Many months ago Erin reviewed the Sony SS CS5 speakers. I had previously developed a modification for that speaker that included a DIY anti-diffraction frame made out of PVC, and a simple resistor short. After discussions with Erin, he agreed to test the anti-diffraction frame by itself. I agreed this was a better option, because it isolated the impact of the frame. If you change 2 things at once it's impossible to know for sure the impact of either modification in isolation.
Erin soon identified an issue with the measurements that showed evidence of a resonance near 2 kHz. His prior measurement of the CS5 didn't show this resonance, so it seemed highly plausible that the frame was causing this resonance; probably vibrating against the cabinet. I mentioned that I had heard no evidence of a resonance when listening to the speaker with the frame attached, and Erin also noted no issues during listening. We figured the resonance was too narrowband to be impactful on most music selections.
It turns out that Erin attached the frame to the "2nd unit" in the pair of CS5s, while he had initially measured the "1st unit" in his review. The resonance was a feature of the 2nd unit with or without the frame. Erin discovered this by removing the frame and measuring unit 2 without it. As a result, the comparative measurements I have for the frame are on unit 2, which suffers from a resonance near 2 kHz. When viewing the graphs, the reader will simply have to take into account that the resonance behavior at 2 kHz appears to be atypical for this speaker, and should largely be ignored. Also it's not a result of the frame, and should not be attributed to the frame.
I have included a picture of the speaker with the frame attached, as well as an animated gif that switches back and forth between Spin summaries with and without the frame.
The most obvious on-axis frequency response differences made by the frame are a reduction of energy from 950 Hz to 2900 Hz (including the problematic peak at 1100 Hz), and an increase of energy below 950 Hz that gets smaller and smaller until it vanishes around 200 Hz. Both of these are welcome changes that improve the perceived balance of the speaker. We attribute the increased energy in the lower midrange to the effective widening of the baffle.
Interestingly, the DI for the speaker with frames (aka wings) shows an extremely consistent response from 500 Hz up to 10 kHz. The merits of that type of response can be argued, but it's interesting that it happened here with no specific intent to obtain that result. I'll include follow-up posts with dispersion graphs.
Erin soon identified an issue with the measurements that showed evidence of a resonance near 2 kHz. His prior measurement of the CS5 didn't show this resonance, so it seemed highly plausible that the frame was causing this resonance; probably vibrating against the cabinet. I mentioned that I had heard no evidence of a resonance when listening to the speaker with the frame attached, and Erin also noted no issues during listening. We figured the resonance was too narrowband to be impactful on most music selections.
It turns out that Erin attached the frame to the "2nd unit" in the pair of CS5s, while he had initially measured the "1st unit" in his review. The resonance was a feature of the 2nd unit with or without the frame. Erin discovered this by removing the frame and measuring unit 2 without it. As a result, the comparative measurements I have for the frame are on unit 2, which suffers from a resonance near 2 kHz. When viewing the graphs, the reader will simply have to take into account that the resonance behavior at 2 kHz appears to be atypical for this speaker, and should largely be ignored. Also it's not a result of the frame, and should not be attributed to the frame.
I have included a picture of the speaker with the frame attached, as well as an animated gif that switches back and forth between Spin summaries with and without the frame.
The most obvious on-axis frequency response differences made by the frame are a reduction of energy from 950 Hz to 2900 Hz (including the problematic peak at 1100 Hz), and an increase of energy below 950 Hz that gets smaller and smaller until it vanishes around 200 Hz. Both of these are welcome changes that improve the perceived balance of the speaker. We attribute the increased energy in the lower midrange to the effective widening of the baffle.
Interestingly, the DI for the speaker with frames (aka wings) shows an extremely consistent response from 500 Hz up to 10 kHz. The merits of that type of response can be argued, but it's interesting that it happened here with no specific intent to obtain that result. I'll include follow-up posts with dispersion graphs.