I'm stupid: Now that we're clear on that, what's a power amp?!!!

Discussion in 'Amps and Cabs [BG]' started by de la mocha, Jun 24, 2008.

  1. de la mocha

    de la mocha

    Aug 20, 2005
    This is my understanding and I maybe wrong, please correct me if I'm wrong! Now, bass amps are usually 250 watts, 500 watts, ect., but power amps, usually used to power PA systems for live sound are 1000 watts, 6000 watts and better. Since we bass players need a lot of power to be heard, and felt, we tend to go to power amps for more head room and sheer power!

    I'm I right s far?


    This is a power amp, right? 1600W/ch @ 2 ohms, 1200W/ch @ 4 ohms, 650W/ch @ 8 ohms, 3200W bridged mono @ 4 ohms, 2400W bridged mono @ 8 ohms. <----I have no idea what this means but that's this power amp's stats.

    But as a bass player, I can't just hook my bass into this and some speakers (I'm not sure why, somebody help me on this).

    I need a pre amp because the power amp and pre amp are not in the same package like regular bass amps, right?

    So now I have to get this....


    This is some sort of pre amp! The only thing I can find are microphone pre amps, I'm not sure if you can use mic preamps for instruments but I believe a pre amp and power amp is needed.

    Now remember, I'm just trying to put this all together folks so I can understand this thing here!

    And to protect and house my amp and pre amp, I need to put it in a case similar to this!


    I hope I'm not looking like a complete idiot here!

    So for the most part, did I nail this thing here? Oh, one last thing:

    Now as far as speakers go, do I use regular PA speakers or regular bass cabs?
  2. Mushroo

    Mushroo Guest

    Apr 2, 2007
    Hi De La Mocha,
    There are no dumb questions here on TB, we are here to help each other out. :)

    Most bass "rigs" have the following 3 components:
    1. Preamp to provide gain and tone shaping (EQ and sometimes extras like compression)
    2. Power amp to make it LOUD
    3. Speakers

    A "head" combines 1 & 2 into one package. A "combo" combines all three into one box. Some people prefer an all-in-one package, others prefer to mix and match separate components. It's really a matter of preference.

    To answer your specific question about preamps, you want one because the signal from your bass may not be "hot" enough to get the most out of the power amp. Also, you probably want some sort of EQ control. You can use a mic preamp (lots of people on TB do) but there are also lots of preamps designed specifically for bass. Most amp companies make at least one preamp--you will find them if you look hard enough! :)

    Oh and speakers, I would recommend bass-specific speakers. A few bassists do use PA speakers though. There is no one solution that works for everyone. Good luck!
  3. Geddyfleaharris

    Geddyfleaharris Supporting Member

    First off....I am no techie either so i will give you my non-technical take on things.

    Overall you are pretty close. An all-in-one bass head is essentially a preamp and a power amp together in one package. The preamp takes your bass signal and boosts it to a level that the power amp can use to produce sound in your cabinets. Plus the preamp usually has an EQ whereas the power amp doesn't. A lot of players do use separate pre amps and power amps. There are preamps that are specific for bass. You don't have to use a mic preamp. Tech 21 Sansamp RBI or RPM are examples of bass preamps. There are several other companies with preamps on the market. I suppose you could use bass bins for cabinets but that's not really practical from a sound or weight point of view. I would use bass specific cabinets.

    IF you are going the preamp/power amp route then a rack is pretty much essential IMO.

    Hope some of this helps. :)
  4. RickenBoogie


    Jul 22, 2007
    Dallas, TX
    Everything said so far gets the ole +1 here. As for bass preamps, there are many, and the prices are all over the place. Do some searching here for preamps. As to speakers, again, I'd go with bass cabs. The only thing that really doesn't matter is the poweramp itself. Afaik, any reputable brand with the power rating you want will work fine. The preamp is all about the actual tone you'll hear, so carefull research on that component would be suggested, as well as the spkr cabs, tons to choose from, lots of good advice on these forums. Now, go get 'em, and have fun with it.
  5. amimbari


    May 6, 2008
    Pittsburgh, PA
    as far as what I use, it is a very simple setup...

    my preamp is not shown, but it is a Behringer with 4 outputs so I can drive 4 separate amps from it if necessary. the rest is what you see. I use the CARVIN for the subs, and the BGW for the 4x10 - the Hafler is for a backup ( just in case, cause playing thru the PA SUCKS when your amp fails, and you have to finish a show ) -- been there done that
    tuner/compressor/"virtulizer"( glorified reverb )-for those times when DRY sound just isn't right, and a couple good cabinets I usually use a 1x18 or my 2x15 and a 4x10 on top of it.

    My bass can plug right into the power amp, as it has EMG 35 actives in it, but I like the tonal difference I can get from the preamp better ( IMO )

    IF the show is that large or outdoors, then I drag out the BIG cabs and QSC power amps for either side of the stage. --remember the 80's "WALL of sound" crap? --hehehe

    as far as USING PA speaker cabs, I have done that hundreds of times in a pinch, but generally DON'T use them and just use cabs I have that were "meant" for bass use.

    Rickenboogie is correct, you don't need to spend 5000.00 on a Crown or whatever amp, spend that on the BASS instead, as that is where the "TONE" starts...lol
  6. +1

    Very kool thread. Kool tech-heads + kool, factual info make for a timeless reference that members can go check and make plans with over and over again.. well done.
  7. de la mocha

    de la mocha

    Aug 20, 2005
    Thanks everyone! Now I Really, REALLY, REALLY understand now! Thanks!
  8. yay, someone else asked a question I had!

    what wonderful help from everyone!
  9. +1 to all the above (including what a great and helpful place TB is)!

    I'll add one more thing. Both the SPL of the speaker (how loud per watt a speaker gets) and the tone you actually attempt to achieve should be taken into consideration when you are deciding on the power needed.

    For most of us who use bass cabinets that have a 'reasonably high' low end -3db limit (like 45 or 55 hz... like Eden, Epifani, Markbass, SWR cabs, etc.), there really is no need for huge power... 500-750 watts will drive the heck out of a cab like that (e.g., a good quality, high SPL 4ohm 410). This allows for a nice, compact, relatively small all in one 'head'... simple, loud, easy! This type of rig is great for a full but mid punchy type of tone.

    On the other hand, if you are one that goes after that 'bass guitar sounding like a 9 foot grand piano' type tone... with huge, extended, deep low end, that requires a speaker cabinet with a lot of low end extension, like, for example, the Acme cabs. Lot's of low end extension and/or a wide, 'scooped' tone with lot's of deep lows, sparkly highs, and 'polite' midrange can take LOT's of power, since those speakers typically are low SPL (i.e., require a lot of power to deliver that wide, pure, tone). So, in those circumstances, a whopping power amp or 1000 watts or more and a separate preamp might be the way to go.

    Finally, technique also has an impact on this. If you are a slapper that uses a lot of thumb hits on the E string, which results in those strong 'peaks' in power delivery, you will probably need more watts and more 'cone area' to deliver that sound cleanly to an audience than moderate finger style playing.

    Just another bit of information to consider. Absolute power is not that meaningful without taking into account speaker SPL and also the amount of pure, deep low end you want in your sound.