GSSL HELP THREAD!!!

[kante1603]

230V is the thing for me, so I´m very happy I didn´t try it the way Somsay did now..

Thanks for the link to, I´ve already seen it, but still a bit uncertain (you know the feeling when you want to be 110% sure how it´s done).
Would be nice to know "the red goes to.. and the black goes..." etc

Sorry, just a bit new to this!

Thanks

m

Hello mingus,

I don´t know what transformer you are using,but if you are in 230 Volts-Land and the primaries are 115v each then the red + black wires must be connected to each other (this forms 115v+115v=230v your primary winding).Yellow and violet wires are your mains wires then (Live and Neutral).
Don´t forget to put in a fuse.
If the secondaries are 2 x 15 or 18vac then your wiring seems to be correct,but as said I don´t know the specs.

Best regards from germany,

Udo.

Edit:May I recommend to put in crcrc-board-bewares you from a lot of possible trouble like hum etc.?

 

[Harpo]

Thanks for your quick reply there! And sorry for not having updated my profile, I´m pretty new on the forum thing.
230V is the thing for me, so I´m very happy I didn´t try it the way Somsay did now..

Thanks for the link to, I´ve already seen it, but still a bit uncertain (you know the feeling when you want to be 110% sure how it´s done).
Would be nice to know "the red goes to.. and the black goes..." etc

For your Amveco 62063 transformer you won't get a much better primary wiring explanation than from the manufacturer of your transformer (colour of transformer lead wires are not standarized, so a different manufacturer might use a different colour scheme), so 'For 230V operation, connect primaries in series by connecting black and red lead wires together and apply 230V across yellow and violet leads wires.'. Make sure, this black and red wire connection is isolated.
Secondary wiring shown in somsays schematic is correct.

 

[mingus]

230V is the thing for me, so I´m very happy I didn´t try it the way Somsay did now..

Thanks for the link to, I´ve already seen it, but still a bit uncertain (you know the feeling when you want to be 110% sure how it´s done).
Would be nice to know "the red goes to.. and the black goes..." etc

Sorry, just a bit new to this!

Thanks

m

Hello mingus,

I don´t know what transformer you are using,but if you are in 230 Volts-Land and the primaries are 115v each then the red + black wires must be connected to each other (this forms 115v+115v=230v your primary winding).Yellow and violet wires are your mains wires then (Live and Neutral).
Don´t forget to put in a fuse.
If the secondaries are 2 x 15 or 18vac then your wiring seems to be correct,but as said I don´t know the specs.

Best regards from germany,

Udo.

Edit:May I recommend to put in crcrc-board-bewares you from a lot of possible trouble like hum etc.?

Thanks! I´ve got the Amveco 15V (http://parts.digikey.com/1/parts/1000040-transfrmr-15v-1-664a-wires-62063-p2s02.html)
And I also have the CRC board ready, thanks for the tip though.
I guess your explanation something like what it says at the Amveco site too (http://www.amveco.com/Miniature_Low_Profile_Transformers_2.htm)
Of what I understand the red and black should be connected to each other and NOT be connected to the pcb right?

Feel a bit stupid, but better stupid than fried..

Thanks a lot for your reply!

m

 

[kante1603]

Of what I understand the red and black should be connected to each other and NOT be connected to the pcb right?

Hello mingus,

yes-red + black to each other (again: 2 primary windings in series at 115v form 1 winding at 230v).
This connection must be isolated and must not touch anything else (I mean really nothing!!!)

Best,

Udo.

 

[el-tone]

Hello,

I just finished soldering all the parts and making the connections between the boards and to the xlr's, but no sound comes out of my GSSL... The green LED works when its powered on but nothing happens the meter doesn't show anything, i only had some very loud peep sometime. I measured the voltages +15/-15; +12/-12V on the main pcb and they were nearly correct (+/- some %)

I am very new to electronics and it is my very first soldering job , so I am not sure if I soldered everything correctly.

I uploaded some photos of my clone here, and would be very thankful for any help!
http://www.el-tone.com/gssl/gssl.zip

Greetings, Roland

 

[mingus]

Of what I understand the red and black should be connected to each other and NOT be connected to the pcb right?

Hello mingus,

yes-red + black to each other (again: 2 primary windings in series at 115v form 1 winding at 230v).
This connection must be isolated and must not touch anything else (I mean really nothing!!!)

Best,

Udo.

Thanks! Feels like I´m ready to do some soldering now.

Thanks again!

m

 

[ptron]

Hello,

I just finished soldering all the parts and making the connections between the boards and to the xlr's, but no sound comes out of my GSSL... The green LED works when its powered on but nothing happens the meter doesn't show anything, i only had some very loud peep sometime. I measured the voltages +15/-15; +12/-12V on the main pcb and they were nearly correct (+/- some %)

I am very new to electronics and it is my very first soldering job , so I am not sure if I soldered everything correctly.

I uploaded some photos of my clone here, and would be very thankful for any help!
http://www.el-tone.com/gssl/gssl.zip

Greetings, Roland

No sound at all? Not even a ground loop or some sort of thing in between the odd bleep?

Ps.. Did u check xlr outs + and - are reverse from ins? Id say wiring problem since u got all voltages within measures but then again im no less newb than u my friend
I hope u find the fault soon

 

[el-tone]

No sound at all? Not even a ground loop or some sort of thing in between the odd bleep?

Ps.. Did u check xlr outs + and - are reverse from ins? Id say wiring problem since u got all voltages within measures but then again im no less newb than u my friend
I hope u find the fault soon

The connections of the xlrs +/- are ok...

 

[Harpo]

The connections of the xlrs +/- are ok...

You only might have swapped the input/output molex connectors on gssl-mainboard, otherwise follow signal to see where it is lost.
http://www.groupdiy.com/index.php?topic=47.msg483540#msg483540

 

[beatnik]

I've tried this project for led gain reduction meter in my GSSL.

http://www.axaprospect.ro/electro/gssl/GRMETER.pdf
http://www.axaprospect.ro/electro/gssl/GRMETER.zip

I can't manage to calibrate the scale correctly. i am sending an oscillator from the console and reading back the output of the compressor.
When meter displays 10 dB gain reduction (ie all leds lighted up with 4k75 resistor) in fact only about 1 dB gain reduction is happening.

The only substitution is that I used LM3915 instead of LM3914. Then put a jumper instead of the 2k resistor on main gssl board.

how can I calibrate the scale properly?

I believe I need more trimmers or change resistors values, but have no clue on how doing it. Any input is highly appreciated. I attached the schematic. Thanks

 

[beatnik]

I've discovered the 3915 is logaritmic scale, and the 3914 wich the project calls for is linear scale.

This could be the cause of the imprecision of the scale.

Anyway,  is there any voltage I can check, to know if the meter circuit is recieving the right input voltage for measuring the correct gain reduction?

And eventually there is a way to adapt the 3915 to the circuit?

 

[MeToo2]

I've discovered the 3915 is logaritmic scale, and the 3914 wich the project calls for is linear scale.

This could be the cause of the imprecision of the scale.

Anyway,  is there any voltage I can check, to know if the meter circuit is recieving the right input voltage for measuring the correct gain reduction?

And eventually there is a way to adapt the 3915 to the circuit?

Where are you taking the feed for the GR from? Is it the 4K7 "meter cal" trimmer is on the circuit diagram = point G?

You can check the voltage at the output of the TL074 pin 8 marked "meter cal". It depends which emulator circuit you've built or which DBX VCA you've used about the exact sensitivity of the control law. According to the measurements I did, I think about 5.46V CV should give about 40dB of GR.  2.71V CV about 20dB GR.

This signal is definitely already logarithmic as you can see (double control voltage = double GR _in_dB_ ), because the control voltage to the DBX VCA emulator is logarithmic. That's why the GR meter is a linear meter (100uA / dB).

I really don't see any convenient way of using your 3915. Maybe someone else can.

 

[beatnik]

I have placed a jumper instead of meter trimmer, and send the signal from here to the led meter circuit. Is this ok or I have to keep the trimmer?

I'll try to measure the voltage at the sidechain TL074 and see if correspond to your values.

Then I would like to know if it's coming the right voltage to LM3915 input. What would be the ideal voltage on LM3915 pin 5 (input signal)?

For example, if 10dB gain reduction is happening, according to your measurements I should read 1.35 V on TL074 pin 8, but what on LM3915 pin 5?

 

[MeToo2]

I have placed a jumper instead of meter trimmer, and send the signal from here to the led meter circuit. Is this ok or I have to keep the trimmer?

I'll try to measure the voltage at the sidechain TL074 and see if correspond to your values.

Then I would like to know if it's coming the right voltage to LM3915 input. What would be the ideal voltage on LM3915 pin 5 (input signal)?

For example, if 10dB gain reduction is happening, according to your measurements I should read 1.35 V on TL074 pin 8, but what on LM3915 pin 5?

Hmm. Let me think.

I haven't seen your board before.....

My data shows 10dB is around 1.34V at the output of the TL074. Yours could be a little different of course.

The trimmer is there in the original circuit because a moving coil meter is fundamentally a current device. The voltage isn't that relevant to the moving coil meter: it moves 1mA full scale or 50% for 0.5mA. My build used a traditional meter.

An IC meter is fundamentally a voltage measurement device. So using a link could be fine instead of the trimmer, but you'll probably need some way of adjusting the sensitivity.

Now looking at the sensitivity.

Looks like R1 R2 & R3 do that on your board. First TL072 is a simple inverter = gain of 1.
Second TL072 is also a simple inverting amp with a gain of R4/R1 or R4/R2 or R4/R3 depending on the jumper setting.

So that would be ±1.34v * 91K/9.53K = 12.79V or 1.34*91K/4.75K = 25.67V or 1.34*91K/2.45 = 49.8V (!)

That sounds rather a lot, to say the least. Seems way too sensitive to me.

Especially when looking at the data sheet: Vref = 1.25V (R2=0) Iled = ±10mA. So full scale deflection of the bar graph meter is only 1.2V according to the data sheet in this configuration.

Is this meter board meant to be fitted in parallel to a moving coil meter, or to replace a moving coil meter, or be connected directly to the VCA control signal after the potential divider resistors?????

To me this only looks like it would make sense if your GR meter input (pin 3 IC2a) was connected directly to the control voltage control pin on the VCA (pin 5 of the 2181) which works at 6.1mV/dB.

If that were the case the that would be 10dB * ±6.1mV/dB *91k / 4.75k = 1.16V at pin 5 of the LM3914, which would be about right for 10dB full scale of 1.2V......

What did the kit provider say?

None of this is going to solve your logarithmic issue though of the LM3915.

 

[beatnik]

this is great information and lot of help.

seems tha the usual place of the standard meter is not suitable for this circuit.

the problem is, i tried to contact the developer of the project for asking help, but didn't get answer. and the project doesn't give information on where to connect to the mainboard.

I try to connect the circuit directly to pin5 of the VCA. do you mean sidechain VCA, right?

 

[MeToo2]

this is great information and lot of help.

seems tha the usual place of the standard meter is not suitable for this circuit.

the problem is, i tried to contact the developer of the project for asking help, but didn't get answer. and the project doesn't give information on where to connect to the mainboard.

I try to connect the circuit directly to pin5 of the VCA. do you mean sidechain VCA, right?

Sorry that should be pin 3. Not pin 5. Yes you could try the SC VCA. Not ideal because of the threshold offset. The other problem is that if you use the main VCA you also get the make up gain.....

Another, perhaps better, option would be to change the ratio on the second amplifier on your GR board to make it less sensitive by changing R4 (the 91K). You can calculate the correct ratio yourself I guess to make the voltage at the output of IC2B of the TL072 to be 1.2V when the compressor is compressing by 10dB. It'll be somewhere about 1.2/1.34*4.75K = 4K7 trimmer I guess.

 

[prescott]

HI All!

I've just finished my Gssl, and works nice but I have a problem:

Under 200Hz the left and right channel is not on the same gain level.

I checked with a signal generator. From 20.000 to 200hz there is no problem, but if i go downer and downer the stereo balance is going from bad to worse.

Can U guys help me in this?

(I have a -60 dB noise at about 100-120Hz, but I ordered the crc board(not yet arrived), maybe this is the reason for the problem?)

 

[Harpo]

Under 200Hz the left and right channel is not on the same gain level.
I checked with a signal generator. From 20.000 to 200hz there is no problem, but if i go downer and downer the stereo balance is going from bad to worse.

double check HPF C/R values (22uFs on input, 22uFs after NE5534s, 100uFs after NE5532s, same resistor values connecting to ground or virtual ground after each of previously mentioned caps).

(I have a -60 dB noise at about 100-120Hz, but I ordered the crc board(not yet arrived), maybe this is the reason for the problem?)

Your frequency dependant imbalance (whatever fraction of dB it might be) is not power supply related. The crcrc board will adress your 120Hz hum.

 

[frazzman]

Arghhhhh... so I decided to retro fit a turbo board to one of my old gssls...everythings wired up and i seem to have hit a snag...unit is wired for permanent turbo, as soon as unit is out of bypass meter pegs far right and no audio passes.

As as i disconnect turbo pcb everything goes back normal

If i disconnect 'c' connection from turbo pcb to mainboard the meter stops pegging and things start working again, same happens when i take thetl074 out of turbo pcb.

Very confused, whats the purpose of the 'c' connection anyhow? Havent got my head around the turbo board entirely...

 

[MeToo2]

Very confused, whats the purpose of the 'c' connection anyhow? Havent got my head around the turbo board entirely...

The Turbo board is essentially a second side chain amp/ detector circuit copy of the one on the main board.

Point 'C' is where the output of the Turbo side chain amp/detector circuit and the original main board side chain amp/detector circuit connect back into the original side chain timing filter on the front panel daughter board.

There's a 1n4148 diode on the main board at the output of the original side chain detector, and also one 1n4148 on the output of the Turbo side chain detector board, meaning that point 'C' should be the most negative of the two control voltages = compress both channels by the max of (-CV_L , -CV_R).

Perhaps check for the correct orientation of the diode on the Turbo board connected to pin 14 of the TL074, and also that the output of the Turbo board isn't permanently stuck at Vcc or Vee, before connecting the Turbo board back to point C.