help with Dolby A mod...

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mcfate

Active member
Joined
Jan 5, 2005
Messages
35
Location
LA
Hello all,

Been lurking around here awhile, and this is my first post. I am certainly not very technical, but I did build the requisite ssl clone with the oversight of a Mr. Buzallen - and it even passes signal.

Remember the old dolby A units which were these large frame deals with multiple vertical cards? Folks would use them in a mix as an expander (encode with no decode). You could pull different cards to bypass different filters(?) and emphasize different frequency bands - I guess this was the original sparkle box, pre aural exciter, bbe, etc.

OK, so here's my question: I have some newer cat 22 dolby A cards that live in a 361 chassis. Its my understanding that it is a very simple mod (cutting a few traces?) to accomplish the old school "pull out the cards" trick. Has anyone ever done this? Also, is there a standard recipe for which filters(?) to disable? Thanks a lot,

Gideon
 
**BUMP**

I know it's been a long time since the last post, but I've been trying to track down this mod as well.

Thanks guys, this is an amazing community of brilliant people.

Rob
 
The link isn't working...I poked around on the site and found a page with pics of the mod, but no description of what to do. I see that R109 and R209 need to be cut at one end and patched to some point, but can't tell where.

It looks like they go to one end of R186 and R289... ?

--> freddie
 
I have experimented with various modifications to achieve the desired vocal effect - in the end the best results are very easily achieved with a simple modification to the CAT 22 module. This is also reversible if you don't like it!

It is also an idea to experiment with input levels - I have found that if the level is reduced to 15 to 20dB below normal Dolby level - the best effect is obtained (2 top bands are compressing fully).

The secret of the success of this effect seems to be the Dolby overshoot suppression - which ensures that sibilance never becomes a problem - as it certainly can when trying to do this with other compressors or devices.

I have a PDF document showing the full details - so PM me (with an e-mail address) if you want a copy.

John
 
Hi,

Reviving an old thread here I know, but was poking around, I have a 362 with spare "A" cards

The link above is dead, sonicmook any new link?
 
haima said:
I did a quick blog post a while back on how I modded my Cat22 card - I made it switchable between the two common mods and unmodded - plus combinations of the three states!

http://haima.info/blog/?p=7

Wow, took me this long to get back. If I'm looking at this correctly the mod is just cutting the two resistors out, or in this case wiring them to switch in and out? That simple! Cool.

 
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