POLK PSW505 sub wolfer hookup

LDBennett

I have a Yamaha AS-700 Integrated Amplifier that has no sub wolfer output port. I am buying a POLK Audio PSW505 sub wolfer. I have reviewed the manual and they suggest an interesting hookup for me. Basically you route the left and right channels from the amp to the back of the sub wolfer. Then using separate wires you hook up the left and right channel to the sub wolfer output terminals rather than to the Yamaha AS-700 Integrated Amplifier.

The Yamaha AS-700 Integrated Amplifier actually has two sets of outputs, A and B, for both left and right that are internally connected. That means that the output stage sees both speakers on the A and B terminals as connected in parallel, impacting the output impedance the amp sees. Because of physical location limits, I want to connect up the left and right speakers directly to the A output channels of the amp and the sub wolfer to the B channels.

If the input impedance of the sub wolfer is high, which it probably is as it is the input to an amplifier, then there is little impact on the amp's output terminals. But if the input impedance of the sub wolfer is low, on the order of another speaker, then the impedance the amp sees is a much lower impedance. I have not found a schematic for the amp in the sub wolfer so I cannot verify the input impedance of the sub wolfer and it is not spec'ed.

While the amp could easily handle the two speakers, the physical limitation in my room kind of pushes me towards the distribution of the speakers off of the amp, not the sub wolfer.

So what is the input impedance of the POLK Audio PWS505?

Is there any not so obvious reason I should not do it my way? Could it be the sub wolfer has a crossover inside it that limits the low end frequency response in the outputs to the right and left channels, leaving only the sub wolfer to handle the lowest frequencies?

A schematic would answer all these questions!

LDBennett

larry777

Are you sure your Amp only has the A+B option for the speakers and not A or B also ? If A or B then just use the A terminals L & R on the back to run your wires to the PSW 505 speaker In terminals. Then run another set of wires from the 505 out terminals to your L & R Speakers. Use your A speaker option rather than A+B. I think thats one of the hookup options that came with the 505. For some reason your Amp seems to have a more complicated speaker hookup than just A or B.

John K.

LD, the input impedance of all sub amps is in the tens of thousands of ohms and the precise number is of essentially no significance to your question. As you may know, when units are connected in parallel the resulting impedance is such that its reciprocal is equal to the sum of the reciprocals of the impedances of the connected units. For example, if a speaker with an 8 ohm impedance(at a particular frequency)is run in parallel with a sub amp having a 16000 ohm impedance, the resulting impedance X is such that 1/X= 1/8+1/16000, 1/X=2000/16000+1/16000, 1/X=2001/16000, X=16000/2001, X=7.996(ohms). Therefore, there's no appreciable change in impedance resulting from such connections.

Any connection you'll make with your AS-700, whether you connect both sub amp and speakers to the A terminals, or(more conveniently)connect one to A and one to B and select A+B, is a parallel connection between sub amp and speakers, with resulting impedance calculated as above.

No sub has an internal crossover(just a low-pass filter which affects only the sub, even if speakers are connected through the sub). A very few subs(not including the PSW505)have a separate high-pass filter(commonly fixed at 100Hz)on the speaker level outputs to connected speakers, but otherwise this is just a straight-through connection , just as if the speakers were directly connected to the amplifier. The low-pass filter control on the sub has no effect on the speakers.

Since there's no bass management benefit by connecting through the sub, and the speakers still have to run full range, if you prefer for convenience to connect the speakers directly to the AS-700, do so.

F1nut

sub wolfer

It's subwoofer.

20hz

F1nut wrote: »

It's subwoofer.

I like sub wolfer

20hz

John K. wrote: »

LD, the input impedance of all sub amps is in the tens of thousands of ohms and the precise number is of essentially no significance to your question. As you may know, when units are connected in parallel the resulting impedance is such that its reciprocal is equal to the sum of the reciprocals of the impedances of the connected units. For example, if a speaker with an 8 ohm impedance(at a particular frequency)is run in parallel with a sub amp having a 16000 ohm impedance, the resulting impedance X is such that 1/X= 1/8+1/16000, 1/X=2000/16000+1/16000, 1/X=2001/16000, X=16000/2001, X=7.996(ohms). Therefore, there's no appreciable change in impedance resulting from such connections.

Any connection you'll make with your AS-700, whether you connect both sub amp and speakers to the A terminals, or(more conveniently)connect one to A and one to B and select A+B, is a parallel connection between sub amp and speakers, with resulting impedance calculated as above.

No sub has an internal crossover(just a low-pass filter which affects only the sub, even if speakers are connected through the sub). A very few subs(not including the PSW505)have a separate high-pass filter(commonly fixed at 100Hz)on the speaker level outputs to connected speakers, but otherwise this is just a straight-through connection , just as if the speakers were directly connected to the amplifier. The low-pass filter control on the sub has no effect on the speakers.

Since there's no bass management benefit by connecting through the sub, and the speakers still have to run full range, if you prefer for convenience to connect the speakers directly to the AS-700, do so.

I was thinking aloung those lines most prosound amps have a 10k or 20kohm resistance .
But I had something strange happen I had a older ?denon 5.1? and some large speakers a friend brought over his M&K ?VB1? sub we hooked it up off the speaker wires and ran wires to my speakers we drove it hard for like 10 minutes and the avr died , based on the high impedance I have no idea why it died .
Do you ?

LDBennett

Thanks for the info.

I just really wanted to know the magnitude of the impedance, like high or low. I am an electrical engineer so I understand impedances in parallel. I just did not want to over load the amp if the sub wolfer was a low impedance, like 8 or 4 ohms. POLK does not specify the sub wolfer impedance at all and I could not find a schematic of it (found all kinds of other POLK schematics but not this one). It makes sense the impedance would be high if it was just an amplifier input impedance (typical tens of K ohms).

I know nothing about sub wolfers but I found the recommendation by POLK to run the left and right speakers from the terminals on the sub wolfer (??) a bit weird. While it appears not to be the case, it makes a little sense that they might have a high pass filter in the sub wolfer terminals to the front channel speakers to ease the work of the right and left channel speakers for the sub bass range.

Again, thanks. I'll connect it directly to the amplifier, not to the POLK sub wolfer. It is to be delivered today!!!

LDBennett

LDBennett

I forgot to mention that indeed the speaker selector switch is A on or B on or both on. I kind of glossed over that in my earlier post. There are but two amplifiers: left and right channels. The A output terminals and B output terminals are driven by the same amplifier for each channel. That is to say it is typical for a speaker selection circuit, A or B or both. This Yamaha Integrated Amplifier (pre-amp and two amplifiers, one for left and one for right) does all selections by relays and is internally computer controlled.

LDBennett