Distressor vs. 1176

[rafafredd]

So, who is working on the Dist comp clone PCB?

 

[dale116dot7]

Well, I was thinking about doing sorta a clone but not exactly. First, an exact clone isn't necessarily a good thing for a great way of doing things from a commercial/business sense, you know. Plus, I've got an eye on a bunch of improvements including removing any signal-path capacitors (which tend to be electrolytic), and changing to a microcontroller based front panel with DAC controls of various trimming functions. Plus, I was thinking of adding some neat mods to the gain control stage. One of them is neat, I think - run two JFET attenuator stages in parallel but one with the signal inverted. I was playing on the simulator with this configuration and found that I could make yet more neat 'sounds' this way. I might try breadboarding this idea (at least the gain control part) this weekend, if I have time.

 

[rafafredd]

Yes Dale!

This sounds good.

I always thought that entirely new DIY projects is the best way to go.

 

[chrissugar]

EDIT

chrissugar

 

[mig27]

neat stuff - keep it coming!

 

[daArry]

all in a days work eh dale :wink: awesom stuff!

 

[dale116dot7]

I've been simulating a variant and it's looking pretty good - I need to work on stability and high ratios yet, then I need to know the sound - that means building one - at least on a solderless breadboard. Maybe this weekend or maybe next. I've got a two-day bluegrass gig starting tomorrow (I play upright bass) so that's taking up most of this weekend. I could take my laptop to work on it between sets, I suppose... :guinness:

 

[StephenGiles]

How are we going on this?

 

[ijr]

Hi Dale!

run two JFET attenuator stages in parallel but one with the signal inverted

:thumb:
This was the thing I played with in Russia about 8 years ago...
http://www.geocities.com/igor_jazz/rus_fet_comp.html
Modyfied board finally was done with about 10 opamps
(everything was tweaked , an idea is what remains from this circuit).
If you use matched FET's and good distortion cancellation circuit, it is possible to get here very good results.
Just a littlte thing: due to nature of its inherent distortion, single-ended
FET compressors sounds more fun then "symmetric" brothers ;-))
BTW, another good example of symmetric FET compressor is Drawmmer
(gain reduction stage here is kinda instrumentation amplifier thing with FET
working as gain resistor.) This way, signal on FET allways low and
thus low distortion...
Another way to make nice compressor, is DC coupled vary-mu,
and this thing is possible 'cause I have unit working more than year in the studio. But .. this is a bit OT.

 

[bluebird]

Hey that looks very simple in its original form. I'm assuming it did not sound that good or you would not have modified it?

 

[radiance]

How is the breadboard doin' Dale?

 

[toby]

[quote author="dale116dot7"]There was a thread about the Distressor dissection.

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

i spoke (via email) about this with ted fletcher, and he suggested the was big influence from ADR in the sidechan aswell.


toby

 

[dale116dot7]

I've not been working much on any compressors recently, though I might re-start. Most of my DIY-time has been in building mic capsules, and building a vacuum system to do gold vapour deposition onto the diaphragm. I've got the rest of the mic capsule part figured out.

 

[Svart]

very interested in the design! If we can get a better schematic I would be happy to ATTEMPT laying out a board.. :green:

 

[tony dB]

did anyone say board? :green:

 

[bubba_b]

I am interested, as well.

I imagine Dale has a head the size of a beachball to fit all that brain. Smart dude, you are, Dale.

 

[dale116dot7]

I'd have to recommend against doing the board thing at this point. I had a discussion with the original designer of that compressor, and though it ended up friendly, it's not cool (or legal) to clone something that's being made now... an 1176 or something that was obsoleted by the manufacturer, ok. But something that's current is different. Can we say lawsuit? I thought so. Unfortunately, because I posted the initial schematic, I'd be at least partially liable and I don't really want to do that.

I'd say we try something a bit different.... maybe start with the 1176 but wrench it around differently than Empirical Labs did to make it our own? That would be cool, legal, and make a different, but related, sound. I'm really busy building microphone capsules these days, but I can maybe contribute something here when I have time.

Here's something to start with, though:
- Start by taking an 1176 complete with gain structure, and replace the transistor amplifiers with op-amps.
- do the same with the side-chain amplifier
- buffer the control signal with a low-leakage JFET amplifier to stabilize it
- buffer the low side of the JFET using an invert of the top side only - so the JFET's gate has DC only on it... note this is opposite of the 1176 where the gate voltage is modulated. Trim the gain of this stage (make it variable from 0.5 to 1.5) to minimize control feedthrough. Use a DC coupling around ground so that you don't need a big electrolytic capacitor here.
- Add a DC servo so you can deal without coupling capacitors anywhere. This is critical at the JFET junction.

This looks interesting, similar, but different, and would be a neat DIY project. I would stay away from the feedback mechanism that the EL8 uses, and I would also stay away from the digital switching and use just op-amps, pots, and mechanical switches. Partially for legal reasons, but mostly to make it easier to DIY. Anything that has software or lots of digital logic is a bit tricky to troubleshoot, and it is super-easy to blow up.

-Dale

 

[bubba_b]

I think the way this discussion has lead is very good. This is how new stuff gets invented. Since there really is nothing new under the sun, it's all just variations of a theme anyway. I agree, cloning something that is out now is stealing. Cloning something that is discontinued is resurrecting. Making something new-but-similar is innovation, and I'm all for that.

Being as much of a newb as I am, I think I'll leave the designing up to more experienced folks here, but I will definitely be in on the beta testing.

On this subject, however, how is the GSSL different from the SSL XLogic out now (besides the sidechain, which some guys have also done here), or the 1176 clone we do from the UA 1176 still in production?

At AES this weekend, I talked to one of the API guys for a minute. I mentioned I built a 312....he lost a lot of interest in talking to me after that. :grin: He was kind of a snob to start with, though.

 

[thephatboi]

Dale, you seem like you know the distressor very well. I have a couple of them and was wondering if anybody has ever messed with the front end to make it less susceptible to distortion on the input from a hot incoming signal. I like the distortion for some things but could use this compressor on alot more stuff if I could truly get it "clean" I have messed with turning down the output of my mic pres prior to going into the Distressor and that helps but then I have more noise with the make up gain etc. Any body else complain of this? Any info or ideas appreciated. I am not a tech so would have to hire out any work but would love to mod my Distressors to handle a hotter input cleanly. thanks, Sean

 

[dale116dot7]

How hot? Is it enough to clip the input amplifiers? If so, then there's not much you can do except turn down the input. Does the noise go away when you have a hot input and lower the input gain control (ie same compression point)?