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Installing upright piezos under an electric bridge?

Discussion in 'Pickups & Electronics [BG]' started by dlenaghan, Aug 15, 2012.

  1. So I'd like to install an aftermarket piezo pickup under the bridge of my Guild - How about this one?

    I see a lot of really cheap systems whose quality I don't trust, and integrated systems which would mean replacing the whole bridge. I want to keep the bridge I've got an install a piezo underneath it.

    Has anyone done this before? Any recommended models? A TB search comes up a bit short and most people just replace their bridge with the Hipshot/Ghost system.

    My Guild's bridge has two screws that rest on a body plate and give it this great near-acoustic tone that the neck Bisonic doesn't get so much as the bridge humbucker does, and to be able to blend a real piezo would be priceless, given the demonstrations of the sound reproduction I've heard.

    Here's the bridge in question, for those unfamiliar with the JS-II series: js2-1.

    (This is Chromium's old bass, which happily lives with me now, but it's her sister, a red '71 that will be getting the piezo)

    The stock bridge plate - the one pictured here is custom work - rests on a thinner plate that screws into the body and gives the JS it's customary tone, combined with the stock rosewood saddles. Perfect for a piezo, if I can put it on or under that plate. I'd even wire it so the two magnetic pickups are t/t/v so I don't need to drill another hole: straight volume, no tone for the piezo, and use volumes to blend.

    I've just heard such wonderful examples: the Epiphone Zenith is a very memorable example.

    So - comments? Thoughts?
  2. eddododo

    eddododo Supporting Member

    Apr 7, 2010
    Probably won't work great under the bridge of a solidbody, though with the plate it sits on, who knows..

    I have those pickups.. They certainly aren't AWESOME, but theyd do the trick IF the bridge resonates enough for it to pick up vibrations.. I dont think a metal bridge on a solid body will do well, however.

    If you get the pickup (prolly cheap on ebay) you will need an impedance-matching buffer.
    Search on tb for 'fdeck preamp'
    Or if youre a diy guy GOOGLE (easier to locate result) 'fdeck quick and dirty pre'. Really easy build, makes piezos not sound like garbage through electric bass amps.
  3. Ok, that's one option, though I'd have to have the work done.. The Guild bridge "floats" over the body, with two screws holding the tailing edge into the body so it does vibrate a great deal more than 'full contact' style bridges, which is one reason the tone is so different, but whether it's enough is certainly a question..

    It seems to be hard to find 'AWESOME' pickups or recommendations that aren't for all-in-one systems, and I can certainly understand the advantage of having individual saddles register string pressure separately, but if that's the only option I won't be swapping the bridge: it provides the tone I want to amplify. The pickups do sound very good as they are.
  4. eddododo

    eddododo Supporting Member

    Apr 7, 2010
    Now that I am at a computer i can see the bridge a little better, though im not sure I completely understand it, but I could see how that would work better than your average EB bridge...

    The k&k "double twin" could probably be picked up for pretty cheap if youre resourceful...
    --- actually i just found this for cheap right off the bat ---
    The fishman may be a slightly better pickup (I dont know though, i have not used that particular k&k), but honestly, once I read the review on the Gollihur site, it seems like a stringy-er sound is more ideal for electric (and the fishman is pretty string-y compared to the Gage realist or even the fishman full circle)

    The k&k is cheap new, probably really good deal used, and i think that the coupling of the 4 transducers (vs 2) would lead to a fuller deeper and more balanced sound string-to-string.

    as for the preamp, and someone PLEASE let me know if this is outside of forum rules, I would not mind building you one of the 'quick n dirty' models, as long as youd pay for the parts/shipping (i built mine for less than $20 or so) i have no interest in profit: I am supremely amateur, but a perfectionist and I am looking for anything to wire cause I've built everything within my current ability for myself already :p

    though you may want to research 'buffers' (buffer circuit, buffer preamp, buffer stage in pedal, etc) ; there may be a better way for you, since you'll already have to find a way to combine the piezo and magnet pickup signals. A little mixer/combiner/etc. may already have enough of a buffer to where you wouldnt need a separate preamp at all..

    What kind of amp are you using? If it has high (1-10megOhms or so) input impedence, it may work just fine with the piezo
  5. Well I certainly appreciate the offer - I'm going in tomorrow to have the bridge looked over by a local custom shop I trust.

    About buffering and whatnot -

    I typically play straight into a Sansamp preamp, and there's a long chain of signal effects afterwards, several of which are buffered, others which are true bypass, so I guess the real question is not getting the signal to the amp, but making sure the signal blends with the magnetic pickups. They are all passive, and my single coil is wound to about 6.75k, and I'm not sure what the mini-humbucker is wired to but I'd say just shy of twice that judging form the sound. Is the output impedance from a piezo markedly different than a magnetic pickup? I was thinking just to use a volume control to balance it against the magnetic pickups.

    But if I do need a buffer, I'd be happy to give you a project!:D
  6. About the bridge: basically those two rear screws are the only point of contact. The two forward screws adjust the height of the entire plate from the body, and they rest on a plate which is screwed into the body. The image here is a much heavier bridge, and a much heavier plate than the one I intend on converting, though they both are very acoustic given that they're solid body basses.
  7. So I guess that's actually four points of contact, but you see what I mean. That whole plate 'floats', anchored only by the rear two, I imagine I'd install the transducers with on the underside of the bridge plate, or as an outside possibility, on the saddles. (The saddles on the one I intend to convert are rosewood, not brass as in this particular custom model... though this one's getting professionally de-fretted tomorrow, so perhaps a piezo would be more expressive on it.. decisions, decisions..)
  8. eddododo

    eddododo Supporting Member

    Apr 7, 2010
    I think Piezos are INCREDIBLE with a fretless! with the proper buffer (the sansamp MAY even be enough) piezos have a wild low end (as well as the crystal highs that people tend to associate with piezos).

    as far as the placement of them? the beauty (and often the frustration) of these transducers is you can try them out in as many different positions as you can think of.. I'd be pretty curious as to how well they'd work under the rosewood saddles...
    Also, between the bridge and bridgeplate may be sonically efficient, or even 2 in one place, 2 up top etc.
  9. eddododo

    eddododo Supporting Member

    Apr 7, 2010
    Any luck?
  10. I looked at this thread some time back and thought you might like some help.

    First up I'd say, like others, don't waste your time with the fishman BP1. It's long had it's day. But I'd also say, don't use the K&K either. Both are designed for a specific use on an upright. Electric basses are very different in the way they transfer vibration. Uprights have a lot more vibration and string tension.

    Other thing being, piezo can be good, but it's not perfect for electric. I've just recently finished this bass...


    It's a long thread, but it will give you lots of good ideas to think about and some free buffer circuits as well. The bass has turned out as I desired which is nice. I'm just about to start designing a similar 6 string fretless. Here's some sound files of the bass...

    Just piezo

    All finished with buffers and MM pickup too

  11. ctmullins

    ctmullins fueled by beer and coconut Gold Supporting Member

    Apr 18, 2008
    MS Gulf Coast
    I'm highly opinionated and extremely self-assured
  12. bassbenj


    Aug 11, 2009
    What I'd recommend if you are flush on cash is something from "pickuptheworld" film pickups.


    Not cheap but will work great. You'd glue (double sided sticky tape) the film to the underside of the bridge plate under the saddles.

    Remember this may not work, so you may want to experiment first. Try these:


    These cheapos may have more hum but will give you the idea.

    For a bass you'll need a buffer of at least 10 megohms. Fishman makes some, but for blending with magnetic pickups the Fishman power chip is the way to go. Loads of features. Even does stereo if you plug in the right cable.


    I've used it and it's great. You can't get away with passive in a bass with piezo (it's marginal in a guitar). So your bass is going to end up active. And for that I'd urge you to install a flip-top battery box. It's the icing on the cake.

    The way the power chip works is you first do the standard passive magnetic circuit and then that goes to the chip that mixes with the piezo output. The piezo has it's own volume. Not quite optimum but works.

    Good luck.

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