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Project Specific Discussions => Dynamic Processors => Topic started by: SSLtech on June 22, 2009, 11:46:23 AM

Title: Improve your GSSL... for free!
Post by: SSLtech 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 (http://gyraf.dk/gy_pd/ssl/ssl.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

Title: Re: Improve your GSSL... for free!
Post by: EmRR on June 22, 2009, 11:49:15 AM
excellent
Title: Re: Improve your GSSL... for free!
Post by: Bluzzi on June 22, 2009, 11:52:02 AM
Keith: Thanks for sharing that! .775 to .007 is quite the improvement!

Jim
Title: Re: Improve your GSSL... for free!
Post by: MartyMart on June 22, 2009, 11:56:53 AM
Fanx Keef  :-)

Much appreciated !!

MM.
Title: Re: Improve your GSSL... for free!
Post by: SSLtech 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
Title: Re: Improve your GSSL... for free!
Post by: strangeandbouncy 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
Title: Re: Improve your GSSL... for free!
Post by: Jonkan 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

Title: Re: Improve your GSSL... for free!
Post by: SSLtech 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
Title: Re: Improve your GSSL... for free!
Post by: moamps 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

Title: Re: Improve your GSSL... for free!
Post by: jdbakker 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]
Title: Re: Improve your GSSL... for free!
Post by: Harpo 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 (http://www.hausverwaltung-heger.de/al_leck_trick/ssl_sch_mod.gif) and hookup (http://www.hausverwaltung-heger.de/al_leck_trick/ssl_mod.pdf).

Title: Re: Improve your GSSL... for free!
Post by: SSLtech 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
Title: Re: Improve your GSSL... for free!
Post by: Sarcastic Sound 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  ;)
Title: Re: Improve your GSSL... for free!
Post by: SSLtech 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
Title: Re: Improve your GSSL... for free!
Post by: Sarcastic Sound on June 23, 2009, 08:28:27 PM
FANTASTIC!!!   ;D

Good luck on quick development of the new mods!

Title: Re: Improve your GSSL... for free!
Post by: Silvas 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.
Title: Re: Improve your GSSL... for free!
Post by: audiophreak 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


Title: Re: Improve your GSSL... for free!
Post by: blaisa09 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
Title: Re: Improve your GSSL... for free!
Post by: Whoops on July 06, 2009, 02:47:33 PM
Great stuff,
people were using Igor's bypass PCB to overcome this problem.
Title: Re: Improve your GSSL... for free!
Post by: Nele on July 28, 2009, 08:06:46 PM
cheers!
Title: Re: Improve your GSSL... for free!
Post by: audiophreak on December 25, 2009, 06:48:56 PM
Hi,
    I'm using a DPDT toggle for " Comp. In / Out " instead of a rotary switch, its just what I happen to have,

  quote from SSLtech : 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).

   ... so I would connect the " Com " to the Com. or middle contact on the switch, then the " On " to one of the other contacts, and the " Off " to the other. Is this correct ?, and do I still need to connect a " Ground wire " to the " Off" contact ?

 EDIT : - I just had a DUhhhh moment -  ::) - so do I just solder a bridge for the " Defeat Gain " or do I need to connect the " A pole and A1 " to the DPDT switch ?

  Thanks, sorry for the Newb stuf.. ;D

   Thanks,
              Chip
Title: Re: Improve your GSSL... for free!
Post by: audiophreak on December 25, 2009, 08:35:57 PM
 I really do apologies, I need to think more before taking up space here..

  is this the correct wiring for a DPDT toggle for GSSL bypass ?

Title: Re: Improve your GSSL... for free!
Post by: Harpo on December 25, 2009, 09:29:05 PM
Yes.
Your 'CLOSEST to the 750K resistor' pole connection, trace going to 'E' on the molex-terminal,
the 'A2' pin of your switch drawing (might better be relabled 'A'), going to the wiper of the Makeup pot,
'Off' and 'Ground' of your switch drawing connect to the same 0V rail. Just link both pins at the switch and connect with one wire to 'OFF' on pcb for easier assembly.
Title: Re: Improve your GSSL... for free!
Post by: audiophreak on December 25, 2009, 10:24:53 PM
Thanks Harpo !

               Your help is most appreciated.

EDIT: - on closer inspection, the "A" is the pole of the rotary switch, so I think the " other "  would be " A2 "  as in the GSSL PDF...yes...?  I also re-labeled the graphic in my previous post to try to be as clear as your description.
Title: Re: Improve your GSSL... for free!
Post by: Harpo on December 25, 2009, 11:59:26 PM
EDIT: - on closer inspection, the "A" is the pole of the rotary switch, so I think the " other "  would be " A2 "  as in the GSSL PDF...yes...?  I also re-labeled the graphic in my previous post to try to be as clear as your description.
>.. the "A" was the pole of the rotary/DPDT switch - before this mod.
Whatever you like to call these pins/poles, just reverse both wires connecting to lorlin A/A2 from Jakobs schematic, otherwise the makeup pot dialed cw will shunt the +12V rail to 0V. Keith already explained it perfectly clear.
Title: Re: Improve your GSSL... for free!
Post by: audiophreak on December 26, 2009, 12:06:11 AM
Yes..I think I got it now, if my graphic is confusing, I'll remove it, I don't want to post false information, and  thanks again for your patients. :) 
Title: Re: Improve your GSSL... for free!
Post by: livingnote on December 28, 2009, 01:35:46 AM
Aha? So it's the CV opamp's inverting input to ground it is after the resistor? Kinda getting
my head not quite wrapped around it though - like, does some stray voltage impress itself
on the timing salad before it when the 620k is just dangling in midair like that and that sends
some weird fixed CV to the VCAs?

*scritchscratch*
Title: Re: Improve your GSSL... for free!
Post by: SSLtech on December 28, 2009, 04:11:18 PM
Timing salad?

 ;D

Instead of shorting the input to ground and 'killing' it, it just opens the input, but there's a lot of copling between it and the other lines running to and form the main board, running through the ribbon cable. -In among it all, there's rectification at the detector, and the 'spikes' tend to couple into the (VERY high impedance) input.

So you kill the input by shorting it to ground, and all is well again.

Keith
Title: Re: Improve your GSSL... for free!
Post by: idylldon on December 28, 2009, 09:25:44 PM
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.

Did I miss this?  Is it in a new thread?

Cheers,
--
Don
Title: Re: Improve your GSSL... for free!
Post by: livingnote on December 30, 2009, 03:05:56 AM
Ah...so, here I see CV to SC which lands in the -12v via some
resistors, and then CV to VCA...are they the culprits?
Title: Re: Improve your GSSL... for free!
Post by: SSLtech on December 30, 2009, 09:42:16 AM
Quote from: idylldon
Did I miss this?  Is it in a new thread?

It's the C/R/C. I just installed three new mastering suites, and hooked my current GSSL test mule into one outboard matrix for listening/evaluation.

The bench figures are about 17dB improvement in the noise floor, but that's just numbers, I wanted to HEAR it...

The outboard matrix in this particular room comprises:
1x Maselec MPL-2 (limiter/De-Esser)
1x GML 9500 Mastering Equalizer (with SEPARATE outboard PSU's for each channel... ludicrously obsessive!)
1x Tube-Tech SMC-2B (multiband compressor/limiter)
1x Manley Masive Passive

Listening tests gave the following result:

The noisiest item in the chain is the Tube-Tech.
The Second nosiest item in the chain is the GML.
The remaining items appear to be all more-or-less equally quiet: they are the Maselec, the Manley and the GSSL.

Without the CRC (I made it 'patchable'), the GSSL was the LOUDEST item in the chain.

Quote from: livingnote
Ah...so, here I see CV to SC which lands in the -12v via some resistors, and then CV to VCA...are they the culprits?

I don't think that I understand the question..? Are you asking about which signals crosstalk TO the sidechain CV?

If so, I think it's the lines which go to and from the ratio network, which contain a 'chopped' and 'brutalized' signal, since it's right in the middle of being rectified, and a long way before being smoothed. -And I suspect that they are capacitively-coupled (which means that only the 'sharp transitions' are coupled) into the (very high-Z) input...

Thus the best way to stop it 'spilling' is to make the input look at ground, and stop 'sniffing the air' for interesting-looking waveforms...

Keith

Keith
Title: Re: Improve your GSSL... for free!
Post by: mikeyB on December 30, 2009, 10:33:41 AM
Quote from: idylldon
Did I miss this?  Is it in a new thread?

It's the C/R/C.

Keith

Keith

What IS this mod - am i right in thinking this is a power supply c-r-c filter? I've searched and searched on all ssl related threads and just cannot find the relevant information. Can anybody advise on this, please?
Title: Re: Improve your GSSL... for free!
Post by: bassculture on December 30, 2009, 02:27:28 PM
also, any info on the tube-o-ed GSSL ?

a simple tube stage would be nice...
Title: Re: Improve your GSSL... for free!
Post by: jdbakker on December 30, 2009, 03:15:11 PM
What IS this mod - am i right in thinking this is a power supply c-r-c filter? I've searched and searched on all ssl related threads and just cannot find the relevant information. Can anybody advise on this, please?

http://www.groupdiy.com/index.php?topic=35641.0
http://www.groupdiy.com/index.php?topic=30615.0
http://www.groupdiy.com/index.php?topic=36883.0
http://www.groupdiy.com/index.php?topic=35660.0

JD 'not affiliated' B.
Title: Re: Improve your GSSL... for free!
Post by: mikeyB on December 31, 2009, 08:16:10 PM
What IS this mod - am i right in thinking this is a power supply c-r-c filter? I've searched and searched on all ssl related threads and just cannot find the relevant information. Can anybody advise on this, please?

http://www.groupdiy.com/index.php?topic=35641.0
http://www.groupdiy.com/index.php?topic=30615.0
http://www.groupdiy.com/index.php?topic=36883.0
http://www.groupdiy.com/index.php?topic=35660.0

JD 'not affiliated' B.


Thankyou for pointing me in the right direction. After all that - I had a separate PCB for the PSU, so line noise has not been an issue in my build!!
Good to know though - i'm due to build another soon!!
Thanks once again JD
Title: Re: Improve your GSSL... for free!
Post by: ptron on January 22, 2011, 11:28:20 PM
im just thinking if i got the SSC, turbo and CRC boards, my bypass switch is coming from the SSC board ... is there a need / way of doing this mod??? :)

thanks keef! :)
Title: Re: Improve your GSSL... for free!
Post by: canidoit on January 23, 2011, 12:08:17 AM
Keith is the bypass distortion a musical distortion? Like some people use the API 2500 without compression just so that it adds mojo to audio?
Title: Re: Improve your GSSL... for free!
Post by: sheadstedford on January 23, 2011, 03:24:59 AM
also, any info on the tube-o-ed GSSL ?

a simple tube stage would be nice...

What he said!
Just got a simple srpp and might put it in the output stage....any thoughts
Title: Re: Improve your GSSL... for free!
Post by: jdbakker on January 25, 2011, 06:24:05 AM
also, any info on the tube-o-ed GSSL ?

a simple tube stage would be nice...

What he said!

Read the entire thread.

It was a joke, based on a typo Keith made in Reply #7 (http://www.groupdiy.com/index.php?topic=34219.msg418785#msg418785). To spell it out: he wrote tuboed instead of turboed.

JDB.
Title: Re: Improve your GSSL... for free!
Post by: ptron on March 06, 2011, 01:41:03 PM
bump bump :P
.. sorry to ask same thing again but tbh i dont notice any distortion while on bypass... maybe its my ears or my room or i dont know how it sounds... but is this mod going to help if im using the SSC board`s "sidechain in/out" and not the regular control board`s
Title: Re: Improve your GSSL... for free!
Post by: Harpo on March 06, 2011, 02:56:25 PM
You could mod it back to the original schematic, but actually you have it already built in. ;)
Title: Re: Improve your GSSL... for free!
Post by: ptron on March 06, 2011, 03:47:56 PM
thanks man! i was wondering where were u hehe havent seen many posts from your behalf lately!
greetings man i hope u are well
Title: Re: Improve your GSSL... for free!
Post by: craigmorris74 on March 06, 2011, 04:49:22 PM
Just to make sure I don't mess something up what I try this, in summary, I need to:
1.  Reverse the wires going from A(pole) to A2
2.  Connect A1 to a ground, most easily C1

Is this correct?

Thanks
Craig
Title: Re: Improve your GSSL... for free!
Post by: tzman on March 06, 2011, 06:09:43 PM
Just to make sure I don't mess something up what I try this, in summary, I need to:
1.  Reverse the wires going from A(pole) to A2
2.  Connect A1 to a ground, most easily C1

Is this correct?

Thanks
Craig

If you meant
1.  Reverse the two wires going from A AND (not to) A2,
2.  Connect A1 to ground, most easily C1

then yes, that's all! :)
Title: Re: Improve your GSSL... for free!
Post by: craigmorris74 on March 06, 2011, 07:14:23 PM
Y
If you meant
1.  Reverse the two wires going from A AND (not to) A2,
2.  Connect A1 to ground, most easily C1

then yes, that's all! :)
Yes, that's what I meant, thanks.
Title: Re: Improve your GSSL... for free!
Post by: NorthernLight on March 13, 2011, 12:53:27 PM
I came across this PDF: http://www.hausverwaltung-heger.de/al_leck_trick/ssl_mod.pdf (http://www.hausverwaltung-heger.de/al_leck_trick/ssl_mod.pdf) which supposedly adds a LED to the bypass using only a DPDT toggle switch. I tried to figure out how this works myself but I don't understand the mod, also because it looks like the bypass wires to the front panel board seem to be omitted completely. Can anyone shed some light on it? I already found that some of the suggested points to attach the wires to the PCB can be done easier by using the holes for the 202 VCA's.

Basically what I want to achieve is a DPDT bypass switch that lights a LED when the bypass is NOT active. Preferrably without adding a relay to the equation.

Thanks,  Alex.
Title: Re: Improve your GSSL... for free!
Post by: Harpo on March 13, 2011, 04:48:19 PM
I came across this PDF: http://www.hausverwaltung-heger.de/al_leck_trick/ssl_mod.pdf (http://www.hausverwaltung-heger.de/al_leck_trick/ssl_mod.pdf) which supposedly adds a LED to the bypass using only a DPDT toggle switch. I tried to figure out how this works myself but I don't understand the mod, also because it looks like the bypass wires to the front panel board seem to be omitted completely. Can anyone shed some light on it? I already found that some of the suggested points to attach the wires to the PCB can be done easier by using the holes for the 202 VCA's.

Basically what I want to achieve is a DPDT bypass switch that lights a LED when the bypass is NOT active. Preferrably without adding a relay to the equation.
Right side of the DPDT toggle forces the audio-VCAs in bypass condition.
For LED on when compressor active, take the 1k5 current limiting R from the upper to the lower throw position of the switch instead.
Drawback of this minimalist version is, the meter will still show the amount of compression that would take effect as if not in bypass. Have the LED illuminate the meter might catch a little of this flaw.
Title: Re: Improve your GSSL... for free!
Post by: NorthernLight on March 13, 2011, 06:16:14 PM
Hmm, I guess that minimalist bypass LED mod is not what I want after all then. I'll just have to find me a source of affordable miniature 3PDT switces instead. I have a Purusha case with 5mm LED hole and 5mm toggle switch hole for the bypass, I guess that's all prepared for the relay-based bypass option. I'm not going to go that path, if I would do it the relay way it would have to be true bypass for both channels, too complicated for now.

Thanks for the explanation though :)
Title: Re: Improve your GSSL... for free!
Post by: weiss on October 18, 2018, 12:51:49 PM
Hmm, I guess that minimalist bypass LED mod is not what I want after all then. I'll just have to find me a source of affordable miniature 3PDT switces instead. I have a Purusha case with 5mm LED hole and 5mm toggle switch hole for the bypass, I guess that's all prepared for the relay-based bypass option. I'm not going to go that path, if I would do it the relay way it would have to be true bypass for both channels, too complicated for now.

Thanks for the explanation though :)

hey man, did you find a way to realize what you had planned? i am looking for the exact same thing!
thanks