Pr3Va1L Posted August 8, 2005 Report Share Posted August 8, 2005 Ok so what value should i use for a piezo pickup... I heard that a 25k would tame the higs so it would sound better, and i heard a 1-2 meg pot would be what I need... So, does anyone know?? Thanks!!! Quote Link to comment Share on other sites More sharing options...
transient Posted August 8, 2005 Report Share Posted August 8, 2005 A 5M pot is suggested for passive installation, if you don't want any loss in tone. A lower value pot will cause loss in high & low frequencies, resulting in a "thin" sound. An active preamp would work even better. . e Quote Link to comment Share on other sites More sharing options...
MerlinTheWizard Posted August 8, 2005 Report Share Posted August 8, 2005 Depending on the piezo pickup used, it can have as high an output impedance as a few Megs, which is huge. You need a 10 Meg pot at least, I'd say. That being said, I really advise against using piezos passively. Given their output impedance, the losses along the cable is usually unacceptable. But you can try and see if that's ok with you. Whatever floats your boat... Quote Link to comment Share on other sites More sharing options...
Devon Headen Posted August 8, 2005 Report Share Posted August 8, 2005 Definitely go for a preamp. Search the forum for the Tillman preamp/buffer. There have been several discussions about it, and I've used it with no problems. It doesn't really matter if you use a pot big enough (like the 5M or 10M that have been mentioned), because as soon as the high impedance signal hits your low impedance cable, your signal is going to deteriorate. Quote Link to comment Share on other sites More sharing options...
transient Posted August 8, 2005 Report Share Posted August 8, 2005 (edited) I'm using this preamp with my Ghost piezo saddles, works great: http://www.scotthelmke.com/Mint-box-buffer.html You could also use the Tillman preamp as Devon suggested. I think it would work even better if you use a 10M resistor instead of the 3M in that circuit. . e Edited August 8, 2005 by transient Quote Link to comment Share on other sites More sharing options...
marksound Posted August 8, 2005 Report Share Posted August 8, 2005 I have a Baggs X-Bridge in one of my Strats with the stock passive volume run through a Fishman Model G preamp mounted on my pedalboard. It works so well (and was so cheap) I bought another as a backup. Quote Link to comment Share on other sites More sharing options...
Pr3Va1L Posted August 9, 2005 Author Report Share Posted August 9, 2005 well, the signal will be buffed and everything... I'm thinking of using the MIMF preamp, wich buffes the signals (pups and piezo) and mixes them for mono... but still, i need a volume pot, and I don't know what size would work..... Quote Link to comment Share on other sites More sharing options...
transient Posted August 9, 2005 Report Share Posted August 9, 2005 You can use any pot value (100k, 250k, 500k or whatever) *after* the buffer. . e Quote Link to comment Share on other sites More sharing options...
lovekraft Posted August 9, 2005 Report Share Posted August 9, 2005 (edited) If you're planning on using the MIMF preamp as designed, you don't need a volume pot for the piezos - there's a blend pot in it that allows you to mix as little (or as much) of each pickup set into the final signal as you like, and a volume pot to set the output level of the mix. If for some unknown reason you simply must have a pre-buffer volume pot, a 5 Megohm audio taper will do the trick, but as I said, it's redundant in this particular application. Edited August 9, 2005 by lovekraft Quote Link to comment Share on other sites More sharing options...
Pr3Va1L Posted August 10, 2005 Author Report Share Posted August 10, 2005 thing is i DON'T want a blend pot... I'll find a way to remove it (my dad's an electrician...) but i still need a volume pot... Quote Link to comment Share on other sites More sharing options...
lovekraft Posted August 10, 2005 Report Share Posted August 10, 2005 The blend pot takes the place of two volume pots - why on earth would you not want it? Still, if you don't want a blend pot, why not just use the ( or a pair of them - one for piezos and one for magnetics), and use whatever volume pot you choose after the preamp, as was previously suggested (you can go a slow as 50K with no worries). It makes no sense to "devolve" the MIMF preamp to do less than it was designed to do when there are plenty of simple ciruits (that haven't been painstakingly optimized for a particular job) to use in less sophisticated applications. If all you need is a clawhammer, you don't grab the precision micrometer, even if the weight is about right to drive your nails. Quote Link to comment Share on other sites More sharing options...
Pr3Va1L Posted August 11, 2005 Author Report Share Posted August 11, 2005 whoa triple post !!! lol anyways, I want a volume for each pickups... so 2 volumes anyways, so why have a blend pot The reason for using the MIMF preamp is because i want to BLEND the 2 outputs! I plan on trying to modify it to be able to blend it AND have it stereo... But anyways... the tillman won't blend the outputs so i'm stuck with the mimf preamp. Quote Link to comment Share on other sites More sharing options...
lovekraft Posted August 11, 2005 Report Share Posted August 11, 2005 That's the cool thing about being a Mod - you can clean up your messes! A simple 3PDT toggle switch will remove the blend pot from the circuit and reroute one of the signals for stereo outputs. FWIW, the blend pot in the MIMF preamp is blending the preamp outputs (that output stage is just a summer for blending the two preamps). You're re-inventing the wheel, but I guess that's your prerogative. Good luck with it! Quote Link to comment Share on other sites More sharing options...
Pr3Va1L Posted August 11, 2005 Author Report Share Posted August 11, 2005 yayness thanks a lot!! even on MIMF i didn't get a definitive awnser like that the signal that dosen't get rerouted... wouldn't the sound be somewhat be changed? Me reinventing the wheel?? NEVER!!!! lol Fishman does it, why not me? Quote Link to comment Share on other sites More sharing options...
lovekraft Posted August 12, 2005 Report Share Posted August 12, 2005 the signal that dosen't get rerouted... wouldn't the sound be somewhat be changed?Why would it change? The signal path for it is unchanged, just like when you unplug a mic from one mixer channel, it doesn't mess with the others. Quote Link to comment Share on other sites More sharing options...
Pr3Va1L Posted August 15, 2005 Author Report Share Posted August 15, 2005 i'm sorry i'm just BAD with electronics... I'd need to learn that stuff someday... anyways, it seemed to me (from the schems and some talk in mimf forums) that the signals got transformed a bit after going through the blend pot... mixed togheter using a JFET, no? What if I choose to use a blend pot, could I still switch it somewhat? Quote Link to comment Share on other sites More sharing options...
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