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Author Topic: Dolby Pro Unit 363  (Read 4952 times)

ceved

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Dolby Pro Unit 363
« on: January 16, 2008, 03:50:15 PM »
I note that in the discussion of Dolby and DBX within the BC prerecorded tape thread, members were cautioned about the Model 330 and most Dolby units in general.
Does the same warning apply to the 363?
I should clarify, the 330 was said to be intended for use with cassette tapes. I am wondering if the same holds true for the Model 363.
Thanks in advance.
« Last Edit: January 16, 2008, 04:21:00 PM by ceved »

Offline ironbut

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Re: Dolby Pro Unit 363
« Reply #1 on: January 16, 2008, 06:32:11 PM »
Hey Charles, most of the Pro Dolby units (made by Dolby Labs) you'll see are type A noise reduction. The pre recorded tapes such as the Barclay-Crockers, are encoded with Dolby B. There may be a way to disable the extra filters and use an A type decoder, but that would be a lot of work and would really be best left to someone who knows their way around a decoding card. I believe that the 301 and the 330 were the only ones that did B type decoding. Both of these are getting pretty rare and from what I've heard, would still need modification to sound transparent. The Dolby encoded tapes, like we'd be playing, have a boost in the frequency range that the tape hiss resides. If you listen to them without a decoder, the hiss is there and an emphasis of that band of high frequencies will be present. For now, I'm listening to those tapes without a decoder. It's not super noticeable and once I get caught up in the music, I don't notice it at all. I've been meaning to do some upgrading of a consumer Dolby B decoder but I haven't had a chance to do any serious work on it yet. If you can hold on, I hope to have some good news for 4 track pre recorded tape collectors in the future.
steve koto
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Offline U47

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Re: Dolby Pro Unit 363- and A-301
« Reply #2 on: January 16, 2008, 06:57:47 PM »
The A-301 was Dolby Labs first Dolby A(pro) NR unit. Decca started using it in 1966 and continued with it for many years. All of the Lyrita recordings were made with Dolby A as well. It is a huge all discrete transformer coupled encode/decode device. Charlie King modified one of these about 20 years ago that was switchable between A and B. It pretty much approximated the B curve. Pretty handy and great sounding unit. The later Dolby A (360, 361 and later) were all chip based and sounded like it :-(
I've used the 330 Dolby B NR device and was not that thrilled with the sonics. I just found one for a friend in Canada and he recently reported to me that he is quite happy with it.
I'm waiting for a 301 to come in from Asia shortly. It has 96 electrolytic caps that need to be replaced, as do most of these golden oldies- quite a bit of work...

Rich Brown
Portland, Oregon
Technics 1500 with King/Cello playback electronics, Stellavox SP-7, Technics 1500/Ampex MR70, Tascam BR-20 .

ceved

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Re: Dolby Pro Unit 363
« Reply #3 on: January 16, 2008, 08:03:08 PM »
Thanks to all for your informative replies.
I was hoping that the 363 was the exception, but in the meantime it does not seem to know if it is for sale or not.
Perhaps I will just take the money and use it towards an ATR 102; I wish.
I hear what you are saying about the tape hiss, but gosh I hate it so.
Perhaps if my cardiologist would allow me a glass of wine I would not whine as much.

Offline intell

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Re: Dolby Pro Unit 363- and A-301
« Reply #4 on: January 17, 2008, 02:24:58 AM »
The later Dolby A (360, 361 and later) were all chip based and sounded like it :-(

No! 360/361 cards (cat.22) are fully discrete.
Here is a photo of my cat.22 card:

http://photofile.ru/photo/intell/1369074/large/36319824.jpg

http://photofile.ru/photo/intell/1369074/large/36319763.jpg
Best regards! Anton

Offline U47

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Re: Dolby Pro Unit 363
« Reply #5 on: January 17, 2008, 01:44:11 PM »
Never opened my cat 22 cards to see that they were discreet. Just suspected from the size and sound that they were IC based. It gets me wondering why the later units sound so crappy compared to the earlier 301 unit...

Rich Brown
Portland, Oregon
Technics 1500 with King/Cello playback electronics, Stellavox SP-7, Technics 1500/Ampex MR70, Tascam BR-20 .

Offline ironbut

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Re: Dolby Pro Unit 363
« Reply #6 on: January 17, 2008, 07:27:44 PM »
It seems like the 361 w/cat 22 is a favorite subject for modifications (to improve the sound or just alter it to use as an effect with vocals/drums you name it). In an email correspondence with Mike Papas ( he used a couple with a huge Otari for location recordings if you can fathom that!) , he said that there was a class A output mod that was excellent. I did some searching for more info on that one but never found anything. Anyway, my dreams of using one were put on hold when Doc or Paul told me that the B cards for the 361 are almost non-existent. I had a great deal lined up too,.. a pair of 361's with cat 22 cards tested for $100.
steve koto
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ceved

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Re: Dolby Pro Unit 363
« Reply #7 on: January 17, 2008, 10:09:34 PM »
OK,
So I appreciate that much that is out there will not give the transparency we prefer.
Is the consensus that the preferred approach is to listen au natural so to speak without any decoding hiss and all?
Is anybody using a decoder to listen to Dolby B tapes that they can enjoy or at least tolerate?
I am afraid to even bring up DBX!
Going forward sure, with the TTP tapes, or newly recorded material who needs the extra veil?
I will be quiet now.