GSSL with VCAs using 8 x 2181

[SSLtech]

The first turbo is built, it is tested and it works PERFECTLY!

We're putting the finishing touches to some (hopefully) foolproof instructions (having learned from the 'ultimate' thread that they need to be quite clear and unambiguous).

Yesterday I did shoot a video of a GSSL without the turbo, placed on an SSL 9000 J-series console, and compressing the same stereo buss as the console buss compressor, with similar settings, then I bolted-in the turbo board and re-shot the video with the same settings.

The 'before-and-after' video is most compelling, and hopefully allows everyone to see exactly what the issues with the 'standard' GSSL are. -the meter behaves VASTLY differently to the SSL console compression meter, illustrating perfectly how completely different the standard GSSL behaves on 2-channel material, compared to a true SSL compressor.

The video was shot with the top of the GSSL removed, so that you can see how easily it fits in etc. It also details exactly how to perform the same test yourself, so that you can see your GSSL 'misbehaving' and see it for yourself, first hand.

What's most reassuring is that once the turbo board is fitted, the exact same GSSL with the exact same settings then performs EXACTLY the same as the SSL buss compressor.

I've edited the video and commentary together, but I just have to wait for Rochey to get back into the country and upload it to the Expat Audio site.

I have built and tested several boards, and they've ALL worked perfectly, so we're almost ready to launch this. -Probably best if we start a dedicated thread in the Black Market, I think.

Thanks to everyone for for being patient, but it's done and it works, we're just finishing off the complete 'package' so that everyone has an enjoyable experience with it.

Thanks,

Keith

 

[radiance]

Can't wait to see this video :grin: :grin:

 

[RedNoise]

so can't I ... :thumb:

 

[rrs]

Just wondering it this will play nicly and be easily implimented with the Thrust/ HPF being offered here :

http://www.groupdiy.com/index.php?topic=26669

And also the Steffen HPF that Greg was selling a while back.

 

[SSLtech]

These should work fabulously with the sidechain filters.

I only have one question: I'm looking for the installation instructions for the sidechain filters to see if they go BEFORE or AFTER the 47kΩ summing resistors...

Can anyone point me to a set of comprehensive instructions?

Thanks,

Keith

 

[rrs]

[quote author="SSLtech"]These should work fabulously with the sidechain filters.

I only have one question: I'm looking for the installation instructions for the sidechain filters to see if they go BEFORE or AFTER the 47kΩ summing resistors...

Can anyone point me to a set of comprehensive instructions?

Thanks,

Keith[/quote]

Is this what you need?

http://www.groupdiy.com/index.php?topic=12024

http://members.cox.net/capstanrecording/GSSL_PCB_SCmods.pdf

Not sure about the newer Thrust/ Supersidechain one though.

 

[dissonantstring]

deleted (double post).

 

[dissonantstring]

hi keef,
i'm most likely wrong, but i don't think there are any comprehensive documented instructions for any of the various sidechain filters, but i am almost positive that both greg's sidechain high pass filter and stephan and peter's (clintrubber) sidechain thrust filters replace the 47K summing resistors (meaning, input of the summing resistors goes to the filter pcbs inputs and output of the filter pcbs go back to where the 47K summing resistors link into the sidechain VCA - bypassing the summing resistors). hope it makes sense. i believe barclaycon's super sidechain filter works the same way.
can't wait for your turbo boards to come out!
regards,
grant

 

[barclaycon]

Yep.
Info here:
http://picasaweb.google.com/barclaycon/GSSLSuperSidechainPCB

 

[SSLtech]

Okay, the Turbo goes right AFTER the one of 47k resistors, so if you are using an aftermarket sidechain filter, you'll need TWO sidechain boards, one from L, one from R and return the output of the L to the GSSL, and return the output of the R to the Turbo.

That's it.

I'll make a graphic and add it to the detailed instructions.

Thanks, all!

Keef

 

[jrfred453]

I'm looking forward to the release of the Turbo board!
If you used two aftermarket sidechain boards you'd have to use one requiring a 2 pole 6 position switch as opposed to the eight position ones we just bought? Since there are not any 2 pole 8 position lorin switches.

Also if I use dbx 202 on the main board it seems most people are using dbx 2150 vca for the sidechain, can I still use that configuration with the turbo board? Or are we limited to only the 2181's with the turbo board?

Just thinking ahead.

 

[SSLtech]

2181, 2180, 2151, 2150... all perfect for the turbo.

I just tried a 2181, a 2180 and a 2150... I have a 2151 to try, but I fully expect that it will be fine. -Tracking between channels seems to be fine with any of these.

You can mix-'n'-match: my test 'mule' has 2x 2181s for the signal path and 2x 2150s for the sidechains, but I've kept the 2150 in the GSSL sidechain and swapped the turbo VCA with no measured difference in either compression curves or threshold between left and right channels.

Amplitude sweeps for L & R channels overlay perfectly on the Neutrik A2 for amplitude sweep input/amplitude out transfer graphs, which means that I have every confidence that you should be able to mix and match VCAs, although I have a few 2150s in case anyone wants to match them for the sake of reassurance.

Keith

 

[vertiges]

That's just GREAT !!! :thumb:

Keith, than you so much for doing this !

eD)))

 

[renx]

Should I change the topic of this post?

 

[SSLtech]

Not necessarily... I think the point is valid and also very searchable.

I think that by Monday I'll start a new thread in the Brewery... unless you'd like the thread split...

(never done that yet, so I'm eager to try!) :wink:

Keith

 

[emx]

OMG! This is exactly what I want for completing my build. I have to have one now!

 

[Rochey]

I have a 20 hour flight ahead of me tonight (in abotu 2 hours).... I expect to update the website offline with details of Turbo.

Hopefully, by Saturday night, Dallas time we'll have www.expataudio.com ready for orders.

/R

 

[SSLtech]

I do hope it's not supposed to be on an American Airlines MD-80! :wink:

:green:

Keef

 

[Svart]

so this is just a second sidechain to bring the GSSL to dual mono?

 

[SSLtech]

Yes... sort of. Dual-mono DETECTION, but not fully-independent-dual-mono...

Fully-independent-dual-mono would allow different ratio, attack, release, threshold and makeup gain for each channel. -Oh, and of course, you'd need two gain reduction meters also.

-There's an Alan smart has that, but the original SSL uses dual sidechain detection, which then feeds a common time constant, threshold, ratio and makeup section. When switched to stereo mode, channel 1's controls are relay-switched to control both channels. -That would be possible with two GSSL boards and a few relays, but I haven't played with the Alan Smart compressor for mono instrument tracks, so I haven't talked myself into that yet..

Keith