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Blake

Paul's view on Cables, Audio Precision Analyzer, etc.

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Some may have already listened to this interview and I already posted it in another thread, but I personally found this to be a very interesting interview, worthy of its own thread.  For those interested in the objective/subjective/measurement discussions here on AS, I think it is definitely worth a listen.  I tend to stay out of these sorts of discussions and have no agenda in posting this.  Anyone can feel free to comment as they want.

 

I recommend listening to the whole interview if you have the time, its not just about usb cables. Personally, I think it gets more interesting later on in the interview.

 

https://darko.audio/2020/02/expert-opinion-paul-mcgowan-ps-audio/

 


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Interesting that you include the Audio Precision analyzer in the title of this thread. 

While it is a very nice general purpose unit, it is not well suited to measuring jitter in DACs. What’s that? Heresy!

If you look at the specifications for the ADC in the top-of-the-line APx555, you will see that its own jitter is 600 picoseconds!

So that will swamp the jitter details of a device under test—which might be in the range of 10s of picoseconds. O.o

 

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It is very hard to get 10ps jitter at a device pin and in the layouts I have seen RF techniques are not used and using an external clock and in device clock generation I would say is almost in achievable for commercial audio, and I thought phase related jitter was the new demon!🙂

Listened to quite a few of Paul's technical videos, he works and sells into the audiophile world so there is a bias....

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For jitter, wouldn't better results be obtained by measuring at the clock input to the DAC chip using a (ridiculously expensive) phase noise analyser? These specs for a Rohde & Schwarz instrument should be good enough for most DACs:

image.png.309688c41da2344d46efc5768bd24b6f.png

 

Such a measurement obviously won't take into account any degradation within the DAC chip, which I don't know how bad it might be. Then again, if it is too bad, all those fancy clocks won't be doing any good.

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14 hours ago, mansr said:

As a rule of thumb, if you're looking for the truth, you can take whatever Paul McGowan says and invert it.

is this an objective statement...?


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3 hours ago, mansr said:

For jitter, wouldn't better results be obtained by measuring at the clock input to the DAC chip using a (ridiculously expensive) phase noise analyser? These specs for a Rohde & Schwarz instrument should be good enough for most DACs:

 

The Microsemi units—based on John Miles original Timepod—have better performance for much less money.

133318-5125a-datasheet

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26 minutes ago, Superdad said:

 

The Microsemi units—based on John Miles original Timepod—have better performance for much less money.

133318-5125a-datasheet

 

Except that frequency range is from 1MHz up to 400 MHz...😉 (5125a)

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8 hours ago, Superdad said:

Interesting that you include the Audio Precision analyzer in the title of this thread. 

While it is a very nice general purpose unit, it is not well suited to measuring jitter in DACs. What’s that? Heresy!

If you look at the specifications for the ADC in the top-of-the-line APx555, you will see that its own jitter is 600 picoseconds!

So that will swamp the jitter details of a device under test—which might be in the range of 10s of picoseconds. O.o

 

 

Correct regarding specifications. BTW there are several methods for measuring lower jitter than own equipment, dual ADC + DSP is one of them. 😉

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1 hour ago, Arpiben said:

Except that frequency range is from 1MHz up to 400 MHz...😉 (5125a)

And they seem impossible to buy.

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1 hour ago, mansr said:

And they seem impossible to buy.

John Miles--developer of the original Timepod (upon which the Symmetricon/Microsemi units are based) and author of the terrific and open-source s/w for it--has gone to work for Jackson Labs. His joining them has resulted in the recent introduction of the PhaseStation: http://www.jackson-labs.com/index.php/products/phasestation_signal_source_analyzer, at a much more reasonable $13,460. 

We have been dreaming about getting one for a while, though it may wait a bit longer as we are about to buy a high-speed differential logic analyzer (about $4K with probe kits) for another project.

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11 minutes ago, Superdad said:

John Miles--developer of the original Timepod (upon which the Symmetricon/Microsemi units are based) and author of the terrific and open-source s/w for it--has gone to work for Jackson Labs. His joining them has resulted in the recent introduction of the PhaseStation: http://www.jackson-labs.com/index.php/products/phasestation_signal_source_analyzer, at a much more reasonable $13,460.

That amount of money for a device relying on proprietary software that may or may not work next year is not what I call reasonable.

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25 minutes ago, mansr said:

That amount of money for a device relying on proprietary software that may or may not work next year is not what I call reasonable.

 

How did you discern that the software may not work next year? Is this a subjective opinion?


 

 

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5 minutes ago, mansr said:

Windows updates occasionally break old software, especially device drivers. If the vendor, for whatever reason, stops supporting the product, it is only a matter of time before it breaks. Happens all the time.

 

So you are suggesting it's a calculated risk that you would personally prefer not to take. Do you know this vendor's track record, or are you, perhaps, overgeneralizing because you just don't like the price?


 

 

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20 hours ago, Blake said:

Some may have already listened to this interview and I already posted it in another thread, but I personally found this to be a very interesting interview, worthy of its own thread.  For those interested in the objective/subjective/measurement discussions here on AS, I think it is definitely worth a listen.  I tend to stay out of these sorts of discussions and have no agenda in posting this.  Anyone can feel free to comment as they want.

 

I recommend listening to the whole interview if you have the time, its not just about usb cables. Personally, I think it gets more interesting later on in the interview.

 

https://darko.audio/2020/02/expert-opinion-paul-mcgowan-ps-audio/

 


Blake good pointer. I really liked the interview, Thanks.


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1 hour ago, mansr said:

Windows updates occasionally break old software, especially device drivers. If the vendor, for whatever reason, stops supporting the product, it is only a matter of time before it breaks. Happens all the time.

 Including Wi Fi dongles.

I recently had to replace a Wi Fi dongle due to a Windows update, even though the S/W was the most recent version .


How a Digital Audio file sounds, or a Digital Video file looks, is governed to a large extent by the Power Supply area. All that Identical Checksums gives is the possibility of REGENERATING the file to close to that of the original file.

 

PROFILE UPDATED 26-12-2019

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1 hour ago, sandyk said:

 Including Wi Fi dongles.

I recently had to replace a Wi Fi dongle due to a Windows update, even though the S/W was the most recent version .

 

Oy... Don't get started on that. For the longest time I was getting customers to pay for the upgrade to Windows 10 Pro. The reason is in local policy editor I was able to disable 'Windows Consumer Experience' (i.e. Candy Crush Saga and games like that from the market place from showing up).

 

That was great for years. Then I start getting calls from pissed off business owners because one day games started showing up in the start menu.

 

I drill down to the policy and there's a nice note from M$ saying that you now need either Enterprise or Ultimate edition.

 

 

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@plissken you may want to try this.  The developer has done an incredible amount of work and it's free.

https://www.getblackbird.net/documentation/


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I agree, but loose track when he meanders off topic with his little anecdotes, I must make some notes next time.

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Just started listening, and got to the end of the first anecdote - as in, "What the F did you just do?!!" ... "Umm, changed the USB cable ..." ... couldn't get a better example of what real audio optimisation is all about, 😁.

 

Was the inserted cable, "fabulous" ... ? Nope - in fact it could be a pile of smelly poo, as far as its technical performance was concerned - what mattered is that its characteristics, in areas normally considered irrelevant, and therefore not "measured", were enough to counteract an area of weakness in the playback chain - it was a band aid to compensate for a lack of robustness in the underlying signal path.

 

Which seems almost impossible for most audiophiles to assimilate - so obsessed with Adding Goodness, that the time spent on thinking about Subtracting Badness is tiny in comparison - and hence the often huge struggles to "make the rig sound good!".


Frank

 

http://artofaudioconjuring.blogspot.com/

 

 

Ahhh, Mankind ... Porsche intellect, Trabant emotions ...

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