SSL 552 Summing Box

[mrclunk]

Wow great work chaps!
I saved a 552 for this too.
Thanks for documenting all this

 

[helterbelter]

I replaced the pics in this post :
http://www.groupdiy.com/index.php?topic=43999.msg585977#msg585977

 

[kante1603]

I replaced the pics in this post :
http://www.groupdiy.com/index.php?topic=43999.msg585977#msg585977

Hi Paul,

she's a beauty-really!
How did you manage to mount the small (original) switch for "summing in"?

Well done,

Udo.

 

[helterbelter]

Hi Udo,

the switch is not an SSL switch, only the cap is original. The switch is glued unto a baseplate that slides into the guiderails. this plate also holds a PCB that has the relays for the switching, as described in the same post.

I have picture in my phone, I'll upload that soon.

 

[helterbelter]

Oh, and I have also updated the first post : I added the description for the 552/ GSSL modification.

 

[kante1603]

Hi Udo,

the switch is not an SSL switch, only the cap is original. The switch is glued unto a baseplate that slides into the guiderails. this plate also holds a PCB that has the relays for the switching, as described in the same post.

I have picture in my phone, I'll upload that soon.

Cool,

so it switches the summing resistor network outs to the summing bus inputs when in.
In off-positionoes it activate the "normal" stereo ins via 10Ks to the same bus or do you activate the external ins of the 552 as this is a "standard" line- in?
Just curious because I am thinking about using this part on my build for some other stuff.

Cheers,

Udo.

 

[kante1603]

Oh, and I have also updated the first post : I added the description for the 552/ GSSL modification.

Holy sh*t!!!

Stop it Paul-by now I definetely don't know how to manage my not yet finished builts,hahahaha....

Awesome!

Udo.

 

[helterbelter]

Hi Udo,

the switch is not an SSL switch, only the cap is original. The switch is glued unto a baseplate that slides into the guiderails. this plate also holds a PCB that has the relays for the switching, as described in the same post.

Cool,

so it switches the summing resistor network outs to the summing bus inputs when in.
In off-positionoes it activate the "normal" stereo ins via 10Ks to the same bus or do you activate the external ins of the 552 as this is a "standard" line- in?
Just curious because I am thinking about using this part on my build for some other stuff.

Cheers,

Udo.

No, when the switch is set off, the L+R XLR inputs are routed directly into the 521 line amp.
When switched in, the XLR's are routed to the 10K resistor network, added up with the SubD's, into the 555F summingamp, and the outputs of the 555F go into the 521.

I have made a schematic for this, I'll upload it later today.

 

[kante1603]

O.k.,got it-I only had the 552 in mind and forgot your other modules,hahaha.....now that makes sense of course.

Thx Paul,

Udo.

 

[helterbelter]

You can add this to the 552 also : When switched in, the XLR inputs routed to the summingnetwork, and the pre-vca insertsend routed to the return , when switched off, the XLR's routed to the return directly.

Or, in case you want to use the insert for other equipment, route to an insert-send connector .

The 555F board is the same as the summingpart of the 552, with the only difference that the 552 has an external input added. And now I'm thinking of it : you can use this external input for exactly the same feature, with the difference that you'd have to wire a switch to one of the jumpers, so you can switch between "add" and "replace". The External input switch that's already fitted, turns it on and off. Note though, that the external input feature of the 552 has a different type of input, it has balanced inputs IIRC, but not with those fancy expensive de-balancer chips.

Speaking of the balancing chips :  I found these in the SSL spares shop :
http://store.solidstatelogic.com/catalog/65

Edit : WTF ?!?!? They're used in the MK1 XLogic Stereo Compressor  also !!!!?!!! And in the 9k mastersection.

Hmmmm, I'd really like to see the schematics of those........

 

[DigitalMetal]

Paul thats fantastic work on the compressor!
I have 3 IMO's left so im going to make another unit including the bus comp just as soon as my mixer is finished, (not far from completion now, just putting some more progress pictures up on my thread).
I wont fit the GSSL boards inside my current unit because of the Krone blocks so i will have to make a new one without krones.
The SSL online shop is really getting good too huh!

I just saw your updated pictures too, looks awesome!
I need to talk to you about how you did the lettering/logo on the panels it looks perfect and ive just got to do that with my mixer!  ;D

 

[helterbelter]

You don't need the complete gssl board, just a small piece. But well, it'll be a tight fit anyway.

Regarding my G-SSL / 552 experiment : I have bought a SSL panel from Dan, and today I also received a PPM meter for it (bought it from Hairball Audio). Not sure when I'll finish it up though, I'm currently making great progress on my SSL mixer project, not very much in the mood to put it aside, haha.

The summing lunchbox :
I have used Frontpanel designer for the designs, and they're CNC engraved by Frank (forummember NRG).
Some of his works : http://www.nrg-cnc.de/html/examples.html
He made most of my panels... Really good work. Precise.

"frontpanel designer" :
http://www.schaeffer-ag.de/index.php?id=97&L=1

 

[kante1603]

Hi guys,

cool to hear there's progress everywhere arround.
Bad is that my project is on hold at the moment,but I've got way too much work to do in real life...

@Neil:I second Pauls advice on Franks frontpanels-exept of my first GSSL he did all(!!!) of my fronts ans backpanels,I even let him do my mountingpanels for the innards (my NYD passive mixer described some posts ago is a pretty good example I think).

Have a good time,

Udo.

 

[DigitalMetal]

Cool thanks guys i will get in touch with Frank when i need my panels making 

 

[helterbelter]

Well,

it has been a while, but a week ago I thought it was time to be working on the 552 compressor again, haha. It has been sitting in a closet in an open box for more than a year, hahaha.

But now ..... :
I've got some additional info : It's possible to power the 552 from the GSSL board.
The post VCA send will be the output of the module.
The following things will be removed :
the external input, and the post VCA circuitry including tone and TB insert, and mono output.

There are just a few simple things that need to be done to the 552 boards , then it's possible to take out the logic part, so you won't be needing the -25v line anymore.

That means, that you can use the GSSL +/-15 volt PSU part for powering the 552 module, by changing the 7815 and 7915 to 7818 and 7918 (and use a transformer with a dual 18v secondary.)


Here's how to do it :

The mods must be made on both boards.
Summing stage :
-remove TR1, TR3, TR7, and TR9.
-remove TR2 and TR4, jumper source to drain. (pins 2 and 1).

That’s easy, huh ?

Stuff that’s not in use, best is to take them out to reduce powerconsumption. Except for a few hybrid chips, all are socketed:
T85052 board :
Hybrid chips : H6, H7, H8 , H9, H10, H11, H12
Demux chips : IC 7, 8,9,10,11,12,13, 14, 17,

Plus on the T85152 board :
Audio chips : IC 7,8,9, 15, 16
Hybrid chips :  H6, H7, H8, H9, H10
The audiobalancing chips are valuable, so, keep them as spare. (85501 and 85502). The other hybrids are practically worthless.

 

[DigitalMetal]

Wow that's great!
My building has halted at the moment too, no time no space , it's all rather sad
I'm really eager to do this build so keep up the great work !

 

[helterbelter]

the finished unit :





As said, this is the unit I built just for the experiment, and I have only finished it up to make a decent unit out of it. I have sold this one today to a well known english/dutch producer/engineer, he likes this one very much and says it sounds totally identical to the original. And he isn't fond of the Gyraf clone (However, I think the quality of the original Gyraf depends to how it's built, and which components and VCA's are used).

By the way : I have also Gyraf-modified my SL557 summing module, it sits perfectly in my console

Now, I want to see your modified 552 modules !

 

[DigitalMetal]

Wow that's amazing, well done !
You are making me really want to get moving with mine if only I had some workshop space and time, I will get there eventually but ive got to say a huge thanks to you for documenting it all for me to follow when i get the chance to do it.

Awesome work

 

[helterbelter]

Time and space..... I know, I have the same problems here.
That's also why it took so long to finish this one. But also because I don't need it anyway.

The 557 modification that I started building , is finished about 6 weeks ago, although the extra module I made for it that holds the dual SSC with Thrustfilters, mono/stereo/ext sidechain switching and a CnB, still needs wiring. I think I'll add feedforward/feedback switching as well, probably with integrated lowcut filter for the SC. I'd have to work that out first though...

I have just ordered components for my brother in law. He really wants to build a GSSL, so I gave him an SSL SL524 subgroupamp. The Gyraf SC mod can be applied to that module as well. I wouldn't use the 524 for summing though, so, just the line amp and the VCA's for the compression. We'll be building that unit in august. That means, I'll tell him what to solder, and I only have to doublecheck his soldering skills, hahaha !

 

[jplebre]

Holy Cannoli!
I seen this, read it about 3 times, and send a few emails out trying to get a hold of 552's

You guys are nuts! Keep it coming.