[dakanao]

My feedback on Jitterbug is that I only notised a difference when I used it with MBP from 2013 with a short curious usb cable, i know should be snake oil, but it was not, curious cable made big difference and the jitterbug mad small difference, blacker background but rolled off treble, so depending on what I streamed, Tidal or Qobus it was give or take, some songs sounded better with while other better without, at the end I left ut on as I generally prefered it more pleased with it than not ( i use HD800), that said with any other source I have not used it since no benefit via usb, though the short curious usb cable sounded better than any normal generic one I have, checked 10 + cables and was surprised....of the difference with the MBP, never been a cable guy as I always thought it was and is snake oil, but would recommend if using direct with a PC, laptop or similar! Cant say why but it does....my 2 cents...

Jitterbug works on my laptop with Chord Mojo,makes the sound warmer, smoother with more bass impact, but on my iPad it makes the bass more rolled off and less smooth.

 

[STR-1]

Hi @Rob Watts, are there any teasers you can offer us on progress with your various projects to help us get through these troubled times?

 

[Widell]

D

Jitterbug works on my laptop with Chord Mojo,makes the sound warmer, smoother with more bass impact, but on my iPad it makes the bass more rolled off and less smooth.

its for sure doing somthing but for me its give and take depending on source, less impact if all on battery so maybe some reduction of interference from power sourse, far from an expert and wish someone with knowledge in this field could pitch in here such at Rob Watts himself so we can find out the science behind it, I have all respect for ASR forum and read daily but as previously stated a coin has 2 sides and we should always use our ears to filter out the marketing hypes.

 

[Rob Watts]

Hi @Rob Watts, are there any teasers you can offer us on progress with your various projects to help us get through these troubled times?

Oddly enough I was thinking about such a post later this week - I am awaiting a delivery and will post something when it comes.

D

its for sure doing somthing but for me its give and take depending on source, less impact if all on battery so maybe some reduction of interference from power sourse, far from an expert and wish someone with knowledge in this field could pitch in here such at Rob Watts himself so we can find out the science behind it, I have all respect for ASR forum and read daily but as previously stated a coin has 2 sides and we should always use our ears to filter out the marketing hypes.

I can't comment about the jitterbug directly - but USB is important for two reasons - the RF noise that enters the DAC, and signal correlated noise, which degrades depth perception. This is both due to currents flowing into the DAC - stop current flowing in the ground, and you eliminate the issues. Random RF noise is important as it creates intermodulation distortion with the audio signal, and if the RF is random, the intermod products are also random, and dependent upon the level of the audio signal. Now all this, if the levels are large enough, are easily measurable on a DAC that has zero measurable noise floor modulation; the only contentious issue is the audibility of noise floor modulation - and that's down to doing listening tests. My listening tests have shown noise floor modulation from -180 dB to -200 dB as easily audible; but of course people that never do listening tests will claim that this level is inaudible. That's the heart of the argument between those that listen and those that don't.

Note that all current Chord DACs employ extensive RF filtering or galvanic isolation on the USB, so further treatment is unnecessary.

 

[Triode User]

Oddly enough I was thinking about such a post later this week - I am awaiting a delivery and will post something when it comes.

I can't comment about the jitterbug directly - but USB is important for two reasons - the RF noise that enters the DAC, and signal correlated noise, which degrades depth perception. This is both due to currents flowing into the DAC - stop current flowing in the ground, and you eliminate the issues. Random RF noise is important as it creates intermodulation distortion with the audio signal, and if the RF is random, the intermod products are also random, and dependent upon the level of the audio signal. Now all this, if the levels are large enough, are easily measurable on a DAC that has zero measurable noise floor modulation; the only contentious issue is the audibility of noise floor modulation - and that's down to doing listening tests. My listening tests have shown noise floor modulation from -180 dB to -200 dB as easily audible; but of course people that never do listening tests will claim that this level is inaudible. That's the heart of the argument between those that listen and those that don't.

Note that all current Chord DACs employ extensive RF filtering or galvanic isolation on the USB, so further treatment is unnecessary.

Rob, I will look forward with interest to your update later on . . . . . .

In the meantime, you said, "Note that all current Chord DACs employ extensive RF filtering or galvanic isolation on the USB, so further treatment is unnecessary" and I wonder how that squares with a suggestion that optical is the optimum connection with respect to noise isolation when connecting to the DAC? What I mean is, if further treatment of USB going into current Chord DACs is unnecessary doesn't that imply that USB is the equal of optical in terms of noise when used with your current DACs and we can ignore the optical is better mantra?

By the way, I only use USB, but then my source only has a USB output so I do not have a choice.

 

[Rob Watts]

I was referring to the Jitterbug really there, which benefited with Hugo 1. That said, I remain to be convinced that the "benefits" of USB treatments are just simply increasing RF noise making it appear more transparent as more noise floor modulation makes it sound brighter.

As too USB against optical - that depends upon your system and source. Certainly I could hear no difference with Hugo M scaler with my MSI lap-top of USB against optical; also I couldn't hear a difference with it on a Hugo 2 (headphone mode). I could hear a difference if Hugo 2 was grounded though - consistent with ground loops and the fact that Hugo 2 is not galvanically isolated.

On another note I just bought three Tangerine Dream box sets - 1970 to 1983. Listening to Stratosfear - I haven't heard that since vinyl - sounds way better. Spine tingling good. Brings back rich memories...

 

[manueljenkin]

Hi Rob,

Looking for some guidance. Been reading a few books and articles and have some understanding but unsure if the causation and correlation I have is right/universal.

I have been able to hear distinct differences in the sound of different music player software all in ASIO mode (so essentially bit perfect as probed at the CPU side). Even with players from similar audio libraries, changing the buffer size or even some specific code structures change the sound.

This has been my experience with my topping nx4 and apogee groove. However even people with higher tier gear that supposedly measure good otherwise seem to show significant differences of the same order. My best experience so far has been a Linux distro called wtfplay which strips away almost all daemons and pursues only audio playback. Difference on moving from foobar to wtfplay was way more drastic than say difference between hd598 and hd600 subjectively, and my friends with other gear have same inferences.

Another player I know of that sounds great otherwise has a sheen of harshness to the sound. Looking into the code I found that it was a buffer management issue (amount of data stored to ram at an instant). Yet another player, of same library but with ability to store full song to ram didn't have this issue when set up that for that. They sound similar except this particular harshness. Now here's the interesting part, most of my and my friends DAC correlate that player to being a bit harsh. But another friend experienced the exact opposite, his DAC sounded rounded off with that player. And a few other players that sounded rounded off to me sounded sharper to him. If the differences were purely noise floor modulation, all the dacs should steer the sound in the same way, but that doesn't seem to be happening. Quite interesting imo.

I mentioned the subjective changes here to give an idea of the scale perceived.

Coming back to technical questions. One way of looking at this change is the possibility of noise propagating all the way to the components in the DAC hence modulating their output. This should be possible to solve with effective isolation techniques I guess. CPU activity can impart noise into USB bus. If not isolated well this can be troubling, and some people even report hearing crackle when moving just their mouse. CPU noise can come from polling, or even state shifts from idle to work or different throttle states.

However another possibility, and one that I have personally experienced is a complete fault in the signal integrity. I for example have heard serious buffer underruns that results in a sheen of sudden crackle at times. However, digging deeper, it looks like these buffer issues need not always manifest in a sudden pop or crackle and can be just subtle modulation issues till a particular level of tolerance. I couldn't find any on the usb receivers side but I found a lot of patents on packet loss concealment for telecom and digital voice communications. I am unsure if the usb receivers employ any of that sort. Even if they don't, a delta Sigma DAC can also theoretically behave as a natural packet loss concealer too. Looking at the USB audio protocol it doesn't mandate any complete failure for data integrity issues, going insofar that it doesn't even ensure inter channel signal integrity. There is no error correction, so concealment/interpolation is the only thing I can think of if packets go missing. The fault in signal integrity could be from noise polluting in the cable or noise from computer or even just the inability of the computer to respond back to data request from DAC in the required time. USB data,atleast for audio will need to be fetched from storage -> RAM in burst mode then from RAM to CPU then from CPU to bus controllers and then only to the port after passing through a lot of analog components like level shifters along the way. If the task priorities are messed up and the CPU couldn't respond in time it should result in buffer underrun as I experienced. For certain scenarios this can be checked with a dpc latency monitor but may not be possible all the time.

These are all just my speculations. I would love to hear better from you. Atleast in the devices I and my friend own, the differences are profound, both with cable swaps or with music player software changes. The better softwares surely don't increase noise floor modulation issues to push detail. They sound more effortless and laidback, yet more detailed, just like your description of ideal sound reproduction. I wouldn't even call laidback, I would rather call it unforced, if that makes any sense.

 

[Rob Watts]

Thanks for your post.

I don't think data integrity plays any part in this. When I was testing the M scaler using the AP in the digital domain, the measured noise floor was at -200dB; and some tests took all afternoon. Not once did a bit error occur (when you get a bit error or buffer/data error you see the result immediately).

With Chord DACs on USB and Windows, faulty data packets are re-sent. Not that in practice this really helps, as a faulty data stream is easily audible!

But of course the noise levels being injected into the DAC will affect performance; moreover, other DACs are likely to be jitter sensitive too. So the processors activity could easily have an effect in those cases, and of course different software with different noise levels could have an audible difference.

 

[manueljenkin]

Thanks for your post.

I don't think data integrity plays any part in this. When I was testing the M scaler using the AP in the digital domain, the measured noise floor was at -200dB; and some tests took all afternoon. Not once did a bit error occur (when you get a bit error or buffer/data error you see the result immediately).

With Chord DACs on USB and Windows, faulty data packets are re-sent. Not that in practice this really helps, as a faulty data stream is easily audible!

But of course the noise levels being injected into the DAC will affect performance; moreover, other DACs are likely to be jitter sensitive too. So the processors activity could easily have an effect in those cases, and of course different software with different noise levels could have an audible difference.

Hi Rob. Thank you very much for the detailed reply. So this would mean that if I have a laptop as source, I should be able to use any bit perfect music player or any spec compatible usb cable with the Hugo 2 and get near identical sound?

Few questions again:

Do chord DACs on windows use a custom driver/software stack? I saw the exact opposite on the general universal audio class spec sheet that it doesn't do any retransmissions.

And regarding the tests for bit error, I would like to learn a bit more in detail. What particular tones were used? For a general analysis, typically sines or sine sweeps or at max squares are used. Sometimes particular noise pattern like white noise. Did it show the same result of no data error for a music file too?

 

[naynay]

Obviously I would love to say which ferrites I use but it took me 6 months of evaluation to find the best ones.

Deleted

 

[474194]

Greetings Sir Rob.

I was looking @ low impedance battery solutions and noticed a few car battery posts of yours a few years back.

It was a "portable" battery to enable you to start cars with flat batteries, and was rated at 300A, but I am sure that is just peak surge current rating. It doesn't matter whether it is 300A or 3A; all that is important is ultra low impedance, and ultra low noise, which a car battery has plenty of, way better than any mains linear PSU.

https://www.head-fi.org/threads/chord-electronics-qutest-dac-official-thread.869417/post-14048880

Then I used the best PSU possible - a car battery as it has effectively zero impedance, no RF of LF noise, and 300A of current, and compared this to the supplied charger. With Qute I could indeed hear a huge change with the car battery sounding a lot better - richer, smoother, with better depth and instrument separation. But with 2 Qute I could hear no change at all - this validated the improved isolation within 2 Qute.

https://www.head-fi.org/threads/chord-electronics-qutest-dac-official-thread.869417/post-14046554

What qualifies for this? lead acid battery okay?

https://images-na.ssl-images-amazon.com/images/I/A1vo+S5Sp0L.pdf

https://www.amazon.com/dp/B01JRDV81K/ref=emc_b_5_t?th=1

I was considering utilising the USB ports off a lead acid battery.... Maybe DC one day, but for now just USB...

Also, my Hugo2 warranty should be up in about 3 months. I was considering experimenting with LiFePO4 batteries. Since these are 3.2V increments not 3.7V, would feeding the Hugo2 6.4V be okay? Mojo?

Of course a different connector on the end.

Cheers!

 

[Rob Watts]

Hi Rob. Thank you very much for the detailed reply. So this would mean that if I have a laptop as source, I should be able to use any bit perfect music player or any spec compatible usb cable with the Hugo 2 and get near identical sound?

Few questions again:

Do chord DACs on windows use a custom driver/software stack? I saw the exact opposite on the general universal audio class spec sheet that it doesn't do any retransmissions.

And regarding the tests for bit error, I would like to learn a bit more in detail. What particular tones were used? For a general analysis, typically sines or sine sweeps or at max squares are used. Sometimes particular noise pattern like white noise. Did it show the same result of no data error for a music file too?

Yes Windows is a custom driver, and the universal audio class doesn't. But again, a bit failure is easy to spot (clicks and noise) and I have never heard an error using my mobile for example. So the error rate of standard USB is low enough not to cause an issue in practice.

The tests that take hours involve white noise at full 0dB FS; a thousand averages is used with 1.2M point FFT; if one FFT had a single error you would see it in the averaged response. Other tests that take time are the noise floor modulation tests, but they take an hour only. But again, one error would see visible noise on the spectrum.

Greetings Sir Rob.

I was looking @ low impedance battery solutions and noticed a few car battery posts of yours a few years back.


https://www.head-fi.org/threads/chord-electronics-qutest-dac-official-thread.869417/post-14048880



https://www.head-fi.org/threads/chord-electronics-qutest-dac-official-thread.869417/post-14046554

What qualifies for this? lead acid battery okay?



https://images-na.ssl-images-amazon.com/images/I/A1vo+S5Sp0L.pdf





https://www.amazon.com/dp/B01JRDV81K/ref=emc_b_5_t?th=1

I was considering utilising the USB ports off a lead acid battery.... Maybe DC one day, but for now just USB...

Also, my Hugo2 warranty should be up in about 3 months. I was considering experimenting with LiFePO4 batteries. Since these are 3.2V increments not 3.7V, would feeding the Hugo2 6.4V be okay? Mojo?



Of course a different connector on the end.

Cheers!

No a Hugo 2 and Mojo need at least 6.5v, otherwise it will shut down. And you need 8v to get the best measured performance in terms of OP power too...

I strongly suggest that you do not change the battery, unless you have too; and use the same as the original. The charging circuit is tuned to match those batteries, and you could have a fire or something else serious if you mess around with it!

 

[474194]

No a Hugo 2 and Mojo need at least 6.5v, otherwise it will shut down. And you need 8v to get the best measured performance in terms of OP power too...

I strongly suggest that you do not change the battery, unless you have too; and use the same as the original. The charging circuit is tuned to match those batteries, and you could have a fire or something else serious if you mess around with it!

Thank you for your concern. I'll keep the batteries original for Hugo2 and Mojo.

When you posted a few years back, do you still feel the same about car battery power?

Then I used the best PSU possible - a car battery as it has effectively zero impedance, no RF of LF noise, and 300A of current, and compared this to the supplied charger.

... ultra low impedance, and ultra low noise, which a car battery has plenty of, way better than any mains linear PSU.

https://www.head-fi.org/threads/chord-electronics-qutest-dac-official-thread.869417/post-14046554

Before Chord DACs arrived on the scene, I was considering an R2R DAC powered by a car battery.

Would a Qutest, TT2 or mScaler benefit from car battery power?

 

[Rob Watts]

Yes a car battery is the best possible PSU - huge dynamic current, ultra low impedance and no noise. But the real benefit is batteries, and isolation from the mains, so a car battery is not needed; just use a USB power bank.

TT2 doesn't benefit from it anyway, because of the super caps and the filtering; disconnecting the PSU has no change in measurements or sound quality. The M scaler is helped by using a battery, as it eliminates the 2GHz ground return currents, solving at a stroke the BNC cabling issue.

 

[Triode User]

Yes a car battery is the best possible PSU - huge dynamic current, ultra low impedance and no noise. But the real benefit is batteries, and isolation from the mains, so a car battery is not needed; just use a USB power bank.

TT2 doesn't benefit from it anyway, because of the super caps and the filtering; disconnecting the PSU has no change in measurements or sound quality. The M scaler is helped by using a battery, as it eliminates the 2GHz ground return currents, solving at a stroke the BNC cabling issue.

I'll have a go. After all, the battery isn't needed in my car at the moment!!!