Bits is bits?

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12 hours ago, sandyk said:

I don't claim to have performed DBTs. I leave that to trained professionals, as I did with Martin Colloms.

 

You throw the term “DBT” around and don’t understand that no one who has listened to any of your files has done a DBT. 

 

12 hours ago, sandyk said:

 I don't give a rat's anus about further offering the type of proof demanded in an A.E.S. type of publication.

 

Just say that you listened and heard something — of course you’ve done that 10,000 times already. Avoid the term “proof” if you are going to use scientific terminology. You seem to get frustrated when you insert your listening experiences into technical debates — everyone has heard already 

 

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2 hours ago, sandyk said:

 The title of this thread is Bits is bits?

 There is nothing in Archimago's report that can disprove what I have reported and had confirmed by way of DBTs and also confirmed by quite a few members ,including several more well respected and qualified members recently. 

 

There has not been a single DBT done on your “reports”. 

 

Archimago’s blog seems reasonable and he has supported these already reasonable arguments with measurements. No “proof”.

 

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8 hours ago, Teresa said:

 

Alex, I'm a subjectivist and as a subjectivist I only believe what I experience with my senses, thus the results of these DBTs you keep posting over and over mean nothing to me.

 

If bit identical files sound different:

• Could it be the timing of the bits are different?
• Could it be system noise has somehow gotten in one of the files during or after digital to analog conversion?
• Could it be MD5 checksums are not accurate enough? 

 

Teresa, these are good possibilities, and on-topic for the OP.

 

1) Could it be the timing of the bits be different?

2) Could it be system noise ...?

 

These are two heads of the same coin. Noise can be voltage (or current) and noise could be phase (or timing).

 

Unless @alfe corrects me, it certainly is possible that two copies of a CD might sound different because of embedded noise on the media. It is also possible that two files on a hard drive might sound different.

 

This doesn't mean that the noise on an individual copy of the file somehow becomes embedded when the file is copied. Some people have tried to suggest, via ill-described and contrived  mechanisms, that such embedded noise might make its way onto new copies of the file, or across a network etc. It is this latter suggestion which not only does not conform to my own subjective experience, nor conforms to what we understand of electronics in great detail, and its this latter claim which has never been demonstrated in a convincing way.

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The answer is: yes!

 

😂 yes the eye-pattern is the easiest best way to get a handle on signal integrity. In the vast majority of cases audiophile products do not provide nor likely measure eye-patterns.

 

One of the prime reasons I’ve selected 10Gbe Ethernet (even when run at 1Gbe) is that the standard mandates hitting an eye pattern for conformance. That’s to say you get great SI out of the box with conformant equipment (and these switches are available for much less than pennies on the dollar on eBay).

 

Similarly standard Ethernet cables made from Belden are SOA. These are used in eye pattern testing.

 

There is no evidence that any so-called audiophile Ethernet cable’s are in any way better or even equal to Belden (indeed they might be Belden with a fancy wrapper). 

 

USB I will leave alone. 

 

So could a DAC have SQ problems with an imperfect SI? It’s possible but hasn’t been demonstrated. 

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5 hours ago, sandyk said:

 

 In the vast majority of cases,  audiophile products use transports made by a small number of other manufacturers.

 

Right, so I am saying that rather than spend $10,000 or whatever on a cable that is really Belden under the hood, just use Belden. 

 

Or like the DACs that use a $50 USB interface and charge $10K for the DAC that itself has an ESS chip, there’s a lot of nonsense. 

 

So y’know ya da ya da ya da if someone is selling better SI I want to see the data not just blah blah blah.

 

ill say this for @PeterSt‘s NOS1a, that he uses a unique USB interface and his own USB isolation — this is what I expect.

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4 hours ago, mansr said:

In the last of these scenarios, use of a decrapifier may be justified. For that reason, I'd like to see a simple test performed:

1. Connect a typical source to a USB-S/PDIF converter using a 5 m generic cable.
2. Play a test signal while capturing the output for a few hours. Count the errors.
3. Insert decrapifier and repeat the play/capture. Count the errors.
4. Compare the number of errors in steps 2 and 3.

Has anyone done such a test? What were the results?

 

Nice post and I generally agree. There is a set of situations where the signal hits the eye-pattern but might affect SQ.

 

1) I think perhaps the biggest benefit from one of the devices is to replace a really crappy USB power with a clean 5V supply. I’ve heard hiss & cracked removed and suspect it’s the supply.

 

2) Cables and devices might taper rise time. Too fast a rise time can induce ringing in the receiver — other duty cycle modifications could presumably affect the DACs USB receiver.

 

One could test the ubiquitous  $50 Amanero to see presumably. The specific test that I would do is to send a 50% DSD signal in ie 1/0/1/0 and then do an eye-pattern on the Amanero DSD line(s) ie after conversion from USB ... if noise doesn’t make it to this point, really hard to see how it could affect the DAC.

 

Obviously this will all be DAC dependent.

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5 hours ago, marce said:

 This would be noticeable on the eye diagram.

 

Yes but the eye-diagram rise time lower limit might cause ringing in a $50 USB interface. Not enough to lose bits, but enough, perhaps to affect SQ. Again I’d like to see the I2S/DSD eye-diagram to see if there are effects. If not then end of story.

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3 hours ago, mansr said:

A really poor power supply can of course affect overall performance of a device. However, most serious DACs are self-powered. Moreover, there are requirements regarding bus power quality from a USB host. A bus powered device should be designed to tolerate the worst permissible case without significant degradation.

 

The Pro-next S2D is an outstanding and affordable bus powered DAC that I have found sensitive to power supply in certain situations. My personal experience. 

 

3 hours ago, mansr said:

USB 2.0 specifies a minimum rise/fall time of 500 ps.

 

I’ve seen the minimum rise time specified at 300 ps with a max roughly 1 ns according to the eye diagram (which itself places no lower limit on rise time).

 

Obviously we expect the interface to have a low BER, but again, if there is no effect of variations in rise time (within spec) on the interface’s I2S/DSD eye plot itself then this is a nonissue.

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1 hour ago, Ralf11 said:

Pro-ject S2, right?

 

Pro-next got phoned in

Thankfully our brains (like digital systems) have good pattern matching error correction  

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7 minutes ago, sandyk said:

 

 I don't have a problem with that reply. I use Belden cables wherever possible, and in most cases they do sound better than generic cables.  For example, I use Belden 1855A BLUE 75 Ohm RG59/U Type Coax Cable in my DIY Interconnect leads.

 

Belden is s great company but I don’t have any knowledge that their analog cables are special — OTOH their copper Ethernet twists are bonded so constant impedance, and the REVConnect is special.

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13 minutes ago, Ralf11 said:

 

Agreed, but there is often a fine line between pattern recognition, and pattern imposition.

 

Like making everything either a 1 or a 0, a truth or a false?

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Both!

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4 minutes ago, fas42 said:

Most people are aware of how impressive the playback of a recording that they thought they knew well can come across - when they hear it on a "special rig" ... what I'm saying is that at that moment one is finally hearing the actual content of the recording, without almost no added signature of the playback system, for the first time. If an approach is used that doesn't consider that as a goal, then, yes, I suppose I would say it's "all wrong" ...

 

This is the same post you use to respond to every thread, and has no relationship to the topic of this thread, nor does it to the topic of many other threads you post to. You have your own thread that you are free to post to. 

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4 hours ago, mansr said:

If it's that sensitive to the power supply, I wouldn't call it outstanding.

 

I see. Lots of other folks like it. 

 

4 hours ago, mansr said:

 

Wherever you saw the 300 ps figure, it was wrong.

 

Let’s see 🤔

 

https://www.usb.org/sites/default/files/USB_2_0_Electrical_Compliance_Specificationv1.06.pdf

 

3.2 EL_6

 

 

4 hours ago, mansr said:

 

The I2S timing is mostly irrelevant since the DAC chip buffers the data internally.

 

Which DAC chip ... all of them, in all cases? What about chipless DACs ... point being that if the USB variation doesn’t make it onto the I2S/DSD lines then it can’t make a difference. That’s not saying that it always makes s difference. Those aren’t the same thing.

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3 hours ago, marce said:

 

High Speed 100ps        Fknee approx.  3.5GHz

 

 

 

I believe these are the recommended specs for the oscilloscope used to test the USB signal for more accurate eye-patterns.

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16 minutes ago, mansr said:

So what? Some people like vinyl.

 

The section of the USB 2.0 specification referenced there says 500 ps.

Perhaps too fast a rise time causes your eyes to jitter

 

In any case your post is riddled with subjective opinions. 

 

Perhaps certain cables slow the rise time and this helps out certain USB receivers, I don’t know either way. 

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2 hours ago, Ralf11 said:

Does the discrepancy mean I will need glasses for my eye diagram?

 

It means that in the real world, not everything is black & white. Not everything is true or false, 1 or 0. 

 

In any case the eye-pattern looks like it will accept a rise time as long as 1 ns, and who knows what compliance testing is done on every USB 2 interface or cable. In the real world that is. One would hope that a $10,000 DAC would be more compliant than a $30 DAC but who knows. Same for streamers etc.

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Somewhat related. In one of the textbooks @marce lists (I forget which offhand) there is an illustration showing how a CPU which is moved from one process size to smaller (thus fitting more dies on a wafer) as well as increasing clock frequency, results in significantly higher EMI — the faster rise times while enabling higher clocking, also result in higher EMI, all else being equal. 

 

No doubt not every design gets redone when a smaller transistor size gets used, you know like 10 years after it was initially done. 

 

So shit happens.

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2 hours ago, asdf1000 said:

 

Can you please share details on what certain situations you found the S2D sensitive to power supply?

 

I spent a fair amount of time testing various streamers/NAA with and without the ISO Regen. I picked the Raspberry Pi 3 -,WiFi which is known not to have the greatest clock as a testbed to try and coax the greatest difference. Surprisingly to me my iFi iDSD Micro didn’t show a difference whereas the S2D has a noticeable  improvement — I don’t want to get into all the nitty gritty details of which PSUs I swapped in and out but that’s something. 

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1 hour ago, Ralf11 said:

uh oh!  I still have 2 of them...

 

My CD player is a smart approach because it allows me to play SACDs, DVDs, BlueRay and old CDs I can buy locally and listen before I decide whether to rip to my HDD.  Besides they aren't worth anything.

 

The claim regarding shorter signal paths or simplicity is exactly the sort of red herring consumed on sites devoted to vinyl, and a good reason to not have more of that sort of intellectual chaff cluttering up the internet.

 

Yeah I have a Blu-Ray player — no problem using CDs or disc, of course until you have small kids who trashed their expensive Disney movies in DVD ... pissed me off enough to start me ripping everything to NAS.

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13 hours ago, asdf1000 said:

 

The designer of the Pro-Ject S2D, John Westlake (on Pinkfish or Roon forum) has said using an external PSU (even the included SMPS) should perform a little better than USB powered.... So not surprising.

 

And maybe a difference becomes more noticeable at the highest sample rates supported by the USB input...

 

I am using DSD512

 

I haven’t used an external PSU but upgrading the USB bus power wasn’t just a little better, it removed hum & clicks/crackles.

 

Quote

 

And the Pro-Ject DAC may be more resolving than the micro iDSD DACs...

 

The Pro-ject S2D is a great DAC at a great price point, that said the difference with iFi isn’t that the iFi isn’t resolving enough — I am not reporting a subtle difference — and it’s not all bus power, rather powered by RPi3 with stock wall wart RPi branded supply.

 

This setup was intended to stress the USB connection.