Jitter?

da_phoenix · 16th May 2008, 06:12 AM

I have an MTP-AV that I just hooked up to my mixer and my 2408mkIII via BNC out. The two are daisy chained but I get clicks and pops all the time if the mixer is the first in the chain, and clicks durring playback if the 2408 is. Any idea why?

If i recorded audio w/o this current set up, would the play back noise be from the different sync options at recording?

the_man361 · 16th May 2008, 04:48 PM

im not sure but have you checked all your clocking sources are correct?

joenovice · 16th May 2008, 05:07 PM

Why are you clocking the MTP to the audio card? Unless you have a specific reason to do so, you shouldn't.

Word Clock is for Audio and device sync only. Midi devices can, and should, sync from MIDI Time Code (MTC) or MIDI Machine Control (MMC).

da_phoenix · 17th May 2008, 12:53 AM

All my clocking sources are correct. I did not make the mistake of leaving super clock on. I am confused about the MTC comment. Why wouldn't I sync the 2408 which is my digital interface to the timepiece?

This is the sync order as it exists now:

MTP-AV ---> Digital Mixer ---> 2408

joenovice · 17th May 2008, 01:04 AM

The MTP is mainly a MIDI interface. The only reason it has Word Clock is to provide sync for video in setups that otherwise have no BNC Word connections.

Word Clock is used to sync the clock used in the audio A/D/A conversion process. Since the MTP has no audio and other units have BNC Word, the MTP should be removed from the sync chain. Instead connect it via MIDI or USB.

Typically Clock is sent from the A/D device (in this case your mixer) and recieved by others (2408). You could have problems genetrating a Word Clock from a device that is also recieving digital audio.

Remove the MTP, set the Digital Mixer as the master clock, and recieve on the 2408 and you should have no problems.

da_phoenix · 17th May 2008, 05:11 AM

Ok- I did not realize that as I thought the MTP AV would simply be a better clock than the one i was using. Many external sync devices do not have audio coming in or out of them - Big Ben/ lucid / antelope equivlent- so i did not think this an issue

I connected it in the method you suggested, with the mixer as master and the 2408 as slave and still get this noise when i sync to word. Now i only have word out from the mixer to word in on the 2408- i dont need both right? Maybe the issue is unclean power, because this hiss is driving me crazy

joenovice · 17th May 2008, 05:34 AM

You might need something to terminate the signal. Sometimes this can be a switch on a unit or setting in the driver panel or a physical T-connector with a plug on one stem.

Units like the ones you mention (Big Ben, Lucid) are high quality master clocks or converters. Not the same with MTP.

You may also be sending clock information through the digital cable. Are you using SPDIF or ADAT?

da_phoenix · 17th May 2008, 05:16 PM

I am using both SPDIF- to my PCM81 and ADAT which connects the mixer to the 2408 on all 16 channels. I don't see an option to send clocking info through the digital outputs, although the 2408 can use them as clock sources- something I had done in the past. I dont understand what you mean about a signal terminator. There are no options that say that or switches. Should i close the loop by hooking up the out of the 2408 to the in of the mixer?

joenovice · 17th May 2008, 05:26 PM

This is a terminator T....
Canare BNC 75 ohm Terminator $5.55 each or $5.00 each for 24 or more.

You have a lot of digital connections going all over the place and not much reason to do so.

Why are you sending SPDif to the PCM? It would probably be better to use analog cables on a AUX bus.

ADAT connections carry both audio and clock information. Try to remove the BNC cables and clock via ADAT.

credentialed · 17th May 2008, 05:46 PM

With multiple digital devices you should have an external clock, set as the master, which all of the devices can sync to.

Also, you want to make sure all of the devices are set at the same sample rate.

da_phoenix · 17th May 2008, 06:44 PM

I have been using ADAT as the clock source but that was the problem. I thought that trying to use BNC would lower the noise I was getting from that. Using ADAT if i raise the control room volume, leaving the mix bus constant, the noise really starts to increase once I pass 2. I figured the MTP would be a better external source than what I was using now, which is the 2408 synced to the mixer via ADAT. I use spdif on the PCM 81 because that way I can use it as an aux buss through digital performer, rather than using it on the mixer itself. The reason is due to routing options i did not forsee when I bought the digital 328; using the reverb analog would require feeding back in to two channels on the board, which is already occupied most of the time.

joenovice · 17th May 2008, 09:26 PM

Quote:

Originally Posted by da_phoenix

Iusing the reverb analog would require feeding back in to two channels on the board, which is already occupied most of the time.

yep... the aux returns...

Quote:

I use spdif on the PCM 81 because that way I can use it as an aux buss through digital performer, rather than using it on the mixer itself.

ah... SPDIF from 2408 and not mixer... I see

da_phoenix · 18th May 2008, 07:36 PM

LOL i know what aux returns are but there are no "returns" as on a regular mixer its a dumb set up, not gonna lie.

What would be the advantage to using the board over using SPDIF out of the 2408 though?

16th May 2008, 06:12 AM	#1
da_phoenix Gear interested Join Date: Jan 2008 Posts: 15	Jitter? I have an MTP-AV that I just hooked up to my mixer and my 2408mkIII via BNC out. The two are daisy chained but I get clicks and pops all the time if the mixer is the first in the chain, and clicks durring playback if the 2408 is. Any idea why? If i recorded audio w/o this current set up, would the play back noise be from the different sync options at recording?

17th May 2008, 05:46 PM	#10
credentialed Gear nut Join Date: Mar 2007 Location: New York City Posts: 84	With multiple digital devices you should have an external clock, set as the master, which all of the devices can sync to. Also, you want to make sure all of the devices are set at the same sample rate. __________________ Arthur Nuendo 3.2.2, Powerbook G4, Dual 450 PowerPc G4 (I know), Tascam DVRA1000HD, Aurora 16, FF800, Antelope Isochrone OCX, K+H P110 Avatar Sketched by Steve Remote @http://www.gearslutz.com/board/remot...obile-rig.html

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16th May 2008, 04:48 PM	#2
the_man361 Gear Head Join Date: Apr 2008 Location: Leeds - UK Posts: 74	im not sure but have you checked all your clocking sources are correct?

16th May 2008, 05:07 PM	#3
joenovice Gear addict Join Date: Jun 2006 Posts: 416	Why are you clocking the MTP to the audio card? Unless you have a specific reason to do so, you shouldn't. Word Clock is for Audio and device sync only. Midi devices can, and should, sync from MIDI Time Code (MTC) or MIDI Machine Control (MMC).

17th May 2008, 12:53 AM	#4
da_phoenix Gear interested Join Date: Jan 2008 Posts: 15	All my clocking sources are correct. I did not make the mistake of leaving super clock on. I am confused about the MTC comment. Why wouldn't I sync the 2408 which is my digital interface to the timepiece? This is the sync order as it exists now: MTP-AV ---> Digital Mixer ---> 2408

17th May 2008, 01:04 AM	#5
joenovice Gear addict Join Date: Jun 2006 Posts: 416	The MTP is mainly a MIDI interface. The only reason it has Word Clock is to provide sync for video in setups that otherwise have no BNC Word connections. Word Clock is used to sync the clock used in the audio A/D/A conversion process. Since the MTP has no audio and other units have BNC Word, the MTP should be removed from the sync chain. Instead connect it via MIDI or USB. Typically Clock is sent from the A/D device (in this case your mixer) and recieved by others (2408). You could have problems genetrating a Word Clock from a device that is also recieving digital audio. Remove the MTP, set the Digital Mixer as the master clock, and recieve on the 2408 and you should have no problems.

17th May 2008, 05:11 AM	#6
da_phoenix Gear interested Join Date: Jan 2008 Posts: 15	Ok- I did not realize that as I thought the MTP AV would simply be a better clock than the one i was using. Many external sync devices do not have audio coming in or out of them - Big Ben/ lucid / antelope equivlent- so i did not think this an issue I connected it in the method you suggested, with the mixer as master and the 2408 as slave and still get this noise when i sync to word. Now i only have word out from the mixer to word in on the 2408- i dont need both right? Maybe the issue is unclean power, because this hiss is driving me crazy

17th May 2008, 05:34 AM	#7
joenovice Gear addict Join Date: Jun 2006 Posts: 416	You might need something to terminate the signal. Sometimes this can be a switch on a unit or setting in the driver panel or a physical T-connector with a plug on one stem. Units like the ones you mention (Big Ben, Lucid) are high quality master clocks or converters. Not the same with MTP. You may also be sending clock information through the digital cable. Are you using SPDIF or ADAT?

17th May 2008, 05:16 PM	#8
da_phoenix Gear interested Join Date: Jan 2008 Posts: 15	I am using both SPDIF- to my PCM81 and ADAT which connects the mixer to the 2408 on all 16 channels. I don't see an option to send clocking info through the digital outputs, although the 2408 can use them as clock sources- something I had done in the past. I dont understand what you mean about a signal terminator. There are no options that say that or switches. Should i close the loop by hooking up the out of the 2408 to the in of the mixer?

17th May 2008, 05:26 PM	#9
joenovice Gear addict Join Date: Jun 2006 Posts: 416	This is a terminator T.... Canare BNC 75 ohm Terminator $5.55 each or $5.00 each for 24 or more. You have a lot of digital connections going all over the place and not much reason to do so. Why are you sending SPDif to the PCM? It would probably be better to use analog cables on a AUX bus. ADAT connections carry both audio and clock information. Try to remove the BNC cables and clock via ADAT.

17th May 2008, 06:44 PM	#11
da_phoenix Gear interested Join Date: Jan 2008 Posts: 15	I have been using ADAT as the clock source but that was the problem. I thought that trying to use BNC would lower the noise I was getting from that. Using ADAT if i raise the control room volume, leaving the mix bus constant, the noise really starts to increase once I pass 2. I figured the MTP would be a better external source than what I was using now, which is the 2408 synced to the mixer via ADAT. I use spdif on the PCM 81 because that way I can use it as an aux buss through digital performer, rather than using it on the mixer itself. The reason is due to routing options i did not forsee when I bought the digital 328; using the reverb analog would require feeding back in to two channels on the board, which is already occupied most of the time.

18th May 2008, 07:36 PM	#13
da_phoenix Gear interested Join Date: Jan 2008 Posts: 15	LOL i know what aux returns are but there are no "returns" as on a regular mixer its a dumb set up, not gonna lie. What would be the advantage to using the board over using SPDIF out of the 2408 though?