# Subwoofer sweeps



## robsong (Apr 3, 2010)

Running freq response sweeps in order to help find the best spot for my sub, noticed that my center channel was putting out a lot of sound when running the really low freq sweeps, 10hz, 20hz and 30hz. Verified that center was set to small and crossed at 80z. I can understand getting some noise from the center channel at say 50ish hz and above, but at 10 and 20hz???...and not just a little, the sound was more prominent from the center then it was from the sub, and my sub is more then capable of playing the low freq test tones, and yet I got virtually no sound from it until 30hz to 40hz tones.

Confused as to weather this is normal or not. Interestingly though, there was no noticeable sounds coming from the mains until around 50-60hz tones. Volume on the avr was set between -10 and -15 for the duration. Turned audyssey off and tried the sweeps again and got virtually no sound from any speaker including the sub until around 40hz. If anyone can give some advice or explanation as to what I'm experiencing it would be most appreciated. My sub is HSU VTF-15H, speakers KEF Q900 fronts, Center KEF Q600 and receiver Denon 4311ci. :dontknow:


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## drdoan (Aug 30, 2006)

If you haven't already done so, I would check the center channel's settings on the receiver. It might be that you have to set each channel separately. Next, I would run Audyssey again, and leave it active. Let us know what happens. Have fun. Dennis


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## robsong (Apr 3, 2010)

Got the center at 80hz and fronts 60hz. What do you mean" set each channel separately". Thanks


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## zheka (Jun 11, 2010)

robsong said:


> Running freq response sweeps in order to help find the best spot for my sub, noticed that my center channel was putting out a lot of sound when running the really low freq sweeps, 10hz, 20hz and 30hz. Verified that center was set to small and crossed at 80z. I can understand getting some noise from the center channel at say 50ish hz and above, but at 10 and 20hz???...and not just a little, the sound was more prominent from the center then it was from the sub, and my sub is more then capable of playing the low freq test tones, and yet I got virtually no sound from it until 30hz to 40hz tones.
> 
> Confused as to weather this is normal or not. Interestingly though, there was no noticeable sounds coming from the mains until around 50-60hz tones. Volume on the avr was set between -10 and -15 for the duration. Turned audyssey off and tried the sweeps again and got virtually no sound from any speaker including the sub until around 40hz. If anyone can give some advice or explanation as to what I'm experiencing it would be most appreciated. My sub is HSU VTF-15H, speakers KEF Q900 fronts, Center KEF Q600 and receiver Denon 4311ci. :dontknow:




with your center channel you probably hear both sub and the speaker because bass management is engaged. 
Are you L/R speakers also set to"small"?

how do you run the sweeps? do you use software to generate them or play prerecorded files? how do you measure the output?


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## tonyvdb (Sep 5, 2007)

make sure you dont have pure/direct engaged during the sweeps only use stereo mode. Pure/direct bypasses all settings.


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## drdoan (Aug 30, 2006)

Sounds like you have it set correctly. Not sure what is going on.


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## zheka (Jun 11, 2010)

robsong said:


> Got the center at 80hz and fronts 60hz. What do you mean" set each channel separately". Thanks


make sure your L/R are set to small


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## robsong (Apr 3, 2010)

Have fronts at small 60Hz and center small 80Hz. Will try and set to stereo before doing sweeps and report back. I'm using a software for sub sweeps from 10Hz to 100Hz.


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## robsong (Apr 3, 2010)

Did the test tones in 2 ch stereo and my 2 fronts at 50hz I can hear them and at 20hz I start to hear my sub. Is this right thanks.


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## tonyvdb (Sep 5, 2007)

Yes, that sounds about right. The crossover is not a brick wall rather a slope so their will be some levels below the crossover setting.


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## robsong (Apr 3, 2010)

I thought I was coming mad. The Crossover frequency for my KEF Q900 is 1.8kHz so what crossover should I use on the avr thanks to all for helping me out.


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## tonyvdb (Sep 5, 2007)

No problem.
Thats the internal crossover of the speaker, not he same thing. I would go with 80Hz for a crossover as that is usually the best setting to start with.


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## robsong (Apr 3, 2010)

Will do thanks again for your input. If you every make it out to SF Bay Area I take you out to lunch. :T


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## tonyvdb (Sep 5, 2007)

Thanks  Some day I would love to get down that way.


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## robsong (Apr 3, 2010)

If you ever do just hit me up.


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## DougMac (Jan 24, 2008)

That's interesting. I bet you're hearing harmonics from the center.

I wonder what would happen if you used a blu-ray with a dedicated LFE channel. When I used just a regular CD with sweeps I generated in software and captured, I got a lot of activity in my L/C/R below the crossover point. I now have a copy of Disney's "WOW" disk and its sweeps are directed through the LFE channel and I don't have nearly as much activity in the mains below crossover.


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## needspeed52 (Aug 2, 2008)

DougMac said:


> That's interesting. I bet you're hearing harmonics from the center.
> 
> I wonder what would happen if you used a blu-ray with a dedicated LFE channel. When I used just a regular CD with sweeps I generated in software and captured, I got a lot of activity in my L/C/R below the crossover point. I now have a copy of Disney's "WOW" disk and its sweeps are directed through the LFE channel and I don't have nearly as much activity in the mains below crossover.


I'm looking for a disc that has the FR sweeps rather than downloading and capturing to CD, is the Disney's WOW worth it for audio, I just assumed it was video oriented, look forward to your reply, thanks.
Jeff


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## DougMac (Jan 24, 2008)

needspeed52 said:


> I'm looking for a disc that has the FR sweeps rather than downloading and capturing to CD, is the Disney's WOW worth it for audio, I just assumed it was video oriented, look forward to your reply, thanks.
> Jeff


I think Disney's World of Wonder (WOW) is worth the price. While my Mitshibishi front projector was good out of the box, working through the adjustments did improve PQ. There are a set of basic audio tests, including sweeps and a "rattle" test. It also has some clips from Disney movies that will show off your system.


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## needspeed52 (Aug 2, 2008)

DougMac said:


> I think Disney's World of Wonder (WOW) is worth the price. While my Mitshibishi front projector was good out of the box, working through the adjustments did improve PQ. There are a set of basic audio tests, including sweeps and a "rattle" test. It also has some clips from Disney movies that will show off your system.


Thanks Doug


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## robsong (Apr 3, 2010)

I do have the Disney WOW disc will give it a shot and see what happens.


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