Subwoofer Calibration using Rives CD 2

gene

gene

Audioholics Master Chief
Administrator
One of our forum members Jeff Lawson was so enamored with the results he achieved using the Rives Test CD 2 to calibrate his systems bass response (particularly the subwoofer) that he asked to write an article for us on this topic. In it you will find calibration tips for subwoofer placement, and delay adjustment, along with implementing tweaks such as a subwoofer EQ to smooth things out. All you need is a Radio Shack SPL Meter, the Rives Test CD 2 and you’re good to go.

If you decide to purchase this CD from Rives website. don't forget to type "Audioholics" at checkout to receive a 10% discount or mention us via phone.


Subwoofer Calibration using Rives CD 2
 
Rob Babcock

Rob Babcock

Moderator
Great article. I used a very similar technique, accept that I also have a Behringer DSP-1124 configured as a parametric EQ. Your method is basically the way to set EQ, too.
 
D

docferdie

Audioholic
the concern I've always had about using in line equalizer is how none of the affordable ones have good signal to noise ratios. So even though you get ruler flat frequency response is the musicality or fidelity as good as without it? I would love it if somebody were to evaluate these equalizers at the neutral position to see what changes they make to the audio signal.
 
gene

gene

Audioholics Master Chief
Administrator
Doc;

You do have a valid concern, however remember that the EQ is only connected to the subwoofer channel. Thus the induced noise if any, is filtered out from the sub crossover and natural rolloff of the driver. Its not going to affect your main channels in any way.
 
D

docferdie

Audioholic
gene,
are you saying that since the induced noise is outside the expected frequency response of the subwoofer then the equalizer's presence shouldn't affect the subwoofer's sound quality?
 
Rip Van Woofer

Rip Van Woofer

Audioholic General
Great stuff, and an added incentive for me to get the Rives disc since I'm going to embark on an upgrade of my DIY speakers within the year.

One possible way around the 1/3 octave limitation on the Rives disc is to get a disc with low-frequency sinewave sweeps, say up to 200Hz or so. The Linkwitz test CD has such sweeps, plus tonebursts at various frequencies and pink noise, useful for other room interaction and speaker tests. You can watch the SPL meter wiggle (or the readout change) as the sweep plays. You won't be able to exactly know the frequency at which a given null or peak occurs, though, without some sort of frequency counter. Some DMM's (digital multimeters) have this feature at a not too outlandish cost (and there's always eBay). Or, you could use a stopwatch and some math to find the approximate frequency since the sweeps are of a specific duration, but... :rolleyes: )

Or you could go on eBay and find an old cheap frequency generator like I did.

There are also shareware spectrum analyzers and frequency generators for Mac and PC out there at reasonable prices.

Of course, none of these offers the Radio Shack meter calibration of the Rives disc but they can still be useful additions to it.

That result you got looks awesome!

Oh, and I second Doc's idea of testing affordable EQ units like the Behringer and others! Not just for THD+N (that's important of course) but overall performance.
 
Last edited:
jeffsg4mac

jeffsg4mac

Republican Poster Boy
Thanks guys, I am glad you found it useful :)
 
Rob Babcock

Rob Babcock

Moderator
docferdie said:
gene,
are you saying that since the induced noise is outside the expected frequency response of the subwoofer then the equalizer's presence shouldn't affect the subwoofer's sound quality?
Yes, any "hiss" or thermal noise is mostly well over the range that a sub can reproduce. An EQ (assuming it's a good one) is essentially transparent for subwoofer apps (except of course for the changes you want to perform on the signal).
 
gene

gene

Audioholics Master Chief
Administrator
are you saying that since the induced noise is outside the expected frequency response of the subwoofer then the equalizer's presence shouldn't affect the subwoofer's sound quality?
Yes. And it is a great idea for us to review sub EQ's. I have the Rives PARC in my possession which I plan on reviewing this August. Stay tuned.
 

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