• Arman
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Topic: Incoming 88.2 ADAT signal shows up as 44.1

I'm trying to sync a TC Impact Twin to my RME Babyface via optical In/Out.  I have the Babyface set to "Internal" clock and 88.2, and the Impact Twin is set to ADAT sync source, and 88.2.  The Impact Twin says it is locked to an external source with a sample rate of 88.2 (good).

Problems=

1) The "Clock Master" setting on the Impact Twin won't let me select the Babyface as the master.  It only shows the "Impact Twin" as an option.  The Impact Twin displays a green "M" ... as if it thinks it is the master.
2) The Babyface says the clock source is verified as internal, but it says the ADAT sync is only running at 44.1.
3) If I crank the Impact Twin up to 176.4, the Babyface says the incoming ADAT stream is 88.2.

It seems as if the Impact Twin is halving the sample rate on ADAT output or the Babyface is cutting it in half.

Ultimately, I would like to use the Impact Twin in stand alone mode as an AD into the Babyface (adding more inputs).  The Twin can be set to run in standalone mode.

Any suggestions?

  • Arman
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Re: Incoming 88.2 ADAT signal shows up as 44.1

Anybody??

  • Arman
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Re: Incoming 88.2 ADAT signal shows up as 44.1

FOLLOW UP:

Is it possible that the 88.2 ADAT (SMUX) signal being sent from the the TC interface to the Babyface is only being reported as 44.1 because it is SMUX?  The spec for SMUX says that it is actually sending the streams for a single channel down two lines ... so a 88.2 signal SMUXed through ADAT is actually 2x 44.1 signals.  Is the Babyface just letting me know that the signal is 44.1 before it is reassembled as an 88.2 stream?

  • Jeff
  • Jeff
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Re: Incoming 88.2 ADAT signal shows up as 44.1

Yes, exactly. But there is still something wrong if the TC unit and the UFX both think they are the master clock.

Regards,
Jeff Petersen
Synthax Inc.

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  • Arman
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Re: Incoming 88.2 ADAT signal shows up as 44.1

Thanks Jeff.  So the Babyface is reporting the sample rate BEFORE de-SMUXing.  Okay ... that's a little disconcerting.  I wonder if they can change that in the driver so people know what is actually being piped to the DAW?

It is confusing to me that the Babyface says "Internal clock" and the TC says "Master".  I don't think the Babyface can run as slave.  You can set it to "Internal" or "Optical".  I have the Babyface set to internal and the TC set to ADAT.  The Babyface says that it is synced internally and the TC says that it is locked externally but is still the master.

huh.

6 Reply by MC

  • MC
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Re: Incoming 88.2 ADAT signal shows up as 44.1

How can the BF know 88.2 is coming in when it is a 44.1 signal?

Regards
Matthias Carstens
RME

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7 Reply by Arman (edited by Arman 2011-09-15 22:15:57)

  • Arman
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Re: Incoming 88.2 ADAT signal shows up as 44.1

Well .... the TC is set to send an 88.2 signal through ADAT to the Babyface.  The Babyface is saying that it is getting a 44.1 signal.  It may be receiving an 88.2 signal SMUXed into 44.1 for transmission ... but the Babyface should tell me that signal is meant to be 88.2.  When I read in the driver that the BF is receiving a 44.1 I think that is what is being passed on to the DAW.  That isn't what I want.

I'm just suggesting that if the driver reports the ADAT signal BEFORE it gets de-SMUXed, it is a little misleading to the user.  I want it to say "ADAT 88.2" if that is what is being sent from the other end.  I'm not exactly sure that this is what is happening in my case.  I'll try the BF out with another ADAT interface running at 88.2 and see what the driver tells me.

EDIT:

Also ... if I set the TC interface to 176.4, the Babyface reports 88.2 (essentially the rate before SMUX).

8 Reply by MC

  • MC
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Re: Incoming 88.2 ADAT signal shows up as 44.1

ADAT has an half-official way to signal SMUX (Double Speed). That is correctly implemented in the Status display of the Babyface. But the state is not used to automatically switch the sample rate, because half of the industry has implemented that status indication either wrong or uses very old Alesis chips that had that state as default for single speed operation (means wrong indication).

> if I set the TC interface to 176.4, the Babyface reports 88.2

QED.

Regards
Matthias Carstens
RME

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9 Reply by Arman (edited by Arman 2011-09-16 17:31:57)

  • Arman
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Re: Incoming 88.2 ADAT signal shows up as 44.1

So in this case:
http://www.armanbohn.com/882441.jpg

The TC is set to send the Babyface an 88.2 signal, but the Babyface says "44.1".

MC: Am I getting a 88.2 signal to my DAW through the Babyface?  Is it just telling me that the raw signal is 44.1 and then SMUXing?

In this case:
http://www.armanbohn.com/176482.jpg

The TC is set to send a 176.4 signal and the Babyface says "SPDIF LOCK".  I realize there is a sample rate mismatch ... but The Babyface says it is receiving 88.2 and that is what I want to record.  Why does it say SPDIF if everything is set to ADAT (probably just an artifact of the sample rate mismatch)?  I realize that the ADAT spec doesn't really go over 48 but ???

10 Reply by MC

  • MC
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Re: Incoming 88.2 ADAT signal shows up as 44.1

Your setup 2 is invalid.

- Babyface is set to send 88.2 kHz.
- The Impact Twin is set to be slave to the BF, but to work at 176.4 kHz. How should that work?
- Its output signal therefore is a distorted mess, which the BF interprets as broken SPDIF signal.

Not sure why you waste your time with this. Use the setup in pic one and everything is ok...

Regards
Matthias Carstens
RME

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  • Arman
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Re: Incoming 88.2 ADAT signal shows up as 44.1

The second setup is an experiment to see how changing the sample rate setting on the Impact Twin would influence the the Input Status on the Babyface.  Garbled mess ... I get it. 

With the first setup, the Babyface creates the appropriate number of channels in Total Mix and from your statement I will assume that it is de-SMUXing the reported 44.1 signal into 88.2.  I just wish there was some kind of indication that this is happening.  I guess when the ADAT input track count gets halved, that is the indication.