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#41147 - 04/11/04 06:11 PM Subwoofer set-up advice
mace Offline

Registered: 04/11/04
Posts: 57
Loc: Go Sooners!
Hello all,
Have been lurking around this site some time, and have learned quite a bit from the resident experts. My question concerns subwoofer set-up and phase. I have an HSU-VTF2 sub and a pair of M22’s for stereo only listening. In the VTF-2 manual it suggest to play some material with bass and to set the phase wherever it gives the most output. On my system this is at the 180 degree setting. Recently I have purchased a set-up disc and a
Rad Shack digital SPL meter, and then printed a copy of the corrections for the meter off of HSU’s site to properly set up my system.
I mean, why spend all this dough and not do it right, right?
After taking NUMEROUS readings, moving everything everywhere, the best I could get my settings were 20Hz-77.5dB, 25Hz-79, 31Hz-82, 40Hz-89, 50Hz-72, 63Hz-83, 80Hz-80.5, 100Hz-82.5.
I realize I have a room node around 35Hz, and a suck-out around 52Hz, but I felt that I should be able to get better readings. So once again I get everything ready to take a few more readings and try to improve on my past endeavors, when I get the bright idea to switch the phase to 0 and see what happens. Within 3 readings I was able to come up with 20Hz-83.5, 25Hz-82, 31Hz-82, 40Hz-81.5, 50Hz-77.5, 63Hz-80.5, 80Hz-80.5, 100Hz-85. My reference level was 80dB for all readings
My question is, will running the sub @ 0, degrade or “muddy” the sound., even though it flattens the overall response?
Sorry this is long, and thanks guys

My DIY page

#41148 - 04/12/04 02:42 AM Re: Subwoofer set-up advice
JohnK Offline
shareholder in the making

Registered: 05/11/02
Posts: 10463
Mace, welcome. You haven't described your room dimensions or the location of the sub, but if one dimension is about 16', then yes, there would be an axial mode due to that dimension at around 35Hz(i.e. 560/16). It's possible that the strong response around the peak in the 40Hz area gave the impression of stronger bass at the 180 setting. Your present readings are exceptionally good for in-room response. How could such a flattened response possibly "muddy" the sound? Flatter is better than louder.

Enjoy the music, not the equipment.

#41149 - 04/12/04 02:44 AM Re: Subwoofer set-up advice
Raindance Offline

Registered: 11/30/03
Posts: 170
Loc: Minnesota

You can always boost the frequencies you really like with an EQ when you have a flat response, as well.

#41150 - 04/12/04 03:04 AM Re: Subwoofer set-up advice
2x6spds Offline

Registered: 03/16/02
Posts: 2726
Loc: CA, USA
Best way to use the equalizer is to set your highest levels at the output level (flat) and reduce those frequency bands you want to be lower than the highest. The equalizer is not a good amplifier.

Those are some pretty weird output readings in that neither phase setting gives you the highest SPL output at all frequencies. If you want more bass and your sub has a +3db setting, I'd try that.
Enjoy the Music. Trust your ears. Laugh at Folks Who Claim to Know it All.

#41151 - 04/12/04 08:54 AM Re: Subwoofer set-up advice
Monstermile Offline

Registered: 02/20/04
Posts: 111
Loc: Delaware
In reply to:

and then printed a copy of the corrections for the meter off of HSU’s site to properly set up my system.

Where on the HSU site did you find this???

#41152 - 04/12/04 10:29 AM Re: Subwoofer set-up advice
Ajax Offline

Registered: 12/30/03
Posts: 6272
Loc: Cleveland, Ohio
Here ya go, Steve. This isn't Hsu's web site, but it's the same thing.

Using 40Hz. as an example, and assuming you're calibrating to 75db (substitute 85db if your using Avia), and assuming I remember this correctly, when your meter reads 75db at 40Hz, you're actually getting only 72.5db. So, you want to increase the volume until the meter reads 77.5db. Then you've actually got your 75db.

In other words, add or subtract the amounts in the chart to the initial reading you get on the meter, to make it correct.

"People generally quarrel because they cannot argue." - G. K. Chesterton

#41153 - 04/12/04 12:13 PM Re: Subwoofer set-up advice
mace Offline

Registered: 04/11/04
Posts: 57
Loc: Go Sooners!
First off, thanks to all who replied.

JohnK-My room is 12x14x7.5
Raindance and 2x6-I really don't want an EQ, although before I tried changing the phase, I definitely thought about it.
Also the reason I thought that changing the phase would hurt was because when I initially set up the sub, the 180 setting gave a more distinct presence than the 0.
Once again, thanks all
My DIY page

#41154 - 04/12/04 12:34 PM Re: Subwoofer set-up advice
al1en Offline
old hand

Registered: 03/27/04
Posts: 76
Loc: Wichita, KS
Actually it's the other way around on your meter readings. Your Rat Shack meter is less efficient at reading lower frequencies. You ADD the compensation factor to your meter reading.

If you have the sub distance set up properly in your receiver, you will not need to vary far from 0 degrees on your sub phase. I just spent most of yesterday playing with the phase on my SVS PB2-isd. Fun isn't it. What sounds like the most bass is not necessarily correct and most likely not the flattest response.

And the flattest response should be the best. Try playing a test tone at your crossover frequency, say 80hz, then set the phase to give the loudest reading on your meter.

Taken from:

"The problem? The Radio Shack sound meter is not totally "linear" in its accuracy down there. All such meters are off by the same amount depending on the frequency however, which is good news! So that while its sensitivity below 20Hz is not what it is at 50Hz, there is a simple way to compensate for this deficiency."

At 10Hz add 20dBs to the meter's readings and at ...

12Hz add 16.5dB
16Hz add 11.5dB
20Hz add 7.5dB
25Hz add 5dB
31.5Hz add 3dB
40Hz add 2.5dB
50Hz add 1.5dB
63Hz add 1.5dB
80Hz add 1.5dB
100Hz add 2dB
125Hz add .5dB

Edited by al1en (04/12/04 12:43 PM)
M60s, VP150, QS8s(3), SVS PB12-isd, Denon 3805, Emotiva UPA-7

#41155 - 04/12/04 12:49 PM Re: Subwoofer set-up advice
Ajax Offline

Registered: 12/30/03
Posts: 6272
Loc: Cleveland, Ohio
Thanks David. It is very confusing to me, but that cleared it up. Now all I have to do is remember it. OY!

Just to clarify my previous post: At 40Hz, if your meter is reading 75db, you're actually hearing 77.5 db. So, you want to REDUCE the volume to the point where the meter reads 72.5db, and then you are actually hearing 75db. Whew!

"People generally quarrel because they cannot argue." - G. K. Chesterton

#41156 - 04/12/04 01:05 PM Re: Subwoofer set-up advice
BigWill Offline

Registered: 05/01/03
Posts: 1951
Loc: Corona, Calif. USA!!!
Nice little picture thingee under your handle, 2x6!
I called the wife up to see it.

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