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MDAC First Listen (Part 00101010)

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To me its does not matter if its "typical" or not as no one can say what the quality of the USB ports are like on MDAC / FDAC owners PC's etc. - that's why I don't feel bad about designing the Detox as it will "equalize" the USB signal quality.

Via the Detox, the FDAC / MDAC will be connected to a "known" USB signal source. As a HiFi designer you hope that owners of your product will get to hear your design as you intended / tuned them to sound during the development and final evaluation of the design - the Detox removes a small but unknown variable from the "system" equation.
 
ti33er said:
There is the new nc500 ...causing some commotion on the Vendors Bizarre on DIY Audio "nCore" thread - claim it may have the edge over the nc400

nc400 200/400/580w@20hm
nc500 400/700/550w@20hm

The ATSAH 500 is £1600-1700 a pair from UK Acoustic Imagery ...OEMs can build their own Input Buffer to create the signature they prefer with these new modules
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Yes there has been a lot of noise on that thread recently. Indeed the contributions have created a "confused and noisy disturbance". Going round in circles and adding very little.

The NAD M22s use the nc500 modules
The nc500 modules have more voltage output but the output currents, and therefore the low impedance drive and low impedance power, are pretty much the same.

If you think you want a different "sonic signature" then a different input buffer stage may provide it. But that assumes you do want a different sonic signature.

The individual expressing his preference for the nc500 modules seems to be running them (at 115db at 2.5m if I remember his measurements correctly) where he needs more than the 4ohm/8 ohm power available. Well if does, then he does. If you're running into electrostatic type loads (the MLs you've linked to) then there will be no power difference in practice. It's worth noting that the summits include their own bass power amps (2 x 200WW in each speaker), so whatever you use you're only driving the electrostatic panel.

BE718 said:
Oh bo******, what have I missed? I pushed the button on a pair of 400s last night! :D
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You've missed nothing so far. What speakers are you driving?
 
JohnW said:
To me its does not matter if its "typical" or not as no one can say what the quality of the USB port are like
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Exactly

You want to know that a filter is effective with the poorest sources. With a benign source there's probably no need to have a filter.
 
JohnW said:
To me its does not matter if its "typical" or not as no one can say what the quality of the USB ports are like on MDAC / FDAC owners PC's etc. - that's why I don't feel bad about designing the Detox as it will "equalize" the USB signal quality.

Via the Detox, the FDAC / MDAC will be connected to a "known" USB signal source. As a HiFi designer you hope that owners of your product will get to hear your design as you intended / tuned them to sound during the development and final evaluation of the design - the Detox removes a small but unknown variable from the "system" equation.
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Sure, I understand your logic as regards the Detox but I'm also interested in the cleansing of the "typical" USB signal that the Regen performs in order to put it into some sort of context! If that measured USB signal is an outlier it would make some difference to what the Detox or Regen is improving. If it's pretty much the same signal integrity as typically found on PCs then we have some measure of what's there normally on the USB signal & what can be cleaned up
 
jkeny said:
Sure, I understand your logic as regards the Detox but I'm also interested in the cleansing of the "typical" USB signal that the Regen performs in order to put it into some sort of context! If that measured USB signal is an outlier it would make some difference to what the Detox or Regen is improving. If it's pretty much the same signal integrity as typically found on PCs then we have some measure of what's there normally on the USB signal & what can be cleaned up
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I'm not sure it's within john's remit to do that sort of analysis for the world at large. I think someone else should take up the mantle of determining what is "normal" "typical" "not uncommon" etc.

I haven't looked at the wbf thread for several days, but on a superficial skim when I last looked, I'm not sure that it was quite understood what John's traces were showing and that it wasn't a single "snapshot" eye pattern as most seem to be
 
ChrisPa said:
I'm not sure it's within john's remit to do that sort of analysis for the world at large. I think someone else should take up the mantle of determining what is "normal" "typical" "not uncommon" etc.
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He seems to have a great deal of experience with USB & just wondered how this fit into his experience - a outlier or typical, is all?

I haven't looked at the wbf thread for several days, but on a superficial skim when I last looked, I'm not sure that it was quite understood what John's traces were showing and that it wasn't a single "snapshot" eye pattern as most seem to be
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No eye pattern is a "single shot" by definition - John's is not that different to most - he may have done more sweeps on a finer timebase but in essence, it's the same as other eye patterns measurements, unless I'm missing something.
 
jkeny said:
Sure, I understand your logic as regards the Detox but I'm also interested in the cleansing of the "typical" USB signal that the Regen performs in order to put it into some sort of context! If that measured USB signal is an outlier it would make some difference to what the Detox or Regen is improving. If it's pretty much the same signal integrity as typically found on PCs then we have some measure of what's there normally on the USB signal & what can be cleaned up
Click to expand...

Maybe someone like Samsung, Sony or Cisco Systems would have the resources to provide such information.

Perhaps you could approach them and ask if they would be interested in doing the necessary thousands of tests to provide such an average.

I have been in one of Cisco's buildings and seen the amount of hardware they have racked up to test for compatibility issues. They have many hundreds of buildings.

It seems to me that everyone wants some of Johns time and expertise, with little regard for how much time he has to spend reading and responding to their own personal issues.

Then people question production time slippage........
 
I used colour grading in an attempt to capture the low occurrence events... These events seem heavily influenced by the operating system / processor load...
 
JohnW said:
I used colour grading in an attempt to capture the low occurrence events... These events seem heavily influenced by the operating system / processor load...
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Yes, I understand this - a good idea & that is probably what is missing from other eye pattern plots?

Any idea why the USB 125uS microframe timing which shows up on FFT as 8KHz & harmonics spikes when the Regen is in-line, isn't evident when Regen is removed? The USB protocol is still the same with the same microframe timing.
 
JohnW said:
Mike,

I'm working on the projects 14 to 16 hours a day and I'm as keen as anyone to see them completed so I can move on... It did feel good to be in HK recently to discuss the start of the production process as I can finally see the light at the end of the tunnel :)

Seeing the mechanical design of the VFET / FDAC and now having a partner factory who can support the production is also a huge relief :)
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Hi John,

Really appreciate all your hard work to give us the best you can. I am sure most if not all here feel the same way.

Cheers!
 
I suspect its a measurement error - possibly that the HOST USB computer used is also the measurement computer - so some weird "loop" via the Regens SMPS PSU.... Its not for the faint of heart to be making measurements at -150dB and below...

Or maybe its connected with the fact that the guys at ReGen inserted resistors in the outer USB cables screen... Its not something I'm concerned about as IF they exist then its specific to the ReGen design.

I've not noticed spurie here (I've not looked for them) - I don't believe its a fundamental issue with a USB Hub...

Edit:-

Thinking about the issue a liitle more, the 8KHz PSU spuire prodcuts I measured on the PCB is not a good sign and would be the most likely culprit - but its not for me to "comment" on a 3rd parties design especially when I'm designing a similar product.
 
misterdog said:
Maybe someone like Samsung, Sony or Cisco Systems would have the resources to provide such information.

Perhaps you could approach them and ask if they would be interested in doing the necessary thousands of tests to provide such an average.

I have been in one of Cisco's buildings and seen the amount of hardware they have racked up to test for compatibility issues. They have many hundreds of buildings.

It seems to me that everyone wants some of Johns time and expertise, with little regard for how much time he has to spend reading and responding to their own personal issues.

Then people question production time slippage........
Click to expand...

Great point, I hope people here appreciate this.

I would suggest that at least the ReGen/USB is discussed at WBF and avoided here unless some earth-shattering discovery is made there.
 
JohnW said:
I suspect its a measurement error - possibly that the HOST USB computer used is also the measurement computer - so some weird "loop" via the Regens SMPS PSU.... Its not for the faint of heart to be making measurements at -150dB and below...

Or maybe its connected with the fact that the guys at ReGen inserted resistors in the outer USB cables screen... Its not something I'm concerned about as IF they exist then its specific to the ReGen design.

I've not noticed spurie here (I've not looked for them) - I don't believe its a fundamental issue with a USB Hub...
Click to expand...

I remember you showed these 8KHz spuria on your measurement of ground noise on the output of the Regen when powered by SMPS & by Linear PS.

I thought it was inherent to the Regen & not the PS but as you say may be something to do with resistors in USB cable screen inside the Regen?
 
Purite Audio said:
As a matter of interest when did the original project begin?
Keith.
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According to Wiki ''The project has been officially kicked off on September 5th, 2013''

So about 2 years.... it has expanded quite a bit from where it started...from my point of view the promised end-product will be so much better (with DSP, HQ-Linear-PSU, CD-transport to mention just a few extra dimensions). John should be doing listening tests around xmas I expect.:D
 
timola said:
According to Wiki ''The project has been officially kicked off on September 5th, 2013''

So about 2 years.... it has expanded quite a bit from where it started...from my point of view the promised end-product will be so much better (with DSP, HQ-Linear-PSU, CD-transport to mention just a few extra dimensions). John should be doing listening tests around xmas I expect.:D
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Actually, there were some talks and plans before, it just wasn't materialized very well.

Here's my email to Nick @ hificollective (where we ordered the vishay resistors for "toy" / "fusion" upgrade back when a new PCB wasn't really planned) - I'm proud of the hindsight. :)

(yes, that's 10th of July)
On 07/10/13 15:02, hificollective wrote:

Hi Nick,

> > We can send the TOY kit to John for the upgrade and send the other
> > resistors of the Fusion kit when they arrive with us.
> >
> > or
> >
> > We can send the TOY kit to John for the upgrade and refund the
> > difference. Allowing you to repurchase when the full resistor sets
> > are in stock. I look forward to hearing from you.

Please change my order to "TOY" and refund the difference.

As the new PCB is still months away, my guts tell me that a change
in the "Fusion" version (its components) is possible in the meantime,
as the development progresses.

I plan to order the full "Fusion" kit when the new PCB is ready.

> > Kind regards, Nick
> >

Thank you for the care.

Sincerely,
Jiri
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Oh yeah, "months away" was a poor estimate. :)
 
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