Dolby A Noise Reduction Cat 22 - exciter?

[loner22]

hey guys

i hear those units can work as a subtle enhancer / exciter type of device? i have one laying around, but don't seem to appreciate the effect. anyone uses those? how do you do it?

[Flogger59]

It's an old trick from the 70's, encode the lead vocal with Dolby Type A, and don't decode it for playback. It raises the brightness and pushes the vocal forward.

[WRGKMC]

They are getting harder to find for just that reason, people use them as vocal exciters. Theres also one that has large cards in it taht can be used as a compressor too.

 

I bought a DBX unit awhile back, I though it was the coder, but it wound up being a decoder only. I been using it in my Marshall Valvestate effects loop as an expander.

It makes the amp bark whan you hit the input it hard. Its extremely mild but enough to increase string attack dynamics. This helps a littel when you have multiple effects before the amp including compression. I like compression before drive boxes for sustain. i also use a hush type noise gate which kind of envelopes the sound down. The decoder expands the signal back out to restore some dynamics lost. Some might think why not just omit both the comps and the expander. You probibly can to get a simular sound but its more of a string touch and attack thing used this way especially playing leads.

 

Its not the greatest thing for sure. I wouldnt go buy one just for this application, but if you got one around from your tape recording days it may bw worth pulling out and hooking it up. I think I might have run the two channels of the expander in series. not real sure I have to check it again.

[Warhead]

I've witnessed this done with the old 301A and it was pretty fantastic, very unique presence for sure.

 

War

[Beck]

A great place to hear the effect is on old Carpenters records... mostly used on background vocals for an airy quality. It's very cool for harmonies.

 

Dolby Type-A is the one to use. I would look for something like the Dolby Model 365 w/Cat 22 modules or Model 361 W/Cat 450 modules. I see them on eBay now and then.

 

As Flogger said, you encode but don't decode to get the effect, and the effect is blended into the dry vocal to taste.

 

Listen to the "Sha-la-la-la" backgorund vocals. At 2:23 you can hear the effect on the harmonies turned up a bit... "As they melt the years away." There are limits to what you can hear in MP3, but you can get the idea.

 

[YOUTUBE]qEOGjJe5OLg[/YOUTUBE]

[loner22]

thank you, thank you, thank you )

i have to see which unit I have. it's definitely Cat 22 something, but not sure about the other markings

 

upd: it's dolby 361 A-Type

 

i tried it an hour ago, and in full bypass mode, it seemed to boost treble in a tiny, tiny amount. in ON position, it made my voice sound LPF'ed and HPF'ed at the same time. Sort of radio kind of sound

[loner22]

so i am running Dolby A Type 361 with Cat 22 model - i sthis a wrong combination for my purposes?

[The dman]

Believe it or not I have a Dolby 301A sitting in my rack that I never used. A friend and I picked up a couple dirt cheap on ebay. I know one of the tricks is to pull the low end card if I remember right. Now you guys have my curiosity, I'll have to toy with it a bit sometime soon.

 

I also read that Journey used them too

[WRGKMC]

They were used on allk kinds of stuff. You do pull a card and remember reading an internet article on it some place but you will have to google around to find it.

[loner22]

for anyone interested:

 

You can! The following info was sent to me from Dolby:

 

***********************************

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

***********************************

 

Approach at your own risk.

 

War

 

from Gearslutz

link: http://www.gearslutz.com/board/high-end/128740-dolby-exciter.html

 

[twostone]

Try it on drums if you got to much bleed you'll be surprised how it can help tame down those heavy cymbal rings from your tom mics. Esp. if the drummer likes a low ride. Good luck.

[loner22]

hey, thanks for the tip

[Beck]

As for modifying things, I don't know about any of that. All the stuff I did with Dolby A was pre-internet and I'm not familiar with those mods.

 

The basic idea was an accident... an engineer encoding with Dolby, but forgetting to engage Dolby on playback. Someone said, "Hey, that sounds kinda cool!" The rest is history. I'm sure people have messed with the internals for more extreme effects, but in my experience it was as simple as not decoding the Dolby encoded material. And this only works with Dolby Type-A, so B, C, SR, S or dbx won

[WRGKMC]

The idea of using a pot to vary the low end is a great idea. I'd do it in a snap. Sounds like a simple mod but you would need someone who can solder without messing up the board.

[loner22]

thanks, Beck

mucho fun for me ahead, with the new toy

 

just out of curiosity: here's a link to two small samples (550kb in entire file archive), one is absolutely dry, the other one is Dolby encoded. is it THE effect i am supposed to be getting from the unit?

 

right-click and choose 'save target as..'

 

this is how it was connected:

 

Dry - mic into mic pre into sound card

Dolby In - mic into mic pre into dolby into sound card

 

 

Switches "Record" and Dolby In were "in" on the dolby unit (a-type 361 with cat 22 module)

 

 

and no, you are not high, it's not English (i mean, the sample) :-P

 

edit: the mic is AKG414, the pre is ART Pro Channel, soundcard is MOTU 828, and a-type 361 with cat 22 module

[AluminumNeck]

very interesting. Gonna have to surf the local music shops for some used gear.

[conleycd]

I suspect that the input and output transformers add some pleasant distortion to the signal as well - at least in terms of harmonic exciting.

[WRGKMC]

I doubt they used transformers, but you can look up the schematic. Dolby circuits were extremely clean high quality circuits. The idea was to have "no" distortion of any kind added especially at the high frequencies thay were dealing with. They simply encoded the highs so they could be recorded without loss, then decode them back out for playback. Any kind of distortion there would ruin attempts to do that. For sake of the article, the dolby actls like a high frequency presence booster/EQ. You wouldnt want a distorted EQ mixing, same goes here.

[Phil O'Keefe]

Most analog noise reduction products used high frequency emphasis (encoding / recording) and de-emphasis (playback) along with companding - compression on recording / expansion on playback to reduce tape hiss and noise. That boosted high frequency sound you get when you encode in recording, but don't decode when playing back was the original way to get that effect. It's kind of an "icing" or "sheeny" sounding effect that does sound really cool on vocals sometimes.