Investigating the Denon DVD-9000 noise

Denon 9000 noise tests

To get a better understanding of the noise produced by the Denon DVD-9000 with Emotiva XSP-1 and Tascam DA-3000, I recorded a series of tests shown above unedited and unamplified.  The Emotiva gain was at -4.5dB required for HDCD playback (which produces 4.5dB higher peak levels than anything else with the Denon DVD-9000) however peak output from the player will still reach -0.2dB from clipping the DA-3000 (at -9dB reference level).   

(Strange as it sounds, the Denon 9000 has greater S/N with HDCD than anything else, including DVD-Audio, because the HDCD peak output levels are higher than anything else while the noise from the player is pretty well constant.)

At the start I played bits from the last track of the Mephisto & Co.  HDCD, showing the noise before the track and after pausing.  Finally I just let the track fade out into silence for 5 minutes as the player kept running.  Then I shut the player down.  Then I shut the preamp down.  Then I connected a video cable from the Denon to my TV (through a video isolator).  Then I turned everything back on and tried the Pure Direct switch.

Without any added gain, the noise level is so low it's hard to see what's going on.  Using the audio editing program Audacity I edited out the major peaks shown above and then was able to amplify the rest by 66dB, giving the following result.  Now the noise is a thick line of varying height which can be studied.

Here is a blow by blow account of the edited version of the graph.

The first 5 minutes are just after the HDCD has stopped playing (in Pure Direct mode 2).

At 5 minutes the player is shut down.

At 15 minutes the preamp is shut down.

At 20 minutes a coax 75 ohm video cable is connected from the Denon to a video isolator that connects to a nearby TV.

At 25 minutes the TV is turned on (on a different circuit).

At 30 minutes the preamp is turned back on.

At 35 minutes the Denon is turned back on.

At 39 minutes, Play is pressed on the Denon followed by Pause as quickly as possible.

At 44 minutes, Pure Direct is turned off.

At 49 minutes, cable to TV is removed.

At 54 minutes, a stub cable is attached.

The noise falls noticeably when the player is turned off, and still more when the preamp is turned off, and comes back when the preamp and player are turned back on.  Other than that, there's not much change!

When I turn the Pure Direct mode off with a video cable connected to a TV, the noise rises about 0.3dB to the highest level in this recording (44 minutes).  The noise falls again when the cable to the TV is removed and reaches the lowest fully operating level when a sort stub video cable is connected to the player only.

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I can typically amplify noise portions from the Denon 9000 not containing special peaks by as much as 93dB in Audacity.

It appears this "noise" is about 70% 60 Hz hum, which gets knocked down 27dB by the traditional A weighting.  So if were all hum, that would mean a 120dB S/N ratio.

I'm not claiming it's exactly that good, perhaps more like 108dB for my entire recording chain here.  Consider:

Denon DVD-9000 S/N: 120dB

Emotiva XSP-2:  (unbalanced input to balanced output)  112dB

(balanced in to balanced output is specd at 115dB and is typically 117dB)

Tascam DA-3000 (balanced input): 113dB

The specs (confirmed elsewhere) indicate it's not going to be as good as 112dB, perhaps more like 108dB S/N.  And that seems plausible with my measurements and a guestimate in a previous post.

I can't fully isolate the parts for testing...may just have to live with that hum.

I investigated the noise under a series of conditions:

1.  Prior to playback

2.  After playback

3.  Player turned off

4.  Preamp turned off also

5.  Video cable connected to TV (using isolator)

6.  With and without the highest "Pure Direct Mode"

The Denon DVD-9000 does not cheat with the visible noise level.  There does not appear to be any circuit that suppresses noise during pause or stop.  The noise level before and after the studio noise on any album (which I can clearly see when amplified by 70dB in Audacity) kicks in is identical to the pause noise.  Not much difference when the Denon is even turned off (that's how quiet the Denon is!).  When the Emotiva XSP-1 is turned off, the noise does go down a few dB.  Then I'm looking at just the noise of the DA-3000.  

It does appear the Emotiva is the limiting factor, just as the specs suggest, but not much different than the DA-3000 itself so the noise only falls an additional 2dB or so when the XSP-1 is turned off.

If and only if a video cable is connected to my TV does the "Pure Direct" mode make any difference.  With the video cable connected to the TV, the noise goes up about 0.3dB when "Pure Direct" is turned off.

I measured less noise with the video cable connected and Pure Direct than with the video cable not connected and Pure Direct, but that was probably an experimental fluke.

The least of all noise was measures with short stub video cable connected, and Pure Direct mode.  So that's my setup for the most critical transcriptions.  The stub video cable makes it easy to connect or disconnect the video cable to the TV without getting behind the Denon DVD-9000, which is usually impossible.

Testing an Oppo BDP-205 connected to the Emotiva through balanced inputs instead, I could amplify the output by just over 95dB, a bit more than 2dB higher.

The Emotiva alone is at least that much better with balanced inputs, let alone how good the Oppo is--119.8dB S/N in fast linear phase mode according to Archimago, which on Archimago's recommendation I've just tonight started using...and now that I am using the fast linear phase mode...it's finally sounding as good or better then the various Denons.  (I'm now thinking that Denon's "AL 24 Plus" as used in the DVD-9000 is a linear phase type system too, implemented with FIR probably.  Denon even claims it's "adaptive" suggesting multiple filters...)

So I'm shocked but with either of these two players, the player as such is not the limiting factor but the preamp and the DA-3000, with balanced output players getting some benefit from the lower Emotiva noise with banaced inputs.

Actually this is not fully a test of the preamp because shorted inputs were not used.

The noise from the Denon DVD-9000 is what you could call interface noise, cased by the single ended connections and output resistance mostly.  The balanced "interface" of the Oppo is a mere 2dB better.  Their respective DA chips are hardly even part of the equation with -120dB and -130dB noise respectively.