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How to use multiple power amps?
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ME16510
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7th July 2012
Old 7th July 2012
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How to use multiple power amps?

Hey guys I am really new on here, and am an aspiring audio engineer. I was wondering how would I use multiple power amps for many speakers. My soundboard is around medium sized with 16 channels. It has left and right outputs plus auxiliary outputs. Anyway I was planning on taking the left and right outputs into a crossover and having like 2 amps for high end 2 amps for mids and 2 amps for the lows/subwoofers. My problem is there is only 1 output for the highs/mids/low... How would I plug the 1 output into 2 amps? Hopefully I made sense here. Any help would be appreciated.
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7th July 2012
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7th July 2012
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I thought we left crossovers in the scrap pile in the 80's ,, ha ha... I sure don't miss them.
Are you using real old speaker cabs? Like are they 1 speaker per box or are these full range cabinets?
The crossover should have XLR input(s) and then a XLR output(s) for each frequency band.
If your sending the output to more than one amp then normally the amps have parallel jacks on the back you can use to daisy chain. If not use Y cables.

If these are full range boxes forget the crossover, you'll probably end up with worse sound than if you simply used the power amps to power each speaker pair full range.
Only subs would benefit from hi pass even though most have this built in. Better to filter out unneeded frequencies before the power amp.
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7th July 2012
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Are you sure that your xover is two channels?
Edit: When you say "1 output for high/mid/low", do you mean one stereo pair for each band or one mono out per band?

Stereo subs are unnecessary b/c sub freqs almost always going to be in the center of a mix.
Use both channels of your sub amp in bridged-mono if it allows and as long as the sub can handle the power, of course.
ME16510
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17th July 2012
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Oh no what I meant for a crossover was like one output for the "full range" speakers. And another output for the subwoofers.
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20th July 2012
Old 20th July 2012
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Quote:
Originally Posted by ME16510 View Post
Hey guys I am really new on here, and am an aspiring audio engineer. I was wondering how would I use multiple power amps for many speakers. My soundboard is around medium sized with 16 channels. It has left and right outputs plus auxiliary outputs. Anyway I was planning on taking the left and right outputs into a crossover and having like 2 amps for high end 2 amps for mids and 2 amps for the lows/subwoofers. My problem is there is only 1 output for the highs/mids/low... How would I plug the 1 output into 2 amps? Hopefully I made sense here. Any help would be appreciated.

If you want to do exactly what you've said, you can do it by connecting each of your stereo line outputs to the input of a 3-way electronic crossover (2 complete crossovers required) with adjustable crossover frequencies. The frequencies must be selected to match the frequency range of the speaker drivers you are using. Probably something like 80 Hz and lower for your sub, 80 Hz to possibly 2.5 kHz for your mids and above 2.5 kHz for the high-frequency speakers. The frequencies must match the operating range of the speaker drivers. Any internal passive crossovers in the speaker systems should be removed.

For just a full-range plus sub system (commonly called a 2.1 system), you need only one "stereo crossover" and a "signal-summer" circuit which can be built up using a couple of 1k or more resistors connected to each side (L & R bass out only) to mix the channels into one sub channel. If you use (2) subs (and (2) sub amps.), you don't even need the "summer".

Appropriate electronic crossovers might be the Ashly XR-101 or the Sampson S-3WAY.

If you just want to connect the full-range mixer outputs to (2) power power amplifiers, all you need is a simple XLR (female) to dual XLR (male) "Y" cable. It's no problem connecting one (low impedance) line output to (2) or more inputs. Although you should NEVER connect (2) outputs in parallel to combine them without appropriate combiner circuitry.

The reason you must have the electronic crossovers is that you should not pump the low (sub) frequencies into your mid and hi freq. drivers and you should not pump any mid and high frequencies into the subwoofer.

Virtually all professional studio monitors sold today use electronic crossovers and seperate power amps for each frequency band. Often the amplifiers are different in power ratings and sometimes in design detail so that they are optimized for each frequency band and for the specific speaker drivers thay are matched with.
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20th July 2012
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Amps usually have an XLR input and a TRS 1/4" next to it. It's a point to patch the input of amp to another by going out of it with a TRS/TRS or TRS to XLR. It's called a parallel jack. It's a means of passing the line level thru one amp to another.
No splitter required.
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