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losing bass when using A+B

post #1 of 10
9/1/10 at 2:06pm
Thread Starter 
I apologize if this is an ignorant question, but I can't figure out the speaker set up to get the sound I'm trying to get.

Scenario: my input device is my computer channeled through my receiver. I have two satellite speakers (100W with an 8 ohm impedance) on my desk using them as computer speakers. I have two bookshelf speakers (2 way, tweeter and 8inch woofer). each of the speakers is hooked up to a speaker output using A&B through the receiver (bookshelf speakers = A, sattellite speakers = B).

When only using A (the bookshelf speakers) the woofer sounds great, pleanty of bass, but when using A&B i get good high's and mid's through all 4 speakers, but lose the power to the woofers, and most of the bass.

My goal was to use the bookshelf speakers to give me the bass I want to hear, but still get the highs and mids at my desk for when i'm listening at the computer.

question: why am i losing the bass from the woofers and how can i get it back with out turning off the speakers at my desk?
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post #2 of 10
9/1/10 at 2:17pm
I wonder if the receiver is running out of power with A+B. What specific speakers and receiver are you using?
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post #3 of 10
9/1/10 at 2:45pm
Thread Starter 
its all pretty crappy equipment... but the receiver is an Optimus stv 3790. Sattelite speakers are from a 5.1 set model is TEAC LSR-100B (max input 100W, 8 ohm). Bookshelf speakers are Sound Research AL-7. I can't find anything about them on the internet. It looks like they were an older brand that went under. The speakers sound great though, they have an 8" woofer/mid and a tweeter

i have to admit i'm new to the whole audio thing, I understand most electronics pretty well, but this subject is pretty foreign to me.
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post #4 of 10
9/1/10 at 3:09pm
When you use the A&B speakers together in a stereo receiver you are splitting the power from the amplifier in half. That is most likely why some of the bass is missing. The bass frequencies use the most power.
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post #5 of 10
9/1/10 at 3:27pm
Thread Starter 
If i were to get a stand alone sub woofer and plug it into the sub out jack, would that make up for the loss of bass? or will the subwoofer only work with a 5.1 surround system?
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post #6 of 10
9/1/10 at 4:33pm
Quote:
Originally Posted by ///AMG View Post

If i were to get a stand alone sub woofer and plug it into the sub out jack, would that make up for the loss of bass? or will the subwoofer only work with a 5.1 surround system?

Well, if the sub had its own amp, it would make up for what it can produce. Most sub only go to about 120hz though. If your speakers have lost bass (due to low power), they probably have lost more than just below 120hz or so.

If you just do stereo, I would think for the price of a sub, you could get a somewhat better stereo receiver or amp.
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post #7 of 10
9/1/10 at 4:41pm
I found some specs on your receiver. I was not sure of the specs in my first post. I thought it was a stereo receiver. It looks like your receiver is 5.1. What I said still applies to your 5.1 receiver. When you go from one pair of speakers on the A channel, then add another pair on B channel you are still dividing the available power. The division of wattage may not be in half but it is still not the same as with just 2 channels driven. The idea of adding a sub is a good idea. The sub will do a better job of producing the low frequencies. A sub will work with music.
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post #8 of 10
9/2/10 at 9:13am
The A and B speakers may be out of phase. Have you tried reversing them?

Ed
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post #9 of 10
9/2/10 at 9:16am
Thread Starter 
Quote:
Originally Posted by ekb View Post

The A and B speakers may be out of phase. Have you tried reversing them?

Ed

What do you mean out of phase?....

edit: nevermind, no they are not out of phase... I think it was just the issue of losing low end frequency when the power was split between the two sets of speakers. I hooked up a subwoofer, and got the bass i was looking for, i'm a little worried though because its a 4 ohm speaker. hope it doesn't make too much of a difference
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post #10 of 10
9/2/10 at 5:54pm
Im taking a guess that you have a powered sub. It should have it's own amplifier on the rear of the sub. The subs driver ohm rating makes no difference to your receiver because the sub has it's own amplifier. You are fine as long as the above is what you have.
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