Sub only or Sub + Mains

[dmlee57]

I'm running two Klipsch KLF-10's as front mains and a Polk PSW-505 sub. The mains have two 10's each and handle bass down to 32 Hz.
Receiver is a Yamaha Rx v995 as pre and HK 5 channel amp.

Which set up is better or is it generally a subjective point of view?

When you select LARGE for your front mains, the receiver will send <90 Hz to them. Does (LFE only) being directed to the sub only apply to digital movies?

I know that this subject has probably been beat to death but I haven't been here in a while.

Any opinion would be appreciated.

 

[Sheep]

Sub only.

You only run sub + mains when you have mains that reach down to a MINIMUM of 20hz.

SheepStar

 

[Seth=L]

I'm running two Klipsch KLF-10's as front mains and a Polk PSW-505 sub. The mains have two 10's each and handle bass down to 32 Hz.
Receiver is a Yamaha Rx v995 as pre and HK 5 channel amp.

Which set up is better or is it generally a subjective point of view?

When you select LARGE for your front mains, the receiver will send <90 Hz to them. Does (LFE only) being directed to the sub only apply to digital movies?

I know that this subject has probably been beat to death but I haven't been here in a while.

Any opinion would be appreciated.

If you want your speakers to not play frequencies below 90hz they must be set to small with the receiver's x-over set to that frequency. If the speakers are set to large it runs them full range regardless of the x-over setting. Using the receiver's x-over (all speakers set to small) with the subwoofer's x-over bypassed is typically the most effective way to run a home theater system.

 

[MDS]

When you select LARGE for your front mains, the receiver will send <90 Hz to them. Does (LFE only) being directed to the sub only apply to digital movies?

LFE (the .1 channel) always goes to the subwoofer regardless of whether you have the sub out set to LFE or LFE+MAIN. If you didn't have a sub, the LFE would go to the front speakers.

If the fronts are set to Large and the sub out is set to:

- SUB (or LFE, whatever term the Yamaha uses), the fronts will get the entire full range signal and the sub will get the LFE and any bass from other channels set to Small.

- LFE+MAIN ('Double Bass', 'Plus' for other brands), the fronts will get the entire full range signal, the sub will get the LFE and bass from other channels set to Small, AND bass below the xover from the front channels. That is why the feature is called LFE+MAIN - the sub is playing the LFE + the bass from the mains.

 

[dmlee57]

With the LFE set to 'sub only'. The sub never comes out of standby mode.
The receiver default is 90 Hz. The sub has an adjustable range but I have it also set at 90 Hz.

The only problem with setting the big front mains to small is that when you change to two channel (as in stereo music), you have to switch the mains back to large or you lose out on the reason for having good quality front mains.

 

[MDS]

With the LFE set to 'sub only'. The sub never comes out of standby mode.
The receiver default is 90 Hz. The sub has an adjustable range but I have it also set at 90 Hz.

That is often a calibration issue. If the receiver's sub level is set too low then it will never see a strong enough signal to come out of standby. If you are using the receiver's xover, regardless of whether it is fixed at 90 Hz or adjustable, you want to disable the sub xover or turn it as high as it will go if the sub does not provide a means to disable its internal xover.

The only problem with setting the big front mains to small is that when you change to two channel (as in stereo music), you have to switch the mains back to large or you lose out on the reason for having good quality front mains.

That is a common misperception. You are not 'wasting' the capability of the mains by crossing them over to a sub. By crossing them over to a sub, the mains don't have to deal with very low frequencies nor does the receiver have to amplify those frequencies. The xover is not a brick wall filter and does not cut off at exactly the xover frequency you select. In general, you want the xover to be set 1/2 to 1 octave above the -3 dB point of your speakers for smooth blending. If the speakers can go down to 40 Hz, a suitable xover frequency is 80 Hz (one octave above).

If your sub does not work in stereo mode, then there is something else going on.

 

[dmlee57]

Thanks, I'll give that a try.

These speakers are suppose to handle down to 32 Hz but 80 would still probably be a good cross over point.

Another thing that occured to me while I was reading your response; my sub has an 'unfiltered' input. So as you said, if I'm going to rely on the crossover from the receiver, it would be best to NOT use the cross in the sub !

 

[Halon451]

The xover is not a brick wall filter and does not cut off at exactly the xover frequency you select. In general, you want the xover to be set 1/2 to 1 octave above the -3 dB point of your speakers for smooth blending. If the speakers can go down to 40 Hz, a suitable xover frequency is 80 Hz (one octave above).

If your sub does not work in stereo mode, then there is something else going on.

It is not my intent to hijack this thread at all, but it's not worth starting a new thread with a very similar question, so here goes... the answer may help the OP out anyway, hopefully:

I've got my receiver crossover set now to 90Hz. Now, from the mention above by utlizing the 1/2 to full octave above (the mains) - does this apply to only the front mains or any speakers in the system? My center channel has the highest rolloff frequency in my set (at 80Hz) - so I've dutifully set my RX crossover to the next logical step increment above that. This logic would have me set the crossover at 120Hz (1/2 octave) for smoother blending? All speaker sizes are set to "Small", and I've selected "Sub Only" for LFE.

Or am I just totally off base here, and I'm getting confused - like the OP, I've been wanting to figure out the relationship between sub/main/receiver for a while now, having never truly delved into it before (the hook it up, turn it on and forget-about-it philosophy). I thought I had it locked in until I read this post. Please enlighten me (us).

 

[Warpdrv]

Truly the best way to do this is to do some in-room Freq. measurements... and find out what the best crossover freq should be... using either TrueRTA or REW http://www.trueaudio.com/rta_abt1.htm
http://www.hometheatershack.com/roomeq/

I have experimented with my SMS-1 doing measurements with different x-overs from low to high settings... and settled with 80hz x-over as with a 50hz x-over I had a major dip around 60hz, and with a higher x-over settings I had a huge peak at 90 hz... Clearly I could not have noticed the difference without seeing the on screen response , and I would have had cancellation or bloat with the different choices.

My mains could handle going lower, but releaving them of the duty also smoothed out my response....

What you absolutely DON'T want is to have a dip in the 40 to 50hz range, where the KICK in the chest lies... I hadn't made any adjustments for a while, and when I updated the firmware on the SMS I rechecked my sweeps, and found that I was a touch low in that area... after smoothing and boosting the 40-50hz range that donkey is back KICKIN me in the chest again !!!!! Sweet...

 

[Halon451]

Truly the best way to do this is to do some in-room Freq. measurements... and find out what the best crossover freq should be... using either TrueRTA or REW http://www.trueaudio.com/rta_abt1.htm
http://www.hometheatershack.com/roomeq/

I have experimented with my SMS-1 doing measurements with different x-overs from low to high settings... and settled with 80hz x-over as with a 50hz x-over I had a major dip around 60hz, and with a higher x-over settings I had a huge peak at 90 hz... Clearly I could not have noticed the difference without seeing the on screen response , and I would have had cancellation or bloat with the different choices.

My mains could handle going lower, but releaving them of the duty also smoothed out my response....

What you absolutely DON'T want is to have a dip in the 40 to 50hz range, where the KICK in the chest lies... I hadn't made any adjustments for a while, and when I updated the firmware on the SMS I rechecked my sweeps, and found that I was a touch low in that area... after smoothing and boosting the 40-50hz range that donkey is back KICKIN me in the chest again !!!!! Sweet...

I downloaded the REQ software for my laptop - but I have yet to purchase the external hardware needed to make it more useful in helping identify room nodes and acoustical issues. The most I've done so far is used a Radioshack SPL meter, and ran step frequencies (at 5 Hz increments) from about 160Hz down to 40Hz, both with the sub on and off to see what I got. This was discussed a while in another thread. I too noticed a peak around the 80-90Hz range (additive I'm presuming). This was before switching my settings over and sending all LFE to the sub (excluding the mains), and then setting the fronts to "Small". I didn't go back and re-run the test after that, but audibly it led to vast improvements in sound quality. (Thanks to those on this forum who suggested this advice!!).

I drove the wife out of the house during these measurements, she coudn't take it. By the way, thanks for the additional link for the TrueRTA - yet another great tool. I too love the "kicking" sensation you get from a good juicy bass reponse, just never knew what frequency that sound lived in! Thanks!

 

[Warpdrv]

I too love the "kicking" sensation you get from a good juicy bass reponse, just never knew what frequency that sound lived in! Thanks!

The bass in that area from a really good quality sub is something one will not likely forget... I love that punch it delivers... simply amazing..

Good luck with your testing...