GSSL HELP THREAD!!!

[Bonke]

Hi all!
I finished my first GSSL some years ago and now I´m building three more. My first of the "new" ones is working like a charm but my second has a problem.
It passes audio and the makeup gain is working but there is no compression and the meter is dead. I have tried searching this forum but can not find an answer. It has probably been answered in this thread but it is 200-something pages.... :-\

Can anybody help me in the right direction?
I have swapped all IC´s. Out-ruled the controlboard. (works with the other unit). Searched for solderbridges around sidechain and TL074.

The compressors are built with That 2180´s. The first (working) one has panasonic FM caps and the second one Nichicons. The 3,9K´s resistors besides the VCA´s are changed to slightly different values on the two compressors, 4,8 - 5,0K. Other than that they "should" be identical.

Anyone who has that simple explanation? 

Henrik

As usual it is an easy problem. I have looked over the soldering at least 15 times without finding anything dodgy. Yesterday I looked again and "somebody" had forgot to solder pin1 on the sidechain VCA.
Now it works perfectly! It is nice to have 4 GSSL´s to play with.

Henrik

 

[regularjohn]

1) Can someone give me a straight answer here - When using a THAT2181 should I use the resistor values Gyraf has on his layout/schematic or should I use Matt's values?:
What about the two 15K Resistors next to the VCA's? - should they be changed to 27K?

2) I have Gyraf's board Rev 7 - There is a .1uF Cap on the sidechain VCA between pins 6 & 7.  It is not on his current assembly drawing & not on his schematic.
Should this be installed?  I would think yes, since it appears to be simply a bypass cap.

1) Matt's values.  Actually more in depth is Martie's: http://homepage.mac.com/marten.thielges/gssl/calibration.html
15K should be changed to 27K.
2) That .1uF is a psu bypass and should be installed.

 

[sonolink]

I'm using a Simpson 1542 Edgewise VU meter for my Gssl with the Expat Vu meter Mod.
I would like to know how do you guys illuminate your edgewise meter? With LEDs? Are the Leds placed inside the meter? Behind?
Thanks in advance for all input and help
Cheers
Sono

 

[j.frad]

I'm having a really strange problem on my upcoming gssl: The right channel has a gain of about 6dB, has anybody ever had that? both channels recieve signal from both hot and cold point on the xlrs, so i think it's not a balancing issue in the wiring. I've been struggling with this machine and i'm almost there!

FOUND IT!!!
Ok I'm posting this here so it might help someone else. This particular gssl build was started by someone else who forgot to put in one of the 27k resistors to the vca input. So I put it in but didn't realise hr had put a 15k on the other vca, hence the level difference!
That was it!

 

[johnmellor]

just finished assembling mine. When I power it up the meter works, and so does the makeup gain, but no compression I think there might be a problem with the bypass because if the bypass were working any change to the makeup gain would be bypassed right?

For the bypass I am using a 2pole 6way lorlin. So I've wired it up:

A on the control board -> A on lorlin
A2 -> A2
C/on -> C
C1/off -> C1 (which will be number 7 or lorlin right??)
C2 -> C2 (number 8 right?)

Is that right?? I've traced it back to the main board, and checked joints.
I know it seems like a really stupid mistake but I'm going a bit nuts trying to figure this out  ;D

 

[stereokillah]

i think it's

Com> C
off -> C1
on ->C2

Seems more logic

 

[ruckus328]

1) Can someone give me a straight answer here - When using a THAT2181 should I use the resistor values Gyraf has on his layout/schematic or should I use Matt's values?:
What about the two 15K Resistors next to the VCA's? - should they be changed to 27K?

2) I have Gyraf's board Rev 7 - There is a .1uF Cap on the sidechain VCA between pins 6 & 7.  It is not on his current assembly drawing & not on his schematic.
Should this be installed?  I would think yes, since it appears to be simply a bypass cap.

1) Matt's values.  Actually more in depth is Martie's: http://homepage.mac.com/marten.thielges/gssl/calibration.html
15K should be changed to 27K.
2) That .1uF is a psu bypass and should be installed.

1) Thanks, went with those values.

2) A PS cap?  Where is it on the schematic?  From what I can tell it's acting as a shared bypass cap for the sidechain VCA and the TL074.  There isn't a bypass on the schematic for the VCA, just the 74.  Ideally should they each have thier own?

On a totally different subject, I'm struggling here with grounding schemes on this thing.  I see that most people are daisy chanining pin 1 on the input xlr's, and from there also attaching a wire to the star ground and also to 0v on the main board input connector.  Then on the output xlr's, no star ground connection, just pin 1 daisy cahined and connected to the main board 0V point on the output connector.  OK, simple enough.........

But then I see other guys doing the complete opposite - only the outputs to star, and some people also incoporating a filter cap and resistor between pin 1 xlr outputs and the star ground.

I'm working on a new design, and want to incorporate onboard xlr's, but that changes the name of the game some, so I'm trying to figure out which should connect to star ground - inputs, outputs, or both?

 

[bendrade]

I almost finish my GSSL... but i have a problem.

The ratio seems to not work and the when I move the threshold down the meter shows compression even when there is no sound entering the gssl.

I double check everything 100 times and I can't find why?

can someone help me?

Thanks

 

[johnmellor]

haha after getting some sleep I immediately realized my sidechain vca was back to front. Turned it around and it worked perfectly. I've checked all the components by swapping etc to make sure they're all working. Now my only problem is that I've got 3dB less on right channel than left, which I'm sure will be a classic error soldering issue etc. Also using a spectrum analysis I've got 100Hz ripple, but I've just ordered a crc board which will hopefully sort that out.

Thanks for the help guys although its not quite finished, sounds really good. pumpy!

 

[mitsos]

2) A PS cap?  Where is it on the schematic?  From what I can tell it's acting as a shared bypass cap for the sidechain VCA and the TL074.  There isn't a bypass on the schematic for the VCA, just the 74.  Ideally should they each have thier own?

On a totally different subject, I'm struggling here with grounding schemes on this thing.  I see that most people are daisy chanining pin 1 on the input xlr's, and from there also attaching a wire to the star ground and also to 0v on the main board input connector.  Then on the output xlr's, no star ground connection, just pin 1 daisy cahined and connected to the main board 0V point on the output connector.  OK, simple enough.........

But then I see other guys doing the complete opposite - only the outputs to star, and some people also incoporating a filter cap and resistor between pin 1 xlr outputs and the star ground.

I'm working on a new design, and want to incorporate onboard xlr's, but that changes the name of the game some, so I'm trying to figure out which should connect to star ground - inputs, outputs, or both?

IMHO, .1uF caps are cheap, include them for everything if you want, especially the further away they are from other bypass caps.

RE: the grounding issue, different strokes for different folks, but read the rane paper on the pin 1 problem (google).  The recommended thing to do is tie all your Pin 1s to the case with as short a wire as possible, not to star ground (assuming this is where your circuit grounds meet).  I would then take this star ground, tie it to one side of a switch, and tie the other side to the case, so you can choose when you tie circuit ground to earth.

RF caps? not sure if they're necessary. Since you are doing inboard XLRs, you could have pin1 go to the board, through the RF filter and then have a pad which could be tied to the case, for those who want RF filtering. Those who don't just tie it directly to the case (directly does not mean jumpering the RF filter, it means taking a wire directly to the case).

that said, really looking forward to a new SSL board.

 

[hipolitho]

Had trouble with my 2180s... exchanged for the 2181s and now the thing works perfectly.

Here is, the Busão! - http://twitpic.com/1ks8vq

Thanks for all the help here.

 

[stereokillah]

bendrade

perhaps you have two solder point on the controle borad, where there is 10 wore.
check the signal bewten us.

 

[RedNoise]

Hipolitho : thumb up for the Busao estereo WILD STYLE !!! ;D

 

[sonolink]

I'm using a Simpson 1542 Edgewise VU meter for my Gssl with the Expat Vu meter Mod.
I would like to know how do you guys illuminate your edgewise meter? With LEDs? Are the Leds placed inside the meter? Behind?
Thanks in advance for all input and help
Cheers
Sono

 

[ruckus328]

IMHO, .1uF caps are cheap, include them for everything if you want, especially the further away they are from other bypass caps.

RE: the grounding issue, different strokes for different folks, but read the rane paper on the pin 1 problem (google).  The recommended thing to do is tie all your Pin 1s to the case with as short a wire as possible, not to star ground (assuming this is where your circuit grounds meet).   I would then take this star ground, tie it to one side of a switch, and tie the other side to the case, so you can choose when you tie circuit ground to earth.

RF caps? not sure if they're necessary. Since you are doing inboard XLRs, you could have pin1 go to the board, through the RF filter and then have a pad which could be tied to the case, for those who want RF filtering. Those who don't just tie it directly to the case (directly does not mean jumpering the RF filter, it means taking a wire directly to the case).

that said, really looking forward to a new SSL board.

Thanks for clearing that up.  I had already gone and added bypass caps at every applicable location as soon as I realized how many power pins seemed to be lacking on them.

I'm decided not to board mount the XLR's - too many issues with doing so, so I think I'm good with the ground scheme of things.

________________________________________

OK, so final question (I think) lol:

Almost done my schematic - one thing I'm unclear of - there's a dual sidechain in my new layout (aka turbo), I'm incorporating dual hpf/ext input circuitry also.  But I'm a little unclear here on a couple things -

1) unclear what I do at the "key input" XLR end of things though.  Even though there's dual hpf circuits (one for each sidechain) - I still only need one key input XLR?  and pins 2 & 3 of the XLR go to both hpf circuits?

Does the hpf rotary switch go to both hpf circuits?  Or do I use a 2x6 rotary switch and keep Pole "A" and associated position on 1 sidechain hpf and pole "B" and associated positions on the other sidechain hpf?

 

[ruckus328]

OK, scratch some of my previous question.  I see that I'll need a double gang rotary for the high pass controls.  And that I'll need to put my Turbo switch before the high pass filters.

I'm still scratching my head here though.  Looking at Steffen's high pass filter schematic:

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

When using an external input (for say ducking), it looks like you'd need to complete the loop through external patching between the send and return?) in order for the L/R input signals to continue through the circuit - Otherwise they just stop at the rotary switch?  Or would it work if nothing was attached to the "send"?  - Like if a kick drum was patched in to the "return" for ducking, it would work?  I guess I'm confused what "send" is actually used for.  Obviosuly to send the signal out to an external source, but for what?

And still confused as to whether my "key input" xlr gets wired in parallel to both hpf circuits?  Obviosuly it would be fine while in Turbo mode - but would this case a problem while in Gyraf mode?  Would I have to put in a relay to break the second hpf send/returns then?

 

[Stagefright13]

I have a different sidechain filter than you. On mine you just need the in for ducking. I think the output would be used to duck an additional compressor etc. Or possibly so you can use a TRS channel patch from a mixer. "Channel Patch" = TRS unbalanced I/O wich some mixers have.

Some info here for mine. http://picasaweb.google.com/barclaycon/GSSLSuperSidechainPCB#5193281422346837714

 

[ruckus328]

Yea, I know about the SSC but I'm trying to go with a non-copyrighted design.  And schematic for it is non-existant.  I just looked at the layout for it though, what is the "Snd" for then right next to the "Ext" connector point then?  And do you have the "Ext" wired to an XLR?  It's an unbalanced signal right?  So in that case there's just no connection to pin 2 on the xlr?

I did some more staring at the version I have - what I'm unsure of is with dual sidechains filters, does each sidechain get its own filter and THEN the signals are summed when in GSSL mode?  Or in other words, if I make turb switchable, does the hpf filter go before or after the switch?

If it goes before the switch then both L/R sidechains go through thier own filter all the time, so when in turbo mode they both continue through thier respective sidechain, when in GSSL mode, they are summed through one sidechain.

If the hpf goes in after the switch, then the right channel will only go through the 2nd hpf when in turbo mode, when in GSSL mode, both channels are summed and then go through the 1st hpf.  Hopefully I'm making sense here.

From the looks of it, I could just ommit the "send" if I wanted.  What I'm still stumped on is whether I need 2 xlr's (one for each hpf) or if they get wired in parallel to a single xlr.  If wiring them to a single xlr, then I would think I'd want to put the hpf's before the switch - that way each sidechain is affected the same, and when in GSSL mode they are then summed after the filter has affected both L & R.

 

[Stagefright13]

With my limited knowledge I would leave the sidechain engaged ALL of the time. Cause there is a selection on the lorin for NO sidechain.

And my ext sidechain is a TRS not xlr. And yes it is unbalanced. For the rest of your questions I hope someone more experienced will answer. I am just an amateur.

 

[Pieter001]

Just finnished my ssl clone. I did somthing wrong with the power supply. I read -15v and 0v. The 7815 gets realy hot. I doesnt work. What do i need to do?

Gr, Pieter