Sub Adjustments - Never had one before

dhornick

For a brand new Subwoofer guy never having one before what does “Low Pass” and “Phase” mean?
On my new PSW404 Polk Audio Sub there is a turning knob for Low Pass that goes from 60 to 125 with 90 being the center. And then there is a two position toggle switch that switches from 0 to 180 no in-between it’s just either or.
Then last but not least there is a auto on auto off switch, is it best to just leave it on the auto position?

System consists of:
RT400 - Front Left and Right
CS350LS - Center
M3II - Rear Left and Right
PSW404 Subwoofer
Drivin by Sony STRDG510 Receiver and
Panasonic Plasma TH-58PX60U

zingo

The low pass filter is the cross-over for your subwoofer. (the 60 to 125 being in Hertz) You will set that knob to where ever you want the subwoofer to stop reproducing sound. THX recommends 80 Hz, but it is really whatever sounds best with your speakers and room step-up.

Phase only comes into play with multiple subwoofers. They can in theory "cancel" each other out if they are operating in opposite directions. (think if you had two subs facing each other) Since this is not an issue with you, just leave it at 0.

And last, leave the power switch on Auto unless you want to manually turn your sub on and off every time you want to use it. The Auto setting with let the source turn it on, and then it will turn off after a few minutes if it does not sense a signal.

dhornick

zingo wrote: »

The low pass filter is the cross-over for your subwoofer. (the 60 to 125 being in Hertz) You will set that knob to where ever you want the subwoofer to stop reproducing sound. THX recommends 80 Hz, but it is really whatever sounds best with your speakers and room step-up.

Phase only comes into play with multiple subwoofers. They can in theory "cancel" each other out if they are operating in opposite directions. (think if you had two subs facing each other) Since this is not an issue with you, just leave it at 0.

And last, leave the power switch on Auto unless you want to manually turn your sub on and off every time you want to use it. The Auto setting with let the source turn it on, and then it will turn off after a few minutes if it does not sense a signal.

Thanks for the info. I plan on just using the LFE connection so would these same reccomendations hold true?

zingo

Yes sir

seeclear

Actually if using the LFE on the receiver, you should probably set the "low pass" on the sub all the way up, and use the crossover adjustment in the receiver to set the low pass on the sub. I would set all the speakers to "small" and let the sub do the lower frequencies. FWIW
:D:D:D:D:D:D:D:D

Strong Bad

seeclear wrote: »

Actually if using the LFE on the receiver, you should probably set the "low pass" on the sub all the way up, and use the crossover adjustment in the receiver to set the low pass on the sub. I would set all the speakers to "small" and let the sub do the lower frequencies. FWIW
:D:D:D:D:D:D:D:D

+1 on this one. I went this route and it makes a difference setting all speakers to SMALL. Let the sub do the job it was designed to do. I think most receivers send 80hz and below to the sub.

Go for the BIG SVS!


John

dhornick

Strong Bad wrote: »

+1 on this one. I went this route and it makes a difference setting all speakers to SMALL. Let the sub do the job it was designed to do. I think most receivers send 80hz and below to the sub.

Go for the BIG SVS!


John

Just so I understand.....setting all speakers to small will not affect the output, volume or surrond signal for each designated speaker? I mean my front speakers are RT400's which I physically call big or large and have my AV Receiver set to and my rear are M3 series which are small and I have set to small.

Kex

dhornick wrote: »

Just so I understand.....setting all speakers to small will not affect the output, volume or surrond signal for each designated speaker? I mean my front speakers are RT400's which I physically call big or large and have my AV Receiver set to and my rear are M3 series which are small and I have set to small.

Welcome to the club dhornick! When you set the speakers to "small", it just means that under a certain frequency (usually 80Hz) the signal gets sent by the receiver (or pre/pro) to the subwoofer, not to the speakers. In theory at least, the subwoofer can handle these frequencies much better than a speaker (even fairly large ones). I don't know where the lower 3dB limit is for RT400, but the crossover on your receiver should be above that.

If you set the speakers to large, the low frequencies will be shared by the subwoofer and those speakers. Some of these settings will depend on your receiver, but the CW is that it's best to set all speakers, except "full range" speakers that can go as low as 20-30Hz, to "small", even if that seems odd when using speakers that are, like yours, quite large!

dhornick

Kex wrote: »

Welcome to the club dhornick! When you set the speakers to "small", it just means that under a certain frequency (usually 80Hz) the signal gets sent by the receiver (or pre/pro) to the subwoofer, not to the speakers. In theory at least, the subwoofer can handle these frequencies much better than a speaker (even fairly large ones). I don't know where the lower 3dB limit is for RT400, but the crossover on your receiver should be above that.

If you set the speakers to large, the low frequencies will be shared by the subwoofer and those speakers. Some of these settings will depend on your receiver, but the CW is that it's best to set all speakers, except "full range" speakers that can go as low as 20-30Hz, to "small", even if that seems odd when using speakers that are, like yours, quite large!

Excellent response. Thank you so much.

kuntasensei

FYI: Crossovers aren't a sudden change from speaker to sub; there's a gradual transition. Depending on the receiver, this normally occurs at either 18dB/octave or 24dB/octave. If you set a crossover point of 80Hz, that's usually the point where the sub and speaker are producing that frequency equally. Therefore, a good rule of thumb is to look at the speaker's lowest extension or -3dB point and add 10-20Hz to that to find the right crossover for your AVR if your AVR allows independantly adjustable crossovers. If all you have is Large/Small, small is customarily 80Hz. That doesn't mean that your speakers would no longer produce anything below 80Hz... It just means they would gradually roll off, meaning you would still be utilizing the capabilities of your speakers below that point.

Another reason that you want to turn the sub's crossover to its maximum limit is that crossover circuits can often induce a slight delay, which can put them slightly out of phase with your other speakers. This means that to find the right acoustic delay for your subwoofer, you might have to set it closer than its physical distance when adjusting distance/delay settings on your receiver. On subs with continuously variable phase controls, you can use that to correct this slight delay and line up phase... but with a simple 0/180 toggle, you likely want to use 0 and then alter the subwoofer distance setting on the receiver to get the best result. Considering your STRDG510 does auto-calibration of distance, you should be good. It ought to detect any delay and adjust the distance accordingly.

dhornick

kuntasensei wrote: »

FYI: Crossovers aren't a sudden change from speaker to sub; there's a gradual transition. Depending on the receiver, this normally occurs at either 18dB/octave or 24dB/octave. If you set a crossover point of 80Hz, that's usually the point where the sub and speaker are producing that frequency equally. Therefore, a good rule of thumb is to look at the speaker's lowest extension or -3dB point and add 10-20Hz to that to find the right crossover for your AVR if your AVR allows independantly adjustable crossovers. If all you have is Large/Small, small is customarily 80Hz. That doesn't mean that your speakers would no longer produce anything below 80Hz... It just means they would gradually roll off, meaning you would still be utilizing the capabilities of your speakers below that point.

Another reason that you want to turn the sub's crossover to its maximum limit is that crossover circuits can often induce a slight delay, which can put them slightly out of phase with your other speakers. This means that to find the right acoustic delay for your subwoofer, you might have to set it closer than its physical distance when adjusting distance/delay settings on your receiver. On subs with continuously variable phase controls, you can use that to correct this slight delay and line up phase... but with a simple 0/180 toggle, you likely want to use 0 and then alter the subwoofer distance setting on the receiver to get the best result. Considering your STRDG510 does auto-calibration of distance, you should be good. It ought to detect any delay and adjust the distance accordingly.

Another excellent response and great, great info for us newbies. Thanks so much.