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Mono Preamp, Stereo Power Amp: Not Enough Gain!

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  • Mono Preamp, Stereo Power Amp: Not Enough Gain!

    I'm using a mono Kittyhawk Quattro rack preamp into a Marshall 9000 stereo power amp and it's not as loud as it should be. Could this be because I'm splitting the output of the preamp? Would that mean each channel is getting half as much gain as it should be? What would be an appropriate solution? I'm considering some sort of buffer/booster/splitter that would split the mono signal and bump each half back up to appropriate levels. Does that make sense to you all? Any suggestions for a schematic for such a dealie?

  • #2
    Is it the 9005 tube power amp?
    Can you be more specific about "not as loud as it should be"? If memory serves, this is a shared power supply so it won't be as loud as you would expect from two 50 watt amps.
    Have you had better results with other preamps, or the FX send from another amp?
    Here's how you can test your theory about the "splitting" of the preamp signal:
    Connect it all up as usual, but turn ch.B volume control off. Check how full power sounds.
    Now disconnect the "split", so you have 1 cord from the preamp going only to Ch.A input. Ch.b on but no signal connected.
    Is it any louder?
    Originally posted by Enzo
    I have a sign in my shop that says, "Never think up reasons not to check something."


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    • #3
      Looking closer, Ch.a input automatically sends to B channel unless something is plugged into B input. So in the second part of the test I described, you will need to insert a dummy plug into ch.b input. Or a cord with nothing connected at the other end.
      Originally posted by Enzo
      I have a sign in my shop that says, "Never think up reasons not to check something."


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      • #4
        Clarification

        I'm beginning to wonder if there's something wrong with my Kittyhawk. I did try what you suggested, and it is louder, but I can still sit right in front of the 4x12 and play at max volume without my face bleeding. The preamp distortion from the KH sounds great, but it's just not translating into volume. My Sound City Concord is the same wattage as half the Marshall and I've never been able to turn it up past 2. I tried running a single 12AX7 booster/pre I built directly into the power amp and it's louder than when I use the Kittyhawk! FYI everything is at 10 for the tests I've been doing, preamp & power amp. All the tubes test good.

        I've had this setup for a while, but I've never used it to play live. I'm getting it ready to sell and realized that the spring reverb unit I have in the rig was actually providing a lot of the boost the system needed to get loud. Once I removed the reverb from the circuit, the volume just withered away. I'm frustrated.

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        • #5
          G1, I'm an idiot. I've had this Marshall 9000 for 15 years at least, and I never noticed the MONO label on Channel A. Hooking it up correctly seems to have fixed the problem. My ears are bleeding and all is right with the world. Thanks!

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