curve as the low output pickups, or vice versa, it might be possible to duplicate the curve of that other pickup with a resistor / capacitor network parallel or in series with the pickup. This modeling allows for rapid curve matching through trial and error. The current thinking now is that if you want a pickup that has a resonant peak that is a few hundreds hertz higher or lower, you have to spend another $100, and that might not be necessary.
Also, LTSpice and other circuit simulators only deal with electrical modelling, so things like wood body resonance and acoustic feedback are beyond the scope of what this modelling is capable of.
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Post by sumgai on Dec 21, 2016 19:17:34 GMT -5
But beyond that, the suggestion is actually quite good. I'd probably locate such a new thread right next to newey's Wooden "Stompbox" project, 'cause it's gonna be the same try-and-try-again method of finding the correct (sounding) spot to install the device onto/into the guitar body.
Hmmmm. What about sprinkling a fine powder over the body of the guitar and blasting it with a speaker from beneath? If loud enough, the powder should migrate to the nodes. The exciter would then be placed in the largest void between nodes. My guess is that this would be the best location for the device. Though, of course, the location would vary between guitar body designs and (maybe to a small degree) materials utilised in their construction. Just a thought. Well, I'm gonna bet that such things as cavities, carved tops, tummy cutaways, forearm cutaways, shallow depressions around the knobs (for that below-the-surface look), neck pockets, etc. will all cause strange migration patterns, nodes notwithstanding. Though as a first shot, this ain't a dumb idea.
I should think that the area between the nodes closest to the bridge would be an ideal candidate....
And don't forget the back of the guitar body, that's just as valid a place as any other to strap on an exciter.
HTH
sumgai
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Post by blademaster2 on Dec 22, 2016 11:05:19 GMT -5
This would be great to try, and of course nobody wants to carve up a good guitar or damage its finish just to try it out.
As I implied before, my first suggestion would be to fasten an exciter directly to the wood within the electronics cavity (if there is room for it) and hope that its mechanical impedance can couple the energy reasonably well into the body from there. Since it is designed for that type of coupling, such as furniture, then it might already be well suited. Then an amplified version of the signal from the guitar could be fed to the device either with the plate removed - for experimentation - or by adding a connector to the plate to which the amplifier output cable can mate.
Modeling this would be great, but I have my doubts as to how it could be done accurately so I would rely instead on experimentation and testing. Qualitative testing is easy - just listen to the guitar as the amplified signal fed to the exciter device is varied from zero to full (as much as the exciter can tolerate).
If the results warranted, then selection of the best placement of the device on the guitar might be the next step - if someone really thinks it improves the guitar tone enough to take that step. I would expect that nearest to the pickups or bridge might be best, but to optimize it some form of mechanical impedance matching might be required where other features would be needed on the guitar body design.
I wish I could conduct this type of research in my day job!
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Post by reTrEaD on Dec 22, 2016 12:09:17 GMT -5
There's a lot of "gumbo" going on here so I created a thread just for discussion of the tangent we've taken. How exciting! Adding mechanical feedback to a guitar.Anyone wishing to continue the discussion on exciters should go there. My apologies to antigua for my part in derailing his thread.
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Post by Charlie Honkmeister on Dec 23, 2016 16:21:20 GMT -5
Antigua, Many thanks for taking the time to give a step by step tutorial on using LTSpice to sim guitar circuits. Also, ms, thanks for the Python example. I'd like to throw in a couple of side comments along the lines of Antigua's post, having messed with this stuff for a while now. (I use Circuitlab but that's a paid service; free is good too.) 1. A good LCR meter is a godsend if you are really delving into this pickup voicing stuff to any large degree. The DER EE DE-5000 has been tested to be as good as the Extech (the handheld gold standard) by the technically knowledgeable folks in the Pickup Makers forum. The absolute necessity here is to do your pickup testing at a 100 Hz or 120 Hz test frequency. The reason is that eddy losses in a pickup are proportional to frequency and low test frequencies minimize this error. The DE-5000 is about 110bucks with both sets of test probes on Ebay, less than two big name brand pickups. 2. I completely agree with newey on "marketing." A lot of the mumbo jumbo and mystique in the pickup business serves those who manufacture the pickups. A lot of times, musicians are paying lots of money to swap PU's when they could have some other alternatives (pot values, loading resistors, amp settings, pedals, different tone caps) for creating a different expressive tone with their instrument and rig, as you pointed out. The same "mystique marketing" thing applies to guitars, tonewood, amps, pedals, you name it. 3. I'm a firm believer in active buffering and have (re) discovered that it's really easy if you already are going to use a buffer, to use the buffer to creat a pot-controlled variable capacitor so you can tune and tweak the resonant frequency to your heart's content. This IMHO is vastly better as a tone control than the conventional passive tone control. With some good measurements of the pickup with the LCR meter, I can plug those numbers into Circuitlab to set the resonant frequency and Q of the buffered pickup circuit, without having to worry about what cable/amp/pedal the player is going to use. So that's really the next step of modelling the signal chain - engineering the signal chain. For anyone who's interested, here's a link to a demo I did, and some technical information, on the variable resonance tone control technique: music-electronics-forum.com/t43081/
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Post by antigua on Dec 23, 2016 17:05:42 GMT -5
Antigua, Many thanks for taking the time to give a step by step tutorial on using LTSpice to sim guitar circuits. Also, ms, thanks for the Python example. I'd like to throw in a couple of side comments along the lines of Antigua's post, having messed with this stuff for a while now. (I use Circuitlab but that's a paid service; free is good too.) 1. A good LCR meter is a godsend if you are really delving into this pickup voicing stuff to any large degree. The DER EE DE-5000 has been tested to be as good as the Extech (the handheld gold standard) by the technically knowledgeable folks in the Pickup Makers forum. The absolute necessity here is to do your pickup testing at a 100 Hz or 120 Hz test frequency. The reason is that eddy losses in a pickup are proportional to frequency and low test frequencies minimize this error. The DE-5000 is about 110bucks with both sets of test probes on Ebay, less than two big name brand pickups. 2. I completely agree with newey on "marketing." A lot of the mumbo jumbo and mystique in the pickup business serves those who manufacture the pickups. A lot of times, musicians are paying lots of money to swap PU's when they could have some other alternatives (pot values, loading resistors, amp settings, pedals, different tone caps) for creating a different expressive tone with their instrument and rig, as you pointed out. The same "mystique marketing" thing applies to guitars, tonewood, amps, pedals, you name it. 3. I'm a firm believer in active buffering and have (re) discovered that it's really easy if you already are going to use a buffer, to use the buffer to creat a pot-controlled variable capacitor so you can tune and tweak the resonant frequency to your heart's content. This IMHO is vastly better as a tone control than the conventional passive tone control. With some good measurements of the pickup with the LCR meter, I can plug those numbers into Circuitlab to set the resonant frequency and Q of the buffered pickup circuit, without having to worry about what cable/amp/pedal the player is going to use. So that's really the next step of modelling the signal chain - engineering the signal chain. For anyone who's interested, here's a link to a demo I did, and some technical information, on the variable resonance tone control technique: music-electronics-forum.com/t43081/ The DER-EE-DE-5000 looks promising. I see it tests at 100kHz, which Manfred Zollner said would be preferable to the 120Hz of the Extech, since the 120Hz is a harmonic of 60Hz, meaning EMI could possibly interfere with measurements. I'll link to this device in my other write-up about pickup measurements. As far as marketing, the onus is on us nerds to market ourselves better. I saddens me to see such a wealth of useful information be presented in such arcane language and presentation. Is a wah-wah pedal anything like pot controlled capacitance? It sure sounds a lot like what I would expect such a thing to sound like. Thanks for joining in, and feel free to create a new thread about the variable resonance circuit to give it more exposure. It will also improve the likelihood of a search engines finding your work. I'm currently messing with passive circuits that try to move the resonance to a useful degree without gutting the output voltage. It wouldn't work half as good as an active circuit, but batteries can be sort of a mental and practical hurdle to overcome.
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Post by stratotarts on Dec 23, 2016 18:51:54 GMT -5
Here is a very promising vari-C circuit:
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Post by ashcatlt on Dec 23, 2016 20:26:47 GMT -5
LTSpice will also generate and/or process .wav audio files. It takes forfrickinever, but it works pretty neat. IDK how that could be used in this particular context, but I'm sure you folks can figure something out. Then there's LiveSpice, which I've never used, but was developed by one of the guys over at the diystompboxes forum. It does live audio through your simulated circuit, and is supposed to eventually create VST plugins that you can use in any DAW.
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Post by antigua on Dec 23, 2016 21:34:19 GMT -5
LTSpice will also generate and/or process .wav audio files. It takes forfrickinever, but it works pretty neat. IDK how that could be used in this particular context, but I'm sure you folks can figure something out. Then there's LiveSpice, which I've never used, but was developed by one of the guys over at the diystompboxes forum. It does live audio through your simulated circuit, and is supposed to eventually create VST plugins that you can use in any DAW. Thanks for the tip. That would be very useful, I'll check that out.
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Post by Charlie Honkmeister on Dec 24, 2016 17:32:29 GMT -5
Antigua, you said: "Is a wah-wah pedal anything like pot controlled capacitance? It sure sounds a lot like what I would expect such a thing to sound like." You are 100% on the nose with that supposition. The pot-controlled capacitance trick was first seen in the original Hammond/Vox Cry Baby wah pedal in the '60's. Here's a post I made on the subject which links to R.G. Keen's analysis of the wah pedal. music-electronics-forum.com/t37793-post362519/#post362519In terms of "does it sound like a wah pedal?" the answer is, It depends. If you make it peaky, with large Q values, it can indeed sound like a wah. But in this case we are carefully controlling the Q value and resonance range to get a desired result. Also, there's only a single resonant peak. You aren't taking a pickup signal which already has one resonant peak, and processing it further with a wah with another resonant peak. The variable resonance tone control really is completely changing the pickup tonality in a musically useful natural-sounding way. For what I was targeting, the desired result is: be able to go from Gibson humbucker tonality (1.8 - 2.5 Khz) to Tele/Strat tonality (3-5 Khz) with one knob on the instrument. If you set the Q value to produce a consistent 8-9.5 dB peak over the whole range, you end up with a very good emulation of what the desired emulated pickup sounds like , loaded by open volume and tone controls, and loaded by some reasonable cable capacitance. The guitar sounds good like that, and I also have the push-pull switch to convert the resonant peak control to just a simple lowpass, to be able to have a "flat" or simply rolled off response from the pickup if desired, for going into a DAW and using plugins. So I haven't seen the need to vary the pickup loading that much, as Roly Roper did with his variable R control. Of course pickup magnetic structure , slant, and position under the strings will play a part in how closely you can emulate another pickup type that's physically different. But so far I have been quite pleased with the results I have been getting with my cheap Chinese single coil sized Strat rail humbuckers in my Strat. The VR buffered tone control really is useful musically and it's darn close to a "dial a pickup" knob. It's great to be able to share this with some technically astute folks such as yourselves. -Charlie
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Post by antigua on Dec 24, 2016 19:12:16 GMT -5
Antigua, you said: "Is a wah-wah pedal anything like pot controlled capacitance? It sure sounds a lot like what I would expect such a thing to sound like." You are 100% on the nose with that supposition. The pot-controlled capacitance trick was first seen in the original Hammond/Vox Cry Baby wah pedal in the '60's. Here's a post I made on the subject which links to R.G. Keen's analysis of the wah pedal. music-electronics-forum.com/t37793-post362519/#post362519In terms of "does it sound like a wah pedal?" the answer is, It depends. If you make it peaky, with large Q values, it can indeed sound like a wah. But in this case we are carefully controlling the Q value and resonance range to get a desired result. Also, there's only a single resonant peak. You aren't taking a pickup signal which already has one resonant peak, and processing it further with a wah with another resonant peak. The variable resonance tone control really is completely changing the pickup tonality in a musically useful natural-sounding way. For what I was targeting, the desired result is: be able to go from Gibson humbucker tonality (1.8 - 2.5 Khz) to Tele/Strat tonality (3-5 Khz) with one knob on the instrument. If you set the Q value to produce a consistent 8-9.5 dB peak over the whole range, you end up with a very good emulation of what the desired emulated pickup sounds like , loaded by open volume and tone controls, and loaded by some reasonable cable capacitance. The guitar sounds good like that, and I also have the push-pull switch to convert the resonant peak control to just a simple lowpass, to be able to have a "flat" or simply rolled off response from the pickup if desired, for going into a DAW and using plugins. So I haven't seen the need to vary the pickup loading that much, as Roly Roper did with his variable R control. Of course pickup magnetic structure , slant, and position under the strings will play a part in how closely you can emulate another pickup type that's physically different. But so far I have been quite pleased with the results I have been getting with my cheap Chinese single coil sized Strat rail humbuckers in my Strat. The VR buffered tone control really is useful musically and it's darn close to a "dial a pickup" knob. It's great to be able to share this with some technically astute folks such as yourselves. -Charlie I've seen "humbucker -> single", "single -> humbucker" modes on a Boss multi-effects pedal, and I thought it sounded decent. I don't remember how convincing it was since it died many years ago, but it would certainly get the job done in a gig. Maybe your circuit is somewhat similar in effect to the Boss effect. There are a couple companies that make on board effects, like Dragonfire and Artec, which could be a single OEM for all I know: www.dragonfireguitars.com/Onboard-Effects_c24.htm;jsessionid=56DE0662FD8513210B550D5B1B15CF82.p3plqscsfapp003I think having that H->S, S->H effect in an on-board could be an appealing product, but one of these established manufacturers would copy your idea before you even sold enough units to make back you investment. Some of these are EQ's, and even though I don't see a product that emulates pickup types, they're a burp away from doing it, if they so choose. Some of their products are passive also, basically various veritone schemes, so a lot of the good ideas are in the market place and are just too low volume to catch much attention. Which brings me back to marketing. At the moment, guitarists seem to respond to two things 1) low cost, and 2) vintage correctness. They paradoxically want both. One slant you could put on this is; PAFs were notorious for featuring a variety of winds, from low and clear, to hot and growly, and here is a low cost, hidden on board device that gives one Les Paul the tonal variety of several different PAFs, the number depending only on how fine grained the peaks and Q's are. As an aside, I was disappointed that the Fishman Fluence didn't incorporate much if any of this sort of these peak emulation possibilities in the product. They supposedly have two "voices", but given the platform, and the theme of the product, they could/should have really run with the idea of on-board pickup modeling.
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Post by Charlie Honkmeister on Dec 25, 2016 0:32:51 GMT -5
Antigua, Appreciate your comments. Even with all the external "revoicing" filters/boxes/thingies out there, some of which I've bought before (!), not to mention all the other gee-tar gizmos for 45+ years which have promised to take a player's tone to the pearly gates, there still might be a market for a small, cheap, simple onboard product to really increase the versatility of the instrument for most genres and most amps/FX chains that most of the players will plug into. After all, just in replacement pickups alone, pro and semi-pro players are pretty well used to the idea of dropping $300-500+ for a set of pickups, a wiring scheme, and maybe the tech's installation time, in chasing a "better" sound. In fact, probably 60 to 80% of the current electric guitar/amp/effect/accessory market is based on the business model that a guitarist will chase "the tone" for 10-20 years and never be satisfied, leading to more gear purchases over the long run. Far be it from me to change a proven business model in a $2 billion dollar industry, but I think there's a niche or two available. Maybe it's just working with small builders to custom-voice their instruments, or offering kits on Ebay to allow someone to improve the axe they have without spending the traditional amount of money, or something like that. At least one of my posts a while back was to point out the original articles/Web pages on the variable capacitance tone control, and that it is considered "prior art" and public domain, so one of the big player MI companies couldn't ring-fence the idea with patents. This is a pretty wide-ranging thread and I don't want to divert the stream too much, so I'd like to suggest that we can move the variable resonance tone control discussion to the original thread I posted, guitarnuts2.proboards.com/thread/7823-Charlie
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Post by Charlie Honkmeister on Dec 25, 2016 0:39:45 GMT -5
I also agree with you on the Fishman Fluence. They spent a whiz-bang amount of money developing that, but ended up with just two voicing selections. I've heard they sound good but there's no convincing advantage that the unique coil construction translates into better sound in any way. It's a well engineered product though, just underwhelming in its value proposition.
The way I look at it is that those two voicing selections are just two points on my VR tone control's pot, and I have a lot more choices on the same pot, for a lot less money.
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Post by ashcatlt on Dec 25, 2016 12:41:09 GMT -5
Oops
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Post by antigua on Dec 27, 2016 14:17:43 GMT -5
Antigua, Appreciate your comments. Even with all the external "revoicing" filters/boxes/thingies out there, some of which I've bought before (!), not to mention all the other gee-tar gizmos for 45+ years which have promised to take a player's tone to the pearly gates, there still might be a market for a small, cheap, simple onboard product to really increase the versatility of the instrument for most genres and most amps/FX chains that most of the players will plug into. After all, just in replacement pickups alone, pro and semi-pro players are pretty well used to the idea of dropping $300-500+ for a set of pickups, a wiring scheme, and maybe the tech's installation time, in chasing a "better" sound. In fact, probably 60 to 80% of the current electric guitar/amp/effect/accessory market is based on the business model that a guitarist will chase "the tone" for 10-20 years and never be satisfied, leading to more gear purchases over the long run. I hope you market your product some day. It's not hard to imagine how it can be successfully promoted to guitarists. I think it surpasses the promise of a product like the Fishman Fluence, and would easier to install all at the same time. Personally, I'm "anti-battery" more than anti-buffer, and that's part of why I like the investigation into pickups. It's an investigation into passive circuitry in turn, and this modeling and all this gathered data can be used to get the most mileage out of passive circuits. Vintage guitars are passive, so in a way it's like a re-imaging of history, too. I also like the challenge that passive boundary represents; a de facto set of rules. Going active leaves all that behind.
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Post by Charlie Honkmeister on Dec 30, 2016 10:28:23 GMT -5
Antigua,
I do understand where you are coming from by trying to stay on the passive side when working on enhancing the instrument's tone possibilities. A lot of players feel the same as you do, and I for one, would be appalled at the idea of having to hack up a quality vintage instrument to put anything irreversible in it. I saw too many examples of that in the '70's and '80's.
Having a battery and going active is a big river to cross for a lot of players. But let's use the example of bass players. The majority of basses are active with a battery these days, because performance wise, when it counts, an active bass is capable of a lot more tonality than a passive bass. For those players, that advantage trumped everything else. The same players might have a vintage Precision or Jazz passive in their arsenal, use and enjoy them, but not use them for touring or gigs.
Using active electronics has been done over and over again for electric guitar since it's a mature instrument/market with a lot of people trying to innovate over several decades. I've never been happy with anything active I've built into a guitar until now. For some reason, the EQ wasn't right, or I had too much adjustment and had to dink with too many controls, or it just didn't sound natural, have the mojo whatever that is, etc.
So, the buffer/variable cap trick is absolutely minimalist in terms of how much electronics is added, and uses the pickup itself to form the resonant circuit. That's a key difference from just taking the tone as is, and then doing all kinds of multiple stage filtering to get different sounds out.
I can't overstress how "natural" the variable cap/buffer tone control sounds. But, I did my best to engineer it that way, by using Circuitlab simulation/modeling to select components (loading resistance on the pickup, capacitor values, a few tricks like that) to get realistic resonant peaks that are typical of a passive instrument with pickups loaded by tone and volume pots, and a reasonable cable length to a typical amp input. The surprise was, the modelling and simulation worked and the goal of " dial up another pickup with one knob" was IMHO pretty well achieved.
BTW all of the wiring mods/switching arrangements we have all tried over the years should still be valid with this approach but I prefer to use volume controls after the buffer and, I have no (or vary little) use for passive tone controls as a pot, any more after doing this and hearing the results.
-Charlie
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Post by antigua on Dec 30, 2016 17:09:20 GMT -5
Stratotarts drafted up a circuit design for the V5 integrator and had some PCss' produced, presumably in the East somewhere. I don't know how you go about doing that, but I'd think you could do the same with your schematic, and have them pre-attached to a suitable pot that mounts into most electrics, and boom, you have a product. I've been interested in something like a pickup modeler for a long time, and I was hoping the Fluence would be just that. Even though your device requires batteries, I would buy it, for at least one or two of my guitars.
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Post by Charlie Honkmeister on Jan 4, 2017 0:39:37 GMT -5
Stratotarts drafted up a circuit design for the V5 integrator and had some PCss' produced, presumably in the East somewhere. I don't know how you go about doing that, but I'd think you could do the same with your schematic, and have them pre-attached to a suitable pot that mounts into most electrics, and boom, you have a product. I've been interested in something like a pickup modeler for a long time, and I was hoping the Fluence would be just that. Even though your device requires batteries, I would buy it, for at least one or two of my guitars. The cool thing is that it's really just a buffer, albeit a really good buffer. It can be used for a piezo buffer, mag buffer without variable res tone, or mag buffer with variable res tone. I have it set up so that there's a plug in 8 pin DIP socket which takes a DIP header where you can solder in any RC combination on the input stage as well as the VR cap, so it can work with a variety of PU's , or just jumpered to be a piezo buffer with 10 Meg input impedance. I have SMT PC boards in hand for three variants of the buffer and have built four so far (one clinker with blown traces, three working). I'm getting better at hand soldering the SMT devices and, as long as it's not smaller than an 0805, it's really just a different technique and doesn't require anything more than watching a couple of videos on YouTube to get some hints/tips, and practicing. Of course in production, we are talking solder paste, reflow ovens, and stuff that's more normal for that kind of board. If you have the PCB standardized design files (I use DipTrace), you can get ready-to-stuff boards for about $5.00 for qty. 3 1 inch by 1 inch boards from OSHpark in about a week. So far, the LSK389A (dual monolithic JFET ) board absolutely wins on noise. There's also an extremely subtle tone quality difference that I like, although it may be selection bias on my part. I'm going to be trying another op amp on the op amp SMT board when I get the parts. Yes, a production board which is integrated with a tone pot, would be a good product. Sincerely, thanks for the encouragement. -Charlie
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Post by Charlie Honkmeister on Jan 11, 2017 21:52:02 GMT -5
Apologies for diverting the thread, guys.
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Post by blademaster2 on Jan 13, 2017 16:20:33 GMT -5
BTW all of the wiring mods/switching arrangements we have all tried over the years should still be valid with this approach but I prefer to use volume controls after the buffer and, I have no (or vary little) use for passive tone controls as a pot, any more after doing this and hearing the results. -Charlie In all of my homemade guitars instead of a regular tone control I implemented what I call 'fatness' control, which is all passive. My passive circuit uses a large-value inductor of 1H (that is not a typo) in conjunction with a capacitor and forms a tank circuit to scoop out the mids to a variable extent depending on the rotation of the knob. I simulated it using old-fashioned SPICE many years ago. It allows the guitar tone to be 'thinned' but still preserve the clarity of the attack, and as a result it totally changes the character of the pickup (makes the bridge pick become more 'gentle' than the neck pickup when set to the lowest 'fatness' level). I have never yet used it on the bridge pickup - since those large-value inductors were expensive components - but I might try swapping the bridge and neck tone controls sometime to see how it sounds. Mixing pickups with this control in place adds another dimension to the variety of tone settings it can achieve, and I am still discovering new ways to set it that I never tried before. I was never comfortable with using batteries in my guitars, so my goal was to arrive at a passive tone control solution that would have a stronger effect than conventional controls do. IMHO my design achieved that.
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