you need to remember when you run a loop back you are using both DAC and
ADC. One can be better than the other. Years ago when I discovered RMAA
I started to do measurements at home with M-Audio Transit sound card. My
DAC always produced better numbers then what I was getting with loop
back.
A few screenshots using AP2722 and looking at analog output (XLR).
J-test 16bit 44.1kHz played in all cases.
http://imageshack.us/f/838/transporteranalogjitter.jpg/
Streaming wave file
http://imageshack.us/f/28/transporteranalogjitter.jpg/
RCA input AP2722 source
Archimago wrote:
Thanks! Very nice... Looks like I should see an improvement switching
over from TosLink -- AES/EBU for the digital loop!
That's a huge variability in the TosLink cables - wow! Was this related
to length? Brand name cables?
Do you mind if I add your data to my blog
I corrected my post with measurements for toslink connections. Measured
values are in ns not ps as stated before. 50Hz - 100kHz bandwidth.
I wouldn't rely on peak or average jitter measurements to make any
conclusions. Looking at the spectrum would be more instresting, but even
then I don't know
Archimago wrote:
Thanks tpaxadpom! Will update the blog with your data tonight.
Yeah, I've seen some roundish TosLink plugs which are symmetrical so
you can plug them in without a specific up or down orientation.
Here's the million dollar question - can you hear the degradation in
music
Archimago wrote:
Thanks for the note tpaxadpom! Hey, good luck with Monster Cables; make
sure you pay us a visit when you've made megabux on that patent and
installed kilobuck cables all the way through! :-)
Thank but I may want to hang out here for a little while, I have my
doubts :o.
BTW
Ok I have measured transporter and touch on AP2722. I've only looked at
digital out as promised.
Here is the run down:
Transporter:
AES/EBU 377.3-424.5 ps
SPDIF RCA 566 ps
SPDIF BNC 283-330.2 ps (rca cable with 2 bnc adapters yielded the same
results)
Toslink 1.462 - 4.103 ps depending on the
Archimago wrote:
Hi Mnyb. Yeah, it's hard to get a sense of what the limit of the ADC is
but I agree that the Transporter XLR is hitting the limits already... In
comparison to Stereophile's AP measurements, I suspect I'm maybe missing
the bottom most 3-4dB of what the Transporter is capable
You know I am the wrong guy to ask. I never processed this kind of PO. I
would imagine they are $35k+. BTW built-in signal generator isn't the
last word by any means. I've measured around 1ns of jitter using
toslink.
