I just fooled around with a Digidesign 192 I/O today, and I experienced
something strange: Without SRC enabled on the digital inputs, the ANALOG
inputs (1-8) sounded different!! Or should I dare to say - better

Is there an explanation for this? Does it make sense?
Some serial mojo going on between 1-8 and 9-16?


I am definetly going mad, I know. Just wanted to make sure..


ruudman

For the record: by src I mean sample rate conversion (realtime option on 192I/O)
Clocking is external.

ruudman

ummm, intresting.. i won't be able to test this unitl next week. we just got a hd3 with 192i/o's...

Yeah, please let me know what you find out.. thumbsup

ruudman

more info on this topic would be great

Divine, any impressions?


ruudman

well... its hard to say. the pt system sounds that much better than my old m-audio/nuendo setup.
without the src.. it seems as if the the analongs ins have a little more air to them and perhaps a little more headroom when recording at 24/96 or higher.

i have sync i/o...
i don't think your trippin or going crazy... but i'm not sure what it really is either... i have to go to atlanta pro audio on monday.. i can run this by my guys down there... i only hear a slight difference at at 24/96 or higher at 24/48 i don't hear a difference.. do you

I've noticed the same with O2R 96...
but not that important in live situation, I guess
In the studio I would let the SRC off

M.

Yes, I often use 24/48, BB sync.
I hear a difference, and over the last weeks I've gotten
even more sure.

Please let me know if you get some answers.
Thanks


ruudman

But SRC is not activated for my analog in's, still they get affected
when SRC is only used on the digital in's.
Analog 1-8, digital 9-16, external sync.
My interface up/downsamples the incoming digital signal, and leaves analog alone.
Only but it doesn't...

ruudman

This maybe a question you want to post on the Digi User Conference(DUC) if you haven't already. I did a quick search there but nothing came up. I'll do a test myself later on today and post what I find.

I've posted on DUC also..
only one answer, and he misunderstood the question..

Indeed a sleeper topic, but I bump for justice

But if you find anything related, please post thumbsup

ruudman

http://duc.digidesign.com/showflat.p...=&sb=5&o=&vc=1

Thanks largeunit!

But still it's a mystery for me that the analog section 1-8 gets affected when
using SRC for digital input 9-16, even if the whole studio runs at 24/48 and
no conversion is needed.

Conclusion: SRC affects the interface as a whole, and Digi users should bear
that in mind by switching it off when not needed. It is on at Digi's
standard stetup.

ruudman

Thanks largeunit. Ruudman, where is your post in the DUC?

I suppose that I'm gonna ignite a flame-fest with this but I know that quite a few high end hifi mfgrs (Linn, Naim, Resolution and Arcam, to mention a few that I know of) allow the user to shut off the display (usually LED) since it can spew noise into the signal path because of it's proximity. I would imagine that it's possible that any electronic activity could do the same. (If that's indeed what you mean; that a 'supposedly' unrelated function could affect the analog inputs.)

Thing is, I don't know if it's unrelated.
But I find no info about it in the manual, or on DUC's answerbase.
The manual only links the SRC function to the digital section of the 192 interface

I actually believe the opposite: SRC is activated = all 16 channels get reclocked.
It's a difference, not just hi-fi mambo jambo


ruudman

Hi Ruudman,

I've got a HD rig here and I will try to get some tests done to prove or disprove your theory. I will play a cd from my marantz deck through a DAC1 for DA and record the result into Pro Tools once with the SRC enabled and once without.

DO you think this will reveal the problem/difference? The CD player/DAC-1 combo is my only high quality repeatable analog source. I will try and get this done tomorrow - more soon....

cheers,
Ruairi

Good idea, Ruari thumbsup

One thing I'm not sure of, though:
in order to get SRC to operate (activate, that is), there may have to be some sort of
digital connection in addition to analog. Some kind of input sensing.
- I don't know..

But test it and see if it makes a difference, and please let us know.

ruudman

Ruudman, I did a test at both 44.1kHz and 96kHz with repeatable audio, DAT machine analog out, into channel 1-2 of the 192. One pass with SRC on and one off. I can't tell the difference when A/B-ing between the two. Though when playing back both tracks at once and phase reverse on one and time adjusting, there seems to be subtle differences, as it doesn't cancel it out completely. By all means I'm no expert at this but this is what I found.

Now that's interesting!
Thanks for checking things out

ruudman

Do a null test a see what happens SRC here make difference at all. I have never tested it since 5.3.1 so that's all i can say about it.