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  1. #1
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    Driving 4 speakers with one amplifier

    I have a Behringer EP2500. I was wondering if it would be ok to split the output signals in order to run 2 pairs of speakers in stereo mode. Assuming that is kosher, how about if one pair of speakers is 4 Ohms and the other is 8 Ohms? In both cases assume that I will not be driving this amp at more than 1/4 of what it's rated.

  2. #2
    Unless its changable, only use the Ohms specified by the speaker. If I were you, I wouldn't try splitting the signal, it would degrade it anyways. But, if you need to, as long as its the Ohms specified, it should work. Why would you need to do this though if your not gonna have your amp on all the way anyways? If you don't need all the loudness, why would you want an extra speaker?

  3. #3
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    re: Driving 4 speakers with one amplifier

    I have one amp with outputs for 2 channels (completely seperate 450 watt into 4 Ohm channels). Most of the time 2 speakers will suffice, but there will be times when I would like to add 2 more speakers (pointed in a different direction or in a whole different room, say). Assuming that I am willing to accept a degradation of signal, my question is if it is ok to hook up an extra speaker to each of the amps 2 outputs. That is to say, 2 left channel speakers on one and 2 right channel speakers on the other.

  4. #4
    According to Berhinger it will work without degredation of sound quality. But try it at your own risk.
    'I think my intimate relationship with electronics started as a child when I was playing with a screwdriver and a wall plug, Doc, and...'

  5. #5
    If the amp channels can each run with 4 ohm loads on them, then go for it, as long as the total impedence does not go below 4 ohms per channel you should be OK, that means you can have two (2) eight ohm (8 ohm) speakers hooked up to each channel. so you could run a total of four (4) eight ohm (8 ohm) boxes using both channels. the sound being altered or degraded is only going to happen if the speakers you add on are of lesser quality that the orignal ones. there is no way that changing the imp ratings that the amps see could cause tonal differences.

  6. #6
    I beg to differ with you Bassred. Frequency response characteristics are very much dependant on impedance (Z), which is defined as the square root of the sums of the squares of capacitive reactance (Xc), inductive reactance (XL), plus resistance (R). Both reactances are dependant on frequency. Xc, so that it equals the reciprical of 2 x pi x freq(hz) x capacitance (in farads). XL, so that it equals 2 x pi x freq(hz) x inductance (in Henrys). Nominal impedance as regards speakers (ie 2,4,8ohm, etc.) refers to an abstract quantity. It is the electronic modal equivalant of a "prefered" load according to the designer. It has a real value only when dealing with DC, which of course is not done in audio. It does, however, have a real affect on freq. response.

    Granted, most won't be able to tell the difference, and I am not contradicting my own earlier answer above, (I did say according to Behringer), but in the control room it can be quite noticable.
    Last edited by penniesfromheaven; 15th Nov 2007 at 05:51.
    'I think my intimate relationship with electronics started as a child when I was playing with a screwdriver and a wall plug, Doc, and...'

  7. #7
    pennies, I know the math, but how does that change the sound?? if the speaker that is added has a messed up response curve, then yeah, it'll sound different, but adding a basically decent box to an exhisting rig won't chanve the sound... remember that we are talking about live audio, so no control room was mentioned. Adding a speaker or two (depending on the speakers imp and the amp channels rating) is done every day by the pros, even mixing speaker types in some instances.... the trick is to not buy sh*t gear that is going to sound bad.....

  8. #8
    I'm not going to respond other than to say no sir, you don't know the math.
    'I think my intimate relationship with electronics started as a child when I was playing with a screwdriver and a wall plug, Doc, and...'

  9. #9
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    (QUADROPHONIA = WORKS)
    I have a dual monoblock construction Denon PMA 1500R integrated amp. At the rear it clearly states it's ability to drive 4 speakers so long as they are 8ohms - 16ohms.

    I have 2 * 400 RMS 12" reference speakers driven by butterworth nasa valve technology crossovers.

    Recently decided to use the 2 redundant speaker terminals for some old skool but very good quality Pioneer speakers (my system is in my loft (so stereo focus is not a priority...)

    What a sound!!! At low levels the sound is explicit revealing every detail even the breath on the mic especially when playing Vinyl... When turned up BASSQUAKE! And no loss of mid treble.
    Of course all the best interconnects and speaker cables.
    Best thing to do is to ensure you adhere to manufacturers recommendations regards to impedance (matching them is the best idea). I was about to spend over 2 grand on a meridian power amp to up the sound clarity. I just saved myself a packet! Made an old audiophile stalwart Bang & Olufsen 10 grand + system user almost weep in astoundedness when I played James Brown It's a Mans Man's World

  10. #10
    Electrically, what W2D wants to do will work. The Behringer amp will safely drive loads down to 2 ohms; an 8-ohm and a 4-ohm speaker in parallel is about 2.7 ohms.

    A potential problem is that speakers are not true resistances. Almost all pro speakers are vented; this means there are four low frequencies where their current-vs-voltage phase behavior is radically out of sync. In a lot of amps, this will trigger the protection circuitry every time one of those frequencies comes along. I once tried a Chinese amp that put out 300 watts into a resistive load, but into an actual speaker, wouldn't put out 30 watts at some frequencies. If this happens with the Behringer, it won't hurt anything, but it will sound like garbage.

    The real problem may be the fact that different speakers have hugely different sensitivities. The "extra" pair of speakers may put out so little sound, compared to the main ones, that they are useless. Or they may put out so much sound that they overpower the mains. Easiest way to know is to try.

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