Dolby 361 Mod

[numrologst]

Does anyone have some info on the dolby 361 mod? I found one the other day, now I'd like to know how to modify it.

thanks

[warhead]

This is info I received from Dolby when I was browsing around for a 360 or 361. I'm assuming you want to disable the low freq processing for use during mixdown. Straight from the horses mouth below:

***********************************
Hello -

It is indeed theoretically possible to disable the low-frequency band ("band 1") of a model 360 or 361, but it means getting at the edge-connector into which the Cat.No.22 noise reduction module plugs.

With the top cover removed, and looking from above and from the front, the lower pins are numbered 1 to 16 from left to right. The upper layer is lettered A to T (omitting I and round letters, that is G, O and Q), again left to right. To disable band 1, you need to connect a link between pin F (6th from left) and pin T (ground, at the right hand end). Incidentally, bands 2, 3 and 4 are pins J, M and S.

In addition, in case it is useful, the output impedance at those pins is 2K2, so if instead of a wire you connect a suitable resistor (or even a potentiometer) from a pin to ground, you reduce the degree of compression in that band.

Finally, I strongly recommend that any links or resistors be connected to the edge-connector socket, not to the corresponding fingers on the plug-in module, because it is all to easy to ruin the module.

I hope this may be helpful.

regards

Dolby Customer Support
***********************************

Hope this helps - War

[numrologst]

thanks dude... I'll try to figure that out when i get a chance

[warhead]

Well when you get around to it and hear the results let me know. I've witnessed the old Dolby 301 with the low end card pulled out in action during a mix and was pretty interested in this myself but have never gotten around to buying one to mod so...you'll be the first person I'm in contact with who does this! I take no responsibility by the way, that is literally a cut and paste out of a Dolby tech support email I received.

The 301's are impossible to find, while the 360 / 361 are readily available.

War

[numrologst]

They sound pretty cool, and my buddy had his vocals tracked through one a few months ago and they sounded fantastic.

I had been using an aphex 661, which supposedly is similar, so i guess ill find out

[Plinio]

Can i mod a Cat no. 280 for the same efect?

[warhead]

I would suggest finding Dolby's tech support email contact on their website, emailing them...and then being prepared to wait quite a while for a proper response.

I doubt it though...it's the CAT22 cards that the mix trick has been employed with.

War

[Mixermend]

Don't know what Dolby Labs were thinking about - this mod certainly doesn't work. They really cannot have tried it.....!

There is another Dolby Stretch mod thread on this board - a modification that does work (and is very easy to do) - can be obtained by sending me a PM.

John

[warhead]

Mixermend, I've never performed this mod and was simply passing along that info.

But are you telling me it won't work?

I'd like to know why, because if it won't I won't share it with anyone who asks!

War

[CapstanGreg]

I tried the above mentioned mod last night. It does not work. Shorting those pins does cause the "effect" to change, but on 3 of the 4 a popping noise is present. It was also very evident on my scope.

[Eric Greedy]

at the risk of opening a can of worms for myself i can do this. pm me. I won't be super fast as i have to go to my storage locker and dig an old modded card out to take a photo of it. it is indeed two resistors jumped on the circuit board. I got this from keith olsen many moons ago.

[numrologst]

It has been so long that I don't remember whose advice I followed... I am 99% sure I used Jim's method.

Seems/Seemed to work for me. I've used it on Vox and it is a pretty big night and day difference between when it is on and when it is off. Sounds really cool.

Maybe I didn't do the real mod, but whatever it is that Jim told me to do sounds pretty awesome. It doesn't really compress too much. I would describe it as very light compression with nice high frequency eq

[sleestack]

dolby 301's are not impossible to find. Ive seen 3 of them on ebay in the last year. Oh, and the whole expansion, compression, of different frequency bands detailed on analogrules is incorrect. And apparently they are very noisey

[Sigma]

audio guys are funny dolby made the cat 22 card and DBX the "K9" card for their noise reduction

[Plinio]

This mod is working for me.

[Neale Eckstein]

A clarification. Are the two connections that are side by side pulled from the circuit board completely and then additional connecting wires go to the end of the other two resistors without removing them from the circuit board?

thanks,

Neale Eckstein

[Neale Eckstein]

I didn't hear back from "Flooge" about my question above, but decided from the photo that the jumpers were connected to the resistors that are not next to each other without de-soldering them from the board. The other two are clearly de-soldered and it's also the modification John Gosland sent me. He did some experimenting and didn't like it as much with the jumpers. I decided to try both since I had two cards available. I was turned on to this vocal effect by Eric Pfeifer when he was mixing a project in my studio. He brought in a unit that had not been modified. I decided to see what I could find out. While there are some other threads worth reading, this one had the most useful information.

I've posted a folder at Index of /361_mods

Here's the text from the rtf file I put there for people to decipher it.
---------------------------

Included here is a zipped Pro Tools 7.4 session recorded at 88.2/24 bit. The audio files are labeled and can be loaded into any DAW. It's demonstrating a couple of different mod options for a Dolby 361 with a Cat 22 card. This is also called the "stretch" option. There are threads on Gearslutz.com and other boards describing it.

Dolby 361 Mod

The original vocal snippet is Vanessa Trien for a children's CD I'm producing for her.

I got the "Mod-no jumper" option from John Gosland (Mixermend) of Orchid Electronics. He makes some very nice "magic" boxes for guitar and he provided the PDF showing which resistors to disconnect. Here's his web site.

orchid-electronics.co.uk

"Mod- jumper" is from the photo posted by "Flooge" on the gearslutz thread above.

Then there are two unmodified cards from two different 361 units just to see how they compared to each other since I had to units available.

Neale Eckstein
FoxRun.Org

[jimmyz]

I'm looking to track down a mains lead for my 361 (UK) as the one I bought off ebay came without. Anyone an idea of the model of connector type on the back of the 361? With that info I can start digging for one...

Neale, great info, thanks.

Jim

[JFN]

Hi guys,

some great info in these threads. This seems like a really popular mod!

I was wondering, out of the mods discussed (using the jumpers and the one of simply disconnecting the 2 resistors) which one sounds most like the A301?

[itisnick]

I understand the general concept of re-purposing the Dolby A encoding as an exciter and that we want to lose the low end encoding.

What would you get out of disabling the band that you wouldn't get out of returning the signal as-is and rolling off the bottom end with EQ?

[Bassmankr]

Basically the Dolby A process breaks the signal into four frequency groups and then processes each group. With the old Dolby A301 trick you would physically disengage a couple cards from the front of the unit (just pull back a small distance to remove the card from it's edge connector) which would then disengage a couple of the frequency groups (no power or signal going to those cards). The cutting of two resistors on the newer Cat #22 card imitates the same thing, only processing two of the four frequency groups. The Dolby A process is more akin to compression and expansion than just using EQ. A multiband compressor is along the same lines.

[Doser]

I just did this mod to my 361 at it sounds great! Recorded a male vocalist who resembles Paul Simon in his character and delivery on a U87 through a GML EQ and Limiter into Protools HD7.4 using the 192 interface. I used it on the mix down and it literally popped it out in the mix giving it a greater fidelity in both the high end as well as adding some analogue tone to the sound. The best $150 I spent on ebay!