GSSL HELP THREAD!!!

[RedNoise]

[quote author="vertiges"]rednoise,

What's the frequency of the hum 60Hz, or 120Hz (you're in Paris, right ?)
Does moving the power transformer change anything ?
Does it hum even with nothing connected to the input ?

eD

EDITED : when you said "when I'm "quite quiet" on one out , the buzz is louder on the other and vice versa!!! " What did you mean exactely ?[/quote]

I think I got both 60 and 120!!(Not sure!will check it with appropriate software)
No changes with ovin trafo
Nothing connected to input
>>>I think it's a mix between hum and buzz.My 2181 version is near silence now , I just can hear a lil buzz when makeup is at max.
The problem with my 202 version is : when I move the earth wires(power , pcb , pin 1 of both input xlr) the buzz goes away on only one output.Sometimes it goes away on the left out , sometimes on the right.But never on both channels in the same time...Gone crazy now!!! :green:
Many any thanks to everyone for help.(yes I'm in Paris suburbs!Why???)

 

[RedNoise]

Harpo : thx for your advices towards reg's.I've built some today , will try them tomorow.
:thumb:
Cheers! :green:

Edit:Add soMe "M" that my computer avoid!!!! :wink:
Will post pics of the heatSINK , funny ones!!

 

[RedNoise]

craigmorris74: I've had a problem with no comp , it seems it was the TL074...Maybe your vca ....???
I'm noob , these are just suggestions. :green:

 

[craigmorris74]

Thanks for the quick reply RedNoise. I went back and checked all the opamps to make sure they were sockedted well, and the one on the sidechain filter wasn't.

The last thing I need to clear up is there is about 0.8 dB difference in the channels. I believe I read something abou this in this thread. Time to search!

Craig

 

[vertiges]

[quote author="craigmorris74"]Thanks for the quick reply RedNoise. I went back and checked all the opamps to make sure they were sockedted well, and the one on the sidechain filter wasn't.[/quote]

:green: It's often as simple as this...

[quote author="craigmorris74"]
The last thing I need to clear up is there is about 0.8 dB difference in the channels. I believe I read something abou this in this thread. Time to search!
Craig[/quote]

I put two 50k trimmer resistors instead of the two 27k for fine tuning the output levels and the unity gain.

eD

 

[vertiges]

[quote author="RedNoise"]
>>>I think it's a mix between hum and buzz.My 2181 version is near silence now , I just can hear a lil buzz when makeup is at max.
The problem with my 202 version is : when I move the earth wires(power , pcb , pin 1 of both input xlr) the buzz goes away on only one output.Sometimes it goes away on the left out , sometimes on the right.But never on both channels in the same time...Gone crazy now!!! :green:
Many any thanks to everyone for help.(yes I'm in Paris suburbs!Why???)[/quote]

If you can make it goes away by moving the wires, even if it's only for a few seconds, that's a good sign. Bad contact somewhere ? Or contact in a place it wouldn't have one ?

BTW, where is the center tap of your power transformer ?


[quote author="RedNoise"]
Many any thanks to everyone for help.(yes I'm in Paris suburbs!Why???)[/quote]

I was tired in my previous post... You're in Europe so what you hear is 50Hz, and its harmonics... (not 60 Hz).

eD

 

[craigmorris74]

[quote author="vertiges"]
I put two 50k trimmer resistors instead of the two 27k for fine tuning the output levels and the unity gain.
[/quote]
Interesting idea. Thanks for the tip.
Craig

 

[RedNoise]

Hey Vertiges :
-What are these wires instead of 47k??
-No ground taken directly on the board (I assume it you'd taken it on the external psu)
-I use audio wires for the xlr , maybe my buzz problem comes from here??
Thx.

 

[vertiges]

[quote author="RedNoise"]Hey Vertiges :
-What are these wires instead of 47k??
[/quote]

The send / return of the SuperSideChain filter board.

[quote author="RedNoise"]
-No ground taken directly on the board (I assume it you'd taken it on the external psu)
[/quote]

Yes I use an external PSU.
No, there is a ground between the +/- 15 volts supply, a black and yellow wire (hard to see on the picture)
Each board (excepted the control board) is wired (once) to the star ground.

[quote author="RedNoise"]
-I use audio wires for the xlr , maybe my buzz problem comes from here??
Thx.[/quote]

I don't think so.

Have you grounded the center tap of your power transformer ?

eD

 

[craigmorris74]

Before I try the tripot idea, does a 0.8 dB difference indicate a problem somewhere, or just a minor difference cause by component tolerance?

I did notice a differnce in AC voltage after the 100 ohm output resistors that didn't exist before the resistors. Does this point to anything?

Craig

 

[craigmorris74]

Looked at those "100 ohm" resistors, and now I think they're different. One pair are brown, black, black, black, brown (100 ohm), this side is 0.8 dB less. The other pair are brown, black, black gold, brown (10 ohm), this side is 0.8 dB more. Do I have a winner here?

Thanks,

Craig

 

[RedNoise]

[quote author="vertiges"]Have you grounded the center tap of your power transformer ?eD[/quote]
If the center tap is the screw to attach the power trafo to the rack : No!
It's seems I've seen peoples gluing it (power trafo),but I'll try this solution this afternoon.
thx. :wink:

 

[vertiges]

rednoise,

Forget what I said about the "center tap". :wink:
I've just rechecked your pic, the transformer is correctly wired. I forgot the fact you use 220 volts (primary wired in series).

I don't know about "the glue".
Just pay attention the screw which fixes the toroid (at the bottom panel of your rack) is not in contact with the top panel.

eD

 

[RedNoise]

Hi dears...
As you told me I put some heatSINK (Vertiges: :wink: ) on the reg ...
Sorry they're home made , but apparently efficient!



In the meant time I've had to unsolder them to attach the heatsink...I also found some "non-shiny" solders , I re-solder them.
And you know what??when I put it on , my buzz and hum problem were (nearly) gone!!!
In fact , to be "precise" I just can hear a lil bit of hum (50Hz!) when I put makeup at max (Amplifier at max too).Could we consider it is "normal"???
BTW , many thank for all advices that help me to keep motivation!!
:green: :green: :green:

 

[vertiges]

:shock: Yeah that's "some" heatsink !!!

Be sure they don't touch each other !!!
Aren't they "too heavy" for the regulator... Maybe I've got this impression because the pics are bigs ! :green:

About the hum : if you put your GSSL make up at the maximum position and put your monitoring to a "normal" level, can you hear it ?

"normal" = I mean something like 85 dB when you listen to a pop album.

eD

 

[RedNoise]

When I hear whatever sort of music , I can't listen to the buzz...
Too big???I don't know but with them the temperature seems normal...

 

[vertiges]

[quote author="RedNoise"]When I hear whatever sort of music , I can't listen to the buzz...
Too big???I don't know but with them the temperature seems normal...[/quote]

No, I meant put the volume of your amplifier to a "good reference level", a level which allows you to get about 85 dB when you listen to a pop album.
Let the volume at this level and connect your compressor with the make up to the max and listen... can you hear the hum. (no music is playing)

It's not very scientific test, but if you can't hear the hum, that's OK.

eD

 

[RedNoise]

ok Ed (may I?)
I think it's ok so , because (no music playin) amplifier at max and makeup too : I have to be very close to the loudspeaker to hear that "buzz"...
Let's go to the 202C and 2181 version now!!!
Many thx.

 

[vertiges]

So it's a very little hum... nothing to worry about... :wink:

If you want to make some more scientific measurements and if you are on PC there is a free soft here

eD

 

[craigmorris74]

Thanks for everyone's help on my build. The difference in volume of the channels was due to 10 ohm resistors being installed on the output instead of 100 ohm. Now my channels are less than 0.1 apart. The thing sounds great!

Thanks,
Craig