GSSL HELP THREAD!!!

[pietro_moog]

thanks guys, i'm gonna have check this thing.
i tried the compressor before dinner, it sounds good, just a bit noisy.
also, my make up gain is a bit low.
i expected about 15db of gain, but it's a bit less,i don't know, 5-8 maybe.
could it be the thing with 78&79L12?

 

[pearldrum944]

@Pearldrum, 10 dBFS bears no indication re how that translates to how many dBu now
actually are coming out of your DAC at the end, your comp could be doing just fine while
your DAC is firing a bit high. The sensitivity adjust thing with the resistor does both, changes
sensitivity AND bumps the range up, but before I'd twiddle that I'd check to see how many
dBu are coming out of your DAC at -10dBFS to know what's going on (1kHz tone and
AC volt meter). You can translate this on this thing

Just to make sure I am doing the conversion right, measure + and - input A/C voltages of 1 channel (off the xlr) and sum them together (2.6v), convert to RMS (2.014), calculator gives me a dBu of 8.3.  Is this right?

Also, I have tried a couple resistor options (none, 47k, 220k) at the threshold but it only seemed to change the sensitivity.

 

[livingnote]

>>>Also, I have tried a couple resistor options (none, 47k, 220k) at the threshold but it only seemed to change the sensitivity.

Ah - right. I was thinking from the wrong side of the pot in that case, sorry. You mean it's compressing with the threshhold
all the way up, right, when it shouldn't be? If that's the case then it's odd, because if I have it right in my head you should
be drowning the SC VCA in DC enough to stamp it out pretty much all the way.

Do you have a peak or rms meter? Just not that the thing measures RMS (or some bastardization thereof) and you convert
it to RMS a second time by hand. Either way, you can just take one of the pins' RMS level and add 6dB (or sum the two and
convert but why bother measuring twice) and you'll know what signal level is really in the SSL at any given dBFS level.

From there you can calibrate. But if it's not supposed to compress with thresh all the way up, it simply isn't, then I'd
check the 12V rail voltages (specifically the - one) to make sure the SC VCA gets enough juice in pin 3.

 

[pearldrum944]

>>>Also, I have tried a couple resistor options (none, 47k, 220k) at the threshold but it only seemed to change the sensitivity.

Ah - right. I was thinking from the wrong side of the pot in that case, sorry. You mean it's compressing with the threshhold
all the way up, right, when it shouldn't be? If that's the case then it's odd, because if I have it right in my head you should
be drowning the SC VCA in DC enough to stamp it out pretty much all the way.

Do you have a peak or rms meter? Just not that the thing measures RMS (or some bastardization thereof) and you convert
it to RMS a second time by hand - you can just take one of the pins' level and add 6dB (or x2 each line like your summing)
and you'll know what signal level is really in the SSL at any given dBFS level.

Yes, the compressor is compressing a little when it shouldn't be.

I just have a standard digital multi-meter, so I'm guessing just peak.  I am a little confused as to what you are saying though...I am getting 1.3v peak per pin on my input xlr's...

 

[livingnote]

One way of finding out what your meter does is to stick it in the socket and see if you're getting
115/230V and you'll know for sure. If it says something over 300 or 150, it's peak, otherwise,
RMS for sinewaves. I was just thinking maybe your input is too hot because it might be one of
those non-problems. But it really shouldn't compress when it shouldn't.

Trying to get my head around the Sidechain VCA's pin3 should-be voltages, never calculated that before...

Gotta do that when it's not so late but basically if the thresh isn't giving Pin3 on your SC VCA a high
enough DC voltage then that could be a cause, and that could have as a cause that your 12V rail
voltages could be too low...

 

[pearldrum944]

If I get a chance tomorrow night, I'll check what my meter reads (the manual did not mention rms or peak...and the meter is at the studio). 

My rail voltages are pretty close though.  I think something like -11.86 and 12.08. 

With my wiper I am reading -12v with the threshold at its highest, and almost 0v when it is at its lowest.  (with a 47k resistor in series)  Does this sound right?

Also, let me know if you need me to read voltages off of my s/c vca...

 

[pietro_moog]

you guys were right!
the led was not working because it didn't have enough power!
i took off the turbo board from the circuit,and the led come back in!

so, i image i need to change the 2 resistors before 79&78L12 with a lower value ones.
i have a turbo board, a SSC with 2 leds.
what value do you suggest me?


thanks everyone!

 

[gerardmanvuca]

Weird thing on my GSSL...its al working great with DBX202's, turbo and sidechainboards. But when i run my sound card inputs at -10dB the left channel is a few db louder than the right.....when i run the soundcard at +4db the levels are spot on equal.    Any one have any ideas?....i'd rather run at - 10db than +4  so i can push the gssl a bit more

Any takers ??

 

[livingnote]

@Pietro, here's your problem: The car in this video is your 78L12 and 79L12 and the
camper is the SSC boards and turbo together. You need a bigger regulator, like a normal 7812 and 7912,
which can shovel more electrons at once, i.e. put out higher currents. If you already have everything wired
like you do, the simplest solution would be to remove the 78/79L12s and solder the 7812/7912 into where
they were, with three little wires that adapt them to the board - alternatively, make yourself a separate
little board from Veroboard or something and put the 7812 and 7912 on there, and power everything with
that (you can get the input to that board where the 78L12 and 79L12 get their power, from those two
resistors).

 

[livingnote]

gerardmanvuca, you sure your soundcard is putting out equal levels (just to cross out obvious stuff?)

pearldrum - ok, then the thresh is sending enough volts back to the SC VCA chippedy too...see I was just
thinking that if your thresh is up maybe it's inherent nature of the beast to still be impressed by
stuff that's hot enough at the input regardless - if that's the case, then that's the thing - but I don't
know for sure. At any rate your stuff is wired right.

 

[Biasrocks]

you guys were right!
the led was not working because it didn't have enough power!
i took off the turbo board from the circuit,and the led come back in!

so, i image i need to change the 2 resistors before 79&78L12 with a lower value ones.
i have a turbo board, a SSC with 2 leds.
what value do you suggest me?


thanks everyone!

Check the turbo board very carefully for shorts, solder bridges.

No need to alter the 10R dropping resistors unless you're getting too much voltage into the 12v regs.

Mark

 

[gerardmanvuca]

gerardmanvuca, you sure your soundcard is putting out equal levels (just to cross out obvious stuff?)

Just double checked and im getting exactly the same results across all inputs.... i also have to run my pc outputs at -10db going to the gssl or it is way too loud (running pc inputs at +4db).....if i turn pc inputs to -10db the L+R differs by about 5 db??

 

[ummmdan1]

Hi everybody,


I have just purchased my Gssl PCB, and am a complete newbie to DIY clones n things.
Just trying to get all my parts ordered. One basic first question that I couldn't seem to find an answer to....

Regarding the transformer, I am going to be mounting it off the pcb. I wanted to know whether to connect it to the top left corner of the board where it says 'mount these only if external transformer', or to the four connections where the transformer can be mounted directly onto the board? I have seen people do both, but have no idea why I would choose one over the other!

also which one of these would be best:

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=2239288#header

http://uk.farnell.com/multicomp/mcfe015-15/transformer-15va-2-x-15v/dp/9531670


Any help would be really useful. 

Thanks

Dan

 

[Biasrocks]

Any help would be really useful.  

Thanks

Dan

Hi Dan

Welcome.

First things first. The "search" function is your friend, use it and thoroughly exhaust all possibilities before you post a question. I suggest ignoring the Google search and use the built-in Prodigy search function.

I answered a similar question on the power transformer about 4 pages ago.

http://www.groupdiy.com/index.php?topic=47.msg456081#msg456081

Also, search for "GSSL BOM" (Bill Of Materials), there are several good ones floating around that will point you in a good direction.

There are also META threads contained in the forum which answer many questions.

Here's the one for the GSSL

http://www.groupdiy.com/index.php?topic=110.0

Mark

 

[ummmdan1]

Thanks Mark, I was using the google search, nowhere near as good as the other one! oops

 

[drive]

Any help would be great !

The compression kicks in to late, I have to turn the threshhold to at list 9 o'clock for the comp to start compressing. What would I need too change for it to start compressing sooner?
I tried to change 47K on the threshhold but that does not seem to do much.

 

[Biasrocks]

Any help would be great !

The compression kicks in to late, I have to turn the threshhold to at list 9 o'clock for the comp to start compressing. What would I need too change for it to start compressing sooner?

As I just pointed out, search and META's are your friend.  

From the GSSL META thread.

http://www.groupdiy.com/index.php?topic=2418

That should give you some idea where to look.

Mark

 

[Autophase]

ok so i had my first test with audio tonight, it is passing audio fine, if slightly noisy, but i havent grounded it yet.
But I am getting no compression at all, the makeup and threshold has no affect.
I'm am getting very close to 15v readings on the test spots and I doulbe checked every solder joint for shorts.
Here is a picture showing all the resistors i omited according to advice when using the "THAT2180AL08-U Pre Trimmed VCAs" just incase you think I should have some of them in there

Any ideas?

Also this might sound really stupid to some of you, but does it matter which way round the potentiometers go? obviously the pot should face forward, i only ask because i couldnt identify a + or - pin on the data sheet??

 

[pearldrum944]

pearldrum - ok, then the thresh is sending enough volts back to the SC VCA chippedy too...see I was just
thinking that if your thresh is up maybe it's inherent nature of the beast to still be impressed by
stuff that's hot enough at the input regardless - if that's the case, then that's the thing - but I don't
know for sure. At any rate your stuff is wired right.

Okay, so my meter does read RMS...I was just confused.  This puts my dBu at about 4.5 per pin.  Does this sound about right?

 

[Autophase]

I'm using the the 2180LA VCA's do I need to mount the 2 47k resistors next to the left VCA, I have checked various pages and a question mark remains next to this point.
Also my compressor is passing audio and the make up is working, it appears no compression s being applied when the bypass is in or out.
Any help would be greatly appreciated.
Thanks