misterdog
Not the canine kind
Who said anything about focusing purely on CPU speed?
My wrong, all digital is based on 0/1 so all must be equal, and perfect.
Who said anything about focusing purely on CPU speed?
Yes. It was perhaps underpowered but not anymore.
OTOH I also tried an overpowered i7 with pretty dismal results.
I think Keith misses a lot in most things he talks about not only the fine details unfortunately.
I do think you are the one missing the fine details.
I never said it was because of faster or slower CPUs.
Simply that a PC with a fast CPU can have pretty dismal results and one with a slow CPU can work very well if its OS is properly tweaked.
OK, as I expected the USB HUB does "repackage" the data and remove huge amount of the Host PC's USB Packet jitter - I can no longer see the vast amount of Process related jitter on the scope, its all much cleaner.
The edges of the waveforms still display a "Fuzzyness" which is indicative of jitter - but atleast its not an unholy mess of the direct PC connection.
I see the Regens biggest advantage is removing a lot of the "differences is sound quality" between software players and computers (With Bit Accurate Data).
I'll now have to use a more advance test step up to analyse the jitter as now the jitter is at a more acceptable level - I was worried with my first tests (USB Direct to the PC) as it was such a mess.
Hi John do you plan to continue with the MDAC mix of both XLR and RCA output connectivity? Ive found it useful, though I do appreciate that converter cables are available
Can you explain the process - does the decoded audio data end up in a buffer and clocked out locally? So is the USB packet jitter causing effects through modulating supplies, ground planes etc?
OK, as I expected the USB HUB does "repackage" the data and remove huge amount of the Host PC's USB Packet jitter - I can no longer see the vast amount of Process related jitter on the scope, its all much cleaner.
The edges of the waveforms still display a "Fuzzyness" which is indicative of jitter - but atleast its not an unholy mess of the direct PC connection.
I see the Regens biggest advantage is removing a lot of the "differences is sound quality" between software players and computers (With Bit Accurate Data).
I'll now have to use a more advance test step up to analyse the jitter as now the jitter is at a more acceptable level - I was worried with my first tests (USB Direct to the PC) as it was such a mess.
The Analogue scope measurements of the USB direct and ReGen USB revealed the truly "horrid" nature of the USB traffic from a PC with heavy "CPU Process" jitter modulation - and I've been trying to think how to graphically capture it so I can post it here on PFM.
So I dug up a Digital scope - rearranged the lab to make space for it... I think its the first time I've really used it - I hate them, but it proved useful to capture the data.
https://dl.dropboxusercontent.com/u/86116171/direct usb.jpg
Above is a colour graded eye pattern of the Direct PC USB connection to an XMOS based DAC (streaming 1KHz, 0dB FS) High speed USB.
Note the multitude of lines, but more importantly that the background is not black (Black means no data points fell in this area) - the background its dark blue because during the acquisition low frequency "Runt" waveforms where sampled in this area - these "Runt"waveforms occurred as the PC / operating system processed other applications / Operating system house keeping tasks etc. On the Analogue scope it was a horrific mess...
https://dl.dropboxusercontent.com/u/86116171/regen usb.jpg
Now with the ReGen USB Data, notice not only the much cleaner waveform but far more importantly that there is very little "Runt" data - the background is Black. The USB Hub IC in the Regen has for the most part cleanly repackaged the data.
The colour grade data sample hit size is the same for both plots (20K Hits on the Red).
hmmmm isn't it time that someone invented something revolutionary with all these sub-optimal data transfer mediums that we use - perhaps a true TxRx fibre optical connection port for audio equipment, that isolate electronics by default and are incredibly accurate?
'Someone' please invent a new Industry standard ...come on Mr John, I am sure there are a number of us that would back you...after the FDAC and VFET before I get shot!!! ;-)
John -thanks this is very interesting.The Analogue scope measurements of the USB direct and ReGen USB revealed the truly "horrid" nature of the USB traffic from a PC with heavy "CPU Process" jitter modulation - and I've been trying to think how to graphically capture it so I can post it here on PFM.
So I dug up a Digital scope - rearranged the lab to make space for it... I think its the first time I've really used it - I hate them, but it proved useful to capture the data.
https://dl.dropboxusercontent.com/u/86116171/direct usb.jpg
Above is a colour graded eye pattern of the Direct PC USB connection to an XMOS based DAC (streaming 1KHz, 0dB FS) High speed USB.
Note the multitude of lines, but more importantly that the background is not black (Black means no data points fell in this area) - the background its dark blue because during the acquisition low frequency "Runt" waveforms where sampled in this area - these "Runt"waveforms occurred as the PC / operating system processed other applications / Operating system house keeping tasks etc. On the Analogue scope it was a horrific mess...
https://dl.dropboxusercontent.com/u/86116171/regen usb.jpg
Now with the ReGen USB Data, notice not only the much cleaner waveform but far more importantly that there is very little "Runt" data - the background is Black. The USB Hub IC in the Regen has for the most part cleanly repackaged the data.
The colour grade data sample hit size is the same for both plots (20K Hits on the Red).
I don't want to seem pedantic but it does not show that - it shows that it does something to the signal which carries the data. I would expect that (to some extent) of any change of transmitter. It's true though that the change seems to be beneficial (unlike that on the jitterbug measurement from Paul Miller) in a general way. It also looks like a big change I agree.John,
You don't say anything about PS, so I assume this is with the SMPS, and I'm quite anxious to see what comes from using a linear supply. Nevertheless this is a clear demonstration, probably the first one, that the Regen really does do something measurable to the data.
I agree entirely- very sloppy language on my part. However, it is of course the signal, not the data, which the DAC has to struggle with.I don't want to seem pedantic but it does not show that - it shows that it does something to the signal
It is, but does it struggle? That's the point.I agree entirely- very sloppy language on my part. However, it is of course the signal, not the data, which the DAC has to struggle with.
Bob