Can you use the head of a combo as a preamp???

Discussion in 'Amps and Cabs [BG]' started by dirk, Jun 11, 2001.

  1. dirk


    Apr 6, 2000
    Memphis, TN
    If I had a power amp, would it be possible to use the head in my combo as a preamp until I could afford a better one like the Ampeg Billy Sheehan or the SWR I.O.D. or god forbid the Peavey Max? My combo is the Carvin PB-200 and it has external speaker connections. Another question is how would I run the power amp out of the combo? From what output on the amp would I connect to the power amps input? Thanks in advance for any feedback.

  2. ubersam


    Oct 12, 2000
    If I understand your question correctly, you want to take the non-amplified line-level signal of the combo into the power amp. Don't connect the speaker out of the combo into the power amp.
  3. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    Are you planning to use different speakers too? If not, I'm not sure that you'd get an enormous improvement. You could certainly hook up a bigger and better amp, but the single speaker is still gonna place some constraints on you.

    Alternatively, it might--if possible (depending on the jacks available on the back of the PB200)--be more productive to get a preamp first and use the Carvin as a power amp + speaker until you can upgrade those components as well. You'd do this by taking the output of the preamp and bringing it into the "Amp In" or maybe the "Effects Return" of the PB200.

    My own bias is that taking the second approach might make a more noticeable change in your sound.
  4. does the carvin have an effects loop in between the preamp and power amp? if so, maybe you could run the "effect send" into the power amp input.
  5. Wouldn't the *line out* socket be the one to connect to an external pwer amp? Then, what about the combo's speaker?

    Mike J.
  6. Gabu


    Jan 2, 2001
    Woodland Hills, CA
    This is similar to what I am planning to do. Take a combo amp and run a line from the line out into a power amp. The power amp needs it's own speakers.

    In my case, The combo is going to be acting as my monitor and going to my cyclops which will be the main doodad.

    In answer to the question at hand. Yes. But be careful how you wire it. If you send your ext speaker output to a amp the signal will be way, way too strong and most likely will kill your power amp right away.
  7. JMX

    JMX Vorsprung durch Technik

    Sep 4, 2000
    Cologne, Germany
    Line out/Preamp out/FX Send - usable (connect to poweramp in, FX return or instrument input [not recommended, but ok])

    speaker out - for the love of god, DON'T use it for anything else than speakers!!!

    P.S.: If you have a parallel FX send - don't forget to turn the FX mixer to 100%
  8. MikeyD


    Sep 9, 2000
    Even if your amp doesn't have a line out, it still may be possible to drive a power amplifier with it. You could feed the speaker output of the main amp (make sure it's loaded properly if a tube amp) and pass it into a voltage divider circuit, then to the power amp. For example, the RMS voltage of a 100-watt amp at 8 ohms is about 28V. Most power amps like to see about 1V input at maximum. One could build a divider circuit to get 1V out from the speaker input. This requires a bit of electronics knowledge and attention to safety. If the resistor network is not designed correctly, you can overheat it at high power and make smoke (or start a fire if you're really into screwing up badly!). Or you can fry the power amp's input.

    Anyway, I have done just this kind of thing in a home stereo application wherein I wanted to feed a signal to a remote stereo receiver (line level input in this case), but only had loudspeaker wiring in the walls between the two systems. It worked quite well.
    - Mike
  9. dirk


    Apr 6, 2000
    Memphis, TN
    I plan to use the 15 in the combo plus I'm getting a 4 10 cab. after I get the 4 10 I'm either getting a new head or a power amp. If I get a power amp I am getting a preamp later. I just need to decide if I will be better off in the long run to go preamp/power amp or a head.
  10. hang on
    on my amp i have a PRE amp in and a PWR amp out
    and i run a Peavey tnt115 old version combo.
    so i can add speakers to this by buying a power amp and hooking up a cab from the pwr amp?

    i got no idea about this pwr amp stuff and all
    and all i wanna do is make my rig look bigger and sound louder hehe.

  11. Richard Lindsey

    Richard Lindsey

    Mar 25, 2000
    Metro NYC
    Are you sure you don't mean a preamp OUT and a power amp IN? That's more what you usually see. Then there would typically be one or more speaker outs, which would naturally go to the speaker(s). These speaker outs represent the output of the power amplifier.

    To reiterate what many have said elsewhere, do not, under *any* circumstances, connect the output of a power amp to the input of another power amp. That's a recipe for trouble. What you want to do is to connect a line-level *preamp* output--however that may be labeled on your particular amp (and labels do vary)--to the input of the second amp. If you're unsure how to do this on your unit, ask the mfr or talk to a knowledgeable friend or a tech.
  12. yeh thats the 1 hehehe i wrote that msg at 3a min da morning so yeh..

    well see the thing is, i dont have a speaker out so that has pissed me off and idiot me didnt have knowledge then when i bort the amp so i think i might sell up and but sumfen else
    what do u think can get that is bout $600 AUD (i think bout $300 USD)

    i know its not much but oh well i think its time for a new rig