Here is some info on the three "CD" filter settings available on the SA-11:
The frequency response graphs here are from a very extensive (and technical) test of the SA-11 in the July, 2006 issue of Hi-Fi News and AV Tech Magazine.
The testing was done by Miller Audio Research; the complete test results, with measurements of filters 1-3 for both CD and SACD are available here:
http://www.milleraudioresearch.com/avtech/
(You will have to "register" on the site in order to access the results. It's free, and I haven't gotten any "spam" in the 18 mos. I've been registered).
Here is a comparison of the three filter settings for "Red Book" CD:
(Note the different dB scales for the three graphs.)
Filter 1 has a subtle "softening" effect, with the frequency response being down -.5dB at 14.5kHz and only -1.33dB at 20kHz.
(This filter will take just a bit of the "edge" off bright recordings.)
Filter 2 has a definite HF roll off. FR is down -3dB by 14.5kHz, and is down a whole 5dB at 20k!
Filter 3 has the least effect on frequency response, being down only about .33dB at 20k.
I took some "low tech" oscilloscope photos of the appearance of a 1kHz square wave for each of the three filter settings.
Filter 3 looks just like the square waves produced by my old Magnavox CDB-560, which had a 4x oversampling filter and a "traditional" 16-bit ladder-type DAC. The square wave has the usual symmetrical "Batman" appearance!
The other three photos show the effects of the three filter settings on a constant 20kHz sine wave (actually 19,997Hz, from the CBS CD-1 Test Disc).
Filters 1 and 2 definitely have some kind of modulation effect on the sine wave. This "wavy" effect can be seen on a sine wave sweep as well, and begins to appear at about 10kHz.
So... Filter 3 appears to "do" the least to the music, with almost no effect on frequency response and the least effect on high frequency waveforms.
I do most of my listening using filter 1. It seems to have just a bit of a "sweetening" effect on the sound, and also makes my older, early-digital-era recordings easier to take. I find I can listen to some edgy recordings on the SA-11 that I never could on my previous players. Over-bright recordings don't have me reaching for the "off" button as often either!
I'm sorry I'm not able to find out more about the SACD filter settings. I don't have access to a test SACD!
I do all my listening to SACDs using filter 1. I haven't been able to hear any difference at all between the three filters on SACD.
Ken
