Crush N Blend Rev 6 V3 (CNB / Wet-Dry Circuit) + Support

[TwentyTrees]

Hi all!

A quick question about the Crush-n-Blend circuit - I'm interested in whether it would work plug-n-play style for non-GSSL applications, such as (looking at the build queue) 2254, LA2A or TG1 compressors? Or would any mods be necessary? I can't see why it wouldn't just play nicely (as long as it was inside any I/O transformers) but I have been known to miss really obvious stuff before...

Grateful for any thoughts!

Andy

 

[livingnote]

Yeah basically it should behave well just about anywhere that has line level or thereabouts running
around in it - it's fully buffered and so unless you have like a 40V signal in there or something like that
you ought to be fine. I've even given it trimmers all around (testing the latest version right now that has
trimmers and feedback resistors provided so that you can really gainset to your heart's desire )

 

[TwentyTrees]

Brilliant, thanks! That's really helpful. Much as I thought. I'll be in touch about buying some boards soon...

 

[Eliani]

I took the file separation files and cnc'ed myself the crush'n blend PCB, I used a bunch of left-over components and can't wait to implement this one in my dbx202c gssl...

 

[livingnote]

Stunning 

Keep us up to date on how the project goes!

 

[Eliani]

So I was able to implement the Crush N Blend PCB into my standard (old version PCB) GSSL build. I still need to rip the Gold Can VCA's from my dbx 903 modules, and more functions will probably be added, turbo PCB for oxford mode and maybe the super sidechains for the thrust-functions and probably more important the high-pass filters.

But I was amazed that the Crush N Blend function worked perfect from the get go!! I was thinking to stumble upon some kind of problem, probably because I did the PCB myself... but nothing!

I do have one relay that takes a little longer to let go when I switch the parallel functions off, resulting in a small dropout (2s maybe?). If I were to bypass the blender (which I probably don't want to anyway) during a live mix that would be akward...
I took my 12V for the relays from an externall source for testing, since the old GSSL PCB only has 15V (I think), but then I will probably upgrade the PSU-filtering and add a 12V regulator on the PSU PCB...

please don't Judge my build for clean wiring just yet, this project is far from finished!!

 

[Eliani]

Just fitted the cold cans, that took me the better part of an hour!! Removing the already installed vca's was no problem since I've got a good de-solder device, but I had to move a few components to the bottom of the PCB, but everything fitted as planned!

I found that my external PSU had a slow ramp on the shut-down, so that solved the akward silent moment when switching the blend mode off!!

This is probably the best mod to a GSSL clone I ever did!! Thank you Livingnote!! Now the search starts for the turbo sidechain schematics... I've got those VCA's leftover now!!

 

[livingnote]

Really cool!  How did you turn the PDFs into milling and drill data?

It's really good to know that this is possible because I have been of the
mind that Illustrator and PDFs are a good way to share stuff, but this is
just mind blowing that you can actually haul off and run a CNC machine
off it. I would be super happy to know how to do this because it opens
up a whole new world for making PCBs with something like Illustrator.

 

[Eliani]

Well there are a couple of ways to do this...

- you could screencapture to an image format like jpg or png and have your cad/cam software convert the 2-tone into vectors.

- but the best way is to import the PDF into your cad/cam software, I use Vectric Aspire. A PDF is a vector based file so it imports as a bunch of single lines which you can easely use an expand funtion on to create your traces and have the software write the gcode for cutting the piece...

 

[livingnote]

Ah cool, I'll check it out

I also really like the construction with the PCBs on the solid crossbars
there - must make for good transport-readiness of the unit. I remember
Frank having this concept in his custom cases, might look into that stuff
especially for amp designs and stuff like that.

 

[Eliani]

I remember
Frank having this concept in his custom cases, might look into that stuff.

This is one of franks cases although I'll probably end up building this one is a custom 2 unit case as I'll be adding more funtions to the GSSL. I'll probably do the super sidechains on a single euro PCB, and stack them with the Gyraf PCB.

I derived the second Sidechain circuit out of Jakobs original schematics (don't know if this is the same as the turbo sidechain PCB, but I guess it is as it's got the same parts!)

I might do a custom pcb layout your PCB and the different sidechain filters/oxford/aahron circuits that fits the original layout and kind of shifts into place on to of Jakobs PCB so there's as little wiring as possible! I'll probably want to monitor input and output levels so I might add a VU meter to the project and keep the gain reduction meter seperate... I'll see

 

[Eliani]

So the GSSL is still in the same fashion it was last time I posted the pictures, but I was actually thinking of building a separate Summing/parallel box... so a crush'n blend in a box! what would be the best way to do this balanced? I'm no fan of negative wires to ground, So I guess i/o transformers would be the way to go?

And  what would be the impedance needed for input and output?
10k:10 for input and 10k:600R for output?

 

[livingnote]

Not too sure about transformer possibilities but there is the
capacitor coupled version that was made to be a standalone version
that ought to work. Not sure yet about the cap-to-transformer
coupling, but if you can basically go from a 5532 output through
a capacitor to a transformer then yeah, that ought to work.

 

[Eliani]

I'll just ground the negatives as a test, but I'll have to do so after a matching transformer since otherwise I will ground negative on the signal going to the FX device too! I guess a splitter transformer would do too.

Can you tell what the input and output impedance for the crush 'n blend circuit is?

 

[livingnote]

Well unless I'm overlooking something big - right from the schematic the input impedance
is about 10K and the output around 51 to maybe 100Ω depending on the resistors you use

 

[lukam]

Hi,

looking at the connections of the signals on the GSSL, there may be a problem where the DRY signal is taken from. At that position (after the first balance stage) the signal is inverse polarity to the signal where the WET signal is taken.
Am I missing something? Or does the THAT inverse polarity?
Thanks!
Luka

 

[livingnote]

Hey Luka,

aaaah good question - seems like I had considered it and then forgotten that
I had considered it and now that threw me for a loop. As far as I can tell, the VCA itself
inverts as well, so if you have the wet insert point after the first output opamp phase
post-VCA is identical to pre-VCA (and anybody correct me).

http://www.thatcorp.com/2180-series_Pre-Trimmed_Blackmer_IC_Voltage-Controlled_Amplifiers.shtml

Here's the basic application sheet of the 2180 - from what I took back then, the fundamental
circuit includes the inverting output buffer and the input is called " – in".

I will measure it out again but so far the experience has not included any phasing weirdness
(and it should really cancel a bunch of itself out if that were the case and you hit dry with wet in reverse).

 

[Olegarich]

Hey Lukas,

I just want to say that this Mod is amazing. If I would go for one mod, that would be this one. It's just gives you so much more space for a right comrpesion.
I'm sound producer for a 14 years now and the main problem with bus compressors - easy to over compress, now with that mod, this problem is gone.
Thanks Mate!

 

[steves.mastering]

I agree with the last post, main problem with bus compressors is they need a wet/dry knob.... and also a HPF in the sidechain.

I'd be in for a couple of these boards, one for a compressor I'm working on and maybe one for a stand alone unit for another other compressors.

These PCB's  still available?

 

[livingnote]

Hey yeah, they're still available. Last revision is in the final testing stages and it looks
good from what I'm getting back.