Reducing hum from -94dB to -100dB

It seems like I can improve the S/N from the Denon DVD-9000 dramatically, over 6db, with a simple tweak which might apply whenever unbalanced interconnection is used.  (Or it might be peculiar to this set of components, etc.)

I connected an extra set of stereo cables from my Denon DVD-9000 to the Emotiva XSP-1 Preamp.  I deliberately connected the unused surround outputs to an extra of the preamp.  As the outputs are not carrying any signal during this test, they may act as a better ground connection than the initial stereo pair of cables connected to the main output.  It also turned out that just adding one unused cable made nearly all the difference.  Adding a second unused cable gave little additional improvement, so I suspect more similar cables would only be for the very obsessed.

The results are shocking.  I got over 6dB improvement in peak unweighted S/N ratio from having the extra cables.  Most is clearly hum but some is noises that have a 60 Hz period.  This is similar to improvements I see with balanced interconnects over single ended.

For the test shown I had the Denon DVD-9000 playing a regular CD (not HDCD which might be tricky) but in pause for the entire duration of the test.   The Emotiva XSP-1 gain was set at 0.0dB and not changed.

In the starting condition, I had the two extra cables connected from the surround outputs on the Denon to another input on the Emotiva.  At two minutes, I removed the first extra cable on the Emotiva side.  At 4 minutes, I removed the second extra cable.  At 6 minutes I removed the one of the cable connections on the Denon Side,   Around 8 minutes and 40 seconds I removed the second cable.  Then about 10 minutes I reconnected one of the extra cables.  Around 11 minutes I reconnected the second extra cable, so it was back to the starting condition (to be sure nothing else had changed...and it hadn't changed appreciably, compared to the main effect, which is huge).

DVD-9000 with and without (center) extra interconnects

There is visibly far more hum and noise (it's mostly hum but with some strange high frequency bursts that repeat every 1/60 sec) in the center condition which is just using the two stereo interconnects.  As soon as just one unused extra connection is made, the hum and noise drops 6dB.  Then when the second cable is added it improves a few tenths of a dB more.  What is remaining with the extra cable(s) seems to be almost entirely random high frequency noise and the high frequency bursts at 1/60 sec are eliminated.  It seems hardly worth trying more than two (I have no more good cables to try anyway...I had to buy this pair last week)...but just adding one unused cable is huge.

(Possibly it has something to do with the grounding on the Denon DVD-9000...but everything about the DVD-9000 seems impeccable.  BTW, I have Direct Mode set to 2 which shuts off video output.  Also it could have to do with the grounding on the XSP-1.  The extra cables were connected to Input 3, which is in a different bank.)

Another curious thing is that even connecting the cables on the Denon side alone seems to help.  I also saw that kind of behavior with the Video output--having a stub video cable connected (but not connected to anything else) makes the DVD-9000  quieter, even in Direct Mode 2.

Something that might be even better is connecting a very heavy wire, possibly mostly buss bar, to the grounds of two plugs and use that as the "extra" interconnection.  I think I've seen things like that sold as tweaks before.

Both my original interconnects and the extra interconnects are both Blue Jeans Cable LC-1, which has the best single ended shield configuration and plugs for hum and noise reduction.  The originals, unabused, are just a few years older.  These are very solid and thick cables custom made by Beldon with a double braided shield, and terminated by Blue Jeans with very solid Canare RCA jacks.  It's hard to imagine they could be broken or even slightly out of spec.

(Somehow, leading up to these tests, I had intended to upgrade the previous cables to LC-1 to see if that helped.  From above, it looked like I had been using standard grade Radio Shack cables from the mid 2000's.  Possibly intended only as a temporary fix until I got better cables.  But when I actually got close enough to change the cables I could see they were actually LC-1's.  It's funny how when the picture is unclear my mind can instead give me a clear picture of something wrong.)

Previous measurements shows unweighted peak S/N ratio around 93dB for the Denon DVD-9000, and 95dB for the Oppo BDP-205.  That 2dB difference was entirely hum and showed the benefits of balanced interconnection.  Both players actually have "120dB S/N" specification, the limiting factor is my Tascam DA-3000, which can only sample with 113dB S/N, which like all factor specs is A-Weighted, meaning the unweighted S/N is likely in the 95-105dB range.

With these changes, it looks like the Denon will be either identical to or maybe even better than the Oppo, at least for practical purposes when sampling with the Tascam DA-3000 for transcription or playback through my DSP based system.

If the test seems strange...it's partly because it followed an earlier series of tests which were inconclusive because I could never be sure that either I had reset the starting conditions in an identical way, or that the Denon hadn't started muting in some extra way.  Leaving the player running the whole time and going back to the starting condition at the end were the ways to remove these uncertainties that arose in previous testing despite attempts to control the starting conditions rigorously.  The Audacity screenshot was made after 80dB of Audacity digital amplification.  The noise seems higher than some previous tests because the Emotiva volume control was set to 0dB instead of -4.5dB (which I had been using for HDCD since the Denon actually expands peaks at least that high above the normal CD-level 2V output, though I discovered on album Poems of Thunder that in some cases HDCD peaks reach 5dB).  So add 5dB to the wideband unweighted peak S/N levels for comparison relevant to HDCD which is mainly what I use the Denon for.

Here are the peak levels from various parts of the test (correcting for the 80dB gain but not the additional 5dB available output on HDCD).

First 2 minutes (extra cable pair connected)

-91.05dB   (would be -96.05dB including 5dB extended HDCD peaks...this is better than previous data for Oppo which was -95.3dB)

Second 2 minutes (only one extra cable connected to Emotiva but both on Denon)

-90.3dB

Third 2 minutes (two extra cables connected to Denon but nothing else)

-87dB

Fourth segment (only one extra cable connected to Denon)

-85.5dB

Fifth segment (no extra cables connected to Denon)

-84.4dB (not including some early and late peaks which might be due to connection in progress)

-84.3dB (including suspicious early and late peaks)

Sixth segment (one cable reattached between Denon and Emotiva)

-90.0dB

Seventh segment (both extra cables connected between Denon and Emotiva)

-90.6dB

I could immediately add 5dB to all these numbers for HDCD because HDCD peaks are 5dB higher on the Denon, so I have to turn volume down 5dB on the preamp.  (Although, then the noise of the Emotiva itself would be a larger factor than it is, so results are not completely predictable.)  Then these are all unweighted peak measurements, which would improve by 10-25 dB with RMS and A Weighting.  And I don't know how much of these measurements are proportionally hum and ultrasonics.   It would be complicated to do weighted and RMS measurements on these data (I tried but ran into a snag) and only useful for bragging rights anyway since I don't see how I'm make these improvements significantly better without engineering a fake "grounding bus" interconnect as I suggested above.  This present improvement is great and I'll look for it in future connections.  (Though perhaps I should do more investigations to be sure this is a real effect and not a fault of the old cables, for example.)

My guess is that these numbers are showing at least 108dB properly A weighted RMS S/N, but with a mean guess of around 116dB S/N RMS A-Weighted based on the idea that RMS and A-Weighting would improve things about 20dB...but that can't be true since it exceeds the specs of all equipment I'm using (except the Denon itself, at 120dB S/N).  In reality all the noise levels are somewhat additive, so say if all 3 units (Denon, XSP-1, and DA-3000) had 120dB S/N, the result would be about 110dB S/N.  But the Tascam DA-3000 (balanced in) is at 113dB and the Emotiva XSP-1 is at 115dB (unbalanced in to balanced out).

Though the second additional cable gave only a fraction of a dB additional benefit, the 60 Hz component is still not entirely gone, so there might be some further benefit from grounding bus, etc.

*****

I have decided not to do any further investigations on this for the time being.  It could be, for example, that the initial cables were faulty (though they're fairly new and very rugged Blue Jeans LC-1), so if I swapped the brand new "grounding" cables for the initial ones, I might then have the benefit of low hum with only one pair.

Or it could be how the "grounding cables" are routed differently, perhaps out of EMI fields.

Adding cables might not always help.  I'm not claiming that at all.  I think only that if you see a hum issue, such a thing might be worth investigating.

In this cause there was no audible "hum" issue that I ever noticed.  It's deep down in the noise floor, deeply below the ambient noise in the room.  At -90 to -100dB or so in the electrical signal, at max output around 100dB, it would be 0-10dB, or -24 to -4dB "A Weighted".  If the two initial cables were somehow defective, and they would both have to be defective for there to be hum, one would expect much higher hum level than that.

There could be a straightforward explanation such as that each cable lowers the ground resistance.  Except it doesn't seem to work so incrementally.  Instead, the first extra cable made nearly all the difference.

It really seems like there were additional ground currents between the player and preamp, and routing these additional currents lowered the hum induction that occurred in the interconnect.

But why are these ground currents choosing to go through the additional cable(s) ?

Adding one more cable would in theory not be adding that much more conductance.

Instead, it looks like there is something peculiar going on.  Perhaps the grounding of the surround jacks on the denon is closer to the power supply ground.  And because of that, the extra currents DO choose to go through the new cable(s) selectively, giving a reduction in induced hum.

The Denon 9000 is grounded and so is the Emotiva XSP-1 (IIRC...or it's connected to grounded gear).  Ground loops may be to some degree inevitable, and perhaps it's a wonder they were already so low.

I think therefore that this finding is almost certainly some kind of fluke as I've described, not a general rule.

But it certainly looks like, I have already stumbled upon a lucky optimum.  Any change is likely to make it worse.  Then, assuming micro degrees in cable routing are also a contributing factor, I may find it hard to make it this good again.

And to do this test in the fairly incontrovertible way I have (as opposed to separate tests, in which some extra variable might have changed) means more wear and tear on my equipment, including my beloved Denon DVD-9000, which is very long in the tooth.  (In fact it already started acting up, with the drawer not pulling all the way in once, perhaps in protest.  Now I see it may do that so it looks OK but doesn't register the incoming disc, showing only 0's on the display.)  

To do a proper test proving the initial cables were the problem, I'd have to do lots of cable plugging and re-plugging while it's in pause with a spinning disc.  Almost every time, with the very tight LC-1 Canare connectors, I have to push so hard it jostles the Denon slightly.

To do this test, to make the Denon about as good as the Oppo (which uses balanced connections!), I thought it was worth this, but just once, not for a series of follow up tests to PROVE the causal mechanism, which may not even be possible.

To reduce such wear on my equipment, I'm ending this test here, at what appears to be some kind of lucky optimum in hum reduction.  "If it ain't broke, don't fix it."  At  least for now.  Next time the Denon is removed I'll know to check the cables again.

Stuff in progress

I have some suspicious evidence that HDCD software conversion isn't doing quite as well as my Denon DVD-9000.  The software converted version is indistinguishable visually from DVD-9000 output using Audacity at high signal levels, where you can clearly see the HDCD system working (and I now think it is in fact essential for high dynamic range recording and 16 bits...because real high dynamic range recordings can have 17dB above average peaks).  But at medium levels where the HDCD is barely working, what seems to be happening is there are tiny super-peaks in the 24/96 data from the Denon, so the Denon output looks ever so slightly peakier.

What I think this means is that HDCD is being applied at the 2x oversampling level (or higher), not to the original data stream, and in fact I've always believed that was how it was done (and why no simple software conversion tool would suffice...unless it was doing a compatible form of oversampling as well...and the digital filter changes I always believed were being done).

It's not at present evidence of variable filtering because the recording in question, Poems of Thunder, does not use the variable filter feature!  At least in the output, perhaps variable filter was used in recording (or perhaps not).

Notably Reference Recordings don't show the Transient Filter flag in their HDCD's either.

I was meaning to investigate that, then I noticed my recording had clipped, so I tried lowering the preamp level to -5dB (-4.5dB has been my standard for HDCD for years, to account for the fact the Denon actually puts up to 4.5dB more output with HDCD's than anything else...which it appears nobody else does, or perhaps other like California Audio Labs did too back in the early days of HDCD, I don't know.

So I re-recorded, and then I noticed something I should have been thinking about from the moment I noticed -93dB hum (60Hz) in recordings from the Denon: I'm using a standard grade Radio Shack 3 foot interconnect for the Denon and my Emotiva Preamp.  I've ordered a cable of my new standard (especially where shielding is important): Blue Jeans Cable LC-1.  It's thick and has the best shielding system and low capacitance too.

So I'm holding off on more tests until I get that cable upgraded, and I might even be able to demonstrate a measurable cable difference here, if the LC-1 lowers the hum a few dB.  And what will it do elsewhere?  It might even raise the apparent noise level because low capacitance.  We'll see.

It can't affect the Oppo which is connected with teflon balanced cables.  Recordings from the Oppo show no visual evidence of 60 Hz in their output.  But they show about the same level of high frequency noise, which is apparently therefore the fault of the sampler I'm using now, the DA-3000.

I think the Lavry AD10 is a tad better, the specs suggest 4dB better.   I need to get that fixed too.

Even then, the AD10 will still have quite a bit more noise than the Oppo....even a bit more than the Denon!

It hardly makes sense to concentrate on making reference transcriptions of anything, including vinyl, until I get the Lavry fixed.

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.

*****

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.

No Evidence for HDCD Transient Flag playback operation

Ignore the other channel on bottom, simply compare the top (played on Denon DVD-9000, (attenuated by Emotiva XSP-1, recorded by Tascam DA-3000) with the bottom (original AIF file copied from CD by iTunes). 

Here is visual comparison of a transient with HDCD decoding, and the raw "no-effect HDCD" digital data (having no other feathers than Transient Flag enabled).  The decoding is done to 24/96 from the one player which I thought there was still hope might implement the Transient Flag, the rare and expensive Denon DVD-9000 (which claimed next generation HDCD decoding, one of the first not to use PMD100).  To see the effect of the transient flag, one would have to use a higher sampling rate (I used 24/96 in recording the transient on top...that should be sufficient to show a variable playback filter if it existed).

Nevertheless, they look identical.  Comparing the two graphs I sometimes see a new detail on one, but then when I go and check the other, it has that same identical detail too, as often happens in subjective audio comparisons.  (To "hear differences" may mean not bothering to go back and check when something allegedly "new" is hear.)

Now actually, I don't know that Transient flag is operative on this stretch of audio, it was just the most visibly clear transient in the first track of Fresh Aire III "on HDCD" which has Transient Flags enabled but uses no other HDCD features (peak extension or gain adjustment).

I always thought this Fresh Aire box set sounded especially magical on HDCD players.  However the best evidence now is that in every case it was just lighting the HDCD light, and doing nothing more (on the user side...it did indicate you had an authentically unaltered HDCD recording made with Pacific Microsonics Analog to Digital Converters (either the One or Two).

And those converters were said to be among the best sounding ever...  Many used them because of that AND because of the convenient Peak and Gain Adjustment features, which meant setting setting the exact levels was less important and you didn't have to worry as much about clipping since far out peaks were automatically compressed (and then re-expanded by an HDCD decoder).

When the HDCD Peak and Gain features ARE used, as much as 1 bit or 6dB of effective dynamic range is added (about 4.5dB on the album Mephisto & Co. according to my measurements).  This is not always insignificant.  Inexpensive audio equipment including preamps and amplifiers can have 10-20dB more dynamic range than conventional CD's...120dB.  We can experience at least 130dB (but I recommend not going above 110dB for sake of your hearing).

The argument that the Objectophiles make is that acoustic noise makes this irrelevant.  I don't accept that...acoustic noise is something fundamentally different.

It makes sense to use 24/96 (or 24/88) and nothing higher, as those are essentially beyond the capabilities of even the best audio electronics anyway and can't in any way be felt to be inadequate.

And most of the benefit comes from the first extra bit and bump in sampling rate.

In theory, HDCD did both, with the second coming from a variable playback filter that could be bumped up and down to make transients more transient.  It also made it possible to distribute "media" and "audiophile" versions of recordings at the same time, with audiophiles (who aren't seeking maximum loudness) getting the benefit of the wider (closer to the limits of perception) dynamic range.

The standard story is the variable playback filter was never implemented because the patent for such variable filters was owned by Ed Meitner of Museatex.  HDCD still uses a variable filter prior to digitization, where it's most important anyway, and that's what triggers the flag.  Many experts say that even if implemented the effects of the variable playback filter would be very marginal.

That appears to be the case, and my doubts are mostly evaporated by this test.

But HDCD still delivers nice sounding encoder/decoders with almost 1 bit of dynamic range added.  It's only irrelevant now because true high definition like 24/96 is so easily accessed (if it's even made available).

HDCD files should be expanded if they can't easily be played on HDCD dacs (which are becoming harder to find).  Expanders include HDCD.exe, Foobar2000, and ffmpeg.  I use ffmpeg, which is said to use good code from Foobar2000 if you see the HDCD statistics being reported.

Since these decoders were based on reverse engineering, it's possible that licensed decoders in players are slightly more accurate.  But it hardly matters for the peaks we are talking about.  And it's likely the software decoders are in fact quite accurate as many Objectophiles poured considerable effort into getting them correct.

There is no need to do anything when only the Transient Flag is enabled.

AFAIK and according to these data, anyway.

Software Converting HDCD

I'm finally converting the HDCD albums on my harddrive to 24-bit, using ffmpeg.

I should have done this years ago.  

Instead I depended either on playing the physical discs themselves in my Denon DVD-9000 player (and resampling back to digital for my crossovers and EQ's), or running the SPDIF single into the DVD-9000 from my computer through Sonos.

I spent many hours carefully setting up a HDCD-resampling path to my system.  Every time I changed the system, I had to move things around to keep it still working.  I was doing more of that setup stuff than actually playing HDCD's it seemed.

But there really wasn't any reason not to use a software converter, either foobar2000 or ffmpeg.

A few years ago I installed ffmpeg on my computer mainly so I could just TEST what kind of HDCD features discs had.  I didn't pay attention to the fact that the script was actually doing full conversions of HDCD files so it could make reports about them, and then just trashing the conversions.

Here's the simple script hdcd-convert that will convert all the files that are wildcard specified:

#!/bin/bash

rm junk.flac 2>/dev/null

for name in "$@"

do

    ffmpeg -i "$name" -af hdcd "$name".hdcd.flac

done

I run this script in a terminal with a command like this:

hdcd-convert *.aif

This does both the peak extension and the gain adjustment.  AFAIK nobody does the variable filters in playback, and I'm finally coming to believe that (though I still have a bunch of test resamples of my favorite HDCD discs played on the best HDCD player I have...the Denon DVD-9000).

Checking the actual Denon 9000 manual, no mention is made of Museatex (as I previously reported incorrectly) nor their patent on switched playback filters, which btw is:

5,388,221

The Denon manual does list a bunch of patents used for HDCD, but not that one.  In fact the listed patents for HDCD all have higher numbers than that one too.

5,479,168

5,683,074 

5,640,161 

5,808,574 

5,838,274 

5,854,600 

5,864,311 

5,872,531

The Denon DVD-9000 provides no way to turn HDCD decoding off, so I cant test both ways through the same device.

The peak extension is a VERY BIG DEAL on the discs that have it, which include Mephisto & Co., one of my all time favorites, and most other Reference Recordings CD's (though strangely about half of mine either don't have HDCD or don't use it except for flipping the useless Transient Filter flag).

I'm searching through my other discs for those that use HDCD.  Neil Young, Grateful Dead, and many others used it.

I'm pretty much in line with Charlie Hansen's thinking about HDCD.  It had some good aspects and some scam aspects.  I do not consider it entirely a scam.  In many ways it makes sense, and it could have been a solution to the "loudness wars" (where newbies use the effectively compressed undecoded discs, and Audiophiles get the fuller dynamic range).  But for various reasons, we got the unabated loudness wars instead.

Charlie dismisses the potential usefulness of the transient filter flag (TF) in a weird way.  He says that when the sampler uses a filter with higher leakage of aliases, it makes no sense that the playback decoder would also use a filter with higher leakage of aliases.

Funny because Charlie had his own digital filter design that had very nice impulses but far more alias leakage then the usual digital filters.  He should have known why someone would do that: for better transients!

Actually, in my mind it makes no sense to do what Charlie did, use a "transient correct" but high leakage filter All The Time.  That would contribute grunge to dense passages.  The variable filter option sounds like it might be a better idea than his to me.  The TF should only be used for simple transients, not thick textures.

Arnie Kruger however had a very simple but (mostly) devastating critique of HDCD:

The core problem is that the higher bit depth is not realized in the actual signal, not even in the master recording.

It is easy to make 24 bit recordings where the bottom 9 or more bits are noise. As a matter of fact, that's always what happens when you make real world recordings.

At playback time it doesn't matter whether the bottom 9 or more bits as represented in the analog domain were noise sourced in the original recording environment, or whether they were sourced in the dither of a 16 bit medium. Its all noise, not music.

In this same thread Arnie puts HDCD in the same category as "true high resolution" formats like DVD-Audio, SACD, though it only provides about a bit or so of effectively increased resolution.

(There's no actual increase in resolution at all, except that it's shifted over a slightly wider range, making it "effectively" increased where it's more needed.)

But Arnie simply believes none of that is necessary.

While I completely agree that electronic noise in the recording studio is just as bad as electronic noise in the playback system, acoustic "noise" in my opinion isn't really noise at all...it's part of the product...the ambience.

Early indications are that the noise level from my Denon DVD-9000 transcriptions is around 92dB or so without any kind of weighting.  With proper A Weighting that might improve to around 105dB or so I think, but I'm wondering why I'm not getting closer to the spec for my DA-3000 sampler which is 114dB or the Denon DVD-9000 spec of 118dB.

But I argue now and still that "noise" and "lack of resolution" are not the same thing.

I still believe it's important to capture the "resolution" even if a tad bit of noise is being added.

So that's my second disagreement with Arnie.  Though I feel a bit less strongly about it (the difference between noise and lack of resolution might not be very big in many cases).

Anyway, with my transcription system having unweighted noise around -92dB, when I amplify it way up (by 90dB) I can see when the actual noise from the recording starts a fraction of a second before the music itself.  The "noise" (which includes ambience of course) is easily much higher than -92dB on the recordings I've looked at.

The hardware conversions I'm doing using the Denon 9000 will always have more noise than the software conversions.  There probably isn't a real reason to do the hardware conversions, but I'm doing them to satisfy myself that they aren't necessary.

Background Music is Important

Charlie Hansen was not unique is feeling that Background Music is unnecessary and unimportant.

Perhaps, to alphas like him...  Actually many "serious" audiophiles say that.  Another reason the Audiophile hobby is dying.

(To be fair, audiophiles in my local society are Post Judgemental for the most part.  There's little hectoring people over this or that "transgression," as I'd seen earlier in my life.  And though I'd certainly done it and perhaps even more in earlier years anyway, and even then I'd never heard anyone disparaging everything but "serious listening" except in print a few years ago.  It just wasn't a concern, people do what they do, audio "issues" identified by sighted listening were assumed to be always apparent regardless.)

Anyway, to most actual humans, and especially to people who live alone like me--if not all others, background music (or something) is nearly essential to sanity.

Nowadays "or something" has often become some flavor of "news" broadcast.  Those are often stressful, leaving you concerned about everything but connected to nothing, except the next day's broadcast, to feel on top of nothing much more.

I prefer to play music all the time, and most of the time music without words that allows me to just get on with things, but just thrilled slightly by the music.

So I have two icons for my automatic music playlist generator, either music without words (classical and much new age and jazz) and too much tension, and all the rest.

That's the way to do it.  It never seems to work that way on any music streaming service.  Even if you choose "Electronic" you'll eventually get some vocals.  And you'll often get music that's very stressful, like Oldfield (sometimes) or Ligettii.

I just heard about Oldfield for the first time yesterday, and I had to check him out, starting from his classic album "Tubular Bells."

Well starting from Side One was basically impossible as background music.  It's just too stressful.

In that regards, may I recommend myself, an Artist named Charles Peter Peterson, and my one album, Mythic Rocks.  It becomes slightly stressful in parts, but never enough to disqualify from being potential background music.  That's integral to my music "development" process, which is mostly background listening and weeding out the stuff that absolutely doesn't work.

The local Classical station KPAC and Jazz station KLRN generally work as background music too, as does KSYM when playing Musical Starstreams.

Anything Ambient from Eno works, of course.

Recovery, and HDCD again

Sunday night I decided it was time to play some vinyl.  It had been over a month since I'd last played a vinyl record...one was still sitting on the platter waiting for side 2 to be recorded.  Things are often like that here, and this time I have the excuse of the Holidays.

 Cleaning the stylus with my usual device there wasn't the usual predictable noise, but instead just one coincidentally timed full power pop from my system.  I checked all the levels and if anything they were lower than normal.  Then there was silence when I tried to clean the stylus again.

I tried playing records, even just lowering the stylus to the record.  At first I though I had killed my cartridge.  Perhaps I should never have trusted a "sticky" stylus cleaner, especially one in a metal box.

Once in awhile, there WOULD be another pop, typically when "cleaning" the stylus or lowering it to the record.  But then after that there would be silence (and I was amazed at how little stylus chatter there was too).

I tried re-adjusting the tracking force, rebalancing the arm.  Then I tried removing the damping tape from the back of the arm where it contacts the cueing lifter.  Perhaps the tape had swelled so the stylus wasn't actually making contact.  I currently have difficulty seeing very well close up so I wasn't sure.

Anyway, after removing the tape in the back, of course I had to re-balance the arm and set and check the tracking force all over again.

I was in greatest fear that I had damaged the cantilever with my stylus cleaning device.

But finally it dawned on me that it probably wasn't the cartridge.  With the best reading glasses I could find, the stylus looked OK, I just wasn't used to seeing it in the cartridge wrapped up in tape.

Then I suspected the preamp.  I tried playing other inputs and they didn't seem to work either.  Notably the Denon 9000 on the bottom.

The next morning I removed the new pile of equipment beside the rack so I could remove the connections from the preamp so I could replace it with the other XSP-1 in the bedroom which is mostly unused nowadays.  I also had to clear my bench of the Adcom 535 I'd been checking out (update: for awhile, I believed my conclusion that new filter caps were needed was shown to be in error while measuring the other channel.  There seemed to be only some 60 Hz noise in the distortion residual.  But going back to the first channel, I could now see clearly the "distortion" was that same 60 Hz plus a larger amount of 180 Hz plus some actual 2nd and 3rd order distortion.  So it's only one channel that needs the caps...good thing as I only ordered one pair which has now arrived, and I didn't want to spend even more money on this amp).

But, on the bench, I could clearly see that the Emotiva XSP-1 was working fine.  Something else was wrong with my living room system when playing records.

It occurred to me that the Denon could have gone bad too.  Or something else which had been nearly unthinkable...

The Lavry AD10, after 12 years of continuous use, always being left on, had died.  (In future I'm tending not to leave things ON always as I think it shortens their lifespan.)

The Lavry "seemed" to work in that you could set all the settings.  But level lights weren't responding to any input.  Nor was there any signal being output.  I tried switching the clock to Internal and that didn't help.

Currently the Lavry AD10 is the presumed latest failure, and it's on my bench for checking when I get around to it.  Perhaps the problem was actually a cable connection and not the ADC after all.

So now, at least until I get the Lavry fixed (or proven working again) I had to rig up a completely different analog setup.  I have to convert "analog" sources to digital to even hear them because my system depends on digital processing for EQ and crossovers.

Actually something that I had long considered worthy of trying anyway!

The output of the Emotiva is now going straight into the Tascam DA-3000, which is now dedicated to that purpose.  It plays on my audio system when I press "record" (which is actually "record pause") on the Tascam.  So I'm using the Tascam AD converter, rather than the Lavry AD 10 converter, to hear analog sources, and possibly record them.

The Tascam uses later generation analog to digital chips, and is itself quite high end featuring 192kHz maximum PCM and even 5.6mb DSD.  (Tascam is no longer selling this in the USA???)

Though I imagine a real record label would use something even more special, like a Lavry Gold or Weiss AD converter for PCM anyway.

But the Lavry has always seemed perfect, and the peak level holding lights are perfect for finding the best recording level for any vinyl record.

Why do so few devices have peak hold lights like that???  The Tascam surely needs them.

Also the Lavry may use a slightly higher grade of earlier AD chip.  It may have better AD engineering, and it may gain from being a "dedicated" AD converter as opposed to the converter section of a recorder.  The Lavry "Dynamic Range" spec is a few dB's better than the AD-3000 "S/N" spec, but they are following different standards so it's not really clear which is better that way.   The Lavry has even lower distortion specified at 0.0009% as compared to 0.003%.  Either is as good as my preamp.

Roughly speaking, both are at the same level, which you might call something like "prosumer" or "pentultimate".  So they would be worth comparing perhaps.

My initial impression is that the DA-3000 converters, running at 24/96 (which is my standard for "all that's necessary") sound a bit more transparent than the Lavry, but not as smooth and relaxing as the Lavry, and the Lavry is very transparent also (not unlike a good preamp, I've always said).  So it's almost a draw but it still seems I might like the Lavry better, plus it's peak reading meters.

To continue to have a separate digital path for both playing the FM tuner as background music, AND recording special FM programs, I needed to set up my second digital recorder, something I'd wanted to do anyway.  I removed my old Marantz 480 recorder from the living room system when I got the DA-3000 because the DA-3000 was clearly better in every way.  I was hoping to sell the Marantz (I see they're going for as little as $280, so hardly worth bothering).  Then I got the idea I could put the Marantz back up so that each recorder would have a dedicated purpose.  The Marantz would be dedicated to recording FM, and the DA-3000 would be dedicated for recording vinyl.  That way I wouldn't have to be constantly changing the settings (Sample rate, SRC, and input source).

So this was already turning into a two day project, with all the items (and cables!) that needed to be removed from the rack, and possibly repurposed into a new arrangement and connections.

I also needed to replace the Denon 9000, now also presumed dead (no apparent audio output) with my second unit, which (on last testing) had been able to play DVD-Audio discs.  I had been saving the second unit for that purpose, AND because the first unit I got was always the one that I thought might sound best on CD's and HDCD's, even though it was unable to play DVD-Audio discs anymore, after $150 worth of repairs done by a Denon center didn't help (they said I'd start having to replace boards like the power supply board).

So, I'd wanted to exchange these units as well, which will enable me to make another sampling of the DVD-Audio disk Supernatural by Santana, which seems to sound the most magic when played through Denon DVD players, with the DVD-9000 being the ultimate king of the hill-but never recorded before by me (because I usually had my non-DVD-Audio playing Denon 9000 hooked up).

But now, before before the Second DVD-9000 dies, I also wanted to address a long lingering question about HDCD.  It has been claimed by many audio engineers who have studied the matter (but not Pacific Microsonics, which no longer exists, nor Keith Johnson) that no HDCD decoder uses the "transient filter" that is toggled on many HDCD recordings.  It was apparently used when the recording was being made, and one of the reasons the PM One and Two recorders were so good.  But no decoder was ever set up to do that (according to these audio engineers, including the late Charlie Hansen) because it had already been patented by Ed Meitner, then working at Museatex (but not otherwise used, to my knowledge, and that company no longer exists either IIRC, so it appears the patent did nothing but prevent application of this idea where it would have been most useful).

https://www.head-fi.org/threads/hdcd-list.65414

(Ed Meitner appeared previously in my audio experience in the early 1980's.  His amps were being demonstrated at a meeting of the San Diego Audio Society at the same time as the Apogee 1 ohm speakers.  Someone hooked them up without authorization, and the Meitner amps fried.  Someone who might have been Ed Meitner or his rep scolded someone for hooking up something wrong, I never got the details.  We were supposed to have been using the Krells on the 1 ohm Apogees.)

Here is the definitive HydrogenAudio (Objectophiles) table of which discs use which HDCD features.

I retained hope for several years now that this story about HDCD was wrong.  HDCD's just sounded so much magically better than other discs.  I was sure it wasn't just the "peak expansion."  I truly believed in usefulness of the variable Transient Filter.

And they sounded best of all on the Denon DVD-9000 player, which is the only player that has proven to me it does the "peak unlimiting" thing as PMI would have wanted.  It puts out more than just 2 volts, I determined, reaching nearly 3.8v peak on some HDCD's.

Other players seem to implement Peak Unlimiting by lowering the average level, and only having peaks reach the full output level, which for most disc players is nominally 2V.

Back in the day the DVD-9000 was being sold, a friend of mine complained (either about that exact player, or perhaps another) that HDCD was a gimmick where they raised the level twice as high.  Well, he said, I can just raise the level twice as high on my preamp.  It's not fair!

It seemed like ultimately other manufacturers agreed, and that while some earlier HDCD players may have raised the actual output level to implement Peak Expand, others didn't, they lowered the average level to make Peak Expand possible.

So few other HDCD players do the Peak Expansion in the way that the Denon DVD-9000 does.

Anyway, as I became more and more aware of the stories regarding the Transient Filter flag not actually being used, I was still convinced it was important, because otherwise how could the Fresh Aire HDCD discs from Mannheim Steamroller sound so specially good when played through the Denon DVD-9000.

So good I was convinced that resampling through the DVD-9000 was better than playing the original CD bit stream (which needed no other decoding than the Transient Flag anyway).  I was beginning to believe there was just something special about this high priced and limited production player.

The DVD-9000 literature made note of the "new generation" HDCD decoder, along with the new AL 24 Plus digital filters.  IT DOES NOT HAVE A PMI 100 DECODER, as such.  It is the first Denon that supports HDCD that does not actually have the PMI chip.  Denon paid for those things when they were still being made.  The Denon 9000 included DVD-Audio, but NOT SACD.  It was Denon's last chance to display technologies alternative to SACD.  The Denon manual, IIRC, notes licensing to Museatex but doesn't say why.

After just a few months, the DVD-9000 was discontinued, and replaced (for a while) by the 5900, which uses sigma delta chips and supports SACD.  Sony would not apparently license DSD to Denon for the DVD-9000 which used the very different Burr Brown 1704 resistor based chips.  This also may have affected what Denon was able to do for HDCD.

So it could be, I have long wondered, that Charlie Hanson and others who claim the switchable digital filter thing was never implemented were simply unaware of a small number of exceptions, if they exist, which might have included the Denon DVD-9000.

Not knowing people who would know, another way is to try it, as I've long wanted to try.

So I started recording a series of HDCD's that I know use the transient flag, but no others, on the DVD-9000 through the XSP-1 and directly into the DA-3000.  These are the Fresh Aire series on HDCD from Fresh Aire 1 through Fresh Aire 8.  They all use only the Transient Filter flag from HDCD and no others.  (According to Charlie Hanson, these shouldn't be considered HDCD as they don't require HDCD decoding.)

The Fresh Aire recordings are not even included on the standard list of HDCD recordings, but they say HDCD on their boxes and were sold as such (by Audio Advisor at one point).  They light the HDCD light if a player has it.  But they do nothing but transient filter decoding which I reconfirmed with a little ffmpeg script I still have called hdcd-check:

rm junk.flac 2>/dev/null

for name in "$@"

do

    ffmpeg -i "$name" -af hdcd junk.flac

    rm junk.flac 2>/dev/null

done

At the bottom of the output you get lines like this for all the Fresh Aire discs:

[Parsed_hdcd_0 @ 0x7fdd67e02000] HDCD detected: yes, peak_extend: never enabled, max_gain_adj: 0.0 dB, transient_filter: detected, detectable errors: 0

Not knowing the correct level, and also believing the 9000 might benefit from some warm up time, I played several different Fresh Aire discs at increasing levels, until I zeroed in on the +0.5dB level as being correct for these, causing the highest non-clipping level.  (If theses discs had used Peak Unlimiting, it would be something like 2.5dB lower.)  I ultimately ended with my best recording of Fresh Aire 8, which reached a maximum level of -0.114dB with the Emotiva gain at +0.5dB.  I saved this exactly as recorded AND as releveled (by Audacity) to -0.02dB for audible comparison with the original digital, which has peak level of 0dB (Audacity won't Amplify because it is already at 0dB).

Once again, as I have matched the levels ever closer, I found the differences if any increasingly hard to detect.  The non-decoded HDCD played direct from the digital sounds basically the same as the output of the Denon DVD-9000 with "HDCD decoding" being resampled on the DA-3000.

While I was doing this, I still thought how much more wonderful the DVD-9000 decoding sounded, but now that I have both the original and the decoded copy I can say they are basically impossible to tell apart, so far.

Strangely, however, Roon finds a difference and applies different levels of automatic leveling (which I do on an album basis).  It finds my HDCD version to require 0dB level change, but -2.7dB for the original digital.

This is probably an artifact of the re-recording somehow, but I'll have to figure it out before reading conclusions about the audibility.  Unless I can control the actual playback level and ensure all versions are dBa or dBc matched to within 0.1dB, no conclusions can be made.  The peak level matching I've done apparently works differently.  Perhaps it's because my resampling at 96kHz realizes some of the "intersample overs" which are hidden in the original digital.  And also in ways like that the Lavry might be different too.  I'm finding a difference between the phono-to-CD level change using the Lavry and using the DA-3000.  For some reason, the two digitizers show different relative phono to CD peaks.

Bu at this point, I'm also closer to completely believing Charlie Hanson in these regards.  Even though the level matching doesn't seem to match, there is no special magic that the HDCD transient filter decoding seems to add. But I really want to test some of the earlier recordings too.

Charlie Hanson loved HDCD nonetheless because the original encoding converters (PMI One and Two) were so good, and because he believe even though the dynamic range improvement is little better than one bit at most, it's still important.

Like me, Charlie Hanson also hated DSD and MQA.  But unlike me, he was a believer in some flavor of linear phase reconstruction filter (his own) instead of straightforward minimum phase.  His flavor added significant ultrasonic noise, though not as much as NOS or DSD.

I don't think there is much need for amplifiers with no feedback, which was ultimately his motto.

So in spite of his acclaim, I still consider him sort of tweaky, and perhaps not fully to be trusted for that reason, but perhaps sometimes right anyway, and less connected to the big wheels than many.

An insider/outsider or something like that.  So I sort of like him a lot anyway (while thinking he may have been wrong in several key areas).

I thought the idea and design of Pono were not a bad idea, and often considered buying one, but I'd have had to rig it into my system which means basically resampling...  And I'm not interested in headphones.  And they never got that much support from the music industry which of course really killed it.

I would have been interested in a high resolution front end device with AES connections.  Ultimately I got Roon on my Oppo, at least that has coax digital, and through that I get Qobuz for high resolution which it has in some things.

It sounds like Charlie had a very interesting life and career in audio.  And he was a healthy active guy and everything.  But he died from the complications of a bicycle accident in 2006 after suffering from it increasingly for 11 years.

You can't tell any suffering from his online persona.  He seemed to be bright and cheerfully talking about what HDCD does and doesn't do (even that, something barely connected to his business) up to his last days.  I had been reading the HDCD column and was shocked when it was written that he had passed away.

It would be very funny in a way (for me) if the Transient Filter flag actually does nothing.  Because I believed in it so long.

It shows the power of belief.  Belief can make things special and magical, when they are just ordinary or nothing at all.

I'm suspicious this happens a lot to other audiophiles, but not me.  For one thing, I don't really believe in much of anything anyway, anything outside of mainstream audio engineering, in which audio reproduction is fairly well described by its lack of distortion and frequency response errors.

So when it comes to other things, things that Objectophiles wouldn't believe are audible, I have mostly if not entirely disbelief.

This was not at all true for HDCD.  I really believed in it, and that the Transient Filter was a kind of precursor to SACD that Sony wanted killed because it was nearly as effective and yet far simpler.  One filter for transients and one filter the rest of the time, I thought.  That way you could get the perfect transients that were a (usually unheralded) feature of SACD and DSD and NOS type filters, but just when they are needed so as not to be getting a lot of noise and grunge too.

That belief made HDCD's played on HDCD decoding players always specially magic to me.  I believe I wrote about it here.

That's a huge upside perhaps from mere "belief" if it is a false belief, as it now appears.

The downside is that I was afraid to play HDCD material any other way, including on my Roon/Oppo based system which I use to listen to most music now.

HDCD's were a special category that I didn't want to listen to unless properly decoded.

So I spent hours, and more hours, always making sure that in one way or another I could properly decode HDCD, transient filter operation and all.  I was convinced that software converters were inadequate because few could actually model the effect of different reconstruction filters.

And I avoided listening to my HDCD's in any other way.  If the DVD-9000 was not connected as a digital converter (which is often true because the extra Sonos ZP80 I use to send it digital is often removed as being one to many things when I need more room in the rack), I'd avoid listening to any HDCD's.

So while the power of belief can be magical, it can also produce fear, the well known audiophila nervosa.