PSW10 with amp w/o subwoofer output

Sansho

I did a search and didn't find an answer. Have a new PSW10 hooked up with a low-end Sony receiver that does not have a subwoofer output. So, at this point, I have the subwoofer hooked up using the speaker-level inputs, which works. However, I'd like to retain the full frequency spectrum going to the stereo speakers and have the PSW10 supplement the lower frequencies, as opposed to a cutoff where all the lower frequencies, based on the cutoff, go to the subwoofer. Soooo, the question: The Sony allows A and B speakers. Can I run a speaker-level input to the subwoofer without any output load going back to the speakers, and would doing so cause any unbalance to damage the subwoofer electronics? TIA!

gatemplin

Welcome to CP,

Yes you can run the wires to the sub from speaker output B or in parallel from output A (same thing). The internal resistance is so high in the sub amp that the only load the receiver really sees is the speakers. This way the mains will get the full range signal if that is what you prefer.

(Resistance total)^-1 = (impedance speakers) ^-1 + (sub input resistance)^-1

1/Resistance total = 1/8 ohms + 1/4000ohms

Resistance total = 8 ohms


Since the sub input resistance is so high the total resistance is the same as the speaker impedance.

Sansho

Graham,

Thank you! However, my question was more aimed at the PSW10 end of the equation (sorry I wasn't clear) - is there any issue with running a speaker feed into the PSW10 without having a line out?

gatemplin

Originally posted by Sansho

is there any issue with running a speaker feed into the PSW10 without having a line out?

No problem at all.

John K.

Sansho, Graham's replies are correct and there's no problem at all with using the A and B output terminals on the receiver to make a parallel connection to the sub and speakers. The input impedance of the sub amp is so high(generally in the tens of thousands of ohms)that practically zero power flows(one form of Ohm's Law: power equals voltage squared divided by resistance)and just the music signals carried by the voltage variations are actually used by the sub.

You should be aware though that your present hook-up is already accomplishing your purpose. You appear to think that there's some sort of "cutoff" to the speakers caused by the internal crossover in the sub, but the sub crossover just rolls off the sub response above the selected frequency(e.g. 80Hz)and has nothing to do with the speakers. The sub output terminals to the speakers are simply a straight-through full frequency feed(some subs have a separate filter on the speaker outputs to roll off the speakers below a certain frequency, but your PSW10 doesn't). Use whichever connection is more convenient.