Wednesday, July 26, 2017

The PMD 100 is innocent

I still wonder why I get 13dB higher noise levels from my Denon DVD-9000 players than my Denon DVD-5000 players, the RMAA measurement goes from 88.9dB for the 9000 to 112dB for the 5000.

But it would appear that the PMD 100 is innocent, from all information I have.  PMI spec'd the alias suppression at 120dB, for example, better than many other chips.  Another highly esteemed player using the PMD 100 is the Linn Sondek LP12, which had excellent measurements, with John Atkinson saying (at the time) it was as good as he had ever seen.  The LP12 uses dual differential 1702's, which are usually regarded as inferior to the dual differential 1704's of the DVD-9000.

On the DVD-5000 and DVD-9000, the analog circuitry after the dual differential 1704's is almost the same.  The 9000 does seem to use fewer OP275's and more 5534's, and the output goes through a muting transistor rather than muting by shorting the inputs to a OP275.  To my inexperienced eye, the analog circuitry of the 5000 does look slightly better, still not exactly what I would want.  I would want at least LM4562's, if not OPA211's.  But with noise and distortion levels as low as they are in either case (and certainly by the specs for the 9000, which are far better than I measure) the circuitry is "good enough" to likely fail every attempt to distinguish it in blind testing.

The DVD-9000 uses 5534 to initially amplify the 1mV "current" output of the 1704.  The DVD-5000 uses a slightly more advanced chip.  The DVD-9000 uses a single transistor in the muting circuit.  The DVD-5000 uses a OP275 instead.  Other amplification stages see OP275's in the 5000 replaced with inferior 5534's in the 9000.  These are the "slight" differences I see, enough to account for maybe 3dB of difference, not 13dB.  The Denon noise spec is 3dB better for the 9000 actually (118 vs 115dB).  Perhaps my two units have deteriorated with age?  That seems most likely, but another possibility is that Denon used a different weighting in measuring the noise than RMAA uses.

Back when I was "flying" with the Eagle 2 amplifier, some of the most intense audio ecstasy I've ever experienced, I happened to have been very temporarily using the DVD-9000 as my DAC, and the 9000 did initially distinguish itself by having the smoothest yet most detailed sound of any of my players (I've never used the DVD-5000 as a player).  I do wonder if the 9000 might actually "sound better" than the 5000 despite the increased noise level.  Along with higher noise, it has lower distortion, so maybe the distortion is better hidden in the noise.  I'm beginning to think that distortion should always be hidden like that (which generally is the case in very high feedback designs like the Eagle 2, for example).

In order to use the DVD-9000 as my system DAC, however, I would need 3 of them in addition to the one I now use as an HDCD/DVD-Audio player.  That's because they have far more latency than any other DAC I have, up to 330 msec, and it varies a lot depending on sample rate.

I now have 2x DVD-5000 and just missed an opportunity to get a third.  I'm thinking I might like a 3-stack of DVD-5000 for my system, though it would add a lot of physical complications because I'm running out of room for more equipment.  I can fit 2x DVD-5000's and 1x Emotiva Stealth DC-1 I now use on the subs without any issues.  If I got a third DVD-5000 I would also need a single-ended-to-balanced buffer with some attenuation, and additional space for the two units.  I'd also need a 3rd AES to SPDIF converter (about $135).

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