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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: Steve Alves on January 29, 2014, 12:01:42 PM

Title: Clock at 44.1 or 48??
Post by: Steve Alves on January 29, 2014, 12:01:42 PM
I am using a o1v96i and just purchased a Tascam SS-CDR200. I have the CDR200 connected to the 2TR Digital on the board in and out. Getting clock errors on the o1v96i using the o1v as the master set at 48. If I use the Tascam as master the system drops to 44.1

Any thoughts or experience with this?
Title: Re: Clock at 44.1 or 48??
Post by: Mac Kerr on January 29, 2014, 12:06:06 PM
I am using a o1v96i and just purchased a Tascam SS-CDR200. I have the CDR200 connected to the 2TR Digital on the board in and out. Getting clock errors on the o1v96i using the o1v as the master set at 48. If I use the Tascam as master the system drops to 44.1

Any thoughts or experience with this?

The Tascam is a CD player, it only clocks at 44.1. If it is the master the whole system will be at 44.1. If the console is the master at 48k the Tascam can't sync unless you are using an input the has sample rate conversion.

If you don't have SRC, connecting a CD player digitally means running at 44.1kHz.

Mac
Title: Re: Clock at 44.1 or 48??
Post by: TJ (Tom) Cornish on January 29, 2014, 12:21:56 PM
I am using a o1v96i and just purchased a Tascam SS-CDR200. I have the CDR200 connected to the 2TR Digital on the board in and out. Getting clock errors on the o1v96i using the o1v as the master set at 48. If I use the Tascam as master the system drops to 44.1

Any thoughts or experience with this?
Simplifying Mac's information - unless you have a way to get a wordclock signal back to your Tascam, you're going to have to clock your desk off the CD player.  CDs run at 44.1Khz, therefore your desk will need to as well.

There isn't a significant issue in sound quality between 44.1Khz and 48Khz, but you have created a single point of failure for your desk - if your CD player looses power or gets disconnected, your desk will stop passing audio. 
Title: Re: Clock at 44.1 or 48??
Post by: Geoff Doane on January 29, 2014, 12:44:41 PM
unless you have a way to get a wordclock signal back to your Tascam, you're going to have to clock your desk off the CD player.  CDs run at 44.1Khz, therefore your desk will need to as well.


Simply connecting the digital output of the console (once it's running at 44.1) to the digital input of the CD-R, and putting it in record, will clock the recorder to the console.  As long as you can run the console at its internal 44.1 sampling rate, everything will work fine.

GTD
Title: Re: Clock at 44.1 or 48??
Post by: TJ (Tom) Cornish on January 29, 2014, 01:01:09 PM
Simply connecting the digital output of the console (once it's running at 44.1) to the digital input of the CD-R, and putting it in record, will clock the recorder to the console.  As long as you can run the console at its internal 44.1 sampling rate, everything will work fine.

GTD
Assuming you're intending to record.
Title: Re: Clock at 44.1 or 48??
Post by: Steve Alves on January 29, 2014, 01:09:25 PM
The recorder has src and it is turned on. But with the o1v at 48 I get sync errors if I PLAY a CD from the Tascam. If I send output to the Tascam to record I do not get the errors. Guessing I should just leave the board at 48 using the internal clock and turn off/ignore the errors when playing a CD back to the board.

Sound right??
Title: Re: Clock at 44.1 or 48??
Post by: TJ (Tom) Cornish on January 29, 2014, 01:11:30 PM
The recorder has src and it is turned on. But with the o1v at 48 I get sync errors if I PLAY a CD from the Tascam. If I send output to the Tascam to record I do not get the errors. Guessing I should just leave the board at 48 using the internal clock and turn off/ignore the errors when playing a CD back to the board.

Sound right??
Sync errors aren't a good thing, particularly if devices are actually running at different clock rates.  Either clock your board to the recorder, assuming you want to play and record from the deck, or use analog inputs on the 01v.
Title: Re: Clock at 44.1 or 48??
Post by: Geoff Doane on January 29, 2014, 01:22:55 PM
Assuming you're intending to record.

Yes, I was making that ASSumption.  :-[

It would be interesting to see if the CDR will stay clocked to the 44.1 digital input, even if it's not in record.  I can do that with my Masterlink, although it seems to be an undocumented feature. If not, then analog back into the console is the way to go, even if they are both nominally running at 44.1.

GTD
Title: Re: Clock at 44.1 or 48??
Post by: Steve Alves on January 29, 2014, 01:47:18 PM
My understanding is with src turned on I can feed the 48 from the board and it will convert to 44.1... The issues is really playing CD's at 44.1 back to the board that is running at 48. I guess I could send to the Tascam using the optical and return it analog??


On another issue with this setup, I have allot of headroom usually and rarely have the master fader at unity. It seems that any changes to my master fader will change the input levels to the recorder. I am taking the stereo outputs and patching them to the digital output.

Just trying to be able to make basic board recordings. How are others handling this?
Title: Re: Clock at 44.1 or 48??
Post by: Mac Kerr on January 29, 2014, 01:50:53 PM
My understanding is with src turned on I can feed the 48 from the board and it will convert to 44.1... The issues is really playing CD's at 44.1 back to the board that is running at 48.

If the console is running at 48k the CD cannot be in sync with it because the console does not have SRC. To play back a CD digitally you either have to clock at 44.1k or have SRC on the digital input you are using.

Mac
Title: Re: Clock at 44.1 or 48??
Post by: Jean-Pierre Coetzee on January 29, 2014, 01:57:45 PM
My understanding is with src turned on I can feed the 48 from the board and it will convert to 44.1... The issues is really playing CD's at 44.1 back to the board that is running at 48. I guess I could send to the Tascam using the optical and return it analog??


On another issue with this setup, I have allot of headroom usually and rarely have the master fader at unity. It seems that any changes to my master fader will change the input levels to the recorder. I am taking the stereo outputs and patching them to the digital output.

Just trying to be able to make basic board recordings. How are others handling this?

You should really be slaving the tascam off the Console, it is best to run the AD converters on the pre's off their clock source rather than another clock source, running them off another clock source will likely introduce more jitter specially considering that this is a cd player we are talking about.

I will do some research for you on how to do this if I get time but I am pretty sure someone here will be able to supply you with the information or you can attempt to google it. As others have said it really doesn't make a lot of difference between 44.1 and 48 kHz, the difference can really only be heard around and above 18kHz.
Title: Re: Clock at 44.1 or 48??
Post by: Steve Alves on January 29, 2014, 02:06:11 PM
If the console is running at 48k the CD cannot be in sync with it because the console does not have SRC. To play back a CD digitally you either have to clock at 44.1k or have SRC on the digital input you are using.

Mac

That makes sense. The src needs to be on the receiving side of the signal.
Title: Re: Clock at 44.1 or 48??
Post by: Steve Alves on January 29, 2014, 02:26:28 PM
I will do some research for you on how to do this if I get time but I am pretty sure someone here will be able to supply you with the information or you can attempt to google it. As others have said it really doesn't make a lot of difference between 44.1 and 48 kHz, the difference can really only be heard around and above 18kHz.

Thanks, tried the Google route but the key to Google is having the right search phrase,,, I don't..
Title: Re: Clock at 44.1 or 48??
Post by: TJ (Tom) Cornish on January 29, 2014, 02:51:59 PM
You should really be slaving the tascam off the Console, it is best to run the AD converters on the pre's off their clock source rather than another clock source, running them off another clock source will likely introduce more jitter specially considering that this is a cd player we are talking about.

With all due respect, we're talking about using an 01v96 in a live situation.  Whatever jitter there may be is beyond insignificant in light of the other factors that actually can affect sound quality - namely talent, stage volume, room acoustics, speaker quality, etc.

The only reason I would prefer to run the 01v off its internal clock is the risk of my bumping the power button on the CDR with my knee, causing audio to stop due to losing clock source.
Title: Re: Clock at 44.1 or 48??
Post by: TJ (Tom) Cornish on January 29, 2014, 02:53:55 PM
Just trying to be able to make basic board recordings. How are others handling this?
If you're simply trying to take board recordings, set your 01v to 44K, clock the CDR from the board, and get-er-done.  You're over thinking this.

Your other option, of course, is to use the "i" function of your new 01v and record via USB to a computer.
Title: Re: Clock at 44.1 or 48??
Post by: Geoff Doane on January 29, 2014, 02:54:52 PM
On another issue with this setup, I have allot of headroom usually and rarely have the master fader at unity. It seems that any changes to my master fader will change the input levels to the recorder. I am taking the stereo outputs and patching them to the digital output.


Not only does the master fader change the record level, but the recording also gets any EQ that you've done to the main mix.  To get around this, I double bus everything to both the main stereo mix and a pair of groups.  I like to feed the PA with the groups, and have the master fader on the top layer for adjusting the record level, but you can do whatever works for you. 

Since I usually want more gain in the record feed (since, like you, I tend to leave a lot of headroom on the PA feed), I also stick a bus compressor with some makeup gain on the record feed, so my record level stays closer to 0 dBFS, but is still protected from going over.

Unless there is a compelling reason reason to use a different sampling rate, I try to stick with 44.1 to simplify connections to CD players and recorders.  I don't think there's an audible difference, and this study seems to confirm my suspicions.

http://www.drewdaniels.com/audible.pdf

GTD

Title: Re: Clock at 44.1 or 48??
Post by: Steve Alves on January 29, 2014, 03:04:32 PM
Your other option, of course, is to use the "i" function of your new 01v and record via USB to a computer.

I prefer using Studio manager and not having to deal with Cubase. I use an iPad to mix sometimes and keep studio manager on screen.
Title: Re: Clock at 44.1 or 48??
Post by: Mark McFarlane on January 29, 2014, 03:13:23 PM
My suggestion: Set the console as master at 48K, use Geoff's technique to independently control record level and let the CD player SRC the input, feed your CD playback back via Analog.

Do not run the board at 48 and feed it a 44K digital signal.
Title: Re: Clock at 44.1 or 48??
Post by: Steve Alves on January 29, 2014, 05:09:30 PM
My suggestion: Set the console as master at 48K, use Geoff's technique to independently control record level and let the CD player SRC the input, feed your CD playback back via Analog.

Do not run the board at 48 and feed it a 44K digital signal.

Agreed....