GSSL HELP THREAD!!!

[crisotop]

that the toroids fixing bolt under no circumstances touches the top lid of your case.

That's one thing I remember from building a gainclone amp

How would you mount the trafo and the pcbs? I have one of purushas cases, and the wall thickness of the bottom plate is not that massive, for example to use countersunk screws.

Thanks Harpo!

 

[Harpo]

Nothing wrong with Tat's cases. The bottom plate gets solid when mounted to the rest of the case and there are no heavy parts inside. I used cylindrical screw heads and small rubber feet on mine to prevent scratches on the surface below. The frontpanel is a little higher than the rest of the case and will cover most of this distance. I used ~8mm plastic standoffs for pcb mounting. Doesn't matter that much, but put isolation washers in between, if you'll use metal ones.
You will have to scratch/dremel some painting from the bottom plate where you place your screw for star ground to garantee safe conduction. A sawtooth washer will most probably not go thru this painting.
Have a look in the meta for some already built units and you'll get the idea. http://www.groupdiy.com/index.php?topic=21094

 

[crisotop]

Nothing wrong with Tat's cases

Sorry don't get me wrong - the qualtiy is superb, but I used a Schroeff 2U Case for my last project and they have additional mounting plates inside which are thick as a frontplate.

But you think that plastic-self adhesive PCB standoffs are sufficient? I'm sure I will be carrying the comp around sometimes for mobile recording.

thanks a lot
christoph

 

[Harpo]

they will fall off one day. a countersunk screw could fix this before this happens - or use rubber feet for guitar-boxes/cases like http://www.thomann.de/de/adam_hall_4906_gummifuss_pack.htm and sand them down
a sidenote - please add your location to your profile. it may help to provide information from the same continent/country.

 

[radiance]

I have some problems using the Pic/led meter from this thread.

Looking at the pic below..

I meassure -2,8V DC at the red dot point (when a sifam director shows full scale) . With a Sifam Director meter everything works fine but for the pic/ led meter I only need -120mV.
Question is: is this -2,8 correct? In the thread above it says that the CV at the red dot point should be -120mV.

 

[Frugaljr]

I posted a few days ago about my new GSSL going into overload with the threshold nearly off. Gyraf advised me to check the p.supply. I desoldered the 15 and 12v regulators and found a tiny short between the legs of one of the 12v regs hidden by the solder joints. It wasn't visible to the naked eye, but with the majority of the solder removed, I could see it with a magifying lens. It works great now and sounds super! Nice case by Pursha! It looks very pro.

I don't know how to test the distortion, so I might bring it to a friend for that, but it sounds really good.

Thanks to you all for your wisdom and for helping me!

 

[Sender]

Real quick problem...

I've built mine and it works first time on, very proud of myself!! One thing though. The make up gain pot seems to have zero effect on the output. I checked voltage going into the pot and it's +12. The pot seems to be working fine as a voltage divider, the wiper is getting varied voltage accordingly.

Any ideas?

Fixed: Had the bypass switch wired up wrong

 

[roginator]

I finished GSSL with 202c and 2181 on S/C ...I need to trim distorsion on Channel VCAs ....everything else works great.....
since there are some mods for GSSL with 2181 LA, LB and LC do I need to mod anything on 202c GSSL?????

also Im gonna fit my 2 GSSLs into MCI 532 desk..I have free modules so Im gonna internaly hook them with patch bay and use +/-15 volts from desk PSU and 24v for Bypass relays...so in that case I dont need rectifier, Filter caps, and voltage regulators on GSSL PSU...BUT should I ad any cap as a filter on +/-15v on gssl and maybe a diode for protection of circuit of GSSL

D

 

[bluezplaya]

I have been racking my brain trying to trace signal and voltages on my SSL and can't seem to get it going. I was wondering about voltage drops over resistors. I am tracing the -12.0V from the 79L12 to the 3K9 resistor at the sidechain and it drops to -2.8V over the 3K9. Is that a normal amount of voltage drop?

Also, while tracing the +12V to pin 7 of the sidechain VCA, the voltage carries to the first leg of the capacitor coming out of pin 7 but there is 0 voltage across it. :?

FWIW, I'm getting 15V+- and 12V+- in all the right places on the board and control board, LED lighting up, and the meter jumps when I power on. I'm wondering if I'm having an issue with the IC's or VCA's. I have been tracing signal through the inputs all the way up to pin 1 on the channel VCA's but no farther than that.

Adam

 

[dagoose]

Looks like some other people had the same problem as i have but so far i haven't found the solution so maybe someone can help me out on this one.

I build the clone without any real problems (did a stereo 1176 some time ago) but in some kind of way i can't get the ssl to work, this is what happens.
First of all i have to mention the fact that i had a short circuit in the 7815 circuit somewhere in the sidechain area before the chips where in (testing voltages first).

+ 15v, -15v, +12v en -12v are all present and i get sound from the machine and the makeup gain is working.
But that's actually the only thing that works because i get no compression at all and all settings of the side board except for the makeup gain don't work.
Looks like the sidechain section is not working at all..
I replaced the VCA in the sidechain (pin 4 of all 3 2180LB's are lifted), the TL072 and tl074 and checked input voltages on the board and chips and they all look good as far as i can see.
I also checked the resistors which seem to look fine too.
I read something about voltage changes that should apear on the tl074 when changing the threshold but i don't see any differences at any pins at all

Anyone have an idea what is going on here :?:

 

[gyraf]

Maybe wrong Bypass switch wireing?

Try tracing the signal through your sidechain..?

Jakob E.

 

[drive]

My gssl works great but today the something strange happend. After about 20 minutes of use it go's CRAZY FULL BLAST !!! And the meter stay's to the MAX with no audio going throw it, once I turn it off, let it rest and turn it back on a few minutes later everything is fine again, it never did that befor. I used the comp with an open case and closed the case only yesterday and today the weather is very hot too, could it be that it over heats in the case and go's crazy because of that ?
Or could this be the beggining of something else ?

 

[gyraf]

as suggested before, check powersupply voltages under fault conditions - could be e.g. your -12V acting up because of heat..?

Jakob E.

 

[dagoose]

Found it..
There was a solderblob in the sidechain section.. :twisted:
I thought i had checked it all but i didn't..

ok, it's working and sounds great, now it's time for the rest to be build.

Thanks!

 

[Bluzzi]

After having my boards and parts sitting there I have finally soldered 2 GSSL boards and 2 of Stephen's sidechains.

I have 2 questions.

1: I left the meter sensitivity resistor for last and I can't see using 20db of compression but I am wondering if anyone is. I figure 2 to 6 db should be enough so the 10db scale would be enough.

2: The sidechain L and R signal hook up to the 2 47k resistors on the main board. Thing is I have one drawing advising to remove the resistors. Is that correct?

Thank you my fellow DIYers.

jim

 

[Greg]

Regarding your second question... yes, remove them. They're on the sidechain board. See sidechain schematic.

 

[Bluzzi]

Thanks Greg. I wouldn't have known that.

jim

 

[gerardmanvuca]

I'm totally new to the game, I have read the 146 pages in the SSL Thread and have not found the answer to my questions.
I have a few questions to ask:

- Which way do I put the small caps into the PCB? There is a ''.1'' sign in them.
- Which of all components have a polarity difference?
- I have posted this question already but i thought i would add it in here, just need to know what wires to purchase to tie up the (pots and lorlins) and also the XLR's.

thanks for the help.

 

[Bluzzi]

[quote author="gerardmanvuca"]I'm totally new to the game, I have read the 146 pages in the SSL Thread and have not found the answer to my questions.
I have a few questions to ask:

- Which way do I put the small caps into the PCB? There is a ''.1'' sign in them.
- Which of all components have a polarity difference?
- I have posted this question already but i thought i would add it in here, just need to know what wires to purchase to tie up the (pots and lorlins) and also the XLR's.

thanks for the help.

[/quote]

There are a few small caps so be careful to not mix them up. The .1 are not polarized so it doesn't matter which way you put them.

Polarity MUST be observed for all the electrolytics. Usually the negative side is marked and the positive side has the longer of the 2 leads.

Also your diodes must be inserted the right way. Oh yes the rectifyer and the ICs including the VCAs all have to be inserted in the correct way.

For wire I bought some 24awg multistrand as well as some 22awg. you could use individual wire or ribbon cable of 10 or more wires (just remove the excess ones) for connecting the switch board to the main board. I am doing my own panel design so I can't use the switch boards and have to wire those as well. For the XLR I'll be using shielded wire like mini mike cable .

Hope that helps and I didn't leave out anything. (be careful with the polarity. If you are not sure don't solder them in and hope for the best, come back here and ask until you are positive.) Try looking at pictures of successful builds.

I am getting close to finishing my wiring as well and its getting exciting.

Have fun.

jim

 

[gerardmanvuca]

Jim,

Great!!!
thanks for the reply.
good luck with your project.