Low Pass Filter Functionality?

MLZ

For my two channel system, I have a receiver without a sub out. So I run wire from the right and left outputs to a PSW10’s right & left inputs and then from the PSW10 outputs to my R50’s.

On my HT receiver I have a sub out, I set the speakers set to small and I can set the crossover point. I think this tells the receiver to direct the signal below the crossover point to the sub and above the crossover point to the speakers.

My question is: does the sub perform the same function as the HT receiver - that is if the low pass filter on the sub is set at 100hz, does that mean no signals below 100hz will be passed to the R50s? And does the signal above 100hz go directly to the speakers without passing through the subs amp?

engtaz

1. That is right
2. right again

John K.

ML, no the sub doesn't perform the same function. Although the control on the sub is often referred to as a "crossover", you've used the more accurate term "low pass filter". The difference is that the HT receiver does a full crossover, i.e. it rolls the sub off above the selected frequency and rolls speakers set "small" off below that frequency. The low pass filter on the sub just rolls the sub off above the frequency set on the sub control, but has no effect on the frequencies sent to the speakers, since it has no high pass function. Even when the speakers are connected through the sub using its speaker level outputs, it's simply a straight pass through. A few subs have a separate high pass filter(typically fixed around 100Hz)on their speaker outputs, but the PSW10 isn't one of them.

So, the effect is the same as if you'd directly wired your R50s from the output terminals on your receiver. If you want bass management to take some of the low bass load off the R50s you should consider an HT receiver when the time for replacement comes, even if you choose to not use surround speakers in that setup.

reeltrouble1

yes, you have it correct. this k fellow knows nothing of audio and searches for new people to give his bad advice too. You though have been around for a while.

Enjoy your sub, you have wired it in what is known as the "polk" way, it is actually the way Polk Audio recommends in their manual.

Take care.

RT1

ben62670

If you are running your main L/R to the sub, and then to your main speakers then you have to set your mains to large, or the sub won't receive its info. If your receiver has the ability for a line out to your sub run it that way, and then set your mains at 80hz manually.

Ben

jakelm

ben62670 wrote: »

If you are running your main L/R to the sub, and then to your main speakers then you have to set your mains to large, or the sub won't receive its info. If your receiver has the ability for a line out to your sub run it that way, and then set your mains at 80hz manually.

Ben

++1

Simple and easy.

MLZ

Thanks for the education.

My receiver is a simple two channel Onkyo and without bass management or a sub out, so I wired the sub / speakers the Polk method.

I was just curious about what the sub was doing i.e., if with the Receiver -> Sub -> Speaker hookup, the signal received by the sub and the signal revceived by the R50s, was the same if I wired the "A" speaker outputs to the sub and the "B" speaker outputs to the R50's.

McLoki

MLZ - a simple test if you will indulge me.

I do not know if John K is correct or not that the PSW-10 does not have a high pass filter for your speakers but it would be easy enough to test....

Hooked up the way you have it. (Reciever to sub to speakers) turn the sub volume all the way down as well as the crossover as low as you can. Play a bass heavy song and as it is playing turn the crossover all the way up. If John K is correct, you should not hear any difference in the bass - if not correct - your bass should decrease by quite a bit.

like I said, I do not know the answer but would like to have the info on whether it works or not.

Report back what you find and thanks,

Michael

MLZ

McLoki wrote: »

MLZ - a simple test if you will indulge me.

I do not know if John K is correct or not that the PSW-10 does not have a high pass filter for your speakers but it would be easy enough to test....

Hooked up the way you have it. (Reciever to sub to speakers) turn the sub volume all the way down as well as the crossover as low as you can. Play a bass heavy song and as it is playing turn the crossover all the way up. If John K is correct, you should not hear any difference in the bass - if not correct - your bass should decrease by quite a bit.

like I said, I do not know the answer but would like to have the info on whether it works or not.

Report back what you find and thanks,

Michael

I like the scientific method and will run this test as soon as I can. I live in a 80 year old house and am blowing fuses on the same circuit as the stereo gear. As soon as the electrician locates the short I'll run the experiment and report back.

Thanks.

Mike

MLZ

McLoki -

• Found a copy of the Stereophile Test CD Volume 1
• Set the subs volume knob to zero
• played 40hz, 50hz and 63hz tracks
• swept the low pass filter knob on the PSW10 from 80hz to 160hz

and

• no change in the level of sound output from the R50's

Thanks - shows that John K. was correct and showed me that running a test is a better way to answer a question than just chatting about it.:rolleyes:

Mike

jakelm

MLZ, you need to play the tracks that are within the crossover filter (80-160). To see of there is a highpass filter.

If you play a 100hz sine wave and set the crossover to 80 then the R50 would play the 100hz. If you turn the crossover to 160, then the sub would play the 100 not the r50. Playing below the crossover filter would do nothing. The sub would play it.

McLoki

That was essentially what he was testing. If he was getting output from his R50's at 40hz, 50hz and 63hz with the sub in the loop - there was no high pass filter present. I am sure the sub would have agumented the bass that that level, but it still required the R50's to produce the bass as well. (making the crossover in the sub not the same as the crossover in an AVR)

Live and learn - good call John.

Michael

MLZ

jakelm wrote: »

MLZ, you need to play the tracks that are within the crossover filter (80-160). To see of there is a highpass filter.

If you play a 100hz sine wave and set the crossover to 80 then the R50 would play the 100hz. If you turn the crossover to 160, then the sub would play the 100 not the r50. Playing below the crossover filter would do nothing. The sub would play it.

OK, I just did the same test, but playing 100, 125, 160 and 200hz warble tones and same result - the sound level output by the R50's stayed the same

pwz41

I'm somewhat confused. I run a Carver Sunfire Signature, the HPF on that sub is fixed at 100Hz. The crossover setting on the Sunfire has no bearing on the HPF. Does the Polk's HPF setting change in conjunction with the crossover position? If so, this Polk is the first sub I've know to have this function.

Erik Tracy

This confirms my first hand experience as well.

I had a separate setup with preamp and power amp - no bass management AVR. (I've since tore that down and now have a full HT 5.1 set up with an AVR).

I ran a set of L/R cables from the power amp to the PSW303 sub, then from there ran cables to my RTI4s as the L/R mains.

I experimented quite a bit in finding the right 'blending' of the sub into the mains with the lowpass filter knob on the back of the PSW303.

In my listening tests, I could not hear any difference in sound content coming from the RTI4s if the lowpass was swept from lowest to highest - whereas you can definitely tell what was coming from the PSW303.

Erik