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Discussion Starter #1 (Edited)
Hello,

I have had REW and a usb soundcard for some time but am intimidated by the program.
I've just gone thru and calibrated my soundcard, checked and adjusted levels, then calibrated my analog RS meter.

What do you make of my graph? There seem like there are so many variables I could have messed up when calibrating I'm unsure if my graph is valid.My analisis is that it looks decent but starts to drop off around 40 hz.
This could be due to the corner placement or my sub or could have to do with me incorrectly calibrating my soundcard or radioshack meter.
Any imput would be greatly appreciated This graph is pulled from the "measured" tab

 

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This graph is pulled from the "measured" tab
Better to show the filter adjust tab, so we can see the target crossover you are using in your receiver.

Measure a sub from 0-200Hz.

brucek
 

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Discussion Starter #5
it looks like rew is only measuring to 100hz.
Where do i look to adjust this?
Also, why should we be measuring to 200HZ.
I believe I have the crossover in my receiver set to 80-90 hz
 

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Set the measurement limits in the Measure panel.

200Hz is required to see the entire effect of the crossover.

I would say you didn't run Calibrate SPL after Check Levels, evidenced by the level of your response above the 75dB target line.

Post graphs with a vertical axis of 45dB-105dB, and a horizontal axis of 15hz-200Hz.
 

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Discussion Starter #7
I tried to calibrate the sound meter after check levels. Problem is that the needle varried between 77.5 and 79. So i set it as 78.
I also added the upper frequencies and zoomed thegraph in per your suggestion bruce.
So how am i looking now?

 

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So how am i looking now?
Great.

You've got very good extension. The small peak at 35Hz probably isn't worth doing anything about.

It looks like this plot is with the mains added, as it isn't tracking the target after the crossover. If so, I'd say it's a good response....

brucek
 

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Discussion Starter #9 (Edited)
that sounds good. I'll have to check back later to see if my mains were on. The sub is a pb13 in 15hz tune. I'm thinking i may try to mess with the single band PEQ on it to see if I can bring the curve up in the 40-80hz range.

I'm guessing I would turn the speaker levels all the way down on my mains in my reciever to measure just the sub. Either that or just temporarly just unplug the mains.

Thanks for the imput. I'll continue to report back as i progress.
 

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Can you please elaborate on this a bit more?
Two points on this:

Most people prefer the bass level to slowly increase below the crossover region until about 30Hz, and then level off flat below that. This is usually called a house curve (which you can program into REW's target if you like). Call it what you will, it's to compensate for your hearing, that drops off at lower frequencies. REW's calibration creates flat microphones, so the house curve is usually warranted. You are lucky enough to have a natural rise in your response below the crossover. Why fight it.

On the other hand you have a peak at 35Hz. Any peak like this will tend to overwhelm frequencies below it. Information at 20Hz will be harder to perceive if you have a peak at 35Hz. If you reduce that peak, it will reveal the lower frequencies. All of a sudden, 20hz will appear louder.

brucek
 

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Discussion Starter #13
Thanks for the explanation, I think I get it now.
I'll see what I can do about taming my 35hz peak.
Hopefully my single band peq will do the trick, I have yet to experiment with it yet.
 

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The sub is a pb13 in 15hz tune. I'm thinking i may try to mess with the single band PEQ on it to see if I can bring the curve up in the 40-80hz range.
On top of what brucek said, if the single band PEQ in your sub is like what's included on most other SVS subs, it cuts only - no boosts. If you feel you could benefit by raising that area, you'd need outboard equalization.

Regards,
Wayne

 

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I'll see what I can do about taming my 35hz peak.
Hopefully my single band peq will do the trick, I have yet to experiment with it yet.
Again, if the PEQ is like what's in other SVS subs, its markings aren't calibrated all that well. On of that, it's not an equalizer that REW is programmed for. Rather than take a sweep, tweak the EQ and repeat, repeatedly, you might try using the RTA function. That way you can see the display change in real time as you adjust the PEQ.

Regards,
Wayne

 

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Discussion Starter #16 (Edited)
Ok I've been tweaking the peq and ran like 20-30 sessions of rew with different peq settings.
What do you think of the below.
Have I made an improvement over no eq?
 

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You're certainly on the right track. But notice that you reduced the level of a lot of area beyond (i.e. above and below) the peak. If that was your intent and you think things sound best this way, then you're fine. But if not, I'd try narrowing the filter, if the settings will allow (IIR, the SVS PEQ bandwidth can't be set as narrow as I'd like to see them be able to). Also, it appears that your frequency center is set higher than your peak - note the "new" sharp dip at ~40 Hz.

But basically you're on the right track. You might make a record of your current setting for future reference, for future listening evaluations, should you decide to experiment further.

Regards,
Wayne
 

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Discussion Starter #18
I see what you mean, Wayne. Thanks to you and Bruce for all of your insight. It is helping me overcome the learning curve with rew. Next time I get a chance, I think I'll start over from scratch.

I'm thinking I should start by making the bandwith as narrow as possible and the level all the way up. Then once I have the frequency pinpointed as right in the middle of my peak gradually back the level down. Then if it makes the line look nicer I will also gradually widen the bandwith.

Making notes is a very good idea as it can be easy to lose track when you are making a ton of adjustments (especially when there are 3 variables such as I have).
 

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Using the RTA would make it so much simpler.

Take a measure with the EQ off so you have a reference line on the RTA to compare your dynamic line against while you're adjusting.

Look here for a small blurb on using the RTA feature. Look part way down the post.

brucek
 

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Discussion Starter #20
Using the RTA would make it so much simpler.

Take a measure with the EQ off so you have a reference line on the RTA to compare your dynamic line against while you're adjusting.

Look here for a small blurb on using the RTA feature. Look part way down the post.

brucek
VERY cool. I didnot even know of the realtime alalizer's existance.
I will check this feature our for sure. It will likely make this much easier for me.
 
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