charlesp210
Member
I am grateful for the review by Amir and all the illuminating discussion, including links to reviews of apparently similar performing Marantz processors. I've read every single page here and many of the linked articles. I've loved this ASR website for quite awhile now but have been going through life and email changes so this might be my first post (can't remember if I joined or posted under a previous email). Amir's discussion of EQ in other pages is also extremely important and I mostly agree with everything I've read so far. I've been using manual "room correction" for a decade myself and wouldn't yet have it any other way (though multieq with the editor app looked like a possibility).
Of the issues Amir identified, by far the most shocking to me is the steep rise of distortion above 5kHz, reaching 1% just above 10khz.
I wish Amir had also tried the rated output level of 2.4V. I strongly suspect that would have "fixed" (or covered up) the shocking problem. One need only look at the Secrets review of the 8802(a), reportedly identical in audio output circuitry and specs, where they did measure 10kHz at 2 volts, obtaining a more acceptible 0.002% THD. THEN, they also reported 0.0035% at 5 volts, but only for 24/96 which is moving those pesky aliases up and out of the way. Very curiously, Secrets did not measure 10kHz at 5 volts with 44.1kHz sampling, which leaves just enough room for the shocking issue Amir reports to have been missed (or simply not reported).
If the source of the shocking rise in THD is merely the slower than slow reconstruction filter, why are there no visible aliasing products until you get over 2 volts, and then they take off like mad? It seems to me that aliasing products should increase more like linearly with input level.
I have noticed distortion products increasing like mad in another very different AV product I measured, an Integra Research RDC7. Everything looks fine (well, THD about 0.005% IIRC) until you get to 1V unbalanced and 2V balanced. Then, distortion products take off, and for that reason I was not able to do a direct measurement with my Juli@ card and RMAA at 4V balanced, where distortion exceeded 1%. At first I thought the RDC7 was broken, then I got another one, and after it looked the same I decided to try lower levels. I was pleased to see the distortion essentially disappear at lower levels. But I do not like preamps without distortion free headroom. Preamplifiers should be able to reach an amplifier's peak power, not just rated power, without adding any distortion. Amplifiers typically have 3dB or more headroom above rated power. This is why a 4V requirement is not at all a bad idea.
But meanwhile I wonder if some sort of soft clipping has become the standard for surround processors. I wonder if such a thing might even be required by proprietary standard, I know not which, there are many, such as THX, CSA, ETL, Dolby, DTS, Audyssey, and they may be contingent.
If so, it might be that the huge rise in distortion above 5kHz is caused not just by the slow reconstruction filter, but that in combination with a required (?) soft limiting curve. Just an idea that occurred to me tonight.
[updated to list variety of possible proprietary standards which might require soft clipping and/or certain output level limits]
Of the issues Amir identified, by far the most shocking to me is the steep rise of distortion above 5kHz, reaching 1% just above 10khz.
I wish Amir had also tried the rated output level of 2.4V. I strongly suspect that would have "fixed" (or covered up) the shocking problem. One need only look at the Secrets review of the 8802(a), reportedly identical in audio output circuitry and specs, where they did measure 10kHz at 2 volts, obtaining a more acceptible 0.002% THD. THEN, they also reported 0.0035% at 5 volts, but only for 24/96 which is moving those pesky aliases up and out of the way. Very curiously, Secrets did not measure 10kHz at 5 volts with 44.1kHz sampling, which leaves just enough room for the shocking issue Amir reports to have been missed (or simply not reported).
If the source of the shocking rise in THD is merely the slower than slow reconstruction filter, why are there no visible aliasing products until you get over 2 volts, and then they take off like mad? It seems to me that aliasing products should increase more like linearly with input level.
I have noticed distortion products increasing like mad in another very different AV product I measured, an Integra Research RDC7. Everything looks fine (well, THD about 0.005% IIRC) until you get to 1V unbalanced and 2V balanced. Then, distortion products take off, and for that reason I was not able to do a direct measurement with my Juli@ card and RMAA at 4V balanced, where distortion exceeded 1%. At first I thought the RDC7 was broken, then I got another one, and after it looked the same I decided to try lower levels. I was pleased to see the distortion essentially disappear at lower levels. But I do not like preamps without distortion free headroom. Preamplifiers should be able to reach an amplifier's peak power, not just rated power, without adding any distortion. Amplifiers typically have 3dB or more headroom above rated power. This is why a 4V requirement is not at all a bad idea.
But meanwhile I wonder if some sort of soft clipping has become the standard for surround processors. I wonder if such a thing might even be required by proprietary standard, I know not which, there are many, such as THX, CSA, ETL, Dolby, DTS, Audyssey, and they may be contingent.
If so, it might be that the huge rise in distortion above 5kHz is caused not just by the slow reconstruction filter, but that in combination with a required (?) soft limiting curve. Just an idea that occurred to me tonight.
[updated to list variety of possible proprietary standards which might require soft clipping and/or certain output level limits]
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