Classé Sigma 2200i integrated amplifier Equalization Setup

Sidebar 1: Equalization Setup

To set the Classé's parametric equalization filters, I used the Dayton Audio OmniMic measurement system. While less sophisticated than the setup John Atkinson uses for his in-room measurements, this relatively affordable device ($298 list) is a way for the tech-savvy audiophile to make good use of the PEQ offered in the Sigma 2200i.

The measurements I made were performed at the listening seat, with 1?6-octave smoothing. I made only single-point (not position-averaged) readings, as that was the only way to ensure consistent microphone positions pre- and post-equalization. As for my listening, the speakers were my Monitor Audio Silver 10s, and the subwoofer, when used, was a Revel B15.

The pre-equalized result for the left speaker (fig.1) was taken only with the treble control on +1, and show the sort of bass lumpiness found in all too many listening rooms. The deepest bass was down in level, with a significant dip in both channels at around 40Hz, though this recovered somewhat at 30Hz. A broad elevation centered at around 100Hz leveled out above 400Hz. The latter isn't surprising, as most room-caused response errors occur below this frequency. (It's also possible that some of this rise could be due to the speakers themselves.) Altering the listener and/or speaker positions can often help with this—and should be tried before equalization, if possible—but in my situation the left and right front speakers, and my listening seat, must be placed to accommodate a projection screen for my work for Sound & Vision magazine. The screen is retracted for serious music listening, as for this review, but only small tweaks of the speaker positions are possible.


Fig.1 Monitor Audio Silver 10 (left), 1/6-octave response at listening position without EQ.

I used all of the Sigma 2200i's available parametric equalizers: six per channel. The post-equalization response was much smoother (fig.2). The rise at 30Hz and the dip at 40Hz couldn't be completely tamed (each band of equalization is limited to a maximum of +3dB for good reason), but the remainder of the response is relatively smooth, with a desirable downward slope from below 100Hz to 10kHz; still, some experts might prefer a more aggressive slope.


Fig.2 Monitor Audio Silver 10 (left), 1/6-octave response at listening position with EQ provided by Classé Sigma 2200i.

None of the equalization I employed here, either with or without the subwoofer, was above 400Hz. I wanted to keep the characteristic sound of the Silver 10s as close to their unequalized state as possible across the critical midrange and highs. I wouldn't be using these speakers if I didn't like the way they sounded!

The measured response with a well-positioned and equalized subwoofer in the system, using the high/low-pass filter configuration set to 24dB/octave at 80Hz (fig.3), was dramatically better than with the main speakers alone. But, as I describe in the review, this didn't work well in my situation, due to subwoofer limits and my very large listening space.—Thomas J. Norton


Fig.3 Monitor Audio Silver 10 (left) with Revel B15 subwoofer, 1/6-octave response at listening position with EQ provided by Classé Sigma 2200i.

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georgehifi's picture

"I used Audio Precision's high-order AES17 high-pass filter when measuring distortion, as otherwise the reading would be obscured by the noise."

Hi JA, was this filter also used when measuring/presenting the (fig 9) 1kHz and (fig 10) 10kHz square wave screen shots?

Cheers George

John Atkinson's picture
georgehifi wrote:
was this filter also used when measuring/presenting the (fig 9) 1kHz and (fig 10) 10kHz square wave screen shots?

No, the squarewave images were taken with just the external AP0025 filter as the AES17 brickwall filter would have affected the amplifier's reproduction of squarewaves. The AP0025's rolloff is sufficiently high in frequency not to have an effect other than eliminating RF noise.

John Atkinson
Editor, Stereophile

georgehifi's picture

Ok it's a different AP in line filter, this 20 Hz to 20 kHz passband filter you used
Has a -50db rolloff rate, I take it doesn't handle much power hence the "small-signal" square wave testing you can only do with it in line.

Myself, I would still prefer to see in tests with and without this filter in line, to see what's being sent to the speakers.

Cheers George

caphill's picture

Hello Thomas,
Thanks for the review of the Classe Sigma 2200i integrated. It was interesting to read your comments about the Classe Sigma 2200i being warm sounding tonally. I personally haven't heard the Sigma 2200i but have demoed the Sigma SSP + Sigma Amp5 combo paired with B&W speakers and Wilson Sabrina multiple times and they were very neutral tonally and very transparent imo. The Sigma combo were spectacular sonically. I demoed in both stereo for music in analog / digital bypass mode as well as for home theater (surrounds).

I would assume that the Sigma 2200i would perform very similar.
Did you get to listen to the Sigma separates by any chance?

Richard D. George's picture

I own the Sigma SSP and Sigma Amp 5. They sound spectacular for both home theater and two-channel audio. I have a Bluesound Vault2 connected to the Sigma SSP and high-resolution two-channel audio files sound terrific.

Richard D. George's picture

I also heard the Sigma 2200i demonstrated with Bowers & Wilkins 804 d3 speakers at a 2016 Music Matters event at my local dealer. Sounded fantastic. Heard four or five cuts (all Redbook format, interestingly, no high res) over the course of 40 minutes.

I don't hear the "not neutral" part. Must be my faulty ears.

caphill's picture

Hi Richard,
How did the Sigma 2200i sound compared to your Sigma SSP + Sigma Amp5 separates? What speakers do you have at home?

Richard D. George's picture

Too many variables to directly compare. I thought both sounded good, with no obvious flaws.

In that particular system my speakers are Sonus Faber Venere 3.0 and Venere Center with two REL S/5 subs connected speaker level with Longbow. I may eventually upgrade to Sonus Faber Olympica for L/R/C speakers, or perhaps Bowers & Wilkins 804 d3. Surround speakers are high-end Bowers & Wilkins two-way in-ceiling speakers (don't recall the model number)

caphill's picture

I think both the B&W 804 D3 and the SONUS Faber Olympica are great speakers imo but I think the B&W 804 D3 will have better synergy with your Classe Sigma Amp5.

I myself am using the Classe SSP 800 pre pro with the Classe CA-M 300 monoblock amps (3×) for L/R/C speakers. Using the Classe CA-2300 stereo amp for my surround speakers. My front speakers are the B&W 802 D3 with the matching HTML1 center speaker. My surround speakers are the 804 D3.