[Jawed]

John Swenson's thoughts on ferrites used with USB cables:

https://www.computeraudiophile.com/...row-hammerquot/?do=findComment&comment=382519

Maybe he's changed his mind in the past few years?

Though it reads like someone who is trying to stop people from finding a solution that doesn't involve snake oil.

 

[Articnoise]

Maybe he's changed his mind in the past few years?

Though it reads like someone who is trying to stop people from finding a solution that doesn't involve snake oil.

I seriously doubt that’s his reason.

 

[Jawed]

I seriously doubt that’s his reason.

Well he's talking utter nonsense. So I suppose it goes along with nonsense products.

 

[Articnoise]

Well he's talking utter nonsense. So I suppose it goes along with nonsense products.

I believe someone are talking nonsense, and it’s not John.

 

[flyte3333]

Well he's talking utter nonsense. So I suppose it goes along with nonsense products.

I prefer to be respectful, especially when you consider the number of happy Chord DAC + Sonore Rendu owners and the number of happy Chord DAC + Uptone Regen owners. The numbers probably outweigh the number of happy people using 40 ferrites on their USB cable but I could be wrong. I don't say that to be rude either, I think it's a fair guess. Of course, we shouldn't lose sight of the big picture - there are probably even more happy Chord DAC users using neither of these.

And especially when you consider all this 'snakeoil':

https://uptoneaudio.com/pages/j-swenson-tech-corner

and

https://www.computeraudiophile.com/...-and-grounding/?do=findComment&comment=741273

and

https://www.computeraudiophile.com/...nding/?page=2&tab=comments#comment-723187

and

https://www.computeraudiophile.com/...nding/?page=9&tab=comments#comment-735311

and

https://www.computeraudiophile.com/...ing/?page=172&tab=comments#comment-730361

So taking the respectful approach and using some logic given John's research, there must be a misunderstanding in what he's saying in reply to the person asking the question.

I'll see if I can get clarififcation from John.

Of note, on the subject of leakage currents and RFI, as John mentions in the 2nd link above:

"Of course this is immaterial IF there is no leakage current going through the cable in the first place. So IF you can keep leakage out of the cables, a lot of these cable weirdnesses go out the window."

Not sure if this is also considered 'snakeoil'?

 

[Jawed]

there are probably even more happy Chord DAC users using neither of these

Yeah, that was me for a while. Blissful ignorance.

Rob has already explained quite clearly why he's wrong about using ferrites on a USB cable. There's no havoc!

EDIT: If John is referring to putting ferrites individually onto all four of the conductors in a USB cable, e.g. inside the DAC where the USB signal leaves the socket, then yes that would filter the digital signal and potentially cause problems. But that isn't the way we use ferrites on our USB (or BNC) cables. Instead each ferrite is wrapped around 2 or more conductors and it's because there's 2 or more that the RF filtering works, but the digital data is unaffected.

His posting doesn't make it clear which of these two techniques he's referring to. So it's unfair of me to paint his posting as being categorically wrong (or nonsense). But it is clearly not relevant to how we use ferrites by wrapping them around a cable with 2 or more conductors, because in this situation there is no filtering of the digital data.

Now playing: Nina Nesbitt - Bright Blue Eyes

 

[flyte3333]

Yeah, that was me for a while. Blissful ignorance.

Rob has already explained quite clearly why he's wrong about using ferrites on a USB cable. There's no havoc!

EDIT: If John is referring to putting ferrites individually onto all four of the conductors in a USB cable, e.g. inside the DAC where the USB signal leaves the socket, then yes that would filter the digital signal and potentially cause problems. But that isn't the way we use ferrites on our USB (or BNC) cables. Instead each ferrite is wrapped around 2 or more conductors and it's because there's 2 or more that the RF filtering works, but the digital data is unaffected.

His posting doesn't make it clear which of these two techniques he's referring to. So it's unfair of me to paint his posting as being categorically wrong (or nonsense). But it is clearly not relevant to how we use ferrites by wrapping them around a cable with 2 or more conductors, because in this situation there is no filtering of the digital data.

Now playing: Nina Nesbitt - Bright Blue Eyes

Thanks for your edit. At first I thought things were getting unnecessarily personal.

I just discussed with John privately. There’s really no disagreement with what Rob posted so there’s no pissing contest here

Also, these clamp on ferrites have no effect on leakage currents through the USB cable at all...

See earlier links I posted to determine if you think John's leakage currents research is snakeoil or not...

"Of course this is immaterial IF there is no leakage current going through the cable in the first place. So IF you can keep leakage out of the cables, a lot of these cable weirdnesses go out the window."

 

[Rob Watts]

It depends upon what you mean by leakage currents - if it's audio frequency then sure, ferrites (by which I mean clamp on types) will have no effect. But these leakage currents in practice do not matter at all; it's the RF leakage currents that upsets SQ and degrades noise floor modulation - and these categorically are reduced by ferrites, as the ground connection impedance (the common mode impedance) increases with ferrites. It's an extremely effective way of reducing RF leakage, and with the correct ferrites one can cover 1 MHz through to 5GHz.

As to USB cables - I have not heard a benefit in using ferrites on a quality RF and high speed certified USB cable; but in principle YMMV dependent upon how noisy your source is.

Edit: why is the common mode impedance important? If the impedance was infinite, then no currents can possibly flow, as effectively one has complete isolation. And if no current flows, then the DAC will have a clean ground plane with no added noise from the source, hence no noise floor modulation as there is no source RF noise that the DAC can see. Adding ferrites increases the impedance in line with the data sheet on the particular ferrite.

 

[Malcyg]

It depends upon what you mean by leakage currents - if it's audio frequency then sure, ferrites (by which I mean clamp on types) will have no effect. But these leakage currents in practice do not matter at all; it's the RF leakage currents that upsets SQ and degrades noise floor modulation - and these categorically are reduced by ferrites, as the ground connection impedance (the common mode impedance) increases with ferrites. It's an extremely effective way of reducing RF leakage, and with the correct ferrites one can cover 1 MHz through to 5GHz.

As to USB cables - I have not heard a benefit in using ferrites on a quality RF and high speed certified USB cable; but in principle YMMV dependent upon how noisy your source is.

Edit: why is the common mode impedance important? If the impedance was infinite, then no currents can possibly flow, as effectively one has complete isolation. And if no current flows, then the DAC will have a clean ground plane with no added noise from the source, hence no noise floor modulation as there is no source RF noise that the DAC can see. Adding ferrites increases the impedance in line with the data sheet on the particular ferrite.

I have wondered whether your DAC’s are more susceptible to this noise because of the amount of noise generated by the FPGA - and you have two of those in a BluDave, one feeding into another - or whether it is the greater transparency and clarity that your solutions deliver that makes the noise more easy to detect. Thinking back over my own experiences, maybe a bit of both, but certainly the latter.

I agree regarding USB cables as I heard no benefits from applying ferrites myself and ended up taking them off of mine - but I have spent a lot of effort in cleaning up my source. I only heard benefit on the BNC connection between Blu II and Dave.

Edit - I hope my question does not seem blunt or impolite. I guess I’m just so used to you posting on here Rob that I react the same way as for any other poster. You’re only the chap who has designed the best sounding device that I have ever heard after all.

 

[Jawed]

I have wondered whether your DAC’s are more susceptible to this noise because of the amount of noise generated by the FPGA - and you have two of those in a BluDave, one feeding into another - or whether it is the greater transparency and clarity that your solutions deliver that makes the noise more easy to detect.

It seems the entire history of stand-alone DACs in hi-fi has been subject to RF noise injection from electrical cables. Certainly with my DAC from the 1990s, optical (non TOSLINK) was the best input and many other DACs from that era also had an optical input that was considered the best.

I think it's fair to say as stand-alone DACs get better, the problems caused by RF become more obvious. Self-noise (whether due to an FPGA or other circuitry) then becomes more important and if there is no external source of noise (e.g. with an optical input and assuming that jitter is completely irrelevant) then self-noise is the entire problem.

(It's worth remembering that Rob's pulse array design is a key technique to reduce self-noise. The pulse array itself doesn't produce noise-modulation as it's a constant noise DAC. The higher the element count, the lower the self-noise, so 20 elements in DAVE is the best of all the Chord DACs.)

It also means it's hard to isolate how much of the sound quality benefit of Blu 2 is due to DAVE's FPGA mostly being "off", since WTA 1 filtering is "pass through, unmodified". Because WTA 1 takes most of the FPGA in DAVE, there is theoretically less noise inside DAVE when Blu 2 is feeding 16FS music. The sound quality benefits ascribed to Blu 2 are the same as those for reduced noise floor modulation, so that makes it harder to tell what improvement Blu 2 brings solely due to the extra taps.

We would need a DAC with no WTA 1 and then an upsampler that has two output modes: 16FS with 1 million taps and 16FS wtih 164,000 taps.

The closest we have is that Blu 2 has a "2/3 of a million taps" mode, where the output is 16FS (video mode). This is a non-WTA filter. It should sound worse than the WTA 1 filter in DAVE (because it's not WTA) but apparently people prefer it to DAVE stand-alone. That might indicate that DAVE's self-noise is a very serious problem.

A non-WTA filter should never sound better than a WTA filter, no matter how many taps it has, if WTA is the correct approach. But, the video mode has "0.1s" delay (about the same as DAVE):

The manual on Chord's website is now correct; down is full 705/768. Note that the dither switch is video mode when not using CD; up for full 1M taps, down for lower latency 0.1s for video (2/3 M taps).

which might imply that it incorporates DAVE's WTA filter: 82,000 taps from the future and then about 600,000 taps from the past, with 82,000 of those taps being DAVE taps. So that would make it a pseudo WTA filter: DAVE for about 0.1s into the future and DAVE++ from the past: 0.1s of DAVE WTA + other taps. So then it's a question of whether the asymmetric nature of the filter degrades it to sound worse than DAVE or other pure WTA filters (which are trying to be a sinc filter, which is symmetric). If not, why is it that an asymmetric filter can sound better than a symmetric filter?

Regardless, the video mode versus WTA mode in Blu 2 is the closest we can get to discerning how much of a problem DAVE has from self-noise.

Ideally we would be able to listen to a pulse array DAC which only has a 2048FS input. The self-noise would be solely due to crosstalk between the channels and the element count. Then we would know what sound quality problems the FPGA in DAVE is causing.

It's possible to do a version of this experiment if you have Blu 2, DAVE and Hugo 2. Since DAVE has dual-data mode output and since Hugo 2 has 16FS input using its dual-data mode, you can listen to Hugo 2 with either 1 million taps upsampling from Blu 2 or 164,000 taps upsampling from DAVE. But you will need a lot of ferrites (until adding more makes no difference) on the cable going into Hugo 2, since DAVE's BNC outputs are much noisier than Blu 2's.

Malc, you have everything (except the cable for Hugo 2?) required to do this experiment, don't you? Obviously Hugo 2 has a lower quality of pulse array, so it won't represent DAVE, but it's still potentially an interesting experiment.

@ray-dude also has the electronics needed for this experiment, I believe. Qutest is the other option instead of Hugo 2.

The real problem is getting the data into Hugo 2/Qutest without adding so much RF noise that it swamps the comparison being sought.

Now playing: Max Cooper - Order from Chaos

EDITED for mistakes.

 

[Malcyg]

It seems the entire history of stand-alone DACs in hi-fi has been subject to RF noise injection from electrical cables. Certainly with my DAC from the 1990s, optical (non TOSLINK) was the best input and many other DACs from that era also had an optical input that was considered the best.

I think it's fair to say as stand-alone DACs get better, the problems caused by RF become more obvious. Self-noise (whether due to an FPGA or other circuitry) then becomes more important and if there is no external source of noise (e.g. with an optical input and assuming that jitter is completely irrelevant) then self-noise is the entire problem.

(It's worth remembering that Rob's pulse array design is a key technique to reduce self-noise. The pulse array itself doesn't produce noise-modulation as it's a constant noise DAC. The higher the element count, the lower the self-noise, so 20 elements in DAVE is the best of all the Chord DACs.)

It also means it's hard to isolate how much of the sound quality benefit of Blu 2 is due to DAVE's FPGA mostly being "off", since WTA 1 filtering is "pass through, unmodified". Because WTA 1 takes most of the FPGA in DAVE, there is theoretically less noise inside DAVE when Blu 2 is feeding 16FS music. The sound quality benefits ascribed to Blu 2 are the same as those for reduced noise floor modulation, so that makes it harder to tell what improvement Blu 2 brings doing solely due to the extra taps.

We would need a DAC with no WTA 1 and then an upsampler that has two output modes: 16FS with 1 million taps and 16FS wtih 164,000 taps.

The closest we have is that Blu 2 has a "2/3 of a million taps" mode, where the output is 16FS (video mode). This is a non-WTA filter. It should sound worse than the WTA 1 filter in DAVE (because it's not WTA) but apparently people prefer it to DAVE stand-alone. That might indicate that DAVE's self-noise is a very serious problem.

A non-WTA filter should never sound better than a WTA filter, no matter how many taps it has, if WTA is the correct approach. But, the video mode has "0.1s" delay (about the same as DAVE):



which might imply that it incorporates DAVE's WTA filter: 82,000 taps from the future and then about 600,000 taps from the past, with 82,000 of those taps being DAVE taps. So that would make it a pseudo WTA filter: DAVE for about 0.05s into the future and DAVE++ from the past, 0.05s of DAVE WTA, then other taps. So then it's a question of whether the asymmetric nature of the filter degrades it to sound worse than DAVE or other pure WTA filters (which are trying to be a sinc filter, which is symmetric). If not, why is it that an asymmetric filter can sound better than a symmetric filter?

Regardless, the video mode versus WTA mode in Blu 2 is the closest we can get to discerning how much of a problem DAVE has from self-noise.

Ideally we would be able to listen to a pulse array DAC which only has a 2048FS input. The self-noise would be solely due to crosstalk between the channels and the element count. Then we would know what sound quality problems the FPGA in DAVE is causing.

It's possible to do a version of this experiment if you have Blu 2, DAVE and Hugo 2. Since DAVE has dual-data mode output and since Hugo 2 has 16FS input using its dual-data mode, you can listen to Hugo 2 with either 1 million taps upsampling from Blu 2 or 164,000 taps upsampling from DAVE. But you will need a lot of ferrites (until adding more makes no difference) on the cable going into Hugo 2, since DAVE's BNC outputs are much noisier than Blu 2's.

Malc, you have everything (except the cable for Hugo 2?) required to do this experiment, don't you? Obviously Hugo 2 has a lower quality of pulse array, so it won't represent DAVE, but it's still potentially an interesting experiment.

@ray-dude also has the electronics needed for this experiment, I believe. Qutest is the other option instead of Hugo 2.

The real problem is getting the data into Hugo 2/Qutest without adding so much RF noise that it swamps the comparison being sought.

Now playing: Max Cooper - Order from Chaos

Interesting stuff Jawed, albeit slightly advanced beyond where I feel a need to understand at times. You have given me a lot of useful information in the past about noise and how to address it, mainly by PM, which I appreciate. With regard to the testing that you suggest, that might well be one more for @ray-dude who seems to have a healthy, almost @romaz like, appetite for testing. As @Triode User put it recently, you can lose the will to live a little with extended testing and, like him, I am in full sit back and enjoy mode.

I had two overriding objectives with my system which were both more difficult to achieve than I thought they would be. The first, as you know, was to get my file playback up to and past the level of the Blu CD. I got there in the end and now I quite clearly prefer file playback to Blu II CD in terms of sound quality, let alone convenience. (@AndrewOld - there’s simply no need to say it!)

My second objective was to get my speakers to sound as good, or better, than my HE-1000 V2 plugged directly into BluDave - a tall order indeed. I have achieved this at last and the sound quality that I am getting now is really quite astonishing and more even than I was aiming for. But it has taken more time and certainly cost more than I would have liked.

One component in achieving this, and I hate to admit it, was the ferrites that @marcmccalmont generously sent to me to complement the CA cables that we both have. I can’t recall exactly what he posted about all that now, but I know from the PM’s that we have exchanged that we are hearing very similar results in our systems. The other final piece of the jigsaw was the SotM sCLK-OCKX10 Master Clock for the tX-U. That together with the necessary sPS-500 power supply means that I now have a trifecta of little black boxes! Having spoken out on here against multiple black box solutions as well as ferrites more recently, it is not easy for me to admit all this publicly, but I feel obliged to do so and take any stick that might come my way.

Having said all that, it all sounds so incredibly good that I don’t care. If all my name dropping here seems like an Oscars acceptance, it is probably because I am done now and therefore unlikely to be posting as much moving forwards.

 

[RobinTim]

My second objective was to get my speakers to sound as good, or better, than my HE-1000 V2 plugged directly into BluDave - a tall order indeed. I have achieved this at last and the sound quality that I am getting now is really quite astonishing and more even than I was aiming for. But it has taken more time and certainly cost more than I would have liked.

Sorry if I overlooked it, I am new to this, but what speakers did you get?

 

[Malcyg]

Sorry if I overlooked it, I am new to this, but what speakers did you get?

I don’t think I ever said actually, I’m not sure, but I have KEF Blade 2. I had Dali Euphonia MS4’s which I had been very happy with for 7 years or more and always thought of them as my final pair of speakers. Then I got a Blu II and, when I heard HE-1000 straight into BluDave, it was quite a glorious but also sobering experience. The MS4’s days were numbered - and my wife wasn’t happy about it because she loved the Alpi finish. She was even less happy when she saw the frosted copper black blade 2’s sat in her lounge!

 

[Jawed]

With regard to the testing that you suggest, that might well be one more for @ray-dude who seems to have a healthy, almost @romaz like, appetite for testing. As @Triode User put it recently, you can lose the will to live a little with extended testing and, like him, I am in full sit back and enjoy mode.

Yes, I'm in sit-back and enjoy mode, I'm really not interested in comparing stuff or shopping for a Blu 2.

It's occurred to me that @Triode User has, according to his signature, 2 DAVEs. So he has the best setup for this experiment. Blu 2 or DAVE dual-data output into DAVE

When the power pulse array amplifiers become available that will be another way to do the experiment, as I'm expecting Blu 2 or DAVE can output directly into the PPA.

Now playing: Oscar Peterson - People

 

[Triode User]

Yes, I'm in sit-back and enjoy mode, I'm really not interested in comparing stuff or shopping for a Blu 2.

It's occurred to me that @Triode User has, according to his signature, 2 DAVEs. So he has the best setup for this experiment. Blu 2 or DAVE dual-data output into DAVE

When the power pulse array amplifiers become available that will be another way to do the experiment, as I'm expecting Blu 2 or DAVE can output directly into the PPA.

Now playing: Oscar Peterson - People

Yes, I do have double Dave. I have two systems. Why would I want one system to have an inferior Dac?