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Acoustic bass preamp (internal or external)

Discussion in 'Pickups & Electronics [BG]' started by -Asdfgh-, Apr 14, 2014.


  1. -Asdfgh-

    -Asdfgh-

    Joined:
    Apr 13, 2010
    I have a fretless ABG. It sounds great acoustically (nicely EUB like with tapewounds). The issue is that the preamp is a generic one and is all mids and spoils the amplified sound. I can tame it a bit with neutral amping and pulling mids out, but it's not ideal. Replacing it with something that will fit in the same cavity is going to be tricky.

    I have a soundhole pickup for guitar (Fishman) which sounds pretty reasonable on guitar but just results in boomy bass on the the ABG.

    One thing that occurs to me is wiring the piezo output direct to the end pin. I have an old Award-Session preamp which is apparently able to take very high impedance inputs, but that gives me limited EQ options and I haven't tested it as I need to find my adapters that take a 2.5mm connection which is the output of the piezo. Any recommendations or things to look out for?
     
  2. lz4005

    lz4005

    Joined:
    Oct 22, 2013
    Good idea to test it before doing permanent mods, as it sounds like you're planning.

    One thing to keep in mind is that high impedence signals can be a lot more sensitive to long cable runs than regular instrument signals are. Try to keep it as short as possible between the piezo and the pre.
     
  3. -Asdfgh-

    -Asdfgh-

    Joined:
    Apr 13, 2010
    Yes, that's a good point.

    I thought by just bypassing the existing preamp and going piezo to endpin I could make the changes minimal at first (i.e. leave the existing preamp in to fill the hole in the body) but a short cable could suggest something on belt/strap clip.

    It's a shame there doesn''t seem to be any soundhole pickups that might offer something acceptable but I haven't spotted any.
     
  4. 4Mal

    4Mal Supporting Member

    Joined:
    Jun 2, 2002
    Media:
    1
    Location:
    Columbia River Gorge
    Had a Tacoma cb-10 with Fishman on board. I upgraded the pickup to a K&K pure system wired to the jack and used a Fishman Pure Platinum Pro EQ/Preamp. That worked great. Had my luthier pull the fishman on board electronics and make a koa plate to fill the hole.
     
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  6. line6man

    line6man

    Joined:
    Jun 20, 2008
    Location:
    Close to Los Angeles, CA
    It is never a good idea to have an outboard piezo buffer. Due to the high signal impedance, cable capacitance becomes more significant than with standard magnetic pickup signals. The effect is a loss of low frequencies. Piezo elements should always be buffered before the signal exits the instrument.
     
  7. lz4005

    lz4005

    Joined:
    Oct 22, 2013
    A strap or belt mounted preamp will be just fine. And could in theory be closer than a preamp in the upper bout of the instrument.

    In your testing you should try 1, 3 and 6 foot cable to see if it makes a difference to your ears. With a 6 footer you could easily use a floor preamp.
     
  8. -Asdfgh-

    -Asdfgh-

    Joined:
    Apr 13, 2010
    I ran an acoustic guitar long, long ago that was purely passive into an external preamp. Again, cheap guitar for messing around on, sounded great acoustically and I had paid no attention to the piezo in it as I never expected to play it out until the band I was in needed a back-up acoustic guitar. It sounded pretty rough! But it was a cheap piezo set up.

    Anyway, that guitar died when I was going out of a room when someone was coming in and the neck got in the way of the door.
     
  9. 4Mal

    4Mal Supporting Member

    Joined:
    Jun 2, 2002
    Media:
    1
    Location:
    Columbia River Gorge
    Agreed in theory. In my case, going to a better set of transducers and a higher quality floor preamp far outweighed any loss from a 10 to 12 foot cable. That rig was my main player for quite awhile. In those days my trio was normally seated so the relatively short cable wasn't an issue.

    Not sure if the K&K system has different loading characteristics or not...
     
  10. SirMjac28

    SirMjac28 Patiently Waiting For The Next British Invasion Gold Supporting Member

    Joined:
    Aug 25, 2010
    Location:
    The Great Midwest
    I use a BBE Acoustimax I think it's hard to beat with all of it's features.
     
  11. -Asdfgh-

    -Asdfgh-

    Joined:
    Apr 13, 2010
    Thanks for the hints. I can't find any figures for the impedance of one of the preamps I have that I thought might have a very high input impedance but I will give it a try. It's a cheap bass so I don't want to spend more on a preamp than the bass!
     

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