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Jazz with piezo bridge and rotary switches

Discussion in 'Pickups & Electronics [BG]' started by fatboy250, Sep 3, 2008.


  1. I will be adding a piezo bridge to a standard 5 string jazz. What I am considering is:

    - No volume or tone pots

    - Rotary for pickup selection [maybe a 5 way or 6 way, do they make more or is there a better option?] N, N+B, B, N+P, B+P, P, N+B+P?

    - Rotory switch with caps for master tone[maybe no cap, .01, .033, and .047] Not sure which grouping would sound best for each pickup/pickup grouping. Any suggestions welcome.

    - Last hole?? Mojo knob ?? or Maybe resistor selector to assist with master tone [blank, 100k, 250k, 500k, other choices??] Maybe something that will warm up the piezo tone? What's generally used in an acoustic bass or guitar? If possible I would like to stay away from adding a buffer.

    Any insight or experience with any part of this proposed configuration would be greatly appreciated. This will be EADGC tuning with roundwound strings and I plan to run this through a Digitech BP8 processor which has a tube preamp and 4 band digital EQ.

    Thanks,
    Jason
     
  2. Mushroo

    Mushroo Supporting Member

    Apr 2, 2007
    Massachusetts, USA
    Hi Jason,
    I love piezo bridges! (don't have one currently, except on my ABG, but that's another story.)

    You will definitely need an active buffer if you want to blend the piezo signal with your magnetics. I do not think your pickup selector idea will work, sorry. The magnetics and piezo have such different impedences.

    ps What will you be using for the piezo bridge itself?
     
  3. RyreInc

    RyreInc

    May 11, 2006
    Kalamazoo, MI
    How about two 3-way switches: first does neck/neck+bridge/bridge; second does piezo/piezo+pups/pups only. (I know you want a rotary, but that switching configuration looks confusing to me)

    I like the cap rotary switch, I want one some day!

    Last hole could be a series/parallel switch, phase switch, kill/attenuate switch, or you could have two seperate tone systems for the magnetic pups and the piezo. I also like your idea of a resistor selector.
     
  4. How different will the signals be with the piezo output vs. the mags if they were all running straight to the jack with no volume pots and only the ability to turn them on or off? Is a buffer the only way??

    I purchased a ChoppersMusic 5 string piezo from Ebay for about $75. It looks to be an upgrade in bridge quaility from the stock bridge and I will have the piezo option that I wanted. I thought about going the Radio Shack buzzer route but opted for this instead.

    Will the difference in impedences be so great that caps/resistors with a BP-8 tube preamp/EQ not be good enough to get a good tone? Is it possible to go without caps and still get a good tone?

    If I did use caps or resister for just the piezo would that help? If so, what would you recommend?


    I was thinking that (3) DPDT switches may also do the job. I may be able to have each pickup with (Off//ON w/ no cap//ON with cap and/or resistor). But of course this would only give me one cap per pickup. What do you suggest?

    Then OTOH, do I need caps/resistors if I will be running it all through the BP-8 preamp and EQ??
     
  5. Mushroo

    Mushroo Supporting Member

    Apr 2, 2007
    Massachusetts, USA
    You are heading into relatively unexplored territory, so the best I can say is, give it a try and let us know how it goes! :)

    Personally, I found the sound of an unbuffered piezo on my bass to be unacceptably harsh and thin. Your mileage may vary. ;)
     
  6. I've preamp'd and EQ'd some pretty harsh sounding "naturally aspirated" pups with other projects with good success. They have all had no volume, tone, or caps/resistors. I just thought that maybe I should try something different with the piezo since it is a different "kind" of pickup and I know that they have a tendency to be brittle and harsh to begin with. Do you have any suggestions on caps or resistors for just the piezo?? Do you have any idea what is used in an acoustic guitar or bass?? I was thinking I could run the jazz's straight and have caps/resistors in line with the piezo switching...thoughts?
     
  7. Mushroo

    Mushroo Supporting Member

    Apr 2, 2007
    Massachusetts, USA
    Here's the thing, in a passive circuit, "caps and resistors" can only subtract from the signal, not add to it. Basically you can have tone cut or more tone cut. I am not sure what you're expecting these caps and resistors to do for you.

    Really if you are set on keeping it all-passive, maybe a stereo output so that you can process the mags and piezo separately?

    I have an acoustic bass guitar and it uses a 9v active buffer preamp. I think you will find that 99% of the acoustic/electric guitars on the market use this type of preamp. There is one exception, a luthier who does make a passive magnetic/piezo jazz guitar. Maybe get in touch with him and find out how he does it. http://www.electrocoustic.com/main.html
     
  8. I really am thinking ahead. The piezo, when used, will likely be used alone with EQ settings and preamp, but in the event that I would turn the jazz pickups on I'm thinking that the brittleness and harshness could be "toned down" (nice pun) with the caps in the switch for the piezo. Thoughts?
     
  9. Mushroo

    Mushroo Supporting Member

    Apr 2, 2007
    Massachusetts, USA
    It is really an impedence problem, not an EQ problem. Here's a good intro to piezo technology (Rick Turner knows more about piezos than just about anyone): http://www.bassplayer.com/article/rick-turner-piezo/mar-05/3368
     
  10. Thanks for both links! Good read. I may end up having to just solo the piezo when it gets played and forgo the mags. This bridge style piezo should be able to be EQ'd by itself without a buffer, right? This is definitely new to me, but then so is a lot of this when dealing with pickups and wiring. However, before I knew anything many years ago(not that I know a lot now) I did play a Fender P-bass that came stock with a piezo bridge and I do remember liking the tonal variations.

    If I do solo just the bridge do you have any suggestions for caps or resistors, or should I just leave them out and leave it for the tube preamp and EQ?

    Here's a link to the piezo bridge that I have coming Link
     
  11. Guys, after about 5 different posts asking the kind of questions listed here, I guess I figured there were only a few people that either knew about or want to share concerning adding piezo bridges. For those that did take the time to reply, a big Thank You!!

    Now on to the good stuff. Contrary to popular belief, a piezo bridge can be added to a passive system without a buffer or a preamp. I can say this with certainty because I installed the $73 ebay piezo bridge and it works great! The jazz bass still looks stock (except for this meaty bridge) and works as it did before, but now with a piezo pickup to add to the mix. At this point, the piezo is soldered straight to the jack but is able to be "toned" with the tone knob. Kinda of strange but I guess that's fine too. I guess maybe it's because I have the original bridge ground now under the new piezo bridge. That's all I can figure. In time, I may add a switch to kill the piezo if I want just the jazz pickups. For now though, I will see how I like it mixed at all times. Also, I'm able to dial out the 2 jazz pickups with the stock volume knobs and just have the piezo which really doesn't sound bad all by itself. I do have an "out of phase" type signal when I am crossing over from full on jazz pickup to full off, but just before and just after this threshold I believe it is mixing the two and sounds pretty good. It took me about 3hrs total for the mod. I still have to adjust the intonation and action, but it is playable now and I'm stoked!!:hyper: Total investment for this 5 string SX Jazz with piezo= $187 (Rondo) + ebay nickel strings from a 6 string set (for EADGC tuning) $12 + $73 chrome piezo bridge = $272 :bassist:

    Moral of this story...Don't be afraid to try. Even if you fail, you still learn something. If you succeed, even better!

    All in all, I'm still a better bass player then I am a luthier.:rolleyes: And that's not saying much.

    Still learning,
    Jason
     
  12. Peter Weil

    Peter Weil Seeker of The New Supporting Member

    Mar 29, 2000
    Edinburgh, Scotland
    Hi Jason,

    Nice thread. Do you have any pics of your control cavity? I'd be interested in seeing/duplicating your wiring.

    I have been wondering about doing the same thing with another Jazz Bass I own....I just wonder if, with how you have wired the circuit, whether you have inadvertently done what Dave Wendler does with his MagPi system - the link has been posted elsewhere on this thread - but anyway - http://www.electrocoustic.com/main.html - essentially he says he uses the magnetic pickups to help control the 'phase' of the piezos....?

    Great stuff though.

    Pete
     
  13. Nope - it's because the piezo is in parallel with all the other stuff in the circuit.

    Sounds like it.
     
  14. Hey Pete,
    Sorry I don't have any pics. All I did was take the two wire leads straight to the jack and run the original bridge ground back under the new piezo bridge. Pretty simple stuff for anyone that's been inside of the control cavity before. I, however, am a novice at best that likes to experiment. I also have a few other basses I've "created" - 1) P/P/J 2) P/(JJ-fatjazz 3) Soap/reverse P/Soap 4) J/P/J "Stu-ish" 5) and this one J/J/Piezo. Most I just run without pots and only DPDT switches for series/off/parallel.

    If you try it YOU may consider the on/off switch that I mentioned for the piezo if you want just the mags at some point. I kinda like the "clarity?" that the always-on piezo brings to the mags even when they are full on. Plus, I would have either had to drill the control plate for another switch or made the tone pot hole the on/off switch and just wired the cap in with I guess what would essentially be "full 10" tone.

    Jason
     
  15. Thanks! I'm still not sure how that works but at least I know that it's because it's in parallel with the other stuff. It kinda seems like it would be this way in series, but I'll take your word for it.
     
  16. Peter Weil

    Peter Weil Seeker of The New Supporting Member

    Mar 29, 2000
    Edinburgh, Scotland
    Thanks slyjoe and Jason. This has been helpful.

    I think I may speak directly to Dave Wendler, and ask him more about his method too. It sounds like it is similar to what Jason has done, although I believe Dave uses a 'bias' potentiometer (whatever that is) to control piezo/mag blend on his instruments, as well as having an overall volume control.

    Pete
     
  17. Already been done :)

    http://www.talkbass.com/forum/showthread.php?t=449649&page=2
     
  18. Pete,
    Just wanted to copy this from the other thread and add:
    For my bass, I found that about 3/4 volume on the neck J-pickup, "full on" piezo and full on tone knob I get a good clean yet full sound through the entire range. If I turn the neck volume all the way up I still get a hint of piezo, but starts to sound more like a traditional mag-only setup. I do have a 12AX7 tube preamp with a 4 band eq helping out before it goes into the amp. I've gotten so accustom to this preamp/eq setup that when I run any bass without it I again realize how much this really does add to the overall quality of the final sound. However, I guess if you had an on-board preamp this wouldn't matter as much, but I guess you'd then have to go the buffer route with the piezo.

    Jason
     
  19. Peter Weil

    Peter Weil Seeker of The New Supporting Member

    Mar 29, 2000
    Edinburgh, Scotland
    Thanks for the input, lads.

    I have ordered some of the kit from Dave Wendler, and I will be doing this passive mod to a Jazz-type bass very soon.

    Now, just waiting for all the bits to arrive.

    Pete
     
  20. Mushroo

    Mushroo Supporting Member

    Apr 2, 2007
    Massachusetts, USA
    Nice work Jason, and I apologize for being skeptical earlier. :)
    My previous experiment with piezos did not involve combining the signal with magnetic pickups, so I was not speaking from experience.
     

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