[Petrasescu_Lucian]

Hello !
 
Do these 2 players support 22.05 kHz sample rates via SPDIF ?
 
I know that "officially" they support from 32 to 96 kHz (DacMagic) and 192 kHz (840c), but I've seen DACs that can play just fine such streaming signals eventhough they report they can't get a lock on the incoming SPDIF rate !!!
 
Can anyone please test this and reply ?
 
I have my reasons why I ask this as resampling signals at different rates to a single one such as 44.1 kHz has not been very good (quality wise) in my mixing projects...
 
Thank you !

 

[Petrasescu_Lucian]

Nobody ?

 

[audiofil]

Why on earth would you use 22.05 Khz in the first place?

 

[IPodPJ]

Quote:

Why on earth would you use 22.05 Khz in the first place?

Agreed.  It doesn't seem to make much sense.

 

[Petrasescu_Lucian]

I work with all kinds of material for doing all kinds of TV spots, editing, mixing...etc...but the reason why I use it is quite irelevant to my question in the first place...

 

[audiofil]

The fact that no SPDIF (or even USB) receiver is specified below 32KHz should have been reason enough to question yourself if 20.05Khz is a practical solution.
I think the problem is clocking the signal below the specified 32Khz.
An out of sync stream is no use to a professional.
Nor is a sampling rate lower than what the Nyquist sampling theorem suggests.
 
 
Quote:

I have my reasons why I ask this as resampling signals at different rates to a single one such as 44.1 kHz has not been very good (quality wise) in my mixing projects...

I don't think anybody understood what you want to say here.

 

[Petrasescu_Lucian]

Wow...I guess these days is quite hard to get a simple answer for a simple question...
 
First of all you are mistaken, the AES/EBU standard is not "necesarily" limited downwards to 32 kHz:
 
Digital Audio
Maximum Word Width: 24 bits.
Digital Input Format: S/PDIF coaxial, 0.5V to 5V peak-to-peak.
Digital Input Sample Rate: 8kHz to 96kHz.
Digital Output Format: S/PDIF coaxial, 0.5V peak-to-peak;
AES/EBU data stream over S/PDIF coaxial.
Digital Output Sample Rate: 8kHz to 96kHz.
Connectors: Gold-plated RCA, female, on break-out cable.
 
The above text is taken from M-Audio Audiophile 2496 manual, a card which I own and can confirm is working properly...except for the latest driver which "limits" the AES input-output signal to 22.05 kHz.
 
I've even seen some comercial DACs that can accept and play just fine 8kHz even if the "lock" led doesn't come on...you must understand that the "lock" indicator only comes on if the device can properly interpret the embedded flags in the incoming audio data stream and it's not necesarily "a must" for the audio to be played corectly...and is more of a software bug than anything else !
 
Secondly:
"Nor is a sampling rate lower than what the Nyquist sampling theorem suggests."
 
What is the Nyquist-Shannon sampling theorem ?
 
A digitized analogue signal can be completely reconstructed from its samples if the sampling rate is or excedes 2N samples per second, where N is the Nyquist frequency or the highest frequency of the original analogue signal that was digitized...In short the Nyquist freq is always half the sampling rate in a properly recorded signal...11025 Hz for a 22.05 kHz sample rate, 16kHz for a 32 kHz signal etc...
 
Thirdly: 
 
Probably you didn't understood my words...What I meant is I hate to upsample a lower rate to a higher sampling rate that is "comonly" supported by normal DACs such as 44.1 kHz as upsampling introduces errors in the signal no matter how good the upsampler is, so...it's DEFINITELY better to use a DAC that can sync on the incoming signal no matter how low the sampling rate is...
 
Fourthly:
 
I submit you don't own one of these players from Cambridge.
Please reply if you can confirm (by testing) if DAC Magic, 740c or 840c can or cannot accept and play back correctly a digital stream of 22.05 kHz.
 
Thank you !

 

[audiofil]

I wasn't talking about interface.
 
Quote:

The fact that no SPDIF (or even USB) receiver is specified below 32KHz should have been reason enough to question yourself if 20.05Khz is a practical solution.

 

[Tomoyo]

I tried with DacMagic and the rates below 44.1khz did not work for me, but that is probably due to my SPDIF output since it only supports rates from 44.1khz to 192khz.

 

[Petrasescu_Lucian]

Thank you Tomoyo !
 
Frankly the first useful post so far !
 
I look forward to hearing from you if you can test the DacMagic with a different source in the future !
 
You can use almost any pro PC soundcard.
They normally output via SPDIF any sample rate that they are able to play internally with their converters (meaning as low as 8 kHz), plus you have the advantage of monitoring and manually setting the sampling rates from their control panels.
 
Cards like M-Audio, Lynx, RME, Echo Audio...etc work just fine !
 
Thank you !

 

[pictureguy]

22khz sampling frequency will probably produce sound better than an AM radio,  but certainly not 'high fidelity' or even as good as FM.
If I were doing documentary or simple radio work, such a low sampling rate would be fine.
 
Now, my 840c....and Yes, I do actually own one!  says 22 or 24 khz when I hook up my AE to one of the optical inputs.
I don't believe it is happy with the signal, though, since it periodically loses 'lock' and makes the most awful screeching / buzzing / fingers on a chalk board noise.
CA has sent me the software update which I am chicken to install.  With NO input from the AE, the CA's panel says.....'unlocked    24/384'
 
I'll try an input later, and see what the CA says.......
 
What does CA have to say?  They have some US tech guys who know there stuff and get back to you within 1 business day.....

 

[Petrasescu_Lucian]

Thanks pictureguy !
 
Have you tried an electrical connection ? I've seen several compatibility issues with optical SPDIF, that's why I believe electrical coaxial (unbalanced) and AES XLR (balanced) are regularly used in professional environments rather than optical.
 
When you input 22.05 and 24 kHz to the 840c, does it play the sound corectly when it's not losing its lock ?
 
If the sound is played corectly at the right tempo but it loses periodically its lock than there is a software bug with the player that needs to be fixed by Cambridge...see my explanation in one the above posts:
 
Quote:

I've even seen some comercial DACs that can accept and play just fine 8kHz even if the "lock" led doesn't come on...you must understand that the "lock" indicator only comes on if the device can properly interpret the embedded flags in the incoming audio data stream and it's not necesarily "a must" for the audio to be played corectly...and is more of a software bug than anything else
!

 
I'm curious...what is this software update that CA sent you ? Is it SPDIF related ?
How do you install it ? You burn a blank CD with this new "firmware" and then load it in the player which automatically updates itself ?
 
Thanks

 

[pictureguy]

I haven't fired up the AE and looked at the panel on the CA yet.
The update was (apparently) to fix the issue with the AE.  The AE has poor clock regulation or some such and the CA will not 'lock' (right word?) to the signal and will make an awful sort-of screech periodically.
To do the update you must unpack it....since it comes as a ZIP file.  There is an installer package, and some files and the all important PDF to tell you what to do.  The OTHER issue is that the CA player has ONLY a Serial Port!
This was obsolete in '08 or eve earlier....I'm certain that it was history when the player was released....'05 or '06???   Anyway, you need what is known as a 'Null Modem' cable.  You'll have to Google that one!  Pins are swapped around between ends of the cable, both ends of which are female.......
Unless you have this problem, I don't see a major need to do the update.  
Also, why didn't CA use a USB port?  I don't know if new computers even HAVE a serial port!

 

[Petrasescu_Lucian]

Hmm...I thought the Serial connector was there for external connection with HomeTheatre systems or some kind of synchronization with monitor equipment but I've never tried it as I think it's useless...
 
Anyway, I look forward to hear your final conclusion regarding 22.05 kHz playback via SPDIF after you finish all your testing.
 
Also try using a sound card that has a RCA (electrical) SPDIF output and feed a 22 kHz signal and see what happens.
 
Best regards,
Lucian

 

[pictureguy]

Sorry, guy.  I'm a MAC user and have given up the chase for sound / video cards, drivers and 'tricks' to get stuff to work.  I built several computers over the years and am one of the go-to guys for low-level fixes in my neighborhood.  
Heck, I even had problems with my printer not producing output to match my calibrated monitor.  Epson drivers, even the latest are junk.  I went and installed 'Gutenprint' and the problem simply went away and I have the best printer output I've ever had.   And this is with a cost-no-object 100$ printer.  
 
As near as I can tell, I don't have a 22khz source for anything.  Can a PC sound card output such a signal?   I just need to fire up the CA and AE to see how the CA reads the Airport's output.