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noob pre/power amp question

Discussion in 'Amps and Cabs [BG]' started by tewnty_two, Mar 16, 2010.

  1. Hey long time lurker first time poster here.

    I have a head I like already and want to keep using it but (as always) want more power can I use a pre or power amp to boost the watts to keep the same sound?:confused:

    hope that makes sense and thanks for any help!
  2. Pre: No
    Power amp: probably, and sort of.

    If your head has an effects loop, you can use the effects out to send signal to a power amp.

    How close you'll get to your head's tone, depends on how much of your tone was coming from your heads pre, and how much from its power amp.
  3. jmac


    May 23, 2007
    Horsham, Pa
    The more detailed information that you provide, the better detailed responses you will get.
  4. scottbass

    scottbass Bass lines like a big, funky giant

    Jul 13, 2004
    Southern MN
    If your head is solid state (transistors, no vaccuum tubes) or hybrid (a few small tubes in the preamp section, but all transistors in the power amp section) you will probably get very close to the same sound by sending your preamp (effects send) into a higher-powered solid state power amp and then into your speaker cabinet(s). If your head is all-tube, there may be a substantial difference in sound by using a separate power amp instead of the one built into your head. Also, if your head is all tube, it should not be operated without a speaker of the proper impedance connected to the main (speaker) output jack.
  5. Thanks for the quick replies, I'm in the process of putting together a rig and was wondering if I found a head that I like that is only say, 100 watts, most likely s.s due to budget restraints, if I added a 500 watt power amp to it would it still sound like the o.g. head but with 600 watts of power. I'm looking to push a 4X10 and possibly a seperate 12. With my friends I play punk/ noisy loud rock and with my cousins and uncles I play blues/motown/soul so I want to be able to blast when needed but still have a nice tone when playing with the fam.
    Thanks again
  6. scottbass

    scottbass Bass lines like a big, funky giant

    Jul 13, 2004
    Southern MN
    No, not 600 watts. Only 500 watts. You would not be using your head's built-in 100-watt power amp. The effects send outputs a very low-power signal to your separate 500-watt power amp. Your head's 100-watt amp would not be working at all.

    In your example, you could conceivably connect your head to one speaker cabinet AND connect the effects send from your head to a separate power amp and speaker cabinet, but then you would be driving the first cabinet with only 100 watts and the second cabinet with 500 watts. It would be better to just use the power amp to drive both cabinets at approximatley 250 watts each, assuming equal impedances.
  7. Bardley


    Nov 16, 2007
    Louisville, KY

    You cannot combine the power amps to get 600 watts. You would still have a 500 watt amp and a 100 watt amp. You would need two separate speaker cabs to use both and as said, if you had two cabs you might as well run them together off the bigger amp. Your 100 watt head would only be using the preamp section.
  8. sweet. thanks scottbass and bardley.. like most everyone else Im trying to save cash and I know you get what you pay for but do you think I'll get more bang for my buck by buying seperate power and pre amps or buying a combo head? mind you I'll be buying used.
  9. scottbass

    scottbass Bass lines like a big, funky giant

    Jul 13, 2004
    Southern MN
    It depends on what you buy for a preamp. You can buy a Sansamp Bass Driver DI (BDDI) for $200 new and a Crown XLS 202D power amp for another $250 new. That setup will give you 660W bridged mono @ 4 ohms, 600W bridged mono @ 8 ohms. If you're lucky enough to find those (or similar) items used, you can put together a rig for about $300. You can also spend A LOT more for an Ampeg, Aguilar, Eden, etc. preamp.

    On the other hand, you can buy a new Acoustic B600H head (preamp + power amp in one case) for $500. That will give you 600 watts @ 2 ohms, somewhat less power at 4 ohms and 8 ohms. You could also probably pick up one of those used for about $300.

    But in your original post you said you already have a bass head you like. In that case, all you need is a used power amp. That will be the best bang for your buck to reach your goal of a 500-watt (or more!) rig. You can probably find a nice used power amp for about $200 - maybe less. Just make sure it can be bridged for mono operation. That way you will be able to connect both channels together into one double-the-power (or almost) mono amp to drive a single cabinet if necessary. Then just use the head you already own as a preamp-only by using the effects send to send signal to your standalone power amp.

    What make/model bass head do you already own?
  10. I was using just a crate b20 and it went out on me awhile back. I thought it was the power cord cause it was "modified" with duct tape ( long story ) but I opened it up and the bored had some evidence of bring fried.

    fyi I started out as a drummer taking after my dad but at that time everyone and their mom was a drummer so I picked up the bass and was playing for about 4 years. Then the kids started popping out and that kept me busy. I went back to the drums a year ago but decided I want to play the bass again cause a) ilove the low end and b) I can play after the kids go to bed which is my only "me" time.

    I seen a sansamp bass driver on craigslist at a local pawnshop so i'm gonna check that out tomorrow.
    Ive heard alot of good things about it so hopefully its a good deal.
  11. scottbass

    scottbass Bass lines like a big, funky giant

    Jul 13, 2004
    Southern MN
    Yeah, if the board on that Crate is fried you probably won't be able to use it as a preamp. If you've got a line on a used Sansamp you're halfway there. Then all you need is a used power amp.

    Good luck!
  12. thanks for all the help!
  13. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

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