GSSL HELP THREAD!!!

[Greg]

Often times the LED's spec sheet will specify what value of current limiting resistor to use depending on the rail. I remember the one I used said to use a 1k with a 12V rail, and I think that's what is actually on Jakob's board. I always like to give the spec sheet a glance to make sure.

 

[Guest]

sounds good. I think most just have a max voltage. Something like 3.5 v @20mA.

I thought I post this for any interested. I found a site that'll send you samples of products. LED's specifically if you only needed a few. They have quite a selection.

http://www.marktechopto.com

Brandon

 

[kvintus]

Did we find any solution to the hum problem? I've just finished a GSSL clone that works good but I have a 50Hz hum at -73 dBu in the right channel and -66 dBu in the left channel. Any ideas?

/Anders

 

[gyraf]

I've never had ANY hum above noise level in any of the units I've made..

Check that your +/-15V supply voltage is clean. Too low voltage from the transformer can be a problem.

Redo your grounding - it may be a ground thing.

Check that it actually IS the clone that is humming - measure outputs with shorted inputs.

Jakob E.

 

[kvintus]

My supply voltages do not hum. They have some HF noise at about 5 mV but no hum as far as I can see. I use the 2x18V PCB transformer from farnell that you suggestet (the blue one) and the secondary voltages are ok.

How should the grounding be done, anyway? I know it's a stupid question, and I know how grounding is done (I think), but could you please go through it once more just in case I've missed anything.

Thank you for your help, Jakob!

/Anders

 

[gyraf]

First of all, connect input ground (at the input pcb connector) to chassis at one of the input XLR's. And ONLY connect 0V to chassis here.

If you draw current to a meter light, try disconnecting this.

Does your hum change with makeup gain?

Is your unit boxed or just a PCB on your desk?

Jakob E.

 

[kvintus]

First of all, connect input ground (at the input pcb connector) to chassis at one of the input XLR's. And ONLY connect 0V to chassis here.

Done that. Still humming.

If you draw current to a meter light, try disconnecting this.

No lights connected.

Does your hum change with makeup gain?

Yes. I get -66dBu without makeup gain (or bypass).

Is your unit boxed or just a PCB on your desk?

Sheetmetal box.

/Anders

 

[kvintus]

By the way, I use plastic connectors and the inside of the box is painted with non-conductive paint. I also use plastic washers for the pcb spacers. So there is not any connection to ground except for a wire that goes from input pin 1 to a ground screw in the chassis. Input pin 1 connects to the pcb.

/Anders

 

[kvintus]

Bump...

Still hunting for hum. Could this be anything else than grounding? I have tried to redo the grounding in several different ways but it doesn't change. Can someone tell me what to look for?

Thank you!

/Anders

 

[keithcamilleri]

Hi jakob,

Just wanted to ask whether I need to change the voltages if I try to use 4 x 2181 in parlallel for every channel?

Would it make any difference if I use 2180 instead of 2181s?

Just read that 4 vca in parallel would make the sound better? any truth in that?

Sorry for all the questions

Keith

 

[radiance]

@ Kvintus: I got rid of a lot of hum (well not really a lot but some) by turning my toroid transformer 90º.

 

[andre tchmil]

from time to time when I switch the ssl on, the meter goes full scale to the right and if I remember well , the unit doesn't pass audio.
power off and on again solves the prob.
Any idea what causes this ?
Other than that the clone is really working and sounds great.

 

[gyraf]

Andre,

You probably have a 7815 or a 78L12 latching up. Try to provoke the error by turning on and off some times (allow unit to discharge completely between tries). Once you have the error, measure the +/-15V and +/-12V lines. One of them is probably not working.

There is an issue with certain brands of (specially positive) regulators. Change the bad one to a different brand.

Keith,

I don't think there's much to be gained by paralleling more VCA's. The 2180 is spec'ed better than the original 202C.

Anders,

Try taking your power transformer out of the box to see if it is induced hum, or poser line hum. If physically removing the power transformer helps, try moving it around inside the box to find the location with least hum. If removing the transformer dosen't change anything, try measuring your +/-15V lines for ripple. Does the hum change when you short the inputs?

Jakob E.

 

[andre tchmil]

Thanks Jakob.
Will try that.

 

[gyraf]

Andre,

Here's a thread about the problem:

http://www.groupdiy.com/index.php?topic=440

Jakob E.

 

[edgedaniel]

Hi!

I have som troubel with my SSL!

When i set the Release at 0 it sounds perfect. But when i increase the release time it started to crackle more and more. At the Auto posision its worst.

Do anyone hava any idea of where i should start checking.

Could it be the input that is too high?

Is the SSL working with +4dBv och -10dBu as input?

 

[gyraf]

Make sure that the wire links on the control PCB are in place.

One of the wire links is often overlooked when assembling (there may be something about this earlier in this thread..)

Jakob E.

 

[keithcamilleri]

Hi Jakob,

I am building 2 ssl in one case and I would like to use 1 meter. Would I be doing anything wrong if I'll put a switch and this switch will be used to switch from one compressor to the other.

So that when the switch is on one position I'll be viewing the meter of one compressor and when the switch is on the other I'll be viewing the second compressor...


cheers

 

[gyraf]

Keith,

That should work. But why not two meters?

Jakob E.

 

[Kev]

One of mine has a switch on the meter for a change in sensitivity and also includes an OFF position.

I don't see any problem with leaving the meter drive circuit ... open.

Keith,
where are you from ??
camilleri .... is a name known around these parts ....