radamel
Music Fiend
You were almost funny Keith. Wait... You were the one who talked about level matching digital transports, right?
It resulted in occasional buzz and or clicks. Could never understand why.
MDAC First Listen (Part 00101001)
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You were almost funny Keith. Wait... You were the one who talked about level matching digital transports, right?
It resulted in occasional buzz and or clicks. Could never understand why.
JohnW
pfm member
The Tek has "non visible" trigger jitter - not sure what ts rated, but when triggering on a clean clock - and using the delay time-base and viewing "further on in time" I've never seen any visible jitter,
You can clearly see discrete jumps in time as various windows are open and closed on the PC (and then some LF activity while I presume the OS is doing its house keeping tasks) - also the USB is very heavily modulated by the audio signal, as the frequency content of the audio signal changes, so does the Jitter eye pattern, Bass Frequency content is clearly viable - its a real mess....
There is a surprising amount of LF "Stuff" going on...
Purité Audio
Trade: Purite Audio
So , underpowered click and buzzed, overpowered clicked and buzzed, you need something just right, reminds me of something I used to read to the children....
Keith.
Keith.
radamel
Music Fiend
Not a great reader are you Keith?
Underpowered it seldom paused and clicked.
Overpowered it occasionally buzzed and clicked.
sq225917
Bit of this, bit of that
That is of course assuming that everything else in the computers was identical other than the faster/ slower CPU. Or are you pointlessly trying to make meaningful comparisons between only one single part in two completely different pc?
I don't think it's Keith who's missing the fine details, rather its you ignoring the two different t breeds of elephant in the room..
I don't think it's Keith who's missing the fine details, rather its you ignoring the two different t breeds of elephant in the room..
radamel
Music Fiend
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.
Ciunas Audio
Trade: Ciunas Audio
Good point but the Regen is using the USB2412 USB hub chip with an external USB clock feeding the Xtal_in pin (one pin further away from USB Data+ in pin) instead of a crystal with Xtal_in & Xtal_out - so I guess this obviates some of this? Of course this is all just what we see visible on the chip & not the routing of the chip's internal bond wires from these pins.
misterdog
Not the canine kind
Practically every Win PC has different hardware and software.
Therefore focusing purely on CPU speed is irrelevant unless you have 2 identical PC's but with differing CPU's.
The trick is to cleanse the crap before it enters the DAC.
radamel
Music Fiend
Who said anything about focusing purely on CPU speed?
JohnW
pfm member
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 in 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 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 in 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.
Yes that is exactly what I hope the Detox can do so that I don't have to use ££££ on a music server/streamer/bridge like Aurender or Aurelec Aries.
But instead can use something like a Intel NUC.
Then we can stop the endless discussion about CPU speed and software/windows tweaks
JohnW
pfm member
Yes that is exactly what I hope the Detox can do so that I don't have to use ££££ on a music server/streamer/bridge like Aurender or Aurelec Aries.
But instead can use something like a Intel NUC.
Then we can stop the endless discussion about CPU speed and software/windows tweaks
Rune,
This is exactly why I'm working on the Detox design
jamjar784
Heavy Up
John, that seems encouraging. If you listen to any of your favourite test tracks do you hear any benefit to SQ with the Regen and MDAC 1 or whatever you have available?
JohnW
pfm member
I've also got a "Jitter Bug" for test - but as far as I can tell (looking at the USB Eye pattern) it offers very little filtering on the USB datalines themselves - I suspect its more about filtering the USB power.
Can someone point me to the Paul Miller review as I seem to recall he measured risetimes around 15nS to 20nS which is very slow (must be USB 1.1) - maybe I'm recalling incorrectly...
Can someone point me to the Paul Miller review as I seem to recall he measured risetimes around 15nS to 20nS which is very slow (must be USB 1.1) - maybe I'm recalling incorrectly...
JohnW
pfm member
I'll have to setup a decent system with my ESL's when I'm ready for the listening tests
It well take a little time to get used to the new "System" setup in the lab
Ciunas Audio
Trade: Ciunas Audio
I believe there may well be a common mode filter on the D+/D- in the Jitterbug
I don't think Paul Miller's review is on-line but some graphs & data has been posted in forums http://www.whatsbestforum.com/showt...g-Measurements&p=336508&viewfull=1#post336508
This image is a composite overlay of the with/without eye pattern plots & yet the apparent "reduction" in jitter is stated to be from 22nS to 16nS - yes this was done with a USB device running at FS - the Audioquest Dragonfly (note this is also powered from Vbus). Also there is some speculation that PM reversed the jitter figures & that the jitterbug increased the jitter value as would seem to be correct from the plot & what looks like the action of a LPF
I don't think Paul Miller's review is on-line but some graphs & data has been posted in forums http://www.whatsbestforum.com/showt...g-Measurements&p=336508&viewfull=1#post336508
This image is a composite overlay of the with/without eye pattern plots & yet the apparent "reduction" in jitter is stated to be from 22nS to 16nS - yes this was done with a USB device running at FS - the Audioquest Dragonfly (note this is also powered from Vbus). Also there is some speculation that PM reversed the jitter figures & that the jitterbug increased the jitter value as would seem to be correct from the plot & what looks like the action of a LPF
jamjar784
Heavy Up
Someone has posted some screenshots from the article here http://www.whatsbestforum.com/showthread.php?18311-AQ-Jitterbug-Measurements/page20&
adamdea
You are not a sound quality evaluation device
the measuremnt is supposedly 14.77ns with jitterbug and 21.96 without
As you can see from those plots, which I referred to last week, the changes look more like a degradation (as you would expect from a low pass filter). The overlay which JK linked to shows it best. The supposedly improved risetime makes no sense other than as a technical measurement anomaly (at best). Pretty much what I expect from Paul Miller since he started printing rubbish about flac files being congested compared with WAV
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