power amps and biamping

Discussion in 'Amps and Cabs [BG]' started by superbassman2000, Oct 27, 2004.

  1. ok, another question about power amps. i've got my cab, which is biamp capable. can i take one power amp out and plug that into the high input, and take the other amp out and plug it in the low input?

    maybe just to clarify, i'd be doing this with a 200-300 watt power amp, i was thinking QSC, but i am open to anything.

  2. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    what kind of cabinet are we talking here?

    yes, you can use a stereo poweramp for bi-amping but the biamp signal must be sent to the two channels of the poweramp prior to being sent to the different speakers/inputs of the cab. This would entail using a preamp with a crossover, or using a seperate crossover in between your preamp and poweramp. In that scenario you would take the high out of the preamp/crossover, plug into one channel of the poweramp and then plug the output of that channel into your speaker (or speaker input) thatwould be getting the highs, and taking the low out of the preamp/crossover and putting it into the other channel of the poweramp and plugging the output of that channel to the cabinet/input that would be getting the lows.

    you have to be careful that the cabinet or component getting the "highs" is capable of handling the kind of wattage you are going to be throwing at it, and that you are crossing over at the right frequency. If you are using a cabinet with woofers and a horn i would seriously advise against doing this unless you have the specific amp designed to be used with it. (i seem to remember gk or someone making a cab liek this designed to be biamped with some head of theirs). On the other hand, if you're using a speaker like the bag end af-1 which can be run full range or biamped (where the lows go to an 18", and the highs go to a 12" and a horn) then what you're suggesting is cool. Generally, when people biamp they do so with two cabinets, like a 1x15 and a 2x10.
  3. well, i have a peavey 1810, which splits the highs and lows at 500 hz (i think...i remember the 500) anyways the highs go to two 10" speakers and the lows go to an 18". anyways i also have an ART nightbass SE, which has high and low outputs...i hope this helps!

  4. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    well that's better. if your cabinet has seperate inputs for high and low in addition to the full range input then that's fine. If it has a non-bypassable internal crossover in the cabinet and just has a full range input then just run it full range, Don't try to reinvent the wheel.
  5. redneck2wild


    Nov 27, 2002
    Memphis, TN
    I had a 1820 cab back in the late 80s. The internal crossover is decent but sending low mids (200hz-500hz) to the 18 does produce some mud. At the time I used a crossover set to 150hz - this took out some of the muddy frequencies out of the 18.
    You do have to watch out for the amount of power that you send the 10's - I don't think they are designed to handle much.
    Is the 18 a Black Widow? If so, it can proabably handle plenty of power (and most of your power is going to be in the lows.)
  6. yeah, the 18 is a black widow...as for the low mids, would this work? since both the cab and the preamp have crossover, and the preamp has a dial that you can set the crossover point, what if i set it at around 300 hz, which would send the 400-500 hz range to the tens (high input). since the crossover on the 1810 is 500hz, it would not play those frequencies. of course that would probably mean that the low mids would be cut completely out...wouldn't it?

  7. so now, i am looking at the QSC RMX 850. it say in stereo mode, it puts out 300 watts at 4 ohms. is that 300 watts on both sides total, as in 150 watts per channel, or 300 watts per channel?
  8. Bob Lee (QSC)

    Bob Lee (QSC) In case you missed it, I work for QSC Audio! Gold Supporting Member Commercial User

    Jul 3, 2001
    Costa Mesa, Calif.
    Technical Communications Developer, QSC Audio
    The per-channel power ratings are for each channel.
  9. IvanMike

    IvanMike Player Characters fear me... Staff Member Supporting Member

    Nov 10, 2002
    Middletown CT, USA
    super -
    if the cabinet has a full range input and seperate inputs for the 18 and the tens, more than likely the internal crossover on the cabinet will be bypassed by plugging into the high and low inputs
    im guessing the cabinet innards are;
    full range input > crossover >hi and low inputs > speakers