GSSL HELP THREAD!!!

GroupDIY Audio Forum

Help Support GroupDIY Audio Forum:

Juanaca

Well-known member
Joined
Dec 8, 2019
Messages
141
wow, it didn't work, the impedance problem is even greater, a lot of saturation. the vu meter has stopped working. what is the path of the vcas signal to the meter? It seems that I must put some bridge in the resistances that I have removed.
 

Juanaca

Well-known member
Joined
Dec 8, 2019
Messages
141
change the 2 27k input resistors for 15k ones and a 50k trim pin1 windshield input output. I changed the 2 15k resistors near the 5532 for 2 27k resistors. sounds like a lot of saturation
 

Harpo

Well-known member
Joined
Oct 29, 2005
Messages
2,424
Location
Rahden, Germany
change the 2 27k input resistors for 15k ones and a 50k trim pin1 windshield input output. I changed the 2 15k resistors near the 5532 for 2 27k resistors. sounds like a lot of saturation
I don't have the slightest idea, what "a 50k trim pin1 windshield input output" might be.
Your mixup of 15k in front and 27k feedback nearly quadruples the overall gain, so depending on input level, this might/will saturate your GSSL. For a DBX202C, I wouldn't go lower than 27k as input resistor in order to not exceed the allowed input current with a not rail2rail driving stage in front, YMMV.
Either keep both 27k input resistors or substitute both 27k fixed resistors with 50k trimmers, trimmer pretrim value about centered, trimmer hooked up as variable resistor, NOT as a voltage divider. (these VCA's are current in/current out devices, not voltage in/out devices). Both feedback resistors at the current-to-voltage-converters NE5532 (15k) will be half the value of the corresponding input resistor in front of the DBX202C VCA in order to get overall unity gain with the following inverting gain stage. (hint: with 27k in front, two 27k resistors in parallel =13k5 instead of the single 15k feedback resistor will get you there easiest and exactly, keeping the 15k feedback with 27k in front will slightly increase overall gain by +0.915dB). Double check your GSSL for overall clean unity gain by temporary pulling the DBX202C and linking VCA-in with VCA-out with a piece of wire/snip-off/paper-clip in order to exclude other build errors or faulty parts.
Are your DBX202C's known working at all?
 

Juanaca

Well-known member
Joined
Dec 8, 2019
Messages
141
Hi Harpo, thank you very much for taking your time. What I meant to say is that I have bypassed the 27k resistor and added a 50k potentiometer to the input pin of the dbx202c. the vca both compress and behave equally, I have to adjust the 50k potentiometer a bit to match them. I have managed to remove enough saturation thanks to this. I think I have the problem in the 15k resistors of the 5532, I have been trying different resistors and the one that works best is with 5k and it works even better with a 2.2k one, but this affects the output level of the "make-up". I also have an oscillation when I do very severe compressions.
 

Juanaca

Well-known member
Joined
Dec 8, 2019
Messages
141
I'm going to try what you say, put the input resistor dbx202c at 27k and the 5532 resistor at 13.5k Thank you very much for the advice.
 

chilidawg

Well-known member
Joined
Nov 27, 2013
Messages
153
Is the DBX202 emulation circuit not good enough?

I have used SSL 4K, 5K, 6K, 8K, 9K, AWS, Duality desks a lot in the time I was still actively mixing, as well as the old SSL bus compressor rack units, then later the 500 version which a couple of friends/clients owned. Maybe it's just me, that despite still having a perfect hearing for an adult, I just couldn't tell the difference between those and a GSSL installed with a DBX202 emulation circuit. I also think all the additional stuff which came later to mod the plain GSSL have no significant improvement whatsoever (no offense, it's just my personal opinion), other than overcomplicate the circuit and of course, increasing component counts and spending more money to buy them components.
 

Ricardus

WILL SOLDER FOR FOOD
Joined
Dec 2, 2018
Messages
1,661
Location
No longer in NY and below the Mason Dixon line.
Is the DBX202 emulation circuit not good enough?

I have used SSL 4K, 5K, 6K, 8K, 9K, AWS, Duality desks a lot in the time I was still actively mixing, as well as the old SSL bus compressor rack units, then later the 500 version which a couple of friends/clients owned. Maybe it's just me, that despite still having a perfect hearing for an adult, I just couldn't tell the difference between those and a GSSL installed with a DBX202 emulation circuit. I also think all the additional stuff which came later to mod the plain GSSL have no significant improvement whatsoever (no offense, it's just my personal opinion), other than overcomplicate the circuit and of course, increasing component counts and spending more money to buy them components.
DIY Recording as well as some very good tech friends of mine have tested a variety of VCAs, and Peterson tested a bunch of VCAs for their new SSL Buss Comp product (which is in pre order right now) and they could not measure nor hear any meaningful difference between any of the VCAs.
 

craigmorris74

Well-known member
GDIY Supporter
Joined
Sep 9, 2005
Messages
829
Location
benton, ky
Hi Harpo, thank you very much for taking your time. What I meant to say is that I have bypassed the 27k resistor and added a 50k potentiometer to the input pin of the dbx202c. the vca both compress and behave equally, I have to adjust the 50k potentiometer a bit to match them. I have managed to remove enough saturation thanks to this. I think I have the problem in the 15k resistors of the 5532, I have been trying different resistors and the one that works best is with 5k and it works even better with a 2.2k one, but this affects the output level of the "make-up". I also have an oscillation when I do very severe compressions.
Have you read the document from this link:
202 VCAs

It tells you the recommended surrounding components of all the 202 VCAs.

I added a trimpot in series with one of the 15k resistors on the output 5532 to match the L and R sides.
 

thomasdf

Well-known member
GDIY Supporter
Joined
Aug 10, 2011
Messages
700
Location
Paris, France
Hello
I don’t know if it has been dealed with already but it feels like my Hairball 8027 meter has very poor balistics, it’s jumping around and makes it very hard to read when it’s moving fast, I can def tell the needle goes further than what’s it’s supposed to, some sort of inertia.
Has anybody fixed this ?
In studio use it doesn’t bother me as I compress lightly, but I am starting to use it for FOH duties and in these conditions I’d feel better if my eyes could confirm what I ear :)
Cheers
 

gyraf

Well-known member
Staff member
GDIY Supporter
Moderator
Joined
Jun 4, 2004
Messages
10,950
Location
Aarhus, Denmark
Thomas - I'd definitely talk to hairball about that, meter ballistics is a parameter we can't really fix-in-the-mix (electronically). You may be lucky enough to be able to solder on an air-impedance-fin to the needle's counterbalance, but this is obviously dangerous to the health of the meter..

/Jakob E.
 

Ricardus

WILL SOLDER FOR FOOD
Joined
Dec 2, 2018
Messages
1,661
Location
No longer in NY and below the Mason Dixon line.
But the reality is analog meter ballistics don't reflect what's happening with the signal in the BEST of situations. It's just not possible to keep up with sharp transients when you have to move the mass of a needle. This is an issue with analog tape decks when you're recording tambourine for example. You need to record much lower than you would think and what the meter is showing you.
 

atticus1872

Active member
Joined
Aug 12, 2021
Messages
37
Location
USA
I didn't ask you to test continuity between pin 6 and ground.
I asked you to test continuity between the V+ supply pin and ground to make sure there's no short to ground.


For NE5534, the V+ supply is at pin 7.
View attachment 99323
For NE5532, is at pin 8.
View attachment 99324

Anyway, if there's no short, the next move is to check the 7815 regulator itself.


To check the 7815 regulator, set your multimeter to DC voltage mode, put the black probe at pin 2.
First, check for input voltage. Put the red probe at pin 1.
Then check for output voltage. Put the red probe at pin 3.
View attachment 99322
My apologies I misunderstood, I checked for continuity and I have confirmed that there's no short to ground. I measured at pin one of the 7815 voltage regulator and the input voltage is 27.76V The voltage output at pin 3 is 14.94V
 

atticus1872

Active member
Joined
Aug 12, 2021
Messages
37
Location
USA
Why don't you post some hi-res pics of the top and bottom of your board?

Also, I'm finding this thread hard to follow, but are you missing the +15 at some opamps but you have it at others? Check to see that you didn't miss installing this jumper, which I didn't notice at first when I built mine.
Ill post a pic of my board but mine might be a different version of yours but i did verify that the jumpers are installed correctly.
 

atticus1872

Active member
Joined
Aug 12, 2021
Messages
37
Location
USA
Awesome. Hi res fotos are always helpful.

Once I realized I had missed that jumper mine worked perfectly.
I double checked and I'm not missing any jumpers on the board. I honestly have no idea whats wrong or where to go from here. Im considering just sending it off to have someone else diagnose and fix it since im lost in the dark on this one.
 

gyraf

Well-known member
Staff member
GDIY Supporter
Moderator
Joined
Jun 4, 2004
Messages
10,950
Location
Aarhus, Denmark
Atticus,

Your methodology is unclear, as is your problem. When your posts are spaced so far between, it's hard to keep track of what we've found so far..

As I understand it, we have now established that you have +15 and -15V. Do you have these voltages present at the in/out opamp (5534/5532) sockets?

Next, do you have the +/-12V lines? Also present at the TL074?

Have you read this help thread for previous similar problems?

/Jakob E.
 

atticus1872

Active member
Joined
Aug 12, 2021
Messages
37
Location
USA
Atticus,

Your methodology is unclear, as is your problem. When your posts are spaced so far between, it's hard to keep track of what we've found so far..

As I understand it, we have now established that you have +15 and -15V. Do you have these voltages present at the in/out opamp (5534/5532) sockets?

Next, do you have the +/-12V lines? Also present at the TL074?

Have you read this help thread for previous similar problems?

/Jakob E.
Jakob I sincerely Apologize, Ill admit I'm new to this and I purchased a partial kit that was honestly, well a nightmare in its documentation on both its BOM as well as Schematics and assembly instructions. I have that worked out now but I also apologize for my absence I've been gone for weeks at a time away from home working on a project. But luckily that's finished now and this has my full undivided attention. I understand that things got confusing with such a delay in my reply and i had so many replays i was trying so many different things at once to diagnose my issue, some of them made sense to me and some did not. But considering I don't know what my issue is i was in no position to question anyone. My initial post was this

Hey all I apologize in advance but I've spent days/weeks maybe even up to a month now on this help thread looking for someone who has or has had a similar issue to mine but I haven't really found anything (unless I missed something of course) so I feel compelled to ask. I recently finished building the GSSl from a partial kit (missing case, knobs, meter and transformer which is a Triad VPT36-690) Everything powers on from what I can tell and the meter works but one of the issues I'm having is while the compressor does pass audio its cutting the signal way way down. I understand thats what a compressor does but no matter where I have it set its just reducing the signal a major amount and the make up gain has no effect and the threshold knob almost acts as if its working in reverse. when the knob is turned all the way counter clockwise the meter is buried at 20db and with it all the way clockwise its sitting at zero (with the attack on slow and the release on fast) If I put the attack on fast and the release on auto it changes to about 2db) Ive never see anything like this before and I have no idea where to even begin after checking the obvious. Any advice anyone could offer would be much appreciated thank you for your time in advance!

To answer you questions I've got +15 and -15v on the 5534 opamp but at the 5532 I've got +29 and -29 and at the TL074 I've got +/- 24V present.
Also yes I went through this thread in its entirety and couldn't find anything similar to my issues. I apologize if there is a post and i was unable to find it but like I had mentioned earlier I've spent a vast amount of time looking through these forums and couldn't find anything. I hope this info helps answer your questions and I will reply the same day from now on when I get a reply. Thank you for your help I greatly appreciate it!
 

Ricardus

WILL SOLDER FOR FOOD
Joined
Dec 2, 2018
Messages
1,661
Location
No longer in NY and below the Mason Dixon line.
To answer you questions I've got +15 and -15v on the 5534 opamp but at the 5532 I've got +29 and -29 and at the TL074 I've got +/- 24V present.
Also yes I went through this thread in its entirety and couldn't find anything similar to my issues. I apologize if there is a post and i was unable to find it but like I had mentioned earlier I've spent a vast amount of time looking through these forums and couldn't find anything. I hope this info helps answer your questions and I will reply the same day from now on when I get a reply. Thank you for your help I greatly appreciate it!
I feel like you have to be measuring the voltages wrong at the 5532 and the 074 because those are exactly double the correct voltages. So I'm guessing you're measuring wrong and the voltages are correct.
 
Top