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My Informal Jitter listening tests with a high jitter audio device...

post #1 of 20
Thread Starter 
Okay, this is hardly scientifically rigorous, but here goes. A while back I was discussing jitter and discovered the worst measured jitter for any audio device, it was for the Pansonic SL220 portable CD player with anti-shock enabled and it was measured at -38db. A good 70db worse than a half decent well anything modern really.

I have tried for several months to get one of this babies but to no avail. However I do have an old Technics SL-XP240 (Panasonic/Technics are just 2 labels of Matsush1ta) and the XP240 is , as far as I can tell (near) identical to the 220 , it is the same vintage i.e mid/late 1990s, it has the same anti-shock and the same specs viz noise and output level. Also after extensive searching it is clear that anti-shock on **any** portable leads to massive jitter sidebands. So while I cannot prove that my Technics is totally identical to the Panasonic I can totally guarantee that it's jitter figure will certainly be *no better than* - 55db i.e at least 65db worse than anything current, excepting the Oppo 970 of course (where the margin is a mere 35db) .

So I set my Technics up with Anti-shock enabled and also took a Wav of the same test track (Saint-Saens Piano Concerto No 1 Mvt 1) to be played back in FooBar (using an external soundcard TBAAM). I carefully set the volumes on the PC and CD player to the same and connected them to a switch box and synchronized the tracks. The amp was a Nikko TRM-210 and the headphones are AKG K240S.

I then did some non blind listening switching between the two, I did this several times. Frankly I could not tell them apart. By a bizarre coincidence I have two identical copies of the CD in question so I can also test the portable against a proper CD player this weekend.

Now I cannot of course say what the jitter levels on my Sound card are which makes conclusions tentative, what I can say is that through an external amp and decent headphones a portable CD player that has frankly apalling jitter figures is eminently listenable. If ps of jitter are really audible then this unit would be utterly unlistenable , not just meh. At the weekend I will wire it up to my proper headphone rig (M^3 and AT700s/HD580s) and see how it does...
post #2 of 20
Do you know how much jitter there is with an Optimus CD-3640?
post #3 of 20
Interesting indeed. Thanks for your impressions.
post #4 of 20
Thread Starter 
Quote:
Originally Posted by i_don't_know View Post
Do you know how much jitter there is with an Optimus CD-3640?
No, sorry, but I know how much there is on the related 3400, 404ps through analog out.

Are you sure you mean 3640 and not 3460 ? - the 3460 has the same specs as the 3400

The 3640 is a boombox
post #5 of 20
Quote:
Originally Posted by nick_charles View Post
No, sorry, but I know how much there is on the related 3400, 404ps through analog out.

Are you sure you mean 3640 and not 3460 ? - the 3460 has the same specs as the 3400

The 3640 is a boombox
I'm positive. It's a portable CD player from 1999 and it says right on it "CD-3640 PORTABLE COMPACT DISC PLAYER"

And is 404ps a lot?
post #6 of 20
Jitter in home audio components is at levels that are totally inaudible, IDK. It isn't anything to worry about.
post #7 of 20
Thread Starter 
Quote:
Originally Posted by i_don't_know View Post
I'm positive. It's a portable CD player from 1999 and it says right on it "CD-3640 PORTABLE COMPACT DISC PLAYER"

And is 404ps a lot?
My mistake, RS used the number 3640 for 2 different items

http://support.radioshack.com/suppor...oc61/61379.pdf

http://support.radioshack.com/suppor...oc63/63482.pdf


Quote:
And is 404ps a lot?
Yes and No. The Oppo 970 has jitter at ~4ns i.e 4000ps. Ojectively random jitter at 404ps lowers resolution in a 16 bit system to below 16 bits so instead of getting 96db you are getting more like 92 - 94db. Jittter as low level noise is reasonably unobtrusive, jitter can though appear as signal-correlated sidebands, this can be obtrusive if the bands are big enough, what marks the Pansonic out as notable is that it has sidebands that are just 38 db down on the music signal, this should be easily audible, however thanks to the miracle of masking it may not really be a big problem after all.

For reference the jitter on my DAC is about ~ 179ps and on my most modern CD player about 680ps.

Numerous attempts have been made to assess how easly people can hear different levels of jitter. Some people maintain that they can hear the difference between 50ps of jitter and 60ps of jitter, I am skeptical since no controlled test has shown the ability to detect jitter at less than 20ns in music.
post #8 of 20
Is there a portable CD player that exists that has either no jitter or a ridiculously low amount of jitter? With good SQ?
post #9 of 20
Thread Starter 
Quote:
Originally Posted by i_don't_know View Post
Is there a portable CD player that exists that has either no jitter or a ridiculously low amount of jitter? With good SQ?
No, if using ridiculously low as a criteria then no, if you mean inaudibly low then probably pretty much any modern machine *with anti-shock disabled* will clock in with levels of jitter that have never been shown to be audible in controlled testing ( ~ -88 to -110db).

For a really good read and details of controlled listening tests see

Theoretical and Audible Effects of Jitter on Digital Audio Quality
Eric Benjamin and Benjamin Gannon
AES Convention , 1998
post #10 of 20
IDK: What Nick is saying is that jitter doesn't matter. Any CD player you buy will have no jitter that you can possibly hear.
post #11 of 20
Okay, that's nice to know.

I still wish CD's had the dynamic range of vinyl, though. :\
post #12 of 20
Quote:
Originally Posted by i_don't_know View Post
Okay, that's nice to know.

I still wish CD's had the dynamic range of vinyl, though. :\
you could use the "vinylizer" plugin to add it in if you really want to degrade CD S/N to typical phonograph playback levels

"loudness war" signal compression is a production room choice, not a CD media limitation


"
Vinylizer: vinyl-disk emulation.




Vinylizer is a new plugin for ProStationAudio (any version) for creating vintage sounds by inserting disk artifacts (rumble and dust/scratches) in the signal flow. It features also pick-up head EQ presets.

"
post #13 of 20
Quote:
Originally Posted by i_don't_know View Post
Okay, that's nice to know.

I still wish CD's had the dynamic range of vinyl, though. :\
Unless I remember totally incorrectly, CDs have a larger possible dynamic range than vinyl. Problem is that CD releases are often compressed more than vinyl releases.
post #14 of 20
Quote:
Originally Posted by monolith View Post
Unless I remember totally incorrectly, CDs have a larger possible dynamic range than vinyl. Problem is that CD releases are often compressed more than vinyl releases.
That's what pisses me off. Stupid recording studios...
post #15 of 20
Thread Starter 
Quote:
Originally Posted by i_don't_know View Post
That's what pisses me off. Stupid recording studios...
If you want dynamic range then classical music is a better option lots of yummy dynamic range.

Final comment, wired the Technics up to the proper listening rig, wow what a difference a proper listening environment makes, it still sounds fine but now I can hear the drive noise in background

Comparisons vs my other CD players are a bit tricky, the output Line level on the Technics is only 700mV which means I have to keep adjusting the amp so I cannot make any definitive conclusions there...
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