GSSL HELP THREAD!!!

[Harpo]

[quote author="kryckmeister"]Here's the values with the TL072 and TL074 still inserted.

Gave with 7915, 7815 and the TL074 and 072...[/quote]
At 1st sight the -15V rail voltage at NE5534 Pin 4 of Audio-VCA's is missing. Maybe lifted/broken trace ?

 

[kryckmeister]

It's the same on both of them actually... Any ideas?

On the 7915 apart from the three pins which have the potential given on the picture on the previous side. I also have -23.7V on the top of it. 0V on 15... How wrong is this?

 

[Harpo]

[quote author="kryckmeister"]It's the same on both of them actually... Any ideas?

On the 7915 apart from the three pins which have the potential given on the picture on the previous side. I also have -23.7V on the top of it. 0V on 15... How wrong is this?[/quote]
Your regulators all seem fine. Your 2x18V AC transformer secondary get rectified to +/-23.6V DC, feeding your regulator inputs. These 78xx/79xx have a different pinout (+Vin,gnd,+Vout for 78xx and gnd,-Vin,-Vout for 79xx).
From your pic the 7915 is delivering -15V that do not arrive at pin 4 of your NE5534s in the audio-VCA substitution circuit, so there is a trace lifted or broken in between. Check the trace of your -15V rail.

 

[kryckmeister]

Thanks for that. It's now taken care of. I now have -15V on pin 4 on both my NE5534's. Still I have this weird problem with my meter. I
m now talking about no audio passing through. When bypassed nothing happens, but when I turn it on, the meter first jumps a bit and if I bring threshold down the meter starts hitting "maximum compression" and if I bring ratio up to 10:1 instead of just 2:1 it hits even harder. Still, this is what's happening on the table, NO audio.

 

[Harpo]

From your pic you seem to use That2180 VCA's (maybe not). The schemo of Jakob and your pcb are labled for dbx2150 as substitution for the dbx202/xt, so you may have some resistors wrong.
Have a look at this great site by Matt Fischer http://diy.fischerworks.com/gssl_vca.shtml to match the required values according to your built in VCA's.
Also check wiering of your bypass switch according to the schemo.
Did you set your multimeter to AC for measuring audio?
Your jumping meter issues, whatever meter you may have, are covered in the meta.

 

[kryckmeister]

It is a 2180 and I'll look into the resistor thing. That shouldn't be the problem though cuz this guy put together everything for a lot of people at this Swedish forum (no profit) and wrote some "how to's" and all. A lot of the people who actually bought the kit have finished them and they sound good. I did find a burnt capacitor that I'll replace asap, but i still have a hard time finding a good idea about the meter.

Audio I haven't measured at all, mainly because of the weird behaviour with no audio plus the groce distortion.

 

[Dr nEon]

Hi all!

I have a gssl with balanced i/o which i need to interface with an unbalanced patchbay.

I am making up cables to go to the patchbay , and desparately need advice on which is the correct way to wire the xlr plugs at the gssl end.

I've been reading the Rane literature , and Douglas Selfs articles , and I'm still confused as to whether I should leave pin 3 of the xlr plug disconnected , or strap it to pin 1 in the xlr plug.

From what I'm reading ,it seems you need to know the balancing method used in the design of the unit , in order to make the correct decision.

Are the Gssl outputs "Quasi Floating" , and is this the same thing as a "differential" output?

Or is this a cross coupled output?


This quandry has opened up a new chapter of discovery for me... I had no idea there were so many ways you could create a "balanced" output!


Thanks in advance,


nEon

 

[Harpo]

[quote author="Dr nEon"]I have a gssl with balanced i/o which i need to interface with an unbalanced patchbay.[/quote]
For send (gssl-input), connect Pin2 to tip, XLR pin3 strapped to gnd-pin1.

For return (gssl-output), XLR pin2 to tip and pin1 to sleve, leaving XLR pin3 disconnected.

 

[Dr nEon]

Thanks Harpo!

For the send to the gssl ,when you say "xlr pin 3 strapped to ground" , should i do that at the patchbay end or in the xlr plug?

I am also wondering if this method of connecting would also apply to the calrec pq1549 eq.

Really appreciate the help!!!


Cheers

nEon.

 

[Harpo]

[quote author="Dr nEon"]For the send to the gssl ,when you say "xlr pin 3 strapped to ground" , should i do that at the patchbay end or in the xlr plug?
I am also wondering if this method of connecting would also apply to the calrec pq1549 eq.[/quote]
I think it's a matter of taste, cause the effect would be the same, but do it consistent for all your bal/unbal wiring. I would do it at the patchbay cause of easier fixing in case you exchange your bay with a ballanced one someday, but soldering a patchbay isn't that much fun for usual, so your preferences may differ.
The calrec uses the same balancing stages on input and output as the gssl.

 

[Dr nEon]

Harpo

Thanks again, mate...You're a hero!

Cheers

nEon.

 

[Nadege]

Hello,

here is my problem with my second GSSL compressor. (The first one was success... :grin: )

I've carefully double check all component value, checked for short,... Before posting.

I first have to say That I checked ALL my voltage and they are ALL just nice, as excpected.

My problem is: the compressor seems to work and compress just like the fisrt one except that the output level is something like 60dB too low... I then looked at the meter and saw that the indication on the meter was really low also. So I bring in my scope, and trace the signal.

The signal is ok up to 27k resistor before the L/R VCA and is also ok up to the two 47k resistor just before the sidechain VCA, after those resistor, nearly no more signal...

I really wonder what's happening.

Any help is more than welcome

Nadege

 

[Nadege]

here is a link with my problem point in the schematic.

http://www.twin-x.com/groupdiy/displayimage.php?album=90&pos=8

 

[Nadege]

Ok, I spoke a little bit too fast

I found the problem, it was a dead TLO74....

sorry for making this thread a little bit longer.

(but my compressor is working :grin: )

just one important question, I have a 100ma meter, is the value330r for the resistor I have to add corect?

 

[Harpo]

[quote author="Nadege"]here is a link with my problem point in the schematic.

http://www.twin-x.com/groupdiy/displayimage.php?album=90&pos=8[/quote]
pic 8 shows a broken trace above the threshold on control pcb.

 

[Harpo]

[quote author="Nadege"]just one important question, I have a 100ma meter, is the value330r for the resistor I have to add corect?[/quote]
Only, if your 100mA was a typo and you have a 100uA meter for real. Your TL074 will not drive this to usable/full deflection. Try to get a meter reading 1mA linear-scale (or 100uA with 330r shunt).

Nice build btw and glad you fixed it. :thumb:

 

[Nadege]

it was a typo.. :wink:

 

[crisotop]

Could any of you recommend a suitable cable for wiring audio projects like the gssl? Especially what diameter would be sufficient?

Many thanks
Christoph

 

[gyraf]

Just about any type of wire will do fine in the GSSL - but for the mains voltage parts you need to use mains-certified cable!.

For the signal and control wires (again, not for mains), I think I used standard KAT5 computer-network cable that I split into individual pairs.

This because I prefer to work with solid-core wires, you may prefer stranded-wire.

Jakob E.

(edited: clarified that KAT5 is for signal only, not for mains)

 

[crisotop]

Thanks Jakob! Good Idea to use Kat5s, I'm sure I have some flying around.

regards,
christoph