AQ Jitterbug Measurements

mauidan

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Yes. I also have the Audiophilleo USB to S/PDIF bridge that I will test with. I will also take apart the AQ and do a write up/show images of what is inside it. Time allowing, I will also scope out electrically and see what is there. Or isn't :).

How much are the other devices like it by the way?



http://www.audiostream.com/content/...b-data-power-noise-filter#LFOGsVP0PgQb8pVk.97
 

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YashN

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The UpTone REGEN is probably one of the most hyped products in recent memory, but I have to say it really does work...on both a $499 iFi DAC and a $6000 Simaudio DAC.

It's not 'hyped' as in 'the manufacturer made a large social media, advertising campaigns and hired celebrities to tout the product'. It is getting a lot of attention because people bought the product and are giving great feedback and the SQ results they have (wide variety of DACs). This makes it a very good example of how Word of Mouth can work when the product is genuine.
 

YashN

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I have a Mark Levinson DAC driven by Berkeley USB to AES/EBU converter. I see no signature of USB noise as he is mentioning in there down to near -130 dbFS.

Do you at least see the packet/protocol noise at 8kHz and higher multiples? I could see that with a rather rudimentary DIY probe circuit connected to the Mac and using a software Scope through WINE.

The PDN noise is apparently observed in specific instances linked to lower signal integrity, which can commission into operation a lot of the modules needed to define the data, this in turn generates current, voltage noise affecting SQ.
 

YashN

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And make no mistake, the fellow behind the Regen, John Swenson, is highly respected and has high integrity.

It's not his first product either, John has collaborated with Bottlehead, also designed a great Power Supply Unit with Uptone (which by virtue of the Regen Halo effect seems to also be currently in demand), and with Jesus R of Sonore.

He's one of the most knowledgeable and solid Engineers in the field today, IMO.

To know more about him, read the Audiostream Q & A with him, it's three parts chock-full of info.

He also hangs out sometimes over at Computeraudiophile.com.
 

Andre Marc

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It's not 'hyped' as in 'the manufacturer made a large social media, advertising campaigns and hired celebrities to tout the product'. It is getting a lot of attention because people bought the product and are giving great feedback and the SQ results they have (wide variety of DACs). This makes it a very good example of how Word of Mouth can work when the product is genuine.

Spot on. UpTone is a two person entity. And the product is as you say, legit.

That is why I asked the OP to clarify what he meant by "mass hysteria".
 

Andre Marc

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It's not his first product either, John has collaborated with Bottlehead, also designed a great Power Supply Unit with Uptone (which by virtue of the Regen Halo effect seems to also be currently in demand), and with Jesus R of Sonore.

He's one of the most knowledgeable and solid Engineers in the field today, IMO.

To know more about him, read the Audiostream Q & A with him, it's three parts chock-full of info.

He also hangs out sometimes over at Computeraudiophile.com.
Absolutely. I'm very familiar with his work. He is one of the very, very, very few not in it for the money.
 

Orb

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It's not 'hyped' as in 'the manufacturer made a large social media, advertising campaigns and hired celebrities to tout the product'. It is getting a lot of attention because people bought the product and are giving great feedback and the SQ results they have (wide variety of DACs). This makes it a very good example of how Word of Mouth can work when the product is genuine.
Yeah, also he was pretty upfront on a forum about the costs involved in making the product with a bit of a breakdown as well.
Cheers
Orb
 

jkeny

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I know, at least, Gordon is a good dude. My RF engineer buddy, Pat, would vouch for him. Pat says Gordan has the right gear to measure, which costs about $40,000. Having said that, nobody really knows how a measurement in the digital domain which can only be uncovered with uber expensive research lab gear will actually sound in the wild. There haven't been any tests or studies done on it yet. Also, neither Gordon or Swenson have ever published one graph, even though they claim improvements in the digital domain.

So, just because someone is a good dude, doesn't mean they are infallible either. It's funny that folks have a sliding scale when it comes to this stuff. It's like anything under $200; buy it! If it doesn't work, oh well. For me, $200 is nothing. It's a dinner I have with my wife or whatever. But for a lot of folks that's real money.
Yes, it's true what you say about the measurements in the digital domain Vs audibility.
Your RF engineering buddy, Pat (Giacommo? - aka Jocko Homo) who has vast experience in RF, particularly with oscillators, contends that oscillator phase noise below 1Hz is the important measure for SQ but I haven't seen any published graphs or theory from him to explain this. I have an open mind about this but have never bought the expensive SC cut crystals or products that contain such crystals to check it out for myself - have you?.

I guess there is a lot of this in audio - we either don't have the time, money or inclination to try everything that is claimed to be an audible improvement - we keep an open mind on things based on perception & gut feeling about what may work & what we dismiss as snake-oil - I would suggest that it's hardly ever based on just rational thought - most decisions are taken before rational thought is engaged.

One interesting thought that may have occurred to you - what do you think is the strength of the effect (psychological biasing) of seeing supporting measurements has on you - in other words how much better do you perceive the audio to be once you have seen the measurements & does this not give you pause for thought before "gushing" praise on such audio devices?
 
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jkeny

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I like John and have no issues with what he is explaining. But what he is saying is fully quantifiable and he sadly has no numbers at all in there. It would take me two minutes to measure all of that and show the effect.

I'm wondering too how you would go about testing the Regen for which the mode of operation is stated to be dependent on the signal integrity of the USB signal? What would you intend to test for & what test signals used?

As others have asked - have you been able to measure the 8KHz noise spike associated with the USB packet protocol - not that this has anything to do with the Regen's operation but it would show a measurement capability which would lend credence to other USB measurements of a similar nature & level - actually, I believe the effect of bad SI is in producing a modulating noise floor which I think the Regen may well improve (lessen the modulation) - measuring this will be quiet a challenge so I'm interested in your approach.

Again, I think that this the interesting area that needed investigating in the now closed Measurements thread - what measurements & how they would be approached is the far more interesting (to me, anyway) topic than simply measurements Vs audibility.

I feel a lot of the analysis of measurements is just glossed over because it takes thought, experience & ingenuity to do "proper" measurements (I'm not getting at you, Amir, just stating my thinking about the whole area of audio measurements when it comes to digital audio)
 

Orb

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In context of this thread-discussion; Aren't we interested in the analogue output performance of the DAC as it pertains to recreating the digital sine waves 20hz to say 30khz played from the MacBook?
OK sine waves are a simple test but we may correlate noise and distortion with signal/frequency.
Could also do a jitter test file from MacBook, although differences if any should be small.
Pain but worth repeating also at hirez sampling rates, assumption is 24-bit all the time to assist measuring (compare 16-bit and 24-bit measurements when doing noise and distortion against signal level and frequency to see what I am saying).

Cheers
Orb
 

amirm

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Do you at least see the packet/protocol noise at 8kHz and higher multiples? I could see that with a rather rudimentary DIY probe circuit connected to the Mac and using a software Scope through WINE.
Where do you see that? On the output of the DAC?
 

dallasjustice

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In context of this thread-discussion; Aren't we interested in the analogue output performance of the DAC as it pertains to recreating the digital sine waves 20hz to say 30khz played from the MacBook?
OK sine waves are a simple test but we may correlate noise and distortion with signal/frequency.
Could also do a jitter test file from MacBook, although differences if any should be small.
Pain but worth repeating also at hirez sampling rates, assumption is 24-bit all the time to assist measuring (compare 16-bit and 24-bit measurements when doing noise and distortion against signal level and frequency to see what I am saying).

Cheers
Orb

Yes, that's true. But jitter can only be directly measured in the digital domain. The J-test is a very reliable indirect measurement of jitter in the analog domain. However, the j-test cannot give you real jitter results.

Jitter results will be different for every device since they are each designed in a different way. To my knowledge, the only way to measure what the jitterbug is doing or not doing, would be to have the $40,000 Tektronix analyzer referenced in JA's measurements section. It can measure USB. I know that Gordon Rankin has one and uses it. I don't know whether Swenson has one. Gordon could post his measurement, but doesn't. My guess is that Gordon doesn't want to have to explain what they mean, to him. Jitter is complex and takes some real skill to know how to measure it in the digital domain. It also requires very expensive gear.

Having said all of the above, I still think there are some excellent tests which could be done in the analog domain which should shed more light on what these devices actually do or don't do. I'd be interested in seeing what Amir can do with his high-end testing gear.

The thing that was most interesting for me with JA's measurements is the big difference on IM products with the 1khz sine wave using a laptop powered off battery versus A/C adapter. That was a really big difference. However, the difference using the Jitterbucks was barely even measurable. That comparison really puts things into perspective for me.
 

amirm

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I'm wondering too how you would go about testing the Regen for which the mode of operation is stated to be dependent on the signal integrity of the USB signal? What would you intend to test for & what test signals used?
It is (relatively) easy to simulate that with extra long cables. Or less than optimal USB host implementations.

As others have asked - have you been able to measure the 8KHz noise spike associated with the USB packet protocol - not that this has anything to do with the Regen's operation but it would show a measurement capability which would lend credence to other USB measurements of a similar nature & level - actually, I believe the effect of bad SI is in producing a modulating noise floor which I think the Regen may well improve (lessen the modulation) - measuring this will be quiet a challenge so I'm interested in your approach.
For this analysis I will try to instrument the USB bus. But for my prior work, all I care about is what comes out of my DAC and USB adapter, and there, as I mentioned, down to -130 dbFS or so, I don't see such noises. Has anyone else measured otherwise on a high performance DAC? I am not saying it doesn't exist but I have only seen USB dependent noise in cheap sync DACs.

Again, I think that this the interesting area that needed investigating in the now closed Measurements thread - what measurements & how they would be approached is the far more interesting (to me, anyway) topic than simply measurements Vs audibility.
I don't know how to resolve that puzzle, nor will I try. :) I just like to characterize what the devices do or don't from design perspective. There seem to be different approaches with one using a USB hub and the other, analog filtering. There will be differences there of value for some people to know.

I feel a lot of the analysis of measurements is just glossed over because it takes thought, experience & ingenuity to do "proper" measurements (I'm not getting at you, Amir, just stating my thinking about the whole area of audio measurements when it comes to digital audio)
Just want to be clear that while I will be also testing using typical audio measurements, my goal is a circuit analysis at USB level. For sure you can't try to correlate those directly with audibility because what the DAC does with what comes out or doesn't come out of these devices is an unknown.
 

amirm

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Thanks. That was a very good read with good info. I hope to go beyond the picture he took though :). On pictures, what he is doing here raises the eyebrow from engineering point of view on such a device:



This device is an analog low-pass filter. A low-pass filter gets rid of energy above certain frequency. That energy must go someplace and that place is the ground. The ground exists inside the computer. When you hook up to it using that long blue USB cable, it represents pretty high impedance at high frequencies and as such, doesn't act much like a ground. Ergo little filtering actually occurs. I suspect the manufacturer does not recommend such use.

Question: does anyone know how you put two of these in "parallel?" The device has only one in and one out. How do you get two of them on the same port???
 

Andre Marc

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Thanks. That was a very good read with good info. I hope to go beyond the picture he took though :). On pictures, what he is doing here raises the eyebrow from engineering point of view on such a device:



This device is an analog low-pass filter. A low-pass filter gets rid of energy above certain frequency. That energy must go someplace and that place is the ground. The ground exists inside the computer. When you hook up to it using that long blue USB cable, it represents pretty high impedance at high frequencies and as such, doesn't act much like a ground. Ergo little filtering actually occurs. I suspect the manufacturer does not recommend such use.

Question: does anyone know how you put two of these in "parallel?" The device has only one in and one out. How do you get two of them on the same port???

You don't use them on the same port. You run them in "parallel" on any open port.
 

Orb

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Yes, that's true. But jitter can only be directly measured in the digital domain. The J-test is a very reliable indirect measurement of jitter in the analog domain. However, the j-test cannot give you real jitter results.

Jitter results will be different for every device since they are each designed in a different way. To my knowledge, the only way to measure what the jitterbug is doing or not doing, would be to have the $40,000 Tektronix analyzer referenced in JA's measurements section. It can measure USB. I know that Gordon Rankin has one and uses it. I don't know whether Swenson has one. Gordon could post his measurement, but doesn't. My guess is that Gordon doesn't want to have to explain what they mean, to him. Jitter is complex and takes some real skill to know how to measure it in the digital domain. It also requires very expensive gear.

Having said all of the above, I still think there are some excellent tests which could be done in the analog domain which should shed more light on what these devices actually do or don't do. I'd be interested in seeing what Amir can do with his high-end testing gear.

The thing that was most interesting for me with JA's measurements is the big difference on IM products with the 1khz sine wave using a laptop powered off battery versus A/C adapter. That was a really big difference. However, the difference using the Jitterbucks was barely even measurable. That comparison really puts things into perspective for me.

Yes I appreciate the J-test only stimulates jitter (mentioned that in the past myself), but Hi-fi News has shown it is possible to measure and correlate jitter measurements at the analogue output of a DAC; they have clear examples throughout the years of their testing traditional DACs, ethernet products, hybrid products, scenarios involving MacBook with DAC,etc.
So it is still applicable and is accurate from this perspective and IMO probably one of the better ways to measure jitter for an audio product and component in the context of this thread and recent discussions.
But the point was more than just Jitter Dallas, it was really more about the context of measuring the noise, with jitter also being a viable option to measure and shown to still be of merit by Hi-fi News (Paul Miller was one of the first to develop measurement tools utilising J-test, amongst other tests).
Not sure about IM products with 1khz sine wave myself and its merit *shrug*, I cannot see it being of use in this context but I need to look at that more.

Cheers
Orb
 
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amirm

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BTW, how do people feel about this statement in that review?

"When I first connected the LightSpeed 2G USB Cable and hit "play", Miles stuttered. He skipped. Hmm. I've encountered this before when using other USB cables and the easy fix is to lower the clock setting. Instead I inserted the Jitterbug in between the cable and Mac and no more skipping.
Read more at http://www.audiostream.com/content/audioquest-jitterbug-usb-data-power-noise-filter#dAtpc2CtFGRZGRm2.99"
 

Fitzcaraldo215

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BTW, how do people feel about this statement in that review?

"When I first connected the LightSpeed 2G USB Cable and hit "play", Miles stuttered. He skipped. Hmm. I've encountered this before when using other USB cables and the easy fix is to lower the clock setting. Instead I inserted the Jitterbug in between the cable and Mac and no more skipping.
Read more at http://www.audiostream.com/content/audioquest-jitterbug-usb-data-power-noise-filter#dAtpc2CtFGRZGRm2.99"

I have not tried a lot of different USB cables, but the $50 5-meter one I got from Audio Advisor has worked just fine from the get go. There was never a problem with skipping at 44, 88, 96, 176 or 192k, much of that in 5.1 Mch on my system. Ditto also for stereo at DSD, 2x DSD or 352k DXD sampling rates. I have also pumped Blu-Ray HD video/hi rez audio through a throwaway USB cable with no problems whatsoever.

It appears to me that reviewers and many computer audiophiles are either having apparent USB problems because of other system issues, or else they just want to create and perpetuate some myth about USB deficiencies. USB works great for me. My system is at its highest level ever sonically by quite a bit using USB to my DAC.

Also, based on JA's measurements, I have no plans for a Jitterbug, or multiple ones as some recommend. I just do not trust mere testimony about subjective improvements, even by JA, in sighted listening "tests".

I also have a major ethical problem with AQ and others in the cable or tweaks business for not providing their own evidence via measurements or controlled listening tests as to exactly what performance issues they are supposed to improve. I avoid all of them for that reason. "Extraordinary claims require extraordinary proof", in my book, even for a $50 device.
 

jkeny

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It is (relatively) easy to simulate that with extra long cables. Or less than optimal USB host implementations.
That was not what I was specifically asking but yet your answer means that you will have to characterise the USB signal as having SI problems - can you do this - can you do USB eye diagrams?
What I was really asking was, what dynamic signal are you going to use that will allow you to use a notch filter to remove it on the analogue output so that you can examine the noise floor?


For this analysis I will try to instrument the USB bus. But for my prior work, all I care about is what comes out of my DAC and USB adapter, and there, as I mentioned, down to -130 dbFS or so, I don't see such noises. Has anyone else measured otherwise on a high performance DAC? I am not saying it doesn't exist but I have only seen USB dependent noise in cheap sync DACs.
The theory (& measurements show) that the USB protocol running at high speed (125us microframes) has a resultant 8Khz noise spike as a direct result & easily seen on the analogue output. However if you first use a USB converter & output balanced AES/EBU to your DAC, this arrangement may well suppress such common mode noise?

I don't know how to resolve that puzzle, nor will I try. :) I just like to characterize what the devices do or don't from design perspective. There seem to be different approaches with one using a USB hub and the other, analog filtering. There will be differences there of value for some people to know.
Well, characterising a device is a different issue than running some measurements on it which may or may not be different to the same measurements run on another device


Just want to be clear that while I will be also testing using typical audio measurements, my goal is a circuit analysis at USB level. For sure you can't try to correlate those directly with audibility because what the DAC does with what comes out or doesn't come out of these devices is an unknown.
As I said, the proposed explanation for what the Regen does is to reduce noise in the PDN (power delivery network) that arises when the USB PHY has to deal with USB signals with lower SI. Given this, logic dictates that this will not be a fixed noise level but will fluctuate in the presence of variable USB signal SI.

Again, I believe that "good" measurements are premised on proving/disproving an hypothesis about the operation of a device & using measurements that shine a focussed light on the measurable implications derived from such an hypothesis, rather than using more general measurements that might just shine a diffuse light on the device with the hope of picking up some clues.

In terms of the Jitterbug, it seems clear that it is comprised of inductors which act as low pass filters & when plugged into a USB port act as a suppressor of some of the RF/HF noise on the USB pdn
 

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