bobmirror Posted April 9, 2011 Report Share Posted April 9, 2011 I am posting this question to a number of forums since I'm not sure which are the best. As far as my experience with electronics, I am primarily a musician composer type, but I have soldered quite a few guitar cables in my day. I am looking at adding a piezo pickup to my electric guitar to extend the frequency range and to add a bit of "bite" to the overall sound. Cost is also a factor. I've done a test setup with two separate cables... (the piezo and the stock magnetic pickup being channeled into two tracks in the audio interface of my computer)... I liked the sound after adjusting the gain and correctly mixing the two inside my computer... but it's inconvenient to have to plug in two cables and have unbalanced volume levels right out of the guitar (since I want to be able to use standard guitar FX pedals, etc). I'm just wondering how difficult it would be to mess around in the electronics of my guitar... - to combine the two signals - to add a gain control to the piezo, and - probably to add an amplifier for the piezo as well (unless I can otherwise raise it to the same level as the magnetic pickup, maybe by installing the largest diameter piezo?). Anyone know how to go about this? Even pointing to relevant resources is greatly appreciated. - Lid555 Quote Link to comment Share on other sites More sharing options...
Ripthorn Posted April 11, 2011 Report Share Posted April 11, 2011 This is a pretty simple situation, actually. What I did on my bass was to use a blend pot that blended my two magnetic pickups together. The output of that blend pot went into another blend pot where it was blended with the piezo output. Then I had a master volume and tone. That setup allows for changing the relative volume of all three pickups to have an infinitely variable mix. That would allow you to do away with a gain control on the piezo amplifier (which you will need to avoid a large impedance mismatch on the amplifier end and get the proper sound). It would be a matter of resoldering perhaps a dozen wires and putting together a little preamp (I like the Cafe Walter PZP-1, which has a schematic at his site). It might take a couple hours, tops, and the electronics would cost about $20 - $25 not including the piezo pickup. Quote Link to comment Share on other sites More sharing options...
bobmirror Posted April 15, 2011 Author Report Share Posted April 15, 2011 thanks for the info Ripthorn, I'll break out the ole' soldergun this out this weekend... and see what kind of new guitar tone I come up with. -Lid555 Quote Link to comment Share on other sites More sharing options...
bobmirror Posted April 23, 2011 Author Report Share Posted April 23, 2011 I've done a little minor soldering, but need to find out more or I might mess it up. I've created a wiring diagram of my Charvette guitar (the original wiring). (the coloring isn't related to the color of the wires at all... it's just an attempt at clarity) I tried substituting the piezo for the middle pickup... the level is fine but there's not enough control... (I can't blend it other than with the neck pickup at a mix of 50/50). I'm pretty sure I need a blend pot... Is there any difference between a blend pot and a volume pot or is it just how it's wired? Also... any recommendations as to where in the signal line I would solder? think I'll get a 250 kOhm pot tomorrow... -Lid555 Quote Link to comment Share on other sites More sharing options...
Ripthorn Posted April 25, 2011 Report Share Posted April 25, 2011 A blend pot is different. It has two rows of lugs and in my opinion is much better than just going with a standard pot. What I would do is add another pot (a blend one) that combines the output of the selector switch with the piezo. Run the output of the blend to the volume and tone and have them work as master controls. Of course, your other option is to hang the tone circuit off the output of the selector switch, therefore "only" applying it to the magnetic pickups. I use the quotation marks due to the fact that the blend pot is a passive device and therefore the tone pot will interact with the piezo circuit to some degree. Quote Link to comment Share on other sites More sharing options...
bobmirror Posted April 27, 2011 Author Report Share Posted April 27, 2011 A blend pot is different. It has two rows of lugs and in my opinion is much better than just going with a standard pot. What I would do is add another pot (a blend one) that combines the output of the selector switch with the piezo. Run the output of the blend to the volume and tone and have them work as master controls. Of course, your other option is to hang the tone circuit off the output of the selector switch, therefore "only" applying it to the magnetic pickups. I use the quotation marks due to the fact that the blend pot is a passive device and therefore the tone pot will interact with the piezo circuit to some degree. Thanks for the info Ripthorn, just wondering about the significance of the extra row of lugs... is this then in effect the same as having two regular pots? (controlled with one knob though) In my impatience, I've already gone ahead and done a mod with a regular pot, though I might revise it in the future. I've noticed that there is "bleed" from my magnetic pickup line in my piezo pickup line (ie. even when the knob is turned 100% piezo, 0% magnetic pickups). Is it difficult to get total isolation of signals? (you mentioned that it would also happen with the tone circuit?) Also, one simpler question I had was: is a linear taper best for blending.... or should one still go for audio taper? Quote Link to comment Share on other sites More sharing options...
JohnH Posted May 6, 2011 Report Share Posted May 6, 2011 Hi bob - Ive done pretty much what you are working on. Its all written up on Guitarnuts2: http://guitarnuts2.proboards.com/index.cgi?board=schem&action=display&thread=3718 John Quote Link to comment Share on other sites More sharing options...
ansil Posted December 6, 2011 Report Share Posted December 6, 2011 john i love your work i am pretty sure i bragged on it somewhere else as well much thanks for the link again as i lost it in my bookmarks when the desktop died at my shop. to add to the wonderful peoples posts above i must say that i put mine in the neck pocket. no preamp nothing i ran a shielded cable all the way down the channel and wired it to a 3 way switch. with neutral being off. this way i can get phase reversal with the toggle so i am not locked into one setting. now for the electronics part i used nothing. now i lost a bit of highs this way as you can get some truly beautiful sounds out of it and some lack luster ones as well. its not quite as bright as a traditional bridge placement so YMMV. but for my money of adding a piezo disk to an existing guitar i was completely happy with it. [of course i have a brian moore and a parker fly so if i need traditional piezo sounds i am pretty stacked] for the most part its stock strat wiring with a dpdt on off on switch switching the polarity of the piezo and tying that to the switch output position four is like a wah pedal but not quite. best tone i ever had hardest to describe Quote Link to comment Share on other sites More sharing options...
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