funky compressor

[turing]

anyone ever used a shure level loc compressor? was bowled over sufficiently that i want to try and build one. didn't find anything particularly enlightening on google, was hoping that someone here had any info on it or something similiar.

[Mark Hammer]

I don't know this particular compressor, but if it is a Shure, there is a good chance that what you like about it comes not from the design, but from plugging a guitar into something designed for either mic levels or line levels.  Just a wild guess.  Dig around the net and see if you can find out some info on how it is normally used.

[moosapotamus]

I've built one. Someone was selling level-loc clone kits about a year ago... the "sherlock". I think they stopped, tho. But, there's another "search term" for you, anyway.

It want's to see a mic level input, which means that you'll probably want a preamp to go after it. And, as Mark guessed, the real uniqueness comes when you plug "other things" into it. Much more interesting on a drum track (or an individual snare or cymbal) than it is on bass or guitar, IMO.

As I understand, it was originally designed to mimic the effect of moving a microphone farther away from someone who may be talking loudly. So, the control that sets the amount of compression is a three position switch with the settings... 8", 12", 18"... intended to indicate that those settings should simulate the effect of moving the mic that distance away from the the person.

I believe Shure service documentation can be googled.
You should be able to find a bit more info here, too...
http://www.prodigy-pro.com/forum/
UTSF - use the search function

~ Charlie

[al3151]

Found this- http://www.freeinfosociety.com/electronics/schematics/audio/shurem62v.pdf

[Mark Hammer]

VERY useful link.  Many thanks, indeed.

The schem is at the end of the document (thanks Shure Brothers!).

I think the answer to the initial query is found at the top of page 2.  Attack time roughly 1/2 millisecond.  Decay/recovery time, roughly 700 milliseconds.

When it comes to compressors, time constants is often critical to their feel.  You will note that this is intended to be a vocal mic compressor, so the time constants are selected to meet the needs of voice and not the sorts of transients that might occur in plucked, struck, or percussive instruments.

You will also note the relatively low "high" input impedance (50k).

So, this begs the qustion: Has anyone ever "perverted" their Dynacomp/Ross clone by replacing the 150k/10uf attack/recovery circuit with, say, 4.7uf and 220k? (for faster attack and longer recovery)

[turing]

thanks for the response everybody...........had a dig around for the sherlock but not much luck. it seems to fall into the fuzz factory controversy category.
soooooooooo, can anyone recommend a 'milder' substitute? milder in the sense of less likely to incite e-wrath that is. this will primarily be for drums, and i'm after some of that mad edge the level loc has. trashy is good, punchy is good, pristine is hopeless. don't need control over every parameter; a 'less&more' slider would be fine. attitude is essential though.

[Mark Hammer]

So the unit linked to is not the one you are interested in?

Back in the day, my old band recorded some practice room demos.  We were using a cassette deck (a Yamaha I think) with a built in limiter.  It sounded wonderful on cymbals, largely because of the long recovery time I suspect.  If you are simply looking for oddball compressors or limiters with interesting properties to use as "special effects" during production, keep your eye out for old cassette decks with built-in limiters, or AGC (automatic gain control).  Because cassette has fallen by the wayside, these things can sometimes be bught for very little.  Put it in pause+record and use the line out.

[moosapotamus]

I don't think there is any secrecy or controversy or anything about the Level-Loc or the Sherlock. Shure has even put the schematic out there in the public domain (link above).

The guy who did the Sherlock kits was Drew, and I beleive he was posting here for a while, back when he was offering the kits. I think he just got involved in other stuff and moved on. His web site is http://www.toothpastefordinner.com/ . If you email him, he might send you some documentation, or not, whatever.

Another recommendation for something very similar would be the old DBX boxes... 117 or 118 or 119 or 128... Hi-Fi units from the 70's. They show up on eBay occasionally for pretty cheap money.

~ Charlie