Archimago challenge: USB cables/filters/regenerators

[Julf]

In his latest blog entry Archimago looks at recreating the MQA filter effects, but then finishes off with a challenge:

To close, I was wondering if anyone can show me a single example of where a simple, direct generic USB2.0 cable between a computer / Pi / streamer to a USB DAC actually results in compromised analogue output from the DAC.

The reason I ask is because over the last few years, there has been a proliferation of devices that supposedly clean up the USB interface by doing all kinds of things like "filtering" noise, "regenerating" the data signal with an improved clock to improve jitter (as if this is beneficial with modern asynchronous USB DACs), "isolation" apparently also removing noise in the data lines, "injecting power" with cleaner power supplies, and maybe other stuff not mentioned.

Remarkably, some of these devices even claim that with the device in place, it often "sounds like you are listening to a different DAC"! Really? Like I said, it would be nice to demonstrate just one example where there is objective evidence of such an effect with a description of the computer / streamer and DAC used. It should not be hard to show the difference especially since it could sound like a "different DAC", and differences of this magnitude would be easy to show. (As usual, subjective opinions are easy to find, especially for the faithful early adopters willing to put $$$ down.)

 

[rtrt]

I saw the post yesterday but didn't post there as it seems to need an account elsewhere to post.

I can't help think I must be missing something or maybe Archimago is…

With my mdac and a dell laptop there was very clear digital hash noise as songs dropped in level - for example at the end of a song. This was at normally listening level.

Problem solved by installing an olimex filter from eBay or later by switching the laptop for another.

I can't believe this is so unusual and as I say no measurement needed - clear to my somewhat degraded hearing.

 

[Purité Audio]

I would choose a DAC which is galvonically isolated, if I intended to use USB as a major source.
Keith

 

[Julf]

I can't believe this is so unusual and as I say no measurement needed - clear to my somewhat degraded hearing.

Indeed, statements like that are not unusual. Objective evidence is harder to find, thus the challenge.

If it is that clear to hear, it should be easy to measure.

 

[Joe P]

Julf,

Who's Archie Magoo? Mr. Magoo's brother?

Bet he's into blind testing, just like his brother.

Joe

 

[Hook]

H

 

[rtrt]

I wonder if we’re at cross purposes here. I’ll try to elaborate- in the context of a hypothetical change of cartridge on my turntable.

1. I’m not commenting on;

Improved bass - more punchy, extended reach, kick drums you can feel in your chest…/ Slightly recessed mids - female vocals further back in the mix…/ Extended treble - sense of air around the cymbals...​

2. I am commenting on;

During quiet periods of a classical piece or at the end of a song, there’s a noticeable hum with new cartridge x, that isn’t there with old cartridge y.​

I suspect that many reading the first would be sceptical and want to hear for themselves or see measurements of the extended bass response/recessed mids etc.

How many of those same would want to see a measurement of the level and frequency of the hum as proof of its existence vs how many would immediately think about grounding issues / increased gain for MC / nearby mains transformers.

In the above substitute ‘digital hash’ for hum. For me installation of an olimex removed the ‘hash’, removal of the olimex reintroduced the ‘hash’.

Iirc there were a number of people on here with similar problems and the mdac designer John Westlake himself recommended a usb filter type device. It may even have been sufficient to break the 5V and Gnd lines within the usb cable to achieve the same result - i didn’t try this as I had a solution to my problem.

If you still think the ‘hash' I heard needs to be measured to prove its existence to a wider audience then I can understand that - but dont have the equipment or time to provide it.

If the above doesn’t help clarify, i’ll leave it alone from here.

 

[DNM]

If you still think the ‘hash' I heard needs to be measured to prove its existence to a wider audience then I can understand that - but dont have the equipment or time to provide it.

If the above doesn’t help clarify, i’ll leave it alone from here.

If your problem was caused by RFI getting into the analogue stage of your DAC, thats a separate issue from the type of measurements or any other evidence Archimago is challenging people to come up with, namely the effect on the digital data. Audiophiles seem to confuse digital data with audio signals. Provided the digital data is accurate then the DAC can convert it accurately to audio signals. The premise of the blog as I read it, is that these devices seem to do nothing to improve the accuracy of the digital data and if anything, could potentially damage it.

Whatever the perceived problem, he's advocating saving your cash and avoiding these devices and spend the money on a modern well engineered asynchronous USB DAC instead, which seems good logical advice to me. But then again, when it comes to high end audio, logic seems to be in very short supply.

 

[dtd]

I am one of those poor sods who has a system that warrants 'fiddling' with USB to get the best ouf of it. I have tried the Intona solution (modest improvement) and the Uptone Regen solution (crap), however simply put using a dedicated PCIE USB card with external power reaped the biggest, most noticeable difference.

Could it be the fact I'm streaming DSD 512 (i.e. ~ 50mbit/s) via USB, making timing more of an issue? That I couldn't be absolutely sure of. But there is a stark difference, and simply plugging my DAC back into the bog standard motherboard's USB socket reveals it too.

For the record the DAC is already galvanically isolated, and uses a decent Amanero Combo384 USB board so I'd say they've gone to some effort already. It just happens to shine with a dedicated high quality USB feed.

I'm sure many will cry wolf, and that's fine to be fair as it does sound a bit insane, but there you have it.

Whether the difference would show up in more normal hifi setups and rooms, that remains to be seen.

 

[Purité Audio]

We used to sell the Intona, the designer seemed genuine he never promised an improvement in sound quality when used with a competently designed DAC, I never heard any improvement when we added an Intona to the DACs we had here.
I can easily imagine a poorly designed unit might benefi though, @ DNM I believe the Mdacs were not galvonically isolated.
Keith

 

[DNM]

@ DNM I believe the Mdacs were not galvonically isolated.
Keith

Keith, Yep, I figured that was the case. Maybe Mdac2 will have it, though I suspect USB will be obsolete by the time it sees the light of day!

 

[sq225917]

Well all be using quantum computers by the time mdac2 sees the light of day.

 

[whatsnext]

Gave up on USB trying to hear this misery others moan about. Stupid sod. Bought a galvanically isolated DAC. One dealer on here (gone these days) insisted I needed a super cables so I wasted cash on Supra, Wireworld and only when I had it would I hear the benefit. What a salesman.

 

[Julf]

If you still think the ‘hash' I heard needs to be measured to prove its existence to a wider audience then I can understand that - but dont have the equipment or time to provide it.

All it takes is a computer (or even smart phone) with a halfway decent ADC.

 

[cj66]

I remember being very sceptical of the Uptone Regen when it came out. My interest was only piqued when two on line friends, who don't gush easily about anything let alone tweaky stuff, were singing it's praises.
Still unwilling to buy blind ( despite the return policy) I managed to get a loan of one.

I used it exactly as Uptone recommend for playback and thought it did seem to tidy up timing and dynamics especially..
I then used it in line for recording tracks I use as a reference. That's one recording with the Regen and one without, otherwise identical.

Most notable in the bass area, being more dynamic. I listened with the Regen in and out of line for playback. The improvement was more defined when it was present.

There are huge threads on this alone elsewhere so I won't say more as it's my opinion in my listening environment in my system and I fully accept others opinions to the contrary. YMMV.

I'm yet to try a decent pcie card with external power, whether that outputs USB or spiff.

 

[Julf]

Despite identical checksums I could easily hear not just a difference but an improvement.

So the two recorded files had the same checksum?

 

[LarsS]

So the two recorded files had the same checksum?

Never underestimate an improved bit ... ;-)

 

[cj66]

So the two recorded files had the same checksum?

Nope! Oops. Ignore that, it was the remains of an othrwise edited out comment. Offending part now gone.

 

[Julf]

Nope! Oops. Ignore that, it was the remains of an othrwise edited out comment. Offending part now gone.

Phew! You had me worried there!

 

[AndyU]

Here are some measurements of the effects on noise at the USB port of a variety of isolators/regenerators. There seem to be large, measurable differences. Whether or not this reduction in noise has measurable effects on the output of the DAC is much less clear, but it is surely not impossible. Ages ago I had, briefly, an Arcam rDAC which made clearly audible birdie noises when connected via USB to my laptop. If I ran the laptop off batteries, the noises disappeared.