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Discussion Starter #1 (Edited)
Good morning everyone. I just have a question about this A/B speaker button that you find on an amp or receiver. I understand that you use it if you got two sets of speakers and that is also a good tool for comparing or testing speakers. My question is, is it possible to use both A/B button at the same time? So my main speakers is hook up on speaker terminal (A), then I will tap into the amp speaker terminal B using its signal to connect my subwoofer using the high level speaker level input. I heard this is the best way to get extension of your bass coming from your speakers. Any input please. Thanks.
 

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You only do that if you have to.
A better way is to connect the sub out RCA (if the AVR has one) to the LFE input of the sub.

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You can use A and B at the same time. I have for years, BUT for a separate pair of speakers in another location. With both on obviously the amp power is reduced, so can't turn it way up.

As far as hooking a sub to the B speaker post:
First it would only be one channel left or right correct?
Second it would be amp power, turning down the gain would limit the signal but seems it would be hard to level match to the other speakers.

I could be incorrect, welcome input.
 

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Discussion Starter #4 (Edited)
I]As far as hooking a sub to the B speaker post:
First it would only be one channel left or right correct?
Second it would be amp power, turning down the gain would limit the signal but seems it would be hard to level match to the other speakers.
And third it would be getting the full range not just low notes. And I am guessing - so someone else can answer, but I think the crossover on the sub would not limit the full signal, the crossover on the sub cuts the signal to speakers connected to/thru the sub woofer (old school hook up before LFE.)
I could be incorrect, welcome input.[/I]
I'll be using both the left and right speaker terminals. I will also be using the power from the subwoofer (active). Basically, just using the signal from the power amp speaker terminal. On you third note, I really don't know the answer.

Thanks for providing useful input.
 

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And third it would be getting the full range not just low notes. And I am guessing - so someone else can answer, but I think the crossover on the sub would not limit the full signal, the crossover on the sub cuts the signal to speakers connected to/thru the sub woofer (old school hook up before LFE.)

I could be incorrect, welcome input.

Yeah, normally the crossover is only for the LFE input.
So the sub would be running full range connected with high level inputs.

If the amp has a full range RCA output, you could connect that to the sub, then use the sub crossover to eliminate the higher frequencies.






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Discussion Starter #6
If the amp has a full range RCA output, you could connect that to the sub, then use the sub crossover to eliminate the higher frequencies.
I'll be using speaker cable from the power amp speaker terminal (L/R) to the subwoofer high level speaker level input (L/R). Correct me, if I'm wrong doing it this way. Thanks.
 

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First off not all A/B function exactly the same, you have to consult the manual.

But for you, you don't really need this, you can just hookup your sub in parallel to the mains. The high level input(s) of the sub look like an high-impedance output to the amp, doesn't affect it. Not same as hooking up 2 sets of 8 ohms for example. The decision you have to make is, do you want the mains to remain full-range, or hookup your mains to the sub high level output to take advantage of the sub crossover, consult sub's manual to find out whether its crossover affects the high level output terminals.

Q like this, including me, immediately think of Pre-Out to sub, but Paul of PS Audio does also suggest do it the way you are suggesting. Try it, see which way sound better for you.
 

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If your amp allows you to drive speakers on both the A and B outputs simultaneously, you could do that. However, if you were actually driving speakers, they would be electrically in parallel. That means if both sets of speakers were 8 ohm, the amp would see a 4 ohm load.

You're not doing that. You're just getting a speaker level signal as input to a powered sub. You could wire both your speakers and the sub to the same posts. (It may be convenient to use both sets of posts, depending on whether you're using banana plugs.)

The connection to the sub could be made with much finer wire than you'd use for speakers. The input impedance of the sub should be much higher than the impedance of speakers. Finer wire would have a lower series inductive reactance, but a higher shunt capacitance.

Do you really need to do it that way? If you are using an amp with a sub out, and a full crossover, that's what I'd do. I'd prefer that the mains not be sent the low frequency stuff. I suppose that an audiophile might wish to avoid a crossover, which is typically done digitally now.
 

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Discussion Starter #9
Q like this, including me, immediately think of Pre-Out to sub, but Paul of PS Audio does also suggest do it the way you are suggesting. Try it, see which way sound better for you.
Actually, this is where this idea is coming from. I will be experimenting to find out which sounds better. BTW, I don't have a preout from my preamp/amp.
 

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Discussion Starter #10
You're not doing that. You're just getting a speaker level signal as input to a powered sub. You could wire both your speakers and the sub to the same posts. (It may be convenient to use both sets of posts, depending on whether you're using banana plugs.)
Exactly, that is the plan.
 

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Actually, this is where this idea is coming from. I will be experimenting to find out which sounds better. BTW, I don't have a preout from my preamp/amp.
Well then you don't have a choice, no basis for comparison. And then Paul never went on to explain what to do to the mains, leave them full range or...? Email him, he says to respond, and come back tell us what he says. :)
 

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Discussion Starter #12

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Discussion Starter #13
You can use A and B at the same time. I have for years, BUT for a separate pair of speakers in another location. With both on obviously the amp power is reduced, so can't turn it way up.
I assumed that you run the speaker wires through the ceiling from one room to another.
 

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What if my pre-amp does not have a sub out, is it possible to use the output from the pre-amp going to the sub LFE using this



https://www.audioadvisor.com/prodinfo.asp?number=AQM22FHRD



Please let me know. Thanks.
Yeah that's fine, but never merge two RCA outputs to one input. One output to two inputs is fine.

You will need to adjust the crossover frequency on the sub since the amp will be sending a full range signal.

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Discussion Starter #15
What do you think of this approach?

"If the sub has a line-out, you can connect the subwoofer in a "loop" between the pre-amp and power amp by running a pair of interconnects from the pre-amp outputs to the sub line-level inputs, then another pair of interconnects from the sub line-outs to the power amps. In this configuration the low frequencies played by the sub are typically "stripped off" and the output to the power-amp/main speakers no longer contains this low frequency information."


Still experimenting what will sound better on my system. So far, wiring both speaker and sub at the same post works and sounds great. The only thing is I don't have a control on the sub volume.
 
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