"Crush-n-Blend"

[mikep]

if you are just trying to add a small fixed amount of dry signal to a feed-foreward VCA-type comp that uses a standard current-mode VCA (ssl, dbx etc), you can simply add a resistor in parallel with the VCA. one end of the resistor connects to the VCA input pin, the other end connects to the VCA output pin. doesnt get much simpler.

mike p

 

[dagoose]

[quote author="radiance"]I think the pin numbers in the schematic are wrong.
Looking at the pin out from the ssm2142 pin 3 goes to ground and 4 is input.
8 is output + and 1 is output - but those are swapped to reinvert the signal right?

[/quote]

To livingnote:
have you seen this? Maybe that is wrong... haven't checked your pcb yet tough.
A pcb is interesting indeed, easier to build then vero.

 

[matthias]

if you are just trying to add a small fixed amount of dry signal to a feed-foreward VCA-type comp that uses a standard current-mode VCA (ssl, dbx etc), you can simply add a resistor in parallel with the VCA. one end of the resistor connects to the VCA input pin, the other end connects to the VCA output pin. doesnt get much simpler.

I already tried this and it doesn't work wit good results. the problem is that the make-up gain comes from the vca itself and as more gain you apply ... the compressed output signal flows back through the resistor to the input of the vca.

 

[mikep]

[quote author="matthias"]
I already tried this and it doesn't work wit good results. the problem is that the make-up gain comes from the vca itself and as more gain you apply ... the compressed output signal flows back through the resistor to the input of the vca.[/quote]

if the VCA is providing makeup gain then the amount of dry will change as you adjust the gain, but I was talking about a big value resistor for just a small amount of dry. way less than 50%.

NB: if the VCA is followed by a virtual earth amplifier, no signal will be able to flow back to the input of the VCA.

edit: did you try this with a true feed-forward sidechain? Im not sure about the GSSL, but the SSL G384 uses a seperate VCA in the sidechain, so that the signal is not taken from the output. dbx uses an RMS detector fed from the input.

mike p

 

[livingnote]

Yeah, thanks Dagoose, I tripped over that one while I was designing the copper layer and went "wait a minute..." when I was reading the datasheet. It should be pinned correctly.

Funny thing is that it passes audio, but the audio including distortion doesn't change even when you pull the OPA. I tried this too with the SSL symm in/out and it does the same aria. It seems like there is an underlying method to the principal madness here, but what can I say, I still haven't gotten to opamp theory in my practical electronics course so it's a lot of guesswork.

 

[radiance]

Soooo, is there anyone who has succesfully build this thingy?

 

[radiance]

[quote author="livingnote"]
Funny thing is that it passes audio, but the audio including distortion doesn't change even when you pull the OPA.[/quote]

Have you tried connecting pin 6 from the ssm2141 direct to pin 3 from the ssm2142? It should not be very hard to find out where the distortion is coming from....

 

[dagoose]

[quote author="radiance"]Soooo, is there anyone who has succesfully build this thingy?[/quote]
My parts are in so i'll probably give it a go this coming week when i have the time.
Hope it will work.. first i have to figure out how to wire up all relays, just the flipping of the comp/eq side uses 16 relays. :shock:
I'll think in total my box needs at least 40 relays.. damn..

When it's done (and working) it has 3 inserts for compression (with crush n blend), 3 eq inserts and flipppable order (EQ > comp or comp > eq).
Also it has a bypass for the comp and eq section and will be balanced and it fits an 1u. :green:

 

[livingnote]

Wow, that's some serious relaying in there...for a while there I was thinking about making a dual mono capable edition but then got off the idea because if you do that you end up building at least a 2 HU, with tons of relays and so you have 2 channels in 2 HU rather than just building 2 stereo ones and still being able to shove mono.

The thing with pin 3 to 6 is the next thing I'm going to be trying out, though I'm out of my lab for a few weeks...but my feeling kinda tells me that if you do bypass the pot section then it'll just work like a glorified wire...just a hunch, though...

 

[dagoose]

any news on the not working crush n blend?
I'll probably start next week, this week i'm DIYing my house with paint

 

[livingnote]

Not yet at any rate...I'm in my old hometown, and feel quite castrated without my little component arsenal. I recently went to the only electronics store around and wanted an OPA, and the guy didn't even know what it is. Then I went "well how about a TL072" and he roots around and finds...a TL082 in the old ceramic sandwich and goes "here, this one's better", and sold it for two bucks fifty.

But the etching is fantastic here If you come up with anything, let me know.

 

[dagoose]

OK, started to work on my insert box again and it looks like it worrks :grin:
3 compressor inputs, 3 EQ inputs, all switchable with a lot of relais.
I'm going on a holiday today (sicilie Italy, where the sun shines and the food is gooood!) and when i'm back next week i expect someone here to have build a working crush n blend so i can also start and implement it in my design. :green:

Though i'll probably start to work on my sontec first, the pots came in!! hihaa!

 

[rrs]

So who's making the boards for this thing?? ;-)

 

[livingnote]

Well, I'll be in the lab again this weekend, and then I can figure out what the heck is going on with this distortion issue. Then we can get into making a final board...

 

[radiance]

sooo, what did your visit to the LAB reveal ?

 

[matthias]

if you need some more inspiration have a look at these new units...

http://www.chandlerlimited.com/products/universalmixcontrol.php

http://www.manleylabs.com/containerpages/backbone.html

 

[radiance]

Yeah...saw a little movie tutorial from the Manley on the GS forum.
It's quite a cool & complicated unit if you ask me. Lot's of hidden functions.]


When I first saw your reply I thought you had managed to get hold of the schematics even though it's not even for sale AFAIK :twisted:

 

[dagoose]

[quote author="matthias"]if you need some more inspiration have a look at these new units...

http://www.chandlerlimited.com/products/universalmixcontrol.php

http://www.manleylabs.com/containerpages/backbone.html[/quote]

wow! The manley is kinda like the thing i have build/been building!
Only thing is that it needs the crush n blend installed otherwise it's about the same with 6 inserts (3x comp and 3x eq)
OK... mine doesn't have the MS and level control etc but it's also a mastering inserter with flippable inserts (like i descibed some posts before)

I will post pics tonight, i'm on the road right now..

 

[signalflow]

So I'm doing a parts order and wanted to know, what is being used for VR1a and b? Should it be dual gang linear? If so could some one point me to one cause I'm not having luck finding one within mousers site.

Thank you,

Casey

 

[radiance]

Should be LIN.... Maybe download a data sheet from a potentiometer brand mouser carries and find out the part # for a dual pot. Then search the mouser site..