Distressor vs. 1176

There was a thread about the Distressor dissection.

The 20 pin IC's are something like 74HC573's used to keep the counter values during a power down. They are powered from the super cap.

The analog part of it is basically an 1176 - but replace everything with op-amps.

Distortion generation is by unbalancing the drain channel modulation compensation circuit (The part that feeds audio to the gate along with the control voltage).

There are diodes in there that look like they are clippers for distortion generation - don't get fooled. They are not there for that purpose - they clip the input signal only on an OPEN digital switch to prevent digital MUX feedthrough (when the signal exceeds VDD or VEE on those IC's the appropriate switch turns ON). This fooled me for a few minutes till I watched the signals with the scope.

There is no digital anything in the feedback circuit, and no software to be found. The muxes make it easy to patch things for different sounds, ratios, etc, but they are just that.

I can post a hand-drawn rough schematic (up for correction) on Monday when I get to work (I don't have a scanner at home). I don't think I'll reverse engineer the digital part as it's just a few counters.

Yes!

Please do so!

We love compressor schematics!!!

Jakob E.

Let's try this out...
Some of the R and C values might be out. The missing spot in the side chain are the band-pass and link sections. Also, I haven't done the audio HPF yet.

http://www.telusplanet.net/public/dulan/distressor1.jpg

ah yes....we are back to business :green:
great job so far dale! and thanx for taking the time...
this really looks like a modern version of the 1176/78

steff

So where to go with this? I imagine not so much a clone so much as a similar application with less involved control parameters (ie- not digital)?

tf

something for you in hi res :green:

http://www.soulset.de/distressor2.JPG

Really, really great work!

Can i have a version with pots and no preset recall please?

Just a schematic, a PCB layout, and a component sourcing list would do fine..

:razz:

Jakob E.

Funny thing was I was thinking of doing a PC board up for an op-amp version of the 1176, but between all of my DIY projects I might get to it in July or so. I've been boring holes in my vacuum chamber to get wires in for the evaporation heaters - once I have vacuum and heat I should be able to deposit nickel and gold on mylar.

call me crazy, but I think the digital part is the most interesting. I mean, since the analog portion is based ont he 1176. It seems to me the digital part is where the inovation is happening. I'd love to see the whole thing traced. That's just me....

Mark

what about the meter circuit. That could be used on an 1176 clone to eliminate the need for the expensive moving coil variety. The time constants and finer points are what makes the distresser so usable. The fact that it sounds like a distresser is related to the way it sets up. I guess not too much time was put into making the basic circuit and lots of time went into making the controls feel good and the distortion modes work for the most situations. It turned out to be a modern classic because it is so easy to get good sounds out of, making it have knobs insted of the digitally stepped controls is a bit like going back to an 1176. I would like to know what makes it tick and a big part of that is what resistors are used with the muxes and how the counters are set up in the digital section.

as a side note, I had considered making an 1176 clone using ripplu counters to step through the values, making the interface like a distresser, and using an LED bar graph meter. I guess I was closer to the real thing than I thought!

rock on.

Mark

The digital part are just a bunch of counters that step through the analog MUX settings, that's about it. Basically, it's simply digital mode switching but you could do it with mechanical switches if you wanted to. The 1176 interface is basically the same - input gain, attack, release, output gain, and ratio - same as the majority of the Distressor. I'm a bit reluctant to look at the metering because I need my Distressor together for a mixdown session in the next couple days - and I'd need to pull the boards out to look at that board.

well no rush, but I would love to see what the nitty gritty is all about. Thanks for going this far!

Mark

i don't think you get al the chips sorted out... :sad:
i already had a few good tech having a look at it and there's just too much assumption work to be made.

proof me wrong :razz:

That would ROCK!

I got most of the analog ones figured out. I think every 8-pin IC is a dual op-amp. There are lots of 4051 and 4053 mux IC's and some logic, looks like 74HC573 latches, 74HCxxx counters, etc. Does anyone else have one that they can do the digital side? I'm a bit short on time. Build one? Sure. But I'd like to improve on it some. I've been working on modifying the circuit a little bit (maybe a lot).

how would you mod it? I think it's really good. I like the fact that the controls are digital. In a session you usually don't have the time to try out every crazy combination of controls. The fact that they set up matched threshold and ratio makes it more immediately useful, IMHO. Someone said that the reason recordings in the old days sounded good was because you had fewer options to screw up in the process. Who was that?

Wait, was that even what you meant?

Mark

Wow! This saves a lot of work already!

Errr, jus curious Dale, how do you know all this stuff?
Got some people on the inside or sumptin?
None of my beezwax, never mind.

i'm impressed :shock:

keep up da real good work!!!

:thumb:

I've done a fair bit of reverse engineering in other fields - namely electronic engine controls. So attacking a circuit with an ohmmeter, scope, and voltmeter is no problem. Many automotive controllers use custom IC's or specially numbered IC's so having no part numbers is really no problem. In fact, in the Distressor we know the IC's are off-the-shelf so it's even easier than when you have a custom that you need to map out. Custom mixed-signal (analog/digital) IC's are a major pain to figure out.

My day job is as a circuit designer and software writer for an engine control company, so to me a lot of stuff is pretty obvious but that's because I deal with it all day long too.

The matched threshold and ratio makes sense - that's exactly what the 1176 does.

No inside information. If I had inside info I doubt that I'd be posting anything.

That is very, very good work indeed!

..My deepest respect..

Jakob E.

Amazing!!

Some of you guys around here are just too damn clever!

Excellent work Dale

I'm sure many people are interested in your discovery!.......(including Dave Derr!).

So could the control ideas and distortion generation be implmented to the Gyraf 1176?? Old school sound - modern operation!?

Tom