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Post by JohnH on Oct 9, 2008 6:42:08 GMT -5
I just did something interesting. I took the guts out of a cheap piezo buzzer and put it behind the trem block on my Strat, and made a credible sounding acoustic pickup. This guitar has no trem springs, and so the trem block is pushed back by the string tension, and usually I block it with a coin and a bottle cap. This time, the piezo disk was under that, being squeezed by the string tension and doing a good job of getting the string sound.
I used aligator clips to connect it to a buffer cable, and then into a mixer. It's quite good and I think it may be worth persuing, a different tone than anything I can get from all the usual pickup combos. I could really use this for acoustic parts in our set, since I only need use the one guitar.
To develop it, it needs a proper installation - I think that position behind the trem block is working well, but it needs to be fully screened, and its own small preamp with a bit of gain to match the mag pickups. The basic sound quality seems fine however, and balanced across the strings and up and down the neck.
Anyone tried anything similar?
John
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Post by D2o on Oct 9, 2008 11:33:35 GMT -5
Hi John, Very cool! I have not tried anything like this, but you have piqued my interest as to whether this could also make a credible pickup for an actual acoustic guitar ... any thoughts? D2o
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Post by 4real on Oct 9, 2008 16:18:46 GMT -5
Ive tried this kind of things a few times...
There is also an old but really good thread over at PG where someone epoxied a pair of them onto a strat block.
In my nightmare wired strat with the uber switches...I stuck one under the neck pocket...this gives a more woody tone...but you could combine it with a bridge one as well.
The preamp is important, but enough to stop loading can make a decent sound...
I have an LP in the works two with a piezo under the bridge (a khaler trem) but attached to the wood...under the bridge pickup would work as well...
These piezo things can sound ok...they can add a lot combined with the mag pickups giving you a zing and a percussive edge...often not so good on their own...
However...they make for a radically new texture...they even can work well with a heavy sound giving the guitar extra bite...
I tend to look at them not so much as an "acoustic" but a radically different electric pickup...
...
On a self interested note...I have a project that I am about to do that is a real collision of worlds. This is an arched top acoustic that I will be adding a strat like neck too, possibly a strat trem even, a single filtertron-esque mini hb (artec) in the neck and a full electro acoustic preamp with EQ and tuner built in!
I am not sure if I am going to have problems combining the electro/acoustic system with the mag thing electronically...
I know...sounds like a real wack thing to even contemplate but I have a bunch of student guitars to take apart and it kind of works in the concept...
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Post by newey on Oct 9, 2008 17:50:25 GMT -5
4Real-
This sounds quite interesting, so please keep us posted. I've been thinking of modding a jazz guitar as well, although not to that extent! ;D
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Post by JohnH on Oct 9, 2008 19:25:50 GMT -5
I’m thinking that both magnetic and piezo pickup systems will have their own JFET preamps, to equalise levels and output impedances. Then a simple pot to mix between them and maybe another buffer stage for output.
4real - What type of piezo elements have you tried?
D2o - I think similar homebrewed piezos are put into acoustics, but obviously details vary. I saw one link where a strip if piezo cable was put in the slot of an acoustic bridge.
John
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Post by 4real on Oct 9, 2008 22:22:43 GMT -5
Above is a typical buzzer element in my uber switch strat project. You need to either shim around or slightly hollow out for the buzzer and thin wires and drill through to the neck pickup cavity...but it is a reversable mod and puts out a fair amount of sound. Downside is some finger noise on the neck when playing up high mostly. Pevey and Taylor both have added piezos in a similar way...this is just my take on it. I originally tested it on the old sustainer guitar thing... You could mount the piezo or multiples anywhere...under the pickups or in a control cavity...I use double sided tape typically.. For a preamp...I have used things like the preCHamp DSE kit or failed sustainer experiments ;-) ... I have used those $3 buzzers but have also found that you can find in your $2 bargain shops these window alarm things that contain them. I got three for $2 once and you get the same kind of element, plus a switch, magnet and set of tiny batteries in the deal. Potentially you can cut them up as well...I have tried that and it works...but soldering to the buzzer is a bugger, so I wouldn't advise it. ... I went a little crazy about a year ago and have a bunch of guitars I bought online for some reason...and some parts (I need to sell a bunch...but I am in melbourne..so I don't know what the freight on these things would be. I got a few different acoustic preamps...what you typically find side mounted on an electro. I know there is a fender one and another that has a chromatic tuner on board and 3-4 band EQ and volume sliders for instance. The piezos in these are those undersaddle strip things, but these too could be mounted into the inside of the guitar under the bridge or on a trem block I suspect. ... The thing I am thinking of making is a ply top arched thing but with a kind of ovation like plastic back and a bolt on neck. I sanded off the fake finish on one and it came out a nice blond. For some reason it has 3 small extra sound holes around the neck pickup position as well as the traditional F-holes...so I want to lose those by adding a pickup in there. The neck is OK...but the fretting bad cheap brass frets. I have other guitars (and some superb bass guitars going cheap) so I took the neck of a strat copy and it can be made to fit. Then I thought I could maybe add a strat bridge to it as well...use up some parts, though I may have to open it up for the springs and such... Basically...looking at an electric feeling neck on a trad shaped jazz body with rockabilly like pickup and the acoustic thing...plus it plays as an acoustic without an amp...and it has an indestructible plastic back...perfect travel guitar or sitting strumming by the TV or BBQ. It actually looks pretty cool! There you go...I took a pic exclusively for GN2...strange idea, but kind of works...the mini HB covers these strange holes under there... pete ps...I'd kind of like to avoid another preamp if I have to...I could run separate outs perhaps...or I thought maybe a volume on the mag running into the piezo preamp to out...
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Post by 4real on Oct 10, 2008 4:41:37 GMT -5
Sorry if I have hi-jacked your thread...I have started a PG thread on this guitar project which could go in any direction really... projectguitar.ibforums.com/index.php?showtopic=38688&pid=397382&st=0entry397382If anyone has any mechanical savvy, I could use some ideas on a proposed multi-tuning tailpiece idea... ... Meanwhile...any assistance I can be to you, or you for me to integrate the piezo system... Generally...you aren't going to get a true "acoustic" sound but a valid sound all the same. The use of multiple piezos can help with the effect and balance. The thing to watch for is that the guitar doesn't become too alive so that it picks up finger noise of bridge handling for instance. I also feel that the mix of piezo and magnetic pickups produces the best effect... Piezo buzzer things can work amazingly well even with a simple preamp or buffer. There is a need for a simple circuit...maybe a simple opamp thing to run a piezo and mix mag pickups easily...but the usual tillman like things will also work... If you play with a dirty sound...then perhaps a stero out is advisable...but on the guitar things I am doing at the moment I have been planning on keeping this aspect pretty simple with the ability on the strat to be able to add only to any selection a preset amount of piezo to the magnetic sound and on the LP most likely a volume or mix control for mag and mix only... The "jazzstrat" (working title) has a piezo thing that I dug up this afternoon... I actually have two...one is a fender branded "classic 4T" with 4 band eq and volume plus chromatic tuner...the other a chinese eT-4 which is very similar to the one I have in my acoustic...I am thinking the fender if the project works out... ... The tuner aspect has got me thinking again of a multi-tuning tailpiece that I have always wanted to develop and I think this guitar has the potential and that tuner could come in handy... The concept is to have a separate lever for each string on the tail piece design so that the strings have two settings standard tuning and drop up to a tone to a tuned setting...hence any mechanical ideas over at that thread... So...anyone with ideas on this...over there is probably best... ... Oh...and I see John H has got some wiring credited as a feature on a fabulous looking guitar over at the PG GOTM for November...the best new guitar design I have seen for ages...the wiring scheme seemed to have worked out great with a really neat no fuss well spread out control layout... My tele came 3rd last month...but nothing beats an acoustic...this month will be equally difficult...I have a feeling the reso is going to get up...but you never know... pete
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Post by JohnH on Oct 10, 2008 7:01:09 GMT -5
Thanks for the input. The gadget I got, at Jaycar, was this: www.jaycar.com.au/productView.asp?ID=AB3440&CATID=15&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=291I've been testing it some more this evening, and mixing it in with the mag sound - its true there are some nice combinations. Since the transducer is going to be transfering the full pressure from the trem block, I'm thinking it will be best if it is substantially mounted, with the pressure evenly spread over the active piezo area. So I'm now mounting it in a sandwich with some hard plastic spacers (OK, they're tiddlywinks), and a couple of examples of the Queens coinage to make bearing pads, all fixed together with epoxy, and a new screened wire which completes work for today. I have also been working on the design of the preamp, which I have running as a sim in 5Spice. 3 JFETs will combine both sorts of pickups, with a pan knob to blend them. If this idea keeps seeming to work, it will go into my Dual-sound Strat design, which will then be Tri-sound. The blender which currently controls series combos will have to be used to do mag to piezo blending instead, but i can use the unused half of the 5-way to do the series combinations, reluctantly forgoing the blending function. BTW 4Real, where can I see the November GOTM's?, I couldn't find that month on PG. cheers John
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Post by 4real on Oct 10, 2008 12:01:58 GMT -5
GOTM Novermber... i67.photobucket.com/albums/h284/hooglebug/deco/28.jpgThe build thread... projectguitar.ibforums.com/index.php?showtopic=36757The Guitar's Web Site (where I saw your name mentioned)... www.afguitars.co.uk/deco_s_jnr_.htmThe Guitar... ... Yes...those are the kind that I have used and are commonly available in a number of places. The same kind of thing can be found in a few places...and they turn up in broken toys and things like these cheap alarm things too... Recently someone suggested using the piezos out of electronic cigarette lighters! I am not sure if these would work...but I do know that if you are careful, you can cut the disc with sharp scissors...soldering to them can be a problem though...so I tend to use the soldering points already used or to the cables already connected... That preamp design sounds like just the ticket and the kind of thing that is called for a lot...many a time I've wanted something like that... ... Nice looking guitar...really interesting neck join. pete
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Post by JohnH on Oct 10, 2008 14:10:43 GMT -5
I really like hoodlebugs designs and I'm happy to have my circuit there. Its the same Dual sound design that I've been on about, but in a custom new-build the control layout works more nicely than squeezing it into a Strat.
John
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Post by warmstrat on Oct 10, 2008 17:28:04 GMT -5
Tut tut, John... There we were thinking we owned the only two Dual-Sounds on the planet. And now there's this guy putting them in this snazzy thing that's not even a Strat. What is the world coming to?
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Post by JohnH on Oct 10, 2008 18:19:18 GMT -5
BTW warmstrat. When you get back to your build ideas with the sustainer, you noted that you were going to replace the blender with a 3-position toggle switch. A noted above, I may do this too, to make the blend position for the piezo blending. But instead of adding a toggle, the other half of the 5-way would be used, so instead of being inactive in series mode, it will do BxM, BxM, BxMxN, MxN, MxN and B,B, BxN, N, N. Im not sure yet, I really like the way the series blender currently works'.
Ive got the new piezo/tiddlywink/coin sandwich tested this morning, and it is a more solid sound than before.
One thing I tried that surprised me: I'd always understood that piezos need very high input impedance preamps to get their best bass. I'm testing with a buffer cable which has 2.2M, but I tried putting a pot across it to see what happens at lower impedances, and only below about 50k did I get any noticeable reduction. Maybe this is a relatively beefy piezo.
John
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Post by 4real on Oct 10, 2008 20:30:33 GMT -5
I think the undersaddle things have given the piezo thing a bad rap with a lot of this kind of thing. The way it is mounted, the size and shape of the piezo and especially where you mount it has a huge affect on things like bass response and the quack attack...
For instance...you are not hearing the vibrations of the string pushing down on the actual crystals...you are getting the signal from the whole bridge. The neck thing gives a much more woody sound as it is picking up the vibrations of the body at this crucial area.
With undersaddle things, you are hearing mostly the strings vibration, but on a real guitar...you are hearing the top as much as anything...
Still...if you ignore the "acoustic" aspirations and treat the things as a different form of electric guitar pickup...you can get some interesting and good results without a huge outlay or fancy hex saddle systems with masses of eq to make it sound "natural"!
I was wondering if things like phase between a the mag and piezo systems has much of an effect?
Also...you may find that a preset amount of piezo is sufficient and add with a PP or toggle. An idea I was thinking (though I didn't think hard enough to know how) was an on switch for the piezo but the volume control only affecting the mags...so turning down the volume brings out more of the piezo when it is selected...
pete
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Post by JohnH on Oct 10, 2008 22:32:21 GMT -5
Well heres where Ive got to: www.soundclick.com/bands/page_songInfo.cfm?bandID=674084&songID=6963724This is a direct recording, with piexo and mag pickups to seperate tracks but from the same take. It starts with peizo only, then both, then the mag gets an overdrive, and then back to piezo. After recording, I added a bit of bass to the piezo track and i might build this into the preamp. The levels Im getting from the piezo at the trem block are similar to the bridge single coil. I really like the mixed sounds. Ive also tried phase changes on the mag pickup, and it does interesting things to the stereo image. cheers John
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Post by 4real on Oct 11, 2008 0:12:58 GMT -5
Not bad john You can tell it is a direct recording and a bit of amplifier colour would help a lot. I think the piezo and mag is the better sound...otherwise the piezo sounds a bit like a cheap acoustic... The distortion sounds..nah... The problem is more that the type of chordal strumming sounds that the percussive piezo does well sounds like mush with the distortion. However...running the piezo and mag through distortion can sound good giving the distortion a real quick attack... In all though, it does sound exceptionally good for what it is and could easily do effective duty in a band thing to insert a bit of "acoustic-like" flavor into a song... A touch of the mag pup adds that body to the sound that the piezo lacks for mine... It gives me hope for my several projects on hold at the moment... ... As for my jazzstrat thing...I may have overcomplicated what I want to achieve with that tuning thing...so I will let that sit for a bit...but the piezo thing is a go with the mag for sure...
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Post by D2o on Oct 11, 2008 7:52:06 GMT -5
I like it! 4real has some good points, including that you are only in the early stages and it was a direct recording, but I think it adds some interesting possibilities. Good stuff. D2o
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Post by ashcatlt on Oct 11, 2008 14:40:49 GMT -5
Thanks for the clip, John!
It sounds to me alot like the acoustic sound of an electric guitar*. If I squint (and I haven't got my contacts in yet, so...) it could sound like a poor recording of a cheap acoustic. I know it was just a quick recording, but I don't think that's the reason it seems to lack midrange definition - the woodiness I expect from an acoustic guitar. You might be able to make up for that via some filtering in the preamp.
I think it could work well in a full band situation, where all you want out of an acoustic is that stringiness. That's the generally stated reason for using those horrible under-saddle things in the first place. To my ear this does a much better job, with none of that annoying click-clack thing I hate so much from under-saddle pickups.
* Since I play exclusively with amp modelers, my stage volume tends to be very low. Thus all of my live recordings include this effect to some extent. I've become kind of fond of it, and find myself unconsciously "playing" the mic sometimes - stepping toward the mic to bring up the string sound and backing off or turning away when I want it to fade out.
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Post by JohnH on Oct 11, 2008 15:10:38 GMT -5
Thanks for the comments. As you can hear, the piezo on its own is a bit plinky sounding. Occasionally one has to play the am radio intro to 'wish you were here ' however. I thought id have another go at mixing that same take, to see what can be done with EQ on the piezo signal. Audacity lets you plot a frequency response spectrum from sections of music, and compared to the mag signal, it shows a roll off of bass and a strong mid hump at 500 to 1000, which reduces up to 1500 Hz. So I EQed to compensate and here is the result: www.soundclick.com/bands/page_songInfo.cfm?bandID=674084&songID=6965401I think it is a more balanced sound, but Im not sure if I can come up with a reasonably simple EQ network that will replicate it. John
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Post by JohnH on Oct 11, 2008 15:20:32 GMT -5
Thanks for the clip, John! It sounds to me alot like the acoustic sound of an electric guitar I agree, and It does have that sound, on this particular guitar. And really, I suppose that is what this pickup is doing, picking up the guitars acoustic sound through vibrations
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Post by 4real on Oct 11, 2008 16:05:44 GMT -5
That's right...the piezo is picking up vibrations of whatever you attach it to...in this case a metal bridge block...
However...without extra preamps you can connect any number of these things up and pickup vibrations from elsewhere...wiring in parallel I imagine...
For instance...the neck thing is more woody as it is hearing the vibrations of the body wood...so the wood acts like an EQ to moderate the frequencies...less quack, more wood.
You could use both and mix them till you get a sound that's right...
Also...you could mount them to the wood in the pickup cavities or even control cavities...
On the other hand...it sounds a lot better if mixed with the Mag system to give it body...so on it's own perhaps not so good, but there is no need to use that sound exclusively to get the acoustic effect...plus an amp might make things sound more cultured...
On modelling...some of the acoustic simulators nowadays are doing a reasonable job with the push of a button...but this is guitar nuts and at a couple of bucks... ;D
...
To be fair...mag pickups direct rarely sound that great...I thought the clip was a pretty accurate account of what you are working with...unfortunately my computer didn't like the hi-fi version (stuttering) but I could tell it was a lot better than the low fi download...
...
hope that keeps the enthusiasm up...be aware that these things pick up vibrations a lot and the guitar body can become alive...handling noise could become a problem...the neck thing is clever, but you can hear the sound of your fingers actually fretting the notes especially up high on the neck...
pete
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Post by JohnH on Oct 11, 2008 18:18:14 GMT -5
What Im finding I think, is that the piezo is picking up the full range of frequencies, which can in principle be brought out through EQ. Im testing to see if there are some simple EQ arangements that will bring the signal nearer to be usable with less mag pickup, since that will make it more useful, but I agree that some mag will usually be better.
On stomp boxes Ive used trhe 'Big Muff' tone stack, and tests this morning are showing that this can give a good improvement in the natural tone, and I can get a bass boost and mid dip which seem to do the trick.
Where it is, it is locked in the core of the guitar, in contact with the body and tremblock, and transmitting signals from the strings. So I think it is a good representative place to find a vibration signal.
John
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Post by ashcatlt on Oct 11, 2008 20:08:04 GMT -5
Audacity lets you plot a frequency response spectrum from sections of music... Any chance of a screenshot? Just for fun. You know.
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Post by JohnH on Oct 11, 2008 21:49:46 GMT -5
Well OK, here's another sample (hands over ears please). Its piezo only, first with no EQ, and then again played through a network of resistors and caps. Each has been normalized for level only. The buzzes come from it being strewn all over the desk with aligator clips: www.soundclick.com/bands/default.cfm?bandID=674084&content=songinfo&songID=6966415And here is a screen shot showing the sample trace, two spectrums, and also the RC network for the second sample modelled with Duncans ToneStack Calculator. You can see the big hump around 700 to 1000hz, slightly supressed in the second sample, but still evident, giving it a honky quality (which is growing on me actually). This is fun John
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Post by newey on Oct 11, 2008 23:43:34 GMT -5
This is big fun! The second half of each clip above, with the EQ applied, gives a very usable acoustic sound. Played through an amp for a bit more warmth it would be very fine indeed. If an onboard EQ to replicate your breadboarded version can be done, I'd say you're there.
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Post by 4real on Oct 12, 2008 0:36:48 GMT -5
Yeah...at first I heard the start and thought...meeehhh, better.... ...but then the second time around...sooo much better... Although the acoustic sims are pretty good...nothing like as dynamically real as that...definitely on the right track there... I will definitely try out a preamp circuit when you get it done...I suspect though that different guitars are going to want a bit of tweaking...but the strat block thing is common enough to be consistent... I'm impressed at the speed at which you are doing this...if you ever have time to do a sim of my sustainer circuit (in secret) it would be cool to know some of the charcteristics that are really going on...not just what I think is happening...ahahaha ... So...if you combine the piezo with a mag does it produce similar cancellation like effects as you get with inbetween strat settings...or reinforcement as with series or phase changes?
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Post by JohnH on Oct 12, 2008 1:33:33 GMT -5
thks again for comments. I think its getting somewhere.
Pete - when Ive been combining piezo and mag sounds, Ive been watching out for phase issues, to see if they reinforce or cancell each other out. And it doesnt really seem to happen. On my neck pickup I have a phase switch, and even if the two signals are adjusted to a good balance, you don't get that thinner out of phase sound when you reverse. The two sounds seem to be independent and just sit next to each other in the mix.
So whats happening? Heres my theory: (ah..hem..ah hem)
Lets just think about the fundamental tone of the note, in which the whole string is flapping from side to side. An acoustic guitar, and this piezo, is sensing the change in string tension applied between bridge and neck. The peak of the signal is when string tension is at its max, which is at the extreme of its side to side motion. But for the mag pup, the peak signal is when the string is moving fastest through the magnetic field, which is as it crosses the centre of its travel. So the two signals are basically 90 degrees out of phase, and they still are, even if you change one by 180 degrees.
John
also, happy to look at the sustainer - secrets are safe with me! Have you tried modelling in 5Spice?
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Post by 4real on Oct 12, 2008 2:09:05 GMT -5
Thanks...that is one of the best plausable explanations I have ever heard...leave off the disclaimer and I'd buy it anyway...
But, yes...I think that is what is happening as I have never noticed any difference...I have heard that with multiple piezos you can get some tone shaping effects...
Remember those old piezo bacus berry bugs that you'd stick on your acoustic (not even a preamp on some of them...hehehe)...you used to have to move them around a bit to get a reasonable sound...
...
I tried a few things like spice but I found the learning curve for me was a bit steep...and other things got in my way...
I kind of worked a lot with a pen and paper...build something on a larger circuitboard...build it...change component values...build it again...change a few things...shrink it a little...build it again...
You get the idea, lots of trials and errors...
The circuit is simple enough though so yeah I might send it your way and see what you think might improve it, or might be curious to what it does...all I know is it works in its own fashion with the kind of basic drivers that I build...
I will be making up a limited batch of them in the near future...
I still don't trust myself with those circuit board ordering programs...I can't afford a super expensive mistake in ordering them...so I am stuck with hand engraving the things (hugely inefficient)!
...
Anyway...that piezo thing is really coming along...it's quite impressive and not only do you get that, but you also get to buffer your guitar with the same circuit...bonus!
pete
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Post by andy on Oct 12, 2008 4:47:02 GMT -5
That last clip is sounding really good! In fact I thought the first half sounded not unlike a single-cone resonator guitar, but the second half could have been an acoustic to my mind, if you had told me it was one! That is a rather ambiguous 'network of resistors and caps' though! Shed any light?
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Post by JohnH on Oct 12, 2008 6:15:16 GMT -5
andy - the network is shown schematically in the lower left of the screen-shot above. Now I need to get that incorporated into a built-in preamp, which is looking like it will need four JFETs. All do-able I think.
cheers John
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Post by newey on Oct 12, 2008 9:40:59 GMT -5
JohnH-
+1 for an exciting idea at minimal cost! And for your thorough evaluation thereof.
Your explanation of why phasing is not an issue is probably correct. I had thought of possible phasing issues yesterday and thought to myself that, since the piezo doesn't work by magnetic induction from the vibrating string, phasing wouldn't be an issue. But your explanation is, I think, more accurate.
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