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different output levels from different amps

Discussion in 'Amps, Mics & Pickups [DB]' started by rodsnhawgs, Oct 12, 2018.

  1. rodsnhawgs

    rodsnhawgs Custom builder. G-ratio basses Supporting Member

    Nov 23, 2010
    U.S., WV
    Searched and searched to find how (apparently) impedance of BOTH the DB pickup AND the amp have huge effects on output volume. As most of us have probably tried various gear to maximize our tone, so have I. Here's the scenario(s)...

    Utilizing my old 50s Framus DB and the Realist (under the bridge foot) pickup and Realist docking station as the basis for the comparisons and various cabs (Aguilar (SL, GS), Bergie, Markbass, etc):

    1. Agular TH500 - good response and volume. Able to mix and control EQ
    2. Markbass F1 - same as TH500
    3. GK 1000rb - through the front input, very little output volume. Increasing gain and master has limited effect...didn't pursue it for fear of damaging something
    4. Trickfish Bullhead 1K - same result as the GK

    I've read where some folks use the effects input jack. I'm wondering how this makes a difference.
    I'm also reading where it's important to match pickup impedance to amp impedance to make the signal chain work, apparently avoiding what seems to be happening with the GK and the Trickfish.

    Since I double (electric and DB) occasionally, I don't really want to carry two rigs and I really like the tonality of the GK and Trickfish (one will eventually go) but typically not so much the F1 on electric in some cases.

    Bottom line - is a preamp the solution? Is the effects input the solution? And what is the apparent impedance match/mismatch mystery here?

    Looking forward to an education :) Thanks
  2. This doesn't answer your question directly, but I have never found myself in a situation where I didn't want the preamp. I did a set where my battery died and had to pull the preamp out and the amp handled it fine. When I changed the battery, I gained tone more than volume.
  3. Earl

    Earl Supporting Member

    Try it without the docking station.
    DoubleMIDI and Povl Carstensen like this.
  4. rodsnhawgs

    rodsnhawgs Custom builder. G-ratio basses Supporting Member

    Nov 23, 2010
    U.S., WV
    I've done that....no change
  5. sevenyearsdown

    sevenyearsdown Supporting Member

    Jan 29, 2008
    Sanborn, NY
    I run my preamp into the FX return on my head. It doesn't have anything to do with volume. For me, it simplifies things. It bypasses the preamp EQ and gain stage on the head, turning it into a power amp. The only tone and gain staging I have to worry about is on the upright preamp. Of course you have to be happy with your preamp to run this way, and it has to have a hot enough output to drive a power amp. Some do a better job than others at that last part.

    I'm in the minority here, but I don't feel impedance matching is as important as some others might think. Some preamps sound fine with less than ideal input impedance. Trust what you hear, not what you read in specs.
    Ric Vice and Pat Harris like this.
  6. A low input impedance (in your case the combined impedance of the docking station and the amp) can reduce bass output and also total signal output.
    The amps might have a different sensitivity (with gain fully open) high might be a second source of getting a lower output signal.
    I would never use the Realist (for sound reasons) nor the docking station (because of reducing the input impedance drastically).
    My advice is getting a HPFpre I or II as a high impedance preamp. At least with version II you get a volume knob that does not influence a high input impedance seen by the pickup and the high pass filter is a good add-on. You can mount it under the tailpiece, there are several examples and pictures here on Talkbass.
    Earl, rodsnhawgs and Ric Vice like this.
  7. rodsnhawgs

    rodsnhawgs Custom builder. G-ratio basses Supporting Member

    Nov 23, 2010
    U.S., WV
    Thanks for all the feedback so far. As an update...

    I tried plugging direct into the effects loop input on both the Trickfish and the GK...no change at all. I've tried it with and without the docking station. This is something that (I presume) HAS to be impedance related on these two heads. The little Markbass F1 still works fine.

    I may try a preamp as a test/fix (probably need one anyway to control tone). From what I'm seeing that it appears Fishman or fdeck are the leaders of the pack by way of choice. I also see that there's an HPF 3 out there too.

    Is fdeck still making these?
  8. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    He still makes them. How long have you owned the Realist? If it’s over 4 years old your pickup may be the issue. Have you tried another pickup?
    The Realist can have issues after 4 years.
    DoubleMIDI likes this.
  9. The HPFpre III is made for bass guitar. Francis still thinks the version I or II are better suited to double bass.
    rodsnhawgs and Ric Vice like this.
  10. rodsnhawgs

    rodsnhawgs Custom builder. G-ratio basses Supporting Member

    Nov 23, 2010
    U.S., WV
    It's 4+ for sure. No issues until I tried the DB against the GK and/or the Trickfish. Still works perfectly with the Markbass. I have not tried another p'up.

    This whole impedance matching thing is appears to be really hard to figure out without the specs for amps....or am I missing something very fundamental here?
  11. Ric Vice

    Ric Vice Supporting Member

    Jul 2, 2005
    Olivette, Missouri
    Sometimes it's a PITA since some manufactures don't always make it easy to find the input impedance of their amps, but most do. You usually have to dig deep into the
    owners guide. The 2OOMB is 1 Meg Ohm. Most amps are set at 1 Meg Ohm but there are some notable exceptions. Phil Jones are set at 4 Meg Ohms. The Markbass Big Bang and Nano are 2 Meg Ohms.
    Thing is that even knowing those figures an amplifiers sensitivity, gain structure, and EQ voicing can also effect how it sounds. Your F1 has a 500 K (Kilo) Ohm input impedance.
    Fat bob and rodsnhawgs like this.

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