no shorts to the front. it was working for the past couple of years, then one side stopped passing audio. turned out to be a bad solder joint, and since fixing that I noticed this issue. i built it with turbo + 2 supersc pcbs. When I set the sidechain to EXT the meter drops back down to 0 after 3 short full scale pulses. When I set the sidechain to OFF the meter maxes. At 60Hz and 90Hz it pulses 3 times and drops down to 0. I also removed the extra mods and put the 47k resistors back in for the sidechain input, and am not using the turbo board either, and the issue is still there
GSSL HELP THREAD!!!
- Thread starter hairyandy
- Start date
Help Support GroupDIY Audio Forum:
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- May 22, 2020
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- 32
Hi all,
I want to add the hpf on the side chain but I'm trying to keep it simple without the additonal pcb.
I've found bits and pieces how to make it work that I want to verify.
1). I can simply take the signal from TL074 pin 7, run it trough additional, switchable capacitors and back to the 22 uF before the 20k resistors. True?
2). Do I really need the buffer stage from the super side-chain seperate pcb for an external side chain input? One post by Jakob says "the impedences are quit okay there". I would like to simply inject the external side-chain signal directly. And if possible, does the external input need an additional capacitor or resistor to ground?
3). Whether I turn the side-chain hpf off, engage the hpf or use the external side chain, everything goes trough the 22 uF capacitor before the 20k splitting resistors? This means there are 2 capacitors in series when the hpf is engaged. True?
I've attached this image with some sources and my plan. I hope these are easy questions for some!
PS. I've got an older board without the hpf inserts as seen in the schematic.
Kind regards,
Beinte
I want to add the hpf on the side chain but I'm trying to keep it simple without the additonal pcb.
I've found bits and pieces how to make it work that I want to verify.
1). I can simply take the signal from TL074 pin 7, run it trough additional, switchable capacitors and back to the 22 uF before the 20k resistors. True?
2). Do I really need the buffer stage from the super side-chain seperate pcb for an external side chain input? One post by Jakob says "the impedences are quit okay there". I would like to simply inject the external side-chain signal directly. And if possible, does the external input need an additional capacitor or resistor to ground?
3). Whether I turn the side-chain hpf off, engage the hpf or use the external side chain, everything goes trough the 22 uF capacitor before the 20k splitting resistors? This means there are 2 capacitors in series when the hpf is engaged. True?
I've attached this image with some sources and my plan. I hope these are easy questions for some!
PS. I've got an older board without the hpf inserts as seen in the schematic.
Kind regards,
Beinte
Last edited:
Harpo
Well-known member
1) yes. The on-board 22uF cap provision now is a comfortable spot to solder on your shown red wires. The 22uF cap (NOT 22nF) connects to the switch pole, caps other side back to pcb to the paralleled 20K resistors. (I'd miss a switch position for no external input or higher set hpf than the 22uF/10K = 0.72Hz hpf-off setting. YMMV)
2) no additional buffer needed for these shown 1st order filters. (The additional SSC filter board comes with two different slope filters as well.) The DC-blocking 22uF cap with 2x 20K resistors to virtual ground is already there, so no additional cap/resistor needed.
3) from your schematic there is no off-position (see 1). With hpf engaged, there are two caps in series. ( C series = 1/(1/C1+1/C2) ) This results in a minimal higher hpf setting, FI the 120nF/10K setting for 130Hz front panel label without the 22uF series cap would result in a 132.63Hz hpf on paper, same 120nF cap with 22uF series cap would result in a 133.35Hz hpf on paper instead.
- Joined
- May 22, 2020
- Messages
- 32
Thanks for your reply Harpo!
I adapted the changes into the image for in case others will want to do something similar.
Hi all,
I'm wondering if anyone one can give advice on these different kinds of film capacitors:
I'm looking for film capacitors (for the '25pcs Polyester capacitors - 100nF/63V 5mm pin spacing' from the GSSL BOM).
My options are:
a. Metallized PET
b. Metallized PET stacked
PET is Polyethylene / Polyester?
Are these suitable? If so, which would be best and why?
Thanks
I'm wondering if anyone one can give advice on these different kinds of film capacitors:
I'm looking for film capacitors (for the '25pcs Polyester capacitors - 100nF/63V 5mm pin spacing' from the GSSL BOM).
My options are:
a. Metallized PET
b. Metallized PET stacked
PET is Polyethylene / Polyester?
Are these suitable? If so, which would be best and why?
Thanks
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does not matter here, just use anything you can get in the required 5mm pitch
/Jakob E.
/Jakob E.
Thanks. Is it possible to use same capacitance, but higher voltage rated here, and would this negatively effect the sound?
If it fits in the board, fine. Anything 35V or higher will do.
Clakejr
Active member
Does anyone have an updated GSSL BOM
Here is my most recent:
calaverasgrande
Well-known member
- Joined
- Jan 15, 2015
- Messages
- 91
what are the red scritchy scratches representing? Are these omitted or simply not metal film.
Ignore those.
I think that one is also here: http://gyraf.dk/gy_pd/ssl/ssl_complist.htm
..as it says, let me know if there's changes to be made..
/Jakob E.
..as it says, let me know if there's changes to be made..
/Jakob E.
Clakejr
Active member
Thanks you Guys
tomheavybeats
Well-known member
- Joined
- Dec 11, 2020
- Messages
- 56
Thanks to loads of searching through this thread and the wealth of information I have finally finished and troubleshooted all the issues and have my first GSSL working. The only thing that doesn't feel right is the threshold knob is doing absolutely nothing until the final third of the rotation. I have a B50K Alpha pot there which should be right. I have attached image of my board (note: 1m, 47k and 50k trimmer resistors for the Gold Cans are mounted underneath. Also I've bridged HPF temporarily until I install Turbo card).
The source signal is both a sine wave at -18dbfs out of the computer and a drum loop set to -18dbfs with peaks at -6db. If I crank the gain, threshold reacts sooner but then I get more saturation quicker. Fine with a drum loop but a full mix sounds horrible. I have a Sound Skulptor CP4500 SSL clone and cranking the threshold makes thing slam a lot harder. Read about adding 47k resistor to threshold pot but that reduces sensitivity so would make it worse right? I thought of adding the trimmer for meter sensitivity too but I didn't think it would be to do with this problem.
The source signal is both a sine wave at -18dbfs out of the computer and a drum loop set to -18dbfs with peaks at -6db. If I crank the gain, threshold reacts sooner but then I get more saturation quicker. Fine with a drum loop but a full mix sounds horrible. I have a Sound Skulptor CP4500 SSL clone and cranking the threshold makes thing slam a lot harder. Read about adding 47k resistor to threshold pot but that reduces sensitivity so would make it worse right? I thought of adding the trimmer for meter sensitivity too but I didn't think it would be to do with this problem.
Attachments
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Harpo
Well-known member
A dBfs value without reference voltage doesn't have a relation to the analogue world.
At 1st sight the current setting 5K1 resistor between pin5 and -12VDC at the sidechain-VCA (located below pin8 from the pic) should be 3k9 instead. There might be more...
tomheavybeats
Well-known member
- Joined
- Dec 11, 2020
- Messages
- 56
Many thanks! Ugh totally missed I hadn't put the link in the Control Board by the meter. All working now! Left the 5k1 in as have 2180LB on the sidechain but removed the 47k by the threshold knob. I am very excited its working finally haha
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MiamiBoy
Well-known member
I would highly recommend you to put heatsinks on those two regulators 
tomheavybeats
Well-known member
- Joined
- Dec 11, 2020
- Messages
- 56
Thanks, do you think its a must? Searching back through this thread there's not too many mentions of people using the heatsinks. Can't hurt though I guess!I would highly recommend you to put heatsinks on those two regulators
MiamiBoy
Well-known member
You’re right, there’s no mention.
I’m not an expert on modern components. Maybe they’re good at handling that kind of a heat and will survive for the next 20 years when having your equipment turned on 6 hours a day.
Or maybe only 2 years, idk.
Try feel those components after having your unit on for 1 minute, you’ll almost burn your finger, that’s how hot they get.
So yeah, it wouldn’t hurt to install heat sinks. But I wouldn’t make a new purchase order from mouser just to get 2 heat sinks, if I were you, with the whole shipping prices and all..
I’m not an expert on modern components. Maybe they’re good at handling that kind of a heat and will survive for the next 20 years when having your equipment turned on 6 hours a day.
Or maybe only 2 years, idk.
Try feel those components after having your unit on for 1 minute, you’ll almost burn your finger, that’s how hot they get.
So yeah, it wouldn’t hurt to install heat sinks. But I wouldn’t make a new purchase order from mouser just to get 2 heat sinks, if I were you, with the whole shipping prices and all..
