Film-Tech Forum ARCHIVE: Dolby Cat. 67 Extender

This is topic Dolby Cat. 67 Extender in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Jeremy Weigel (Member # 4208) on 01-13-2008, 02:06 PM:

Is there any company that makes an after-market version of the Dolby Cat. 67 Extender?

Posted by Sam D. Chavez (Member # 1841) on 01-13-2008, 02:21 PM:

VARI in Mexico made something very similar. I will get in touch with them and ask if they still have some.

I made a very compact extender many years ago but at this late date I'm not doing it again.

I added a switch to my version to bypass the EQ so you can see what the b-chain looks likes with no EQ so you don't need to zero out the pots to see the pre-EQ response before deciding whether it needs to be redone.

Posted by Monte L Fullmer (Member # 2797) on 01-13-2008, 06:14 PM:

..and to add to this topic: any 3rd party making the 85C pink noise generators to along with the CAT-67 extenders since there is a lot of us that have the older Dolby C55/65 units still in service?

Posted by Marco Giustini (Member # 4544) on 01-13-2008, 06:39 PM:

Me interested too for cat 67.

Just bought a cat 85, I need an extender now that I'm going to buy by myself if I can't find anything on the market.

Ciao
Marco

Posted by Ken Lackner (Member # 1002) on 01-13-2008, 06:48 PM:

Component Engineering's SG-1 signal generator is compatible with the Cat. 85.

Posted by Monte L Fullmer (Member # 2797) on 01-13-2008, 06:54 PM:

THX Ken, for that CE info - Monte

Posted by Jeremy Weigel (Member # 4208) on 01-13-2008, 11:47 PM:

Yeah, I was fairly surprised that Dolby discontinued this item. There seems to be more than enough processors such as the CP65 and other earlier models that can use it still in service. I'm even more surprised that no one is making a readily available after-market version. I did pick up an SG-1 on ebay a couple of years ago, but still haven't run across an extender. Oh well, maybe Sam will have some good news for us or maybe we can talk him into making his version again. [Wink]

Posted by Scott Norwood (Member # 30) on 01-14-2008, 07:01 AM:

quote: Sam D. Chavez
I added a switch to my version to bypass the EQ so you can see what the b-chain looks likes with no EQ so you don't need to zero out the pots to see the pre-EQ response before deciding whether it needs to be redone.

Wow...I love the idea of the bypass switch. If these ever go back into production, I'll buy one just for that (I already have the Dolby version).

For those who have the SG-1, is it significantly more useful than the cat. 85?

Related question: is there a Dolby-approved (or aftermarket) EQ bypass card? Or some other way to bypass the cat. 64s without having to modify the backplane? I would think that it would be useful in houses where the installed sound system already offers extensive EQ control or installations where parametric EQ would be preferred over third-octave. I'm specifically interested in doing this with the CP65, but if there are ways of doing this on the CP50/55/100/200, that would be interesting to know, too.

Posted by Ken Lackner (Member # 1002) on 01-14-2008, 08:16 AM:

Are you looking for your alternate EQ to be permanent or just for a special screening, etc? If permanent, just set all the dials in the Cat 85 cards to 12 o'clock for no EQ.

The SG-1 has a tone generator, whose frequency is controlled via a dial. Useful for finding problems that occur a specific frequencies.

Posted by Christos Mitsakis (Member # 143) on 01-14-2008, 09:39 AM:

I did my own card extention, a long time ago before I got my cat67 and it worked:

It would have been much better if I made it the size of a dolby card, but that was the plate closer to the original I found on hand.

Scott, If you are into it, just make 3 card plugs and jumpering only pins F (in) and N (out).

Posted by Steve Guttag (Member # 268) on 01-14-2008, 09:59 AM:

Scott, there was the Cat 105 you could search for...it was the Cat 64 Bypass card (CP100 days). This is NOT to be confused with the Cat 105D that was used for bass-enhancement on the CP100.

There is actually a level shift that occurs in the Cat 64. They are fed at 170mV but feed the rest of the chain at 150mV. This only amounts to just over 1dB of change though.

Steve

Posted by Alban Birch (Member # 4121) on 01-14-2008, 12:05 PM:

@Scott
It's quite eqsy to bypass the 64s on a CP55 without Backplanesoldering.
Get a Male DB25 connector and solder
6-19 R
7-20 C
8-21 L
together, plug it into the Tesctconnector J18 and remove the 64s.
Pin 23, 24 and 25 are EQ-inhibit but I don't really know how they work.

Posted by System Notices (Member # 2357) on 06-28-2010, 01:30 AM:

It has been 895 days since the last post.

Posted by Jeremy Weigel (Member # 4208) on 06-28-2010, 01:30 AM:

OK. It's been over 2 years and I haven't seen one of these come up on eBay or else where nor did I get any replies to the request in the equipment wanted forum. So, is there any body out there making after market version yet?

Posted by Louis Bornwasser (Member # 3063) on 06-28-2010, 01:50 PM:

A small hint: I have not used an extender in over 25 years. EQ the center channel first with the other 2 boards removed. There is enough room, barely, for your hand. Set the other two boards the same and verify in the center position. Install all 3 identical boards and then verify proper eq. You have already complete the center channel. The others you may have slight touch ups, but usually not. Louis

Posted by Jeremy Weigel (Member # 4208) on 06-28-2010, 05:53 PM:

Yeah, thats what I've been doing, but its a pain in the arse. Have to keep looking at the diagram to be sure that I'm adjusting the correct pot. Just makes an already tedious job that much more tedious.

Posted by Tony Bandiera Jr (Member # 2365) on 06-28-2010, 06:16 PM:

Jeremy, if I didn't need it for my CP-65 I'd sell you mine. [Smile]

I had another one that I think I sold here on F-T some years ago.

Posted by Sam D. Chavez (Member # 1841) on 06-28-2010, 09:39 PM:

I guess I'm going to have to make a new version of one of these. I have a very streamlined version made for me many years ago that does all the essential tasks including an EQ bypass switch so you can quickly determine what the last Bozo, er, tech did for EQ before re-doing all his work, and it takes very little space.

Posted by Jeremy Weigel (Member # 4208) on 06-28-2010, 11:35 PM:

That would be awesome Sam!

I spoken with Dick Niccum at LIT last year and he had made a batch of 25 Cat 67's based on the sample card he was given, but they were for the Dolby magnetic pre amplifiers. So if anybody needs one of those, I'm sure he probably has a few left. Last he told me was that he was looking for a sample of the cat 67 for the 55/65.

Posted by Tony Bandiera Jr (Member # 2365) on 06-28-2010, 11:58 PM:

Jeremy, Dick is slightly wrong, it is a CAT 92x extender for the mag preamps. [Smile]

His memory is slipping..but still a great guy and good resource for cinema stuff.

I also just remembered you did me a big favor with the Dolby Digital trailers, so if you need to borrow my CAT 67 send a PM and we can iron out the details. [Big Grin]

Posted by Jeremy Weigel (Member # 4208) on 11-18-2010, 12:12 AM:

Tony, you have mail.

Posted by Mark Gulbrandsen (Member # 72) on 11-18-2010, 10:09 AM:

I do it the way Louis does it. I was taught that method by a man from Massachusets whose name we are not allowed to mention here. Works well... touch ups on L & R are sometmies required after words.
I still have my C.E. PN card as well as my CAT 67 extender from 1985! I think the SN on my PN card is something like #27...

Mark