GSSL HELP THREAD!!!

[Greg]

mathflan: Are you measuring output between + and -, or between + and ground?

 

[Purusha]

I have a question regarding my LEDs. I have to put two more and don't know what resistor to use. I bought most regular blue and red LEDs which I plan to connect after my extra 7812 regulator which I am using for feeding the true bypass relays. Can someone help me with this?

How should I connect the LEDs - in parallel or one after another and where do I put the resistance, before or after... ?

Mouser or Digikey... The exact part numbers are in my parts list. Find that thread I started that has all my parts list. It's in there.

Thanks.

 

[mathflan]

mathflan: Are you measuring output between + and -, or between + and ground?

In fact, I didn't test voltage, just with My ears and vu meter on Nuendo.

 

[Purusha]

No one knows what type of resistor goes with normal LEDs and 12V? I am sure this must be a piece of cake for all you experts here :grin:

 

[Purusha]

Don't bother, I just found out.

It's between 600-800 Ohms. 470 Ohms would be also OK if you like bright LEDs :grin:

 

[DQ]

just though i give another update regarding my gssl and hum issues...

..there still was some hum even after i moved the powersupply connection.
I dont know why , but i found out that if i connect the ground near the sidechain to the ground on te chassis ,(probably i think another ground loop) the noise disappears almost completely, considering that i was testing with 20 dB of make-up gain and my desk control room at maximum level.
Maybe i still had some ground loops, whi knows..but I am happy that it sounds better! ..

also i noticed that noise come down even moreif i disconnect the earth from the ground, maybe due to my poor earthing system in my house..

,,,ciao..and thanks for the various suggestions..

 

[sounden]

Hello!
When I connect my "Power ON" LED the current drops from ~+12V to
~+6V, Is this the way it should be?


~ means in this case, about...

 

[muffy1975]

HI there,

I already completed my first project the 1176 without a hitch. MNATS Site guided me through and I it worked straight out of the box. Thanks GYRAF...alot for a great little design. It sounds cool along side my real LA2A and etc etc. So happy.

Ok so lets do the SSL. Its done. Voltages all good at the rails with out ICS (but a little high on one side of the 15V...thats normal until you load the ICS). ICS loaded the Voltages are good enough...15.3V on one side/15.04-V on the other. The 12 volt rails are even better. Both around 12.04 +/-.

Audio goes through the unit in BYpasss. The LED even comes on.
Switch in the compressor and I have no real gain control and the threshold is odd.

Now I've read all 100 pages and my sort of problem has come up and is never answered. The reason surely is cos the answer is either blowing in the wind or there's a solder blob/a short somewhere or a wrong component somewhere. Cool. I'm learning alot.

Here's my first question?

What does -2.4V on PIN 5 of Sidechain VCA mean if that VCA is a 2150 and the main VCA are 2180LA's (and I have not attached the trim pots to these)?

Is there a link to hooking up the threhold/gain pot. I've followed the component layout chart exactly. No questions. Am I missing something here?

Thanks for any help. In the mean time I will keep looking for the answer in all the threads. Its got to be there somewhere right?

Michael de A

 

[muffy1975]

Hi there again,

I've checked continuity the 10 wired between the main PCB and the control PCB. It's good.

With regard my problem in the last post which of these don't you like and could they be causing a problem?

1. I don't won't a meter telling be what I can hear. Theres no meter on my project. I've just left out. No jumpers no nothing.

2. the 4148s are the 200mA/100 v type.

3.The 6.8 tantulum is the 35V variety not the 50V.

I'll come back with some more things

Thanks everybody

Michael de A

 

[muffy1975]

Hello there,

my guess is that one of 3 three things are wrong

1. Dodgy TL074. Thanks Mouser...
2. Dodgy TL072. Thanks Mouser
3. Broken sidechain VCA.

What would you say?

Thanks everybody

Michael de A

 

[rbaker]

I know this has been talked about before but I'm having a little trouble finding what I'm looking for...

I'm about to solder the lorin switches to the pcb and I don't want to do them backwards. I know that they will work either direction, but I have "D" shafts and I don't want to have to unsolder them later in order to make the knobs point in the right direction. I haven't bought knobs yet---so there is no way to tell.

Or, does it REALLY depend on what kind of knobs I get?

Thanks for the help....(sorry, my first diy project)

 

[Twin-x]

[quote author="BR"]Hey there guys,
I just asked Greg for some personal help with some problems I'm having with 2 SSL clones I'm building, since I was afraid of sounding really dumb on the forum. But since, I can really hide it anyways, I thought I should ask here too. Maybe others with similar problems can benefit..

I have 2 units but I'm only going to describe one at the moment.

I have no way to do audio testing at home, so I just decided to start with power and this is what I found:..

7815 23.7V In and 14.7V Out
7915 -23.6V In and -14.9V Out

78L12 23.5V In and 12.2V Out
79L12 -23.5V In and 12.0V Out

I basically comcluded that my power rails are fine with regulators working correctly.

I moved on to checking power at the ICs (with chips in sockets) and this is what I got:

5534 Left input
Pin4 -14.97V
Pin7 14.78V

5534 Right input
Pin4 -14.97V
Pin7 14.77V

5532 Left out
Pin4 -14.97V
Pin8 14.77V

5532 Right out
Pin4 -14.97V
Pin8 14.77V

So I guess it is safe to assume that everything is going fine up to there.

TL072
Pin4 -12.07V
Pin8 12.21V

TL074
Pin4 12.22V
Pin11 -12.07V

I guess everything fine here too..

Time for sidechain VCA

Pin5 -8.62V (?)
Pin7 12.22V

So I figured there is something funky between the output of my 79L12 and the SC VCA but I couldn't find anything... hang on, I'll take another look..
So, by looking at the schem and pcb, I noticed the 3k9 resistor in series with Pin5 of the VCA. That could be what is causing the voltage drop, right? if so, then this reading is correct, right??


I went on to measure the Voltage points that are labeled on the pcb, just to see if everything was OK and poked around and remember something about the Voltage labels on the bottom of the unit not being exactly next to the voltage points. So I measured around on the spots that I thought should be read and they all seem fine.

I guess my questions, after this long description, is the -8.6V on the SC VCA any concern? and is there anything else, power wise, that I should check for??

maybe some DC on the other pins of the chips or anything like that?

WOW.. I just learned so much doing this... this is great.


Thanks a bunch

Gil[/quote]

I have these exact measurements (well maybe afew millivolt diffrence.
Also i am in the same situation i cannot test audio because of missing cables.

The problem i have (not sure) is that when i switch on the unit the meter directly goes to the max. Is this normal? If i do bypass the meter drops.

If i leave out the 074 the meter stays at 0
If i leave out the 072 the meter goes slowly to max

Could someone get me on the right track?

thank,
jef

 

[muffy1975]

Hi,

I'm sure I read earlier that the D Shaft orientation question is not a problem if you get the knobs with hefty side screws (like Maplin ones) before you solder in your lorlins. You'll know then what options you have.

BR...did you post your question again or has someone posted it again because there wasn't an answer to it. Funnily enough.... I printed out this exact posting only!........out of 104 big pages of thread. I'm sure no one gave an ideas.

Anyway I've made some progress and some regression since last time.

My first problem was that the 12V +/- going to the control was being interupted by some evil cable between control panel and main PCB. Evil meaning snapped in secret.

Now I have gain control. Cool. But I need some compression and at the moment I'm just feeling mild depression.

My LED has died and the threshold is kicking around wildly when turned. Maybe the LED is shorting something.I've taken a trip to Gomorra for a few days of relaxation. When I get home the LED's coming out and I'm checking my diode situation. One of them near the 74 is giving me a strange vibe. The diode tester gives me a reading in both directions. When the diode is tested away from the PCB its fine ie it tests in one direction only. So there is something wrong if it tests both ways. Maybe not the diode....the caps near by?????

Ok one hour later 500 miles from the my PCB and my home I've decided to call a bloody repair man who knows what the hell he's doing (...I don't...thought I did building my killer G1176) and give him what ever money he wants to fix the F****** thing. If I spend another day soldering and re soldering stuff and then breaking stuff that did work and destroying stuff that never worked I'll puke.

Oh and when it's working I'll tell you what was wrong and not just say.....its working...see ya.


Lots of love (in a human way)

Michael de A

 

[nicodjhouse]

Hi guys !

I finished yesterday my compressor, perfectly working!
I wanna thank one more time Jakob for his wnderful gyraf website, and Roland Klinkenberg for his help

tell me how add photos and i'll update the post!

 

[Purusha]

you have to upload them somewhere else and write down the link while using the "img" option inside edit window.

Tell us more about which VCAs did you use and what calibration changes you followed to get the compressor working nicely.

 

[nicodjhouse]

I used the 2181LA VCA's, they all work perfectly. For the moment I find the compression a little weak. I'll test it with friends tonight and decide if I have to update some components.

I'll have to change a few components concerning the meter that I find very sensitive (as you can read on the topic "how to calibrate the GSSL")

 

[Twin-x]

bump on http://www.groupdiy.com/index.php?topic=174945#174945

 

[gyraf]

[quote author="Twin-x"]bump on http://www.groupdiy.com/index.php?topic=174945#174945[/quote]

The VCA supply voltage is fed through a resistor, so it won't be full -12V (take a look at the schematic).

From a quick glance, it seems that your voltages are correct.

Jakob E.

 

[Twin-x]

[quote author="gyraf"][quote author="Twin-x"]bump on http://www.groupdiy.com/index.php?topic=174945#174945[/quote]

The VCA supply voltage is fed through a resistor, so it won't be full -12V (take a look at the schematic).

From a quick glance, it seems that your voltages are correct.

Jakob E.[/quote]

Ok after a while of tracking i found out that my 50K pots were logarithmic.
I changed them and now i am getting somewhere.

If the treshold pot is 0 my meter starts to bounch up and down.
If i set attack higher i get more and more hum.

If treshold gets 50% the sound is not audible but i hear popping sound. sometimes the sound comes trough.

I changed the pot 2 times and i have changed all the vca's.

O yeah and if the bypass switch is turned on i get incredible hum.

I have the sidechain attached.

So any more help would be really appreciated

 

[gyraf]

Hi Twin,

Start out without the sidechain filter, just to exclude problems there.

Check proper powersupply voltages.

Check proper cabling - specially around your bypass switch!

To repeat myself, 99% of errors in this circuit is 1)solder shorts. 2)wrong components or orientation. 3)wrong wireing.

Jakob E.