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One preamp two amps?

Marine0811

Marine0811

I love it loud!
I may sound dumb, but here goes. I have a Harmon Kardon PT2500 pre hooked to a Sumo Polaris and a QSC 1200. The Sumo is hooked to a pair of JBL L100T's and the QSC is hooked to JBL 4311's. When I run one at a time they sound fantastic! When I run both, for all four speakers, I loose most LF on the L100T's. It also sounds like the 100's are muffled. I bought splitters for the front outputs from the pre. WTF am I doing wrong. Very frustrating
 
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Is there a possibility the signal ends up out of phase at the espeakers, allowing the LF to cancel? One way to check would be to reverse the connections on one pair of speakers (amp powered off, of course) and try again.
Failing that there may be some interaction between the two input stages of the power amps....
 
One of your amps may be phase inverting, while the other is not. Reverse the red/black speaker connections on one pair of speakers and give it a listen. This will likely solve the problem. When running one pair individually, the sound will be unchanged.
 
^^ Yup, I was gonna say that it sounds like the Polaris speakers are out of phase with the QSC speakers.

Just reverse the wires of both speakers on one amp only and listen. Usually when speakers are out of phase, you will experience noticeable bass loss. This is the problem you come upon when using multiple amps with multiple speaker systems operating like a single stereo system in the same room.

You can use the rear pre outs with the splitters to control both amps. When in phase, you should have some major eyeball rattling going on. :D
 
Now you just learned what phasing speakers means and what it actually does. :thumbsup:

My main system consists of 4 amps and 4 pairs of speakers all running from one main mixer/control unit. I had to phase the other 3 amps with their speakers to the one main amplifier and its speakers.

Using 4 pairs of speakers (8 speakers total) and if even one of them was out of phase with the other 7, it would disrupt all the other speakers and sound like ****.
 
It definitely sounded like ****. Now it sounds great! The biggest problem I have is my listening area. It's my living room. It's approximately 24x24 with 13.5' cathedral ceiling. I'm also deaf in one ear, so to hear it the way I want, I have the knob between 9-10:00. My wife hasn't taken a hammer to me or my gear so I guess I'm good
 
Glad we could help. This is why I always recommend a phase adjustment when people consider adding a subwoofer to their system. Enjoy!
 
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