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#1
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Info on Dolby 361 and cards?
As I mentioned in another thread, I'm looking for that now-classic
"Dolby A" sound. The easiest way seems to be to get an actual Dolby encoder box. I did some Googling, and here's what I found: - The effect was usually done with a Dolby 301, and you simply removed the bass expander card so you only affected (and effected) the mids and highs. But the 301's are huge and not frequently sold on ebay. - According to Bruce Breckenfeld, you can modify the "A" card used by the Dolby 361; you clip R109 and R209, and this disables the bass expansion. (http://www.ears-chicago.org/eardrum/2000.08.shtml) I assume he's talking about the cat-22 card. - The Dolby 363 is a two-channel version of the 361, but it uses different cards, and I wouldn't know what resistors to clip. Questions: - I've also seen Dolby 360s around. How do they differ from the 361? - All the recent 361s for sale had some sort of built-in Dolby A instead of a cat-22 card, with what looks to be a blank plate where the card would go. So I probably couldn't easily perform the modification. Anyone know anything about these units, what the card is that comes with them? Or am I misunderstanding the cat-22 card? Photos I've seen on ebay show a level knob, etc. on the card. For example: - Does anyone have a schematic for the cat-22 card? Maybe if I could identify R109 and R209, I could find their equivalent on the SR/A cards used by the 363 units, which are newer and easier to find. -- Jay Levitt | Wellesley, MA | Hi! Faster: jay at jay dot eff-em | Where are we going? http://www.jay.fm | Why am I in this handbasket? |
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#2
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In article ,
says... Photos I've seen on ebay show a level knob, etc. on the card. For example: Oops.. accidentally posted without the link. Here's an auction for a cat-22 card: http://cgi.ebay.com/ws/eBayISAPI.dll...ry=15199&item= 3736015311&rd=1&ssPageName=WDVW -- Jay Levitt | Wellesley, MA | Hi! Faster: jay at jay dot eff-em | Where are we going? http://www.jay.fm | Why am I in this handbasket? |
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#3
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In article ,
says... Photos I've seen on ebay show a level knob, etc. on the card. For example: Oops.. accidentally posted without the link. Here's an auction for a cat-22 card: http://cgi.ebay.com/ws/eBayISAPI.dll...ry=15199&item= 3736015311&rd=1&ssPageName=WDVW -- Jay Levitt | Wellesley, MA | Hi! Faster: jay at jay dot eff-em | Where are we going? http://www.jay.fm | Why am I in this handbasket? |
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#4
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Those modules look like something taken out of a 24 ch. Dolby system and
appear to sport a CAT 22 card in the middle. Predrag "Jay Levitt" wrote in message ... In article , says... Photos I've seen on ebay show a level knob, etc. on the card. For example: Oops.. accidentally posted without the link. Here's an auction for a cat-22 card: http://cgi.ebay.com/ws/eBayISAPI.dll...ry=15199&item= 3736015311&rd=1&ssPageName=WDVW -- Jay Levitt | Wellesley, MA | Hi! Faster: jay at jay dot eff-em | Where are we going? http://www.jay.fm | Why am I in this handbasket? |
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#5
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Those modules look like something taken out of a 24 ch. Dolby system and
appear to sport a CAT 22 card in the middle. Predrag "Jay Levitt" wrote in message ... In article , says... Photos I've seen on ebay show a level knob, etc. on the card. For example: Oops.. accidentally posted without the link. Here's an auction for a cat-22 card: http://cgi.ebay.com/ws/eBayISAPI.dll...ry=15199&item= 3736015311&rd=1&ssPageName=WDVW -- Jay Levitt | Wellesley, MA | Hi! Faster: jay at jay dot eff-em | Where are we going? http://www.jay.fm | Why am I in this handbasket? |
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#6
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I've been looking for the same info, the one about the mod for the CAT 22
card. Looks like we need the schematics. The blank plate on a Dolby 361 serves as a protection from dust, I presume. The CAT 22 module should be hiding safely in the slot behind it. By the way, I'd like to buy a couple of those blank plates. If anyone has them lying around please let me know. My 361 units came without any. They came with a couple of Telcom NR modules instead. Anybody ever used them, for noise reduction or anything else? Predrag "Jay Levitt" wrote in message ... As I mentioned in another thread, I'm looking for that now-classic "Dolby A" sound. The easiest way seems to be to get an actual Dolby encoder box. I did some Googling, and here's what I found: - The effect was usually done with a Dolby 301, and you simply removed the bass expander card so you only affected (and effected) the mids and highs. But the 301's are huge and not frequently sold on ebay. - According to Bruce Breckenfeld, you can modify the "A" card used by the Dolby 361; you clip R109 and R209, and this disables the bass expansion. (http://www.ears-chicago.org/eardrum/2000.08.shtml) I assume he's talking about the cat-22 card. - The Dolby 363 is a two-channel version of the 361, but it uses different cards, and I wouldn't know what resistors to clip. Questions: - I've also seen Dolby 360s around. How do they differ from the 361? - All the recent 361s for sale had some sort of built-in Dolby A instead of a cat-22 card, with what looks to be a blank plate where the card would go. So I probably couldn't easily perform the modification. Anyone know anything about these units, what the card is that comes with them? Or am I misunderstanding the cat-22 card? Photos I've seen on ebay show a level knob, etc. on the card. For example: - Does anyone have a schematic for the cat-22 card? Maybe if I could identify R109 and R209, I could find their equivalent on the SR/A cards used by the 363 units, which are newer and easier to find. -- Jay Levitt | Wellesley, MA | Hi! Faster: jay at jay dot eff-em | Where are we going? http://www.jay.fm | Why am I in this handbasket? |
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#7
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I've been looking for the same info, the one about the mod for the CAT 22
card. Looks like we need the schematics. The blank plate on a Dolby 361 serves as a protection from dust, I presume. The CAT 22 module should be hiding safely in the slot behind it. By the way, I'd like to buy a couple of those blank plates. If anyone has them lying around please let me know. My 361 units came without any. They came with a couple of Telcom NR modules instead. Anybody ever used them, for noise reduction or anything else? Predrag "Jay Levitt" wrote in message ... As I mentioned in another thread, I'm looking for that now-classic "Dolby A" sound. The easiest way seems to be to get an actual Dolby encoder box. I did some Googling, and here's what I found: - The effect was usually done with a Dolby 301, and you simply removed the bass expander card so you only affected (and effected) the mids and highs. But the 301's are huge and not frequently sold on ebay. - According to Bruce Breckenfeld, you can modify the "A" card used by the Dolby 361; you clip R109 and R209, and this disables the bass expansion. (http://www.ears-chicago.org/eardrum/2000.08.shtml) I assume he's talking about the cat-22 card. - The Dolby 363 is a two-channel version of the 361, but it uses different cards, and I wouldn't know what resistors to clip. Questions: - I've also seen Dolby 360s around. How do they differ from the 361? - All the recent 361s for sale had some sort of built-in Dolby A instead of a cat-22 card, with what looks to be a blank plate where the card would go. So I probably couldn't easily perform the modification. Anyone know anything about these units, what the card is that comes with them? Or am I misunderstanding the cat-22 card? Photos I've seen on ebay show a level knob, etc. on the card. For example: - Does anyone have a schematic for the cat-22 card? Maybe if I could identify R109 and R209, I could find their equivalent on the SR/A cards used by the 363 units, which are newer and easier to find. -- Jay Levitt | Wellesley, MA | Hi! Faster: jay at jay dot eff-em | Where are we going? http://www.jay.fm | Why am I in this handbasket? |
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#8
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Predrag Trpkov wrote:
I've been looking for the same info, the one about the mod for the CAT 22 card. Looks like we need the schematics. Go to www.film-tech.com and look for the service manual for the Dolby CP-50 cinema sound decoder. I believe that should have a chapter on the CAT 22 card, with docs. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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#10
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In article ,
Jay Levitt wrote: In article , says... Go to www.film-tech.com and look for the service manual for the Dolby CP-50 cinema sound decoder. I believe that should have a chapter on the CAT 22 card, with docs. Sadly, no.. looks like the original manual did, in section 10, but that's not on the web site, only the block diagram in section 9. We're getting closer, tho... I looked through a bunch of other CP-* manuals and didn't see anything either. I have the original manual, but it's a few hundred miles away at home. I can probably fax you the schematic if you can wait a week or so. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis." |
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#11
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In article , says...
I have the original manual, but it's a few hundred miles away at home. I can probably fax you the schematic if you can wait a week or so. Sure, no hurry.. whenever you get back and get some time. I'll e-mail you my fax #, and then I can post the doc on my web site for Predrag. -- Jay Levitt | Wellesley, MA | Hi! Faster: jay at jay dot eff-em | Where are we going? http://www.jay.fm | Why am I in this handbasket? |
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#12
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Jay Levitt wrote:
- I've also seen Dolby 360s around. How do they differ from the 361? The 360 and 361 are both single-channel processors, each designed to hold one Cat. 22 Dolby "A" card. Later when Dolby SR was introduced, there were two other cards that could fit this series (one with switchable "A" and SR and one with just SR). If I'm not mistaken the Cat. 280 was one of these, but I don't exactly remember which. The difference between the 360 and the 361 was the switching and connection arrangement. It's simpler on the 360; the 361 allowed you to connect both the inputs and outputs of one recorder channel to the same unit and switch between record (while monitoring the unencoded input) and playback (while monitoring the decoded output), so it had a few more relays and sockets, and cost marginally more than the 360. - All the recent 361s for sale had some sort of built-in Dolby A instead of a cat-22 card, with what looks to be a blank plate where the card would go. ?? A 361 should have a front panel cover held in place by two thumb screws. Behind that cover is a horizontal slot for a Cat. 22 card. |
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#13
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Predrag Trpkov wrote:
They came with a couple of Telcom NR modules instead. Anybody ever used them, for noise reduction or anything else? Sure, I used them a fair amount in the mid- to late 1970s. Telcom c4 also divided the audio spectrum into four bands, but it used a constant 1.5:1 compression ratio in each band for recording, and applied this ratio more or less regardless of signal level. As a result the net amount of noise reduction effect was far greater than with Dolby "A". It was a very effective system but the first series of "C4D" cards (for the Dolby 360 series) was not quite right, and was revised and replaced by Telefunken. |
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#14
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#15
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Thanks for your input.
The cards that came with my 361 are Telcom c4 DM. Would they be the revised ones? What about the audible artefacts? Greater noise reduction, dbx for example, doesn't necessarily mean better sound. Does it mean that there are a lot of masters out there on tapes that are Telcom-encoded? Predrag "David Satz" wrote in message om... Predrag Trpkov wrote: They came with a couple of Telcom NR modules instead. Anybody ever used them, for noise reduction or anything else? Sure, I used them a fair amount in the mid- to late 1970s. Telcom c4 also divided the audio spectrum into four bands, but it used a constant 1.5:1 compression ratio in each band for recording, and applied this ratio more or less regardless of signal level. As a result the net amount of noise reduction effect was far greater than with Dolby "A". It was a very effective system but the first series of "C4D" cards (for the Dolby 360 series) was not quite right, and was revised and replaced by Telefunken. |
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#16
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Jay Levitt wrote:
- All the recent 361s for sale had some sort of built-in Dolby A instead of a cat-22 card, with what looks to be a blank plate where the card would go. So I probably couldn't easily perform the modification. Anyone know anything about these units, what the card is that comes with them? Or am I misunderstanding the cat-22 card? Photos I've seen on ebay show a level knob, etc. on the card. For example: The 361 was simply a box, PSU and I/O that took a Cat 22 card. The Cat 22 card was the 'active' pcb with an edge connector that slotted in and did the signal processing. - Does anyone have a schematic for the cat-22 card? Maybe if I could identify R109 and R209, I could find their equivalent on the SR/A cards used by the 363 units, which are newer and easier to find. I believe I do somewhere - I'll look. Graham |
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#17
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Predrag Trpkov wrote: Those modules look like something taken out of a 24 ch. Dolby system and appear to sport a CAT 22 card in the middle. Yup, the Cat 22 is inside the shiny aluminium can. You need to 'get in and out' of the Cat 22 card and supply power - so these may not be your best buy. Graham |
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#18
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Jay Levitt wrote: In article , says... Photos I've seen on ebay show a level knob, etc. on the card. For example: Oops.. accidentally posted without the link. Here's an auction for a cat-22 card: This is what you need. http://cgi.ebay.com/ws/eBayISAPI.dll...sPageName=WDVW Graham |
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#19
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Predrag Trpkov wrote:
The cards that came with my 361 are Telcom c4 DM. Would they be the revised ones? The "DM" is an even later series than the ones I have. I believe they are physically a bit shorter than the older ones but follow the same specification and circuit behavior. What about the audible artefacts? Greater noise reduction, dbx for example, doesn't necessarily mean better sound. There's a minimum dynamic range that the channel requires in order for systems such as telcom or dbx to work without noise pumping. I once made a recording of a piano concerto using telcom, where the peak levels on tape were about 20 dB below 0 VU; there was definite noise pumping in that recording. But with normal recording levels on ordinary pro-quality equipment and tape, I never heard any such problems with telcom--and I definitely, definitely hear them with dbx on some program material even though some other people (whose hearing I respect) do not. By "systems such as telcom or dbx" I mean: systems in which the same degree of compression/expansion occurs at all signal levels throughout the range, rather than being limited (as in Dolby systems) to a specific part of the range. In Dolby's noise reduction systems there is always some recording level beneath which the system goes back to being 1:1, and that design absolutely prevents noise "breathing" or "pumping" as long as playback levels have been set correctly to the reference tone. Does it mean that there are a lot of masters out there on tapes that are Telcom-encoded? Telcom c4 never achieved the prominence of Dolby "A" anywhere, but it was used in Germany to some extent, particularly for classical orchestral recording. A 15 ips 1/4" analog tape using telcom c4 noise reduction could have nearly the same dynamic range as 16-bit linear PCM. It was very exciting to have so much dynamic range available in the 1970s. When I bought my first set of c4d cards from Gotham Audio, I was only the second customer in the United States; the first was Frank Zappa. (How's that for an anecdotal reply?) --best regards |
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#20
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When I bought my first set of c4d cards from Gotham Audio, I was only the second customer in the United States; the first was Frank Zappa. (How's that for an anecdotal reply?) As colorful as it gets. Thanks again. Predrag |
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#21
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When I bought my first set of c4d cards from Gotham Audio, I was only the second customer in the United States; the first was Frank Zappa. (How's that for an anecdotal reply?) As colorful as it gets. Thanks again. Elliot Mazer used them as well Phil Brown |
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#22
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Without a cat card, a 360/361 does nothing.
But it doesn't have to be a cat 22. When I was doing TV and movies a cat 43 was standard everywhere. May still be. Pretty useful. Phil Brown |
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#23
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in article , Phil Brown at
unged wrote on 7/17/04 8:46 PM: Without a cat card, a 360/361 does nothing. But it doesn't have to be a cat 22. When I was doing TV and movies a cat 43 was standard everywhere. May still be. Pretty useful. A cat 43 does nothing without a cat 22. The cat 43 had a red "card" that docked in the 360/361 unit. The "card" had a 6 foot cable that went to a little control box with 5 slider controls and a dock for the cat 22. |
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