SSL Mixbus Compressor Clone

[guitarguy12387]

Well i currently have about a billion projects that are about half done (and i'm hoping to get a hold of a few of owel's new kits too!). But i figured i'd throw this one up here too for anyone whose interested. I'm building several units... one for a friend. Plus, i didn't realize they were stereo units when i ordered the PCBs, so i'll have a few extra kickin around for a while prolly...

This one's a clone of the mixbus compressor off of the SSL4044E console. I haven't had the time to research it much so i don't know a whole lot about it. It is transfomerless (electrically balanced i/o) which helps make it a fairly cheap build. The heart of the compressor is the VCA (voltage controlled amplifier). This compressor originally housed a pair of DBX 202XT VCAs but they are quite rare. Another common VCA that SSL uses is the DBX 2150. Both of these are supported by the PCBs. There are further options for the VCA: THAT2180/2181 is the latest version of the 2150. I'm probably going to go with the THAT Corp. substitutions.

I'll keep this updated from time to time.

Here's a pic of the boards which are mostly stuffed. Just missing a few trimmers and the VCAs. Also, i still need the switches/pots for the controls. I'll prolly try and find the power transformers next and fire it up and take some voltages before plugging it all in.

[owel]

Hey cool! Nice that somebody else is building these.

Here's my build from a few years ago.
http://www.fivefish.net/diy/SSL4000Comp ... efault.htm

[guitarguy12387]

Wow i hope mine looks that good when it's done . I think i remember seeing that from some time ago too. Did you use the THAT chips in yours?

[owel]

Yes, 2180 I think.

[Hamstertronix]

Wow - you really are keen! Good to see you're building more projects - how are all these things sounding?

Keep up the good work!

Cheers,

James.

[guitarguy12387]

Thanks, James!

The 1176 clone is great on most things. I find it most impressive on my acoustic guitar recordings. It really improves the clarity. I can try and get some samples if ya want.

If memory serves, Owel has some sound samples of the SSL on the link he posted. I haven't completed one yet so i cant tell ya haha!

Hows things with you? Did you ever get a submission in that contest you mentioned a while back? How'd that go?

[Hamstertronix]

We got our record in, but it wasn't accepted. Ken and many others like it though - so we're cool with that - LOL

http://www.soundclick.com/ravensgolde

You'll see it there if you want to take a listen

Cheers,

James.

[guitarguy12387]

Hey owel,

Do you recall what kinda VU meters that are on yours? I like the look of those.

Thanks

[owel]

Hey owel,

Do you recall what kinda VU meters that are on yours? I like the look of those.

Thanks

I got these meters from a radio ham operator selling his old stuff. So they're reeeaaally vintage

If I recall they're 10mA full scale. No backlight.

[guitarguy12387]

Ahhh ok. Too bad. Thanks!

[ecc83]

Have look at this, Model: ERV30VU

www.sifam.com

Rock on,
Dave.

[guitarguy12387]

Very good. Thank you very much Dave. I will have a look at that one. I can't seem to find much information right off the website. I think they suggest a 1mA linear. I'll try contacting them and seeing if i can get a datasheet for that specific meter.

Thanks again!

[ecc83]

No worries!

I also have a very simple single transistor drive circuit, might have sent you that before?

Dave.

[guitarguy12387]

Yeah i think you did send me that before actually. I'll have to dig it up and take a look! Thanks again, Dave.

[guitarguy12387]

Update:

Just got the Expat Audio "turbo mod" boards today. Their purpose is basically to make the GSSL work more like the original SSL desk compressor.
Here's a video for more:

http://www.youtube.com/watch?v=EQD8GPhFGYE

Here's pics of these boards stuffed and also a pic of the meter im thinking of using:




Now i'm just waiting on a single rotary switch and then i can fire her up and test it!

[guitarguy12387]

Update:

Got a shipment from mouser today which contained the last bits for this project! Well... component-wise anyway. Hooked it all up. Fired it up. Nothin. Not even the power led. After about half an hour of searching, my patience was wearing thin... searching for the hum/hiss/oscillations in the API 312 clones wore me out. Finally i realized i had forgot to put the fuse in the mains fuseholder haha! Put 'er in. And voila! Lights. Hook it up to the computer for some audio testing. It passes audio fine. But did not compress! Ok... there could be worse problems i suppose (like wicked hum and oscillation... grrrrr). I search the entire board for solder bridges/cold joints/shorts/whatever. Finally found a lone short across a few of the connections. Fixed it. And voila! we have compression.

I'm not 100% sure its fully functional yet... i was expecting a little more dramatic sound. I believe i do need to switch out some of the R's around the VCA's to optimize performance. We'll see what happens after that. Although i am just noticing that the max compression ration is 1:10... i have to do more testing.

First impressions: Extremely transparent sounding. Particularly compared to the 1176 that i have fallen in love with haha! I tried it on vocals first. Could hardly tell it was there. It was definitely compressing though (confirmed by watching the meters). I'll have to try it some more to really get a feel for it on less dynamic sources. Next i tried throwing it on a drum buss. Still was quite transparent, even on 'extreme' settings. It didn't seem to have a very dramatic pumping sound on those big hits when the kick and crash hit at the same time! Very natural sounding.

All in all, i think it has potential to be a great contrast to the very characteristic 1176 that i use as well. I'll post more later. Pics too!

Next up: ordering the cases and start the drilling!

[ecc83]

Boring old fart intervening here!

Always...ALWAYS! Check your dc conditions first before you try to listen to ANYTHING!

Can save your ears, speakers, time and temper!

B.O.F. Out.

Dave.

[guitarguy12387]

Hehe thanks for the pointers, Dave! Did check this time! Even checked for voltages before plugging in the IC's... which is more than i can usually say haha!

Take it easy.

[SupremeWise]

Any updates?

I'd like to see how the casing looks, if its' done yet.

[guitarguy12387]

Yup! Well i have one clone 98% done. All thats left is to mount the PCB's to the case and get some knobs. I was planning on posting pics of the whole unit once i get those. That will probably happen within the next week or two. FYI, it sounds great IMO! I'll post up some soundclips as well.

I'd like to see how the casing looks, if its' done yet.

Hehe well i have to admit... i get pretty impatient when it comes to the mechanical design, so they aren't the greatest haha. No labels on anything as of yet, either. I HATE drilling the panels lol. With a passion. Most likely because i lack the proper tools to do the job right. At some point, i may go back and use FPD to design some new, pro, front panels at least... but at 60 ish bucks a pop for a 1u faceplate... it can be kinda pricey haha. I need to just buy a drillpress and some bits...

Anyway. I'm currently building 4 of these... one or two for friends... probably sell one or two and keep one for myself. I plan on purchasing a dedicated case for the one i'm keeping. Over at prodigy pro, there's a guy who sells real good lookin cases for lots of DIY equip, including this unit. Also, i managed to get my hands on a 'super-sidechain' board for mine. It is basically a HPF for the sidechain circuit, from what i understand.

So i'll post up the pics of the finished unit i'm finishing now before i move it. Again, probably within a few weeks. And once i get MINE finished, i'll post pics of that too... prolly wont be for a month or so.

Glad to see someone's interested!

[SupremeWise]

Cool!!
Drilling the holes sounds hard, must take lots of patience.

[guitarguy12387]

Hey everyone! Just posted up some soundclips of this compressor. Sounds great to me!

There's 2 files here. 1) 'SSL test' has a comparison of a mix with and without the compressor on the mixbus. It switches back and forth every 15 seconds or so between the mix without the compressor and the mix WITH the SSL. Just to get a taste. FYI, i tried to keep the gains as close as possible for this comparison... so you get a feel for the compression circuit... not the makeup gain lol. 2) 'Money' is the whole song with the compressor on the 2-bus.

Enjoy!

http://www.soundclick.com/guitarguy12387

Feel free to share any thoughts/ideas/opinions/comments/discussion!

Also... here's a pic of some compression in action... Blue = uncompressed, Red = compressed, if you can't tell...

[guitarguy12387]

Oh yeah... these are all in 'Turbo' mode too...

[guitarguy12387]

Hey guys! So i finally got around to uploading some pics of the finished products.

Here's one of the first ones. I've used these alot lately... i really like them. WELL worth the few hundred bucks it costs to put them together.