GSSL HELP THREAD!!!

[gyraf]

Very good walkthrough - thanks...

Jakob E.

 

[artosaudio]

wow! now that's a extremely detailed troubeshoot guide!! Maybe a usefull add to the gssl meta?

I must tell you that I've been busy trying to fix my gssl but after I got a 220v el shock I decided to call it a day. However after reading your post I am full of energy again, so I'm back at it, thank you so much!!

This must be the most helpfull community on the entire internet...

 

[stereokillah]

hi,

i finished one gssl with 202x turbo and two SSC, everything seemed to work find, but some time when i power up idon't have song???

After checked it i found the +15 is about -0.737 some time when i switch the machine power up, but -15 is good,

i've changed the 7815 for another model (for the  both 1.5A input max input +30V) but before the 7815 there is +22V, it's the same thing,

i've tryed without CRC, same thing,

changed the 1000uf , same thing,

without turbo , same thing,

disconect first SSC, same thing,

Finaly when i disconnect the both SSC (unickly when i disconnect the both)  the 15v is back,

so when There is crc turbo and gssl all is fine

my transfomer psu is 15v 15va, need i changed it to 30VA for all this people or any sugestion?

thank you

 

[Harpo]

After checked it i found the +15 is about -0.737 some time when i switch the machine power up, but -15 is good,

i've changed the 7815 for another model (for the  both 1.5A input max input +30V) but before the 7815 there is +22V, it's the same thing,

reading '7815 for another model' as changing brands like STM,TI,Motorola,Fairchild,NationalSC,...
Maybe a diode between 0V and +15V (pin 2 and 3 of the 7815), anode side to 0V/pin2 can help this startup latching.

...with 202x turbo and two SSC...
...my transfomer psu is 15v 15va, need i changed it to 30VA...

Your transformer (assuming dual 15V or 30VCT 15VA) can deliver 15VA/30V=0.5A AC or 0.25A AC each separate winding. Rectified this is about 0.5A/SQR(2)=0.35A DC or 0.175A DC each rail.
Rough estimating your connected load of 2xNE5534, 6xNE5532, 2xTL074, 1xTL072, 18xVCA, 2x relais at whatever coil resistance, maybe 3 LEDs at 10mA, some leakage current ... 15VA looks at least tight, you're more likely running out of steam.

 

[stereokillah]

thanks for reply harpo,

yes i tryed diferents 7815 brands and models 7815 cv and 7815 other but the data shetts are aproximativly the same, i'll try the diode and changed the transformer in the future.

 

[Biasrocks]

thanks for reply harpo,

yes i tryed diferents 7815 brands and models 7815 cv and 7815 other but the data shetts are aproximativly the same, i'll try the diode and changed the transformer in the future.

As I said earlier, the internal supply is seriously close to overload when using 202's. Don't know if this is the case using other VCA's in this design.

I'd suggest an additional PS for the add-on boards, do-dangs, bells and whistles.

A surplus MNat's supply will work or any other high quality supply.

Mark

 

[Harpo]

i finished one gssl with 202x ...

What value did you use for Rin in front of these VCAs ? 6K04 as suggested by THAT design note DN127 ? And about 3K6 Rfb for the following current-to-voltage converter ?

For your connected load the main bottleneck in your supply seems to be the 15VA transformer. Maybe add the from datasheet 'min.required protective resistor' of at least 0.8R for the B40 type or at least 1.6R for the B80 type bridge rectifiers in series with your transformer secondary wires when not using a CRCRC board. Adding the CRCRC board in front will have a similar effect with probably improved results.

 

[stereokillah]

As I said earlier, the internal supply is seriously close to overload when using 202's. Don't know if this is the case using other VCA's in this design.

I'd suggest an additional PS for the add-on boards, do-dangs, bells and whistles.

A surplus MNat's supply will work or any other high quality supply.

Mark

i 've build 5 gssl with turbo and dbx 202 c and x each time the 7815 and 7915 are heater than when it's with that 2180

For your connected load the main bottleneck in your supply seems to be the 15VA transformer.

you mean the tx 15Va is the origine of this problem?

What value did you use for Rin in front of these VCAs ? 6K04 as suggested by THAT design note DN127 ? And about 3K6 Rfb for the following current-to-voltage converter ?

Cause of my poor  english i'm not sure what you mean but don't have upgrade the value, it's origanls dbx 202x and the value on gssl pcb are the ones printed on pcb, only changed the 15k to 27k

Maybe add the from datasheet 'min.required protective resistor' of at least 0.8R for the B40 type or at least 1.6R for the B80 type bridge rectifiers in series with your transformer secondary wires when not using a CRCRC board. Adding the CRCRC board in front will have a similar effect with probably improved results.

I have CRCRC , and my rectifier is  a W05G don't know about B40 or b80

 

[stereokillah]

ok i've put a 1n4003 bewteen ground and output of 7815 and the problem is not resolved

i cant' use another psu card cause don't have place in my rack.

 

[Harpo]

i 've build 5 gssl with turbo and dbx 202 c and x each time the 7815 and 7915 are heater than when it's with that 2180

Obviously 8 VCAs in one housing draw more current than a single one.

For your connected load the main bottleneck in your supply seems to be the 15VA transformer.

you mean the tx 15Va is the origine of this problem?

No. Your actual problem seems to be a latching/missbehaving voltage regulator at start up.
Adding up the estimated current draw of your lot of opamps, VCAs, relais, LEDs, .. might be in range of about 350mA.
This also is the max.current, your 15VA transformer might deliver. Any additional load as meter lights or increased leakage current will be asking too much.

What value did you use for Rin in front of these VCAs ? 6K04 as suggested by THAT design note DN127 ? And about 3K6 Rfb for the following current-to-voltage converter ?

Cause of my poor  english i'm not sure what you mean but don't have upgrade the value, it's origanls dbx 202x and the value on gssl pcb are the ones printed on pcb, only changed the 15k to 27k

My english (if it is english at all) is far from being any better than yours, so please bear with me.
A DBX-202-X and DBX-202-C differ in some aspects. Maybe have a look at this difference showing paper, starting at pg.2.

I have CRCRC , and my rectifier is  a W05G don't know about B40 or b80

Just another common used type of rectifier with round shape to fit the pcb. Obviously not your problem.

 

[stereokillah]

thank  i've  already checked this pdf  about difference Amperage and 6.04k input and  7.3 output but i don't know what is this on gssl pcb
and what should be the changement,
if i put another 7815 brand and model ( a good one) and changed tx to 30 va, do you think i can resolved the problem?

 

[Harpo]

thank  i've  already checked this pdf  about difference Amperage and 6.04k input and  7.3 output but i don't know what is this on gssl pcb
and what should be the changement,

According to these papers, both 27K resistors in front of the DBX-202-X VCA -located between onboard mains transformer silkscreen and DBX202 VCA silkscreen- get substituted by 6.04K.
Both 15K feedback resistors between NE5532 pins 6/7 on pcb (opamp stages on schematic are reversed) -located below the silkscreen label 'OUTPUT'-  get substituted by about 3.6K resistors. (exact value would be (6.04K+1.25K)/2 with perfect parts). This is why for the VCA bypass condition ec=0V you want a -6dB, not 0dB current gain response.
Both 100pF lead compensation caps in parallel to previous 15K, now 3.6K resistors, should be scaled up to 220pF.
Both 1M resistors between symetry adjust trimmer and VCA -located right side next to VCA silkscreen-  get substituted by 200K resistors.
The 22uF caps between line receivers and audio- and sidechain VCAs with the paralleled resistors 47K to sidechain and 6.04K to audio VCAs are a highpassfilter with -3dB cutoff at 1.35Hz. Cap might be scaled up to 47uF for about previous 0.42Hz if it helps better sleep, I'd probably keep it as is.

if i put another 7815 brand and model ( a good one) and changed tx to 30 va, do you think i can resolved the problem?

Hopefully yes.

 

[stereokillah]

oh thanks for this precise description,
i'll check it for the next, perhaps that's why i have a small high sound like exiter at time.

If have time i will modified the gssl draw silkscreen for 202x.

 

[MikeFFG]

Sooo  a little confused about what parts to use for a few things...probably real simple.  What kind of power switch do I need?  I would think SPDT on - off?  Also,  I'm using Dan's GSSL sidechain front panel, so I'm not sure what kind of switch to use for bypass.  I had a Lorlin switch like in the ssl pdf, but it appears to me that on Dan's sidechain board the hole is only big enough for a different type of toggle switch...what would be an acceptable replacement?  I suppose I could always drill the hole a tad bigger if I need to.

Also, the transformer wiring is a little confusing to me.  On the PCB, by the bridge rectifier, there are three holes for connecting to the transformer...what goes to where?  They don't appear to be labeled.  I'm pretty unclear on the rest of the transformer wiring as well but I won't bother you with that here...I know it's covered elsewhere.

Thanks.

 

[ruckus328]

Hey guys, I have a question regarding dual ssc boards regarding the send/ret.  I've been thinking and looking at the schematic, with dual ssc's + turbo, would you only hook up your send/ret to only one of the ssc boards?  As far as I can tell, there wouldn't be a benefit to hooking it up to both ssc, or am I wrong here?  When in turbo mode though, would it screw up the send signal if you didn't have it hooked up to the 2nd ssc board? (the one in series with the turbo board).

 

[regularjohn]

@mikeffg:
power switch can be an spst.  bypass switch needs to be dpdt.  to wire it: the poles (labeled "A" and "C" on the pdf) are the poles of the switch.   C1 and C2 are the throws related to pole C, A2 is the throw related to pole A.  A2 and C2 are on the same throw side.  C1 is on a throw side by itself with an unconnected throw lug next to it.  So only five of the six lugs on the dpdt are used.
power transformer wiring will depend on what transformer you've got.  generally with trafos with dual secondaries (4 wires) 2 of the wires will be your hot leads and the other two get tied together for the 0V center tap. check your transformer's winding code to see which wires are which.

@ruckus328
you'll have two seperate sends and returns, one for each sidechain.

 

[ruckus328]

@ruckus328
you'll have two seperate sends and returns, one for each sidechain.

How does that translate into real world applications though?  Like for example, if I want to do ducking with a mono kick drum?  Do I send the mono kick signal to both sidechains?  And how do those 2 seperate sends and returns get wired up?  I would need 2 XLR's?  If I'm getting this correct though, I could send a stereo signal to the compressor for ducking purposes (L to sidechain #1, R to sidechain #2)?

 

[livingnote]

Basically it doesn't matter for mono or stereo because they either get mixed (Århus/Gyraf) or they get higher-of-two'd (Oxford/Turbo)
so what goes in hits what it should. Stereo can go to comp for ducking sure thing - gets treated according to setting.

For input - debatable if you wanna go to the trouble of an XLR balanced key in - for that you can basically just copy the regular GSSL
input and goody, there's no real merit though because all the compressor is interested in is turning that stuff into CV so you can just
go buffered unbal with one dual opamp. Interesting thing: How are you gonna merge the key in signals, are you gonna make a summing
stage at the SSC input? Gets me thinking what would be smartest - in what applications irl would one use a SC filter for a key in, con-
sidering you're probably getting your signal from the DAW or some channel anyway, you'd almost always have EQs you could punch
in before them...

...but perhaps if you sum it all together, you could get some pretty cool "it compresses AND ducks all at once so it's great for FOH", right?

Only thing then is that you'd have to have a switch to trip the internal SC off the bus, ha ha...or maybe a "this-both-that" switch with
relays.

 

[Harpo]

@ruckus328
you'll have two seperate sends and returns, one for each sidechain.

How does that translate into real world applications though?  Like for example, if I want to do ducking with a mono kick drum?  Do I send the mono kick signal to both sidechains?  And how do those 2 seperate sends and returns get wired up?  I would need 2 XLR's?  If I'm getting this correct though, I could send a stereo signal to the compressor for ducking purposes (L to sidechain #1, R to sidechain #2)?

For ducking you only use the returns as an external key input. Watch out for not shorting/heavy loading the sending opamp when using a single TRS jack for send and return instead of separate jacks or XLRs and someone keys in your kick signal with a TS plug. When using the turbo function, you want this stereo anyway, because the-higher-of-two is already a DC control voltage with rectified audio at double frequency riding on top.
Other uses, you could insert another compressor, maybe FET or opto for different flavour, affecting only your sidechain, so there is only one VCA in the audio signal path instead of a chain of compressors, each deballancing, signalshaping and ballancing again.
Other than in most scf-boards, where you can either filter or reroute to an external loop or key in, you might move this external send/return in front of the filter for having both options.
Just my 2ct

 

[livingnote]

Yeah general sidechain abuse and external CV in totally rules. You can make that box
do just about anything. Important is to make sure that you bump it up to around 0-5V
for I/O or noise'll screw you up good.

Hey Harpo what's keeping you up at 4:20 AM?

Oh what about a balanced CV insert with unbalanced option and TRS/XLR combo jack?

So you'd have really clean tracking. I can imagine it might matter there, if only little...