Dolby SR users: a few questions

numrologst · 25th June 2008, 06:13 AM

Thanks to a fellow gearslut, I got a manual for my new (to me) studer 820.

My only lingering question is about the SR alignment.

I followed the outlined procedure for setting up the in-house standard alignment for the Dolby NRS.

When it came time to test the setup, it appeared to me that the procedure didn't align the SR properly. After telling the machine that the SR should all be at 0vu, I recorded the Dolby tone for SR. Upon playing back thhe dolby tone, it wasn't within +-1db on all channels. The dolby tone fluctuated between -3vu and 0vu. The fluctuation seemed to be pretty fast.

Having never used SR before I don't know what to expect. Are these fluctuations typical of what I should be seeing from the SR?

Then I tried recording a test tone with SR on. The tones all recorded at 0vu, but played back as though the machine wasn't properly aligned. Obviously the machine was aligned properly.

Now I am trying to figure out the proper procedure to align the SR channel by channel. The 820 manual outlines off-tape alignment. Would I use this method to get my SR properly aligned?

It appears as though the Dolby tone is printing at -17 or -18vu instead of -15vu. Would I adjust the SR so that it is printing the dolby tone at -15 and then record a 1 minute pass. Then adjust the SR alignment until I am at 0vu upon playback? That seems to me what I need to do. But I don't understand why the tone would be printing at anything other than -15vu.

Any expert help is appreciated. I know some of you guys are pretty good with this kind of stuff. I'd like to figure this out.

Thanks

The Byre · 25th June 2008, 08:51 AM

It's been many years since I had to deal with Dobbly, but I do remember that most NR setup problems came with poor alignment, dirt and-or worn heads - so make sure that none of these apply before setting up the Dobbly.

On a personal note, when left to do what I prefered, I never used Dobbly or any other NR, but just fed enough signal to the tape and used high octane tape (e.g. GP9).

We have today such clever single ended NR programmes, that there really is no need for encode-decode. But that's just me!

Jim Williams · 25th June 2008, 03:45 PM

If you can't get both green LED's to stay lit, it's most likely dirt on the heads or a transport problem. Any wow/flutter will cause the alignment to constantly drift. A well aligned, maintained tape machine will keep those green LED's lit. I would check the tape path, then check tension with a tentelometer. If anything is off, it will show as drift or dodgy alignment.

Jim Williams
Audio Upgrades

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25th June 2008, 06:13 AM	#1
numrologst Lives for gear Join Date: Sep 2005 Location: Texas Posts: 1,898	Dolby SR users: a few questions Thanks to a fellow gearslut, I got a manual for my new (to me) studer 820. My only lingering question is about the SR alignment. I followed the outlined procedure for setting up the in-house standard alignment for the Dolby NRS. When it came time to test the setup, it appeared to me that the procedure didn't align the SR properly. After telling the machine that the SR should all be at 0vu, I recorded the Dolby tone for SR. Upon playing back thhe dolby tone, it wasn't within +-1db on all channels. The dolby tone fluctuated between -3vu and 0vu. The fluctuation seemed to be pretty fast. Having never used SR before I don't know what to expect. Are these fluctuations typical of what I should be seeing from the SR? Then I tried recording a test tone with SR on. The tones all recorded at 0vu, but played back as though the machine wasn't properly aligned. Obviously the machine was aligned properly. Now I am trying to figure out the proper procedure to align the SR channel by channel. The 820 manual outlines off-tape alignment. Would I use this method to get my SR properly aligned? It appears as though the Dolby tone is printing at -17 or -18vu instead of -15vu. Would I adjust the SR so that it is printing the dolby tone at -15 and then record a 1 minute pass. Then adjust the SR alignment until I am at 0vu upon playback? That seems to me what I need to do. But I don't understand why the tone would be printing at anything other than -15vu. Any expert help is appreciated. I know some of you guys are pretty good with this kind of stuff. I'd like to figure this out. Thanks

25th June 2008, 08:51 AM	#2
The Byre Lives for gear Join Date: Jan 2004 Location: Highlands of Scotland Posts: 1,107	It's been many years since I had to deal with Dobbly, but I do remember that most NR setup problems came with poor alignment, dirt and-or worn heads - so make sure that none of these apply before setting up the Dobbly. On a personal note, when left to do what I prefered, I never used Dobbly or any other NR, but just fed enough signal to the tape and used high octane tape (e.g. GP9). We have today such clever single ended NR programmes, that there really is no need for encode-decode. But that's just me! __________________ http://www.the-byre.com

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25th June 2008, 03:45 PM	#3
Jim Williams Lives for gear Join Date: Feb 2004 Location: beautiful Carlsbad, CA Posts: 4,335	If you can't get both green LED's to stay lit, it's most likely dirt on the heads or a transport problem. Any wow/flutter will cause the alignment to constantly drift. A well aligned, maintained tape machine will keep those green LED's lit. I would check the tape path, then check tension with a tentelometer. If anything is off, it will show as drift or dodgy alignment. Jim Williams Audio Upgrades