SSLtech

Improve your GSSL... for free!
« on: June 22, 2009, 11:46:23 AM »
Rochey and I have been working on a couple of developments for the GSSL, one of which -while not yet ready for announcement (a couple more weeks, we expect)- should significantly improve the performance. -As with the 'turbo', it's designed to be easily retrofittable to any existing GSSL, or incorporated into a new build.

I've been taking a long hard look at the GSSL's noise and distortion behaviour, and one annoying quirk of the GSSL has been hampering my measurements; You'd expect the GSSL to be at it's quietest when switched to 'bypass', and to distort the least when switched to 'bypass' (in reality it doesn't actually 'bypass' anything -it's really a "compression enable/disable" switch)... -But this is not what happens at all. -In actual fact the HIGHEST distortion figures for the GSSL are measured when the compression is DISABLED by the front panel switch.

But I've discovered what's happening, and how to make it stop. -And you can do it for FREE!!! -All it takes is popping the top, swapping a couple of wires and adding a third wire.

One of the two halves of the bypass switch (the part which only has TWO wires going to it) requires a slight modification.

Referring to this pdf:

On the component overlay (second page) two wires going to the "bypass switch" are marked "Defeat makeup when out". One connects to Pole 'A', and the second connects to contact A2.

Firstly, REVERSE these two wires. -If you (as I've done) noticed that it's just a simple "make" connection and possibly just connected them in no particular order, you need to make sure that the wire at the board end which is physocally CLOSEST to the 750K resistorneeds to be connected to the POLE (common contact) of the switch, and the other wire to the second contact.

Now, finally solder a wire to GROUND from the other contact "A1". -There's already a handy ground available at contact 1 of pole 'C' if you need it... ("C1" on the rotary switch as shown).

That's it.

Distortion in bypass is now a thing of the past. -I know that most people don't seem to care about distortion in bypass so long as the performance is unaffected while the unit is switched 'in', but I get distortion readings up to 0.755% worst case (when the unit is in 'bypass', ratio 10:1, threshold set to max) which drops to 0.007% on the unit currently on the bench with this modification.

It only takes a minute to do, and it fixes something which I've always found slightly bothersome, but which has now made my life MUCH easier.

Enjoy!

-Keith

"A waist is a terrible thing to mind"
Quote from: PRR
Ah, but that was 1999; we don't party like that any more.


EmRR

Re: Improve your GSSL... for free!
« Reply #1 on: June 22, 2009, 11:49:15 AM »
excellent
Best,

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde

Bluzzi

Re: Improve your GSSL... for free!
« Reply #2 on: June 22, 2009, 11:52:02 AM »
Keith: Thanks for sharing that! .775 to .007 is quite the improvement!

Jim

MartyMart

Re: Improve your GSSL... for free!
« Reply #3 on: June 22, 2009, 11:56:53 AM »
Fanx Keef  :-)

Much appreciated !!

MM.
"Success is the ability to go from one failure to another with no loss of enthusiasm"

SSLtech

Re: Improve your GSSL... for free!
« Reply #4 on: June 22, 2009, 12:10:53 PM »
Keith: Thanks for sharing that! .775 to .007 is quite the improvement!

Absolutely. -I couldn't dial in the symmetry adjustments properly with all that hash and nonsense in the signal when bypassed.

-All so much better now!

Keith
"A waist is a terrible thing to mind"
Quote from: PRR
Ah, but that was 1999; we don't party like that any more.

strangeandbouncy

Re: Improve your GSSL... for free!
« Reply #5 on: June 22, 2009, 12:56:32 PM »
Hi Keith,


   I noticed something along these lines a while ago, and thought that there might be something wrong with my build, or perhaps something to do with the 2001 vca's . . . .

  i have to confess I actually LIKE this extra distortion, so that I sometimes leave it in circuit in Bypass for a bit of extra punch . . . and erm, noise as well!


   Thank you so much for bringing this to our attention, and I will be trying your mod, oh yes!


      Kindest regards,


   ANdyP
. . . . RUH ROH . . . . .

Jonkan

Re: Improve your GSSL... for free!
« Reply #6 on: June 22, 2009, 02:21:00 PM »
thanks for figuring this out! I was always wondering why the measurements were way off when in bypass. Have you tried lowering treshold aswell? On my unit this severely raises the distorsion in bypass mode.

Btw. Will any of the new mods you are working on work with an Ultimate Gssl with two pcbs like your original version?

/J


SSLtech

Re: Improve your GSSL... for free!
« Reply #7 on: June 22, 2009, 04:23:24 PM »
Yep. -Exactly! -What you describe (the threshold setting affecting the distortion in bypass) becomes a thing of the past with this little mod.

-Andy, you can add a simple switch to remove the extra ground wire which you add, and you can have the switch make the unit alternate between 'clean-bypass' and 'buzzy-bypass' if you like.

Yes, both of our new bolt-on goodies will work with ANY existing GSSL, whether tuboed, 'ultimate' (dual GSSL) or any other version.

Keith
"A waist is a terrible thing to mind"
Quote from: PRR
Ah, but that was 1999; we don't party like that any more.

moamps

Re: Improve your GSSL... for free!
« Reply #8 on: June 22, 2009, 05:40:36 PM »

Hi Keith,

I discussed GSSL-related noise issues in the bypass mode 4 years ago, when I suggested the very same thing:
http://www.groupdiy.com/index.php?topic=10812.msg127729#msg127729

Regards,
Milan


jdbakker

Re: Improve your GSSL... for free!
« Reply #9 on: June 22, 2009, 05:43:04 PM »
tuboed

What? A tube GSSL? Where?

JD 'and can you build me one?' B.
[seriously, good mod, definitely had a so obvious why didn't I think of it-moment there]


Harpo

Re: Improve your GSSL... for free!
« Reply #10 on: June 22, 2009, 07:32:47 PM »
Keith, good/better idea. Thanks for sharing.
Result seems to be similar to my previously posted approach by switching CV of audio VCAs to 0V to set these to a current in=current out condition and don't care of a still indicating gr-meter, as this status gets indicated by an additional LED.
minimalist bypass/LED schematic and hookup.

A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.  -Douglas Adams

SSLtech

Re: Improve your GSSL... for free!
« Reply #11 on: June 22, 2009, 08:58:47 PM »
I discussed GSSL-related noise issues in the bypass mode 4 years ago, when I suggested the very same thing:
http://www.groupdiy.com/index.php?topic=10812.msg127729#msg127729


Yes, I see that we've arrived at the precise same conclusion!

-I wish I'd have seen your post before 're-inventing the wheel' -it would have saved me some time!

None the less, this 'rediscovery' came as part of my desire to improve the performance in a few ways, and I'm glad that I fully investigated this and other issues.

Cheers,

Keith
"A waist is a terrible thing to mind"
Quote from: PRR
Ah, but that was 1999; we don't party like that any more.

Sarcastic Sound

Re: Improve your GSSL... for free!
« Reply #12 on: June 23, 2009, 01:15:15 AM »
ok ok ok... 

so the new release is "top secret"

I can respect that

But as I'm about to blow some big money on a FPE front panel for my dual gssl build (with turbo, of course)

Should I wait on ordering my front panel because of your new guinness development? As in should I wait because there is a switch of some sort that may (or may not) have to end up on the front panel? 

I dont think that would be giving too much away no?

My bank account would appreciate a hint  ;)

SSLtech

Re: Improve your GSSL... for free!
« Reply #13 on: June 23, 2009, 03:39:04 AM »
One will not affect front panel, just improve cleanliness of sound.

The other will affect the metering, making another meter choice available. ;) (and a switch)

keith
"A waist is a terrible thing to mind"
Quote from: PRR
Ah, but that was 1999; we don't party like that any more.

Sarcastic Sound

Re: Improve your GSSL... for free!
« Reply #14 on: June 23, 2009, 08:28:27 PM »
FANTASTIC!!!   ;D

Good luck on quick development of the new mods!


Silvas

Re: Improve your GSSL... for free!
« Reply #15 on: June 23, 2009, 08:52:40 PM »
At last !!!! thought it was mine only...until i built a couple more.

Thanks so much Keith.
Camilo Silva F.
Camilo Silva F. Mastering
Chia, Colombia

audiophreak

Re: Improve your GSSL... for free!
« Reply #16 on: June 23, 2009, 11:27:10 PM »
 Keith, THANKS !
         
   I'm just at the point were I'm connecting boards, pots and switch's.

      Just in time!   ;)

  Thanks again for the work and posting,, cant wait for the other mods  ;)

  Chip


" Music washes away from the soul, the dust of everyday life "   ... in loving memory of my Father.

blaisa09

Re: Improve your GSSL... for free!
« Reply #17 on: June 24, 2009, 03:09:55 AM »
One will not affect front panel, just improve cleanliness of sound.

The other will affect the metering, making another meter choice available. ;) (and a switch)

keith



Great stuff Keith! Greetings to everyone on the forum, this is my first post. I'm about to start my first GSSL w/turbo mod build and also considering adding the dual super side chain mod. I've been doing my homework reading up on the SSL Help thread (actually been about 2 month reading up!!!). I cant wait to see the new mods that are coming up! keep up the awesome work  ;D

BTW one quick question, i'm just about to order all the parts and i was wondering if it was better to use the THAT 2180 (pre trimmed) or the 2181 (and i do have a distortion meter to trim it here), is there a big difference in sound? Thanks for the great info.



John Blais
Puerto Rico
Recording Music = Creating History

Whoops

Re: Improve your GSSL... for free!
« Reply #18 on: July 06, 2009, 02:47:33 PM »
Great stuff,
people were using Igor's bypass PCB to overcome this problem.

Nele

Re: Improve your GSSL... for free!
« Reply #19 on: July 28, 2009, 08:06:46 PM »
cheers!


 

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