GSSL HELP THREAD!!!

[feza]

I am getting ready to order parts but with the capacitors they are getting absolute or not available anymore. Here they are:

http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=P4837-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=P4841-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=P4843-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=P4849-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=P4593-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=P2071-ND

Last one with only an order above the 3K pieces:
http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=399-1359-ND

So looking for other shops but in Holland no success, because they are discontinued.

Any help highly appreciated.

 

[Banu]

Hi.

I have a very easy and maybe stupid question. I bought the Ssl meter from DIY partssupply (Ptownkid's shop). It's a Behringer type and it has an LED inside.
Q: Where on the board do I attach the LED to? Everything is working, meter and all, except there's no light.

It must be easy, right?

Thanx!

 

[tzman]

I am getting ready to order parts but with the capacitors they are getting absolute or not available anymore. Here they are:

http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=P4837-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=P4841-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=P4843-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=P4849-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=P4593-ND
http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=P2071-ND

Last one with only an order above the 3K pieces:
http://search.digikey.com/scripts/DkSearch/dksus.dll?detail&name=399-1359-ND

So looking for other shops but in Holland no success, because they are discontinued.

Any help highly appreciated.

Hi Feze,

Don't be thrown off by those particular capacitors. I'm guessing you're using the BOM made by Gregory?
For the ceramic caps, any brand will do... for example, the 10pF, you could use reichelt.de partnr. KERKO 10P. Also Banzaimusic.com has a great catalogue...
Same story for the tantalums caps. You could use 50V in stead of 35V, the only thing that really changes are the dimensions.

Good luck!

Tom

 

[feza]

Thanks!

Yes that makes senses. Will post for the Europeans a new list from a different shop.  

 

[lukev]

Well, this is the first time I have posted on Prodigy but I have learned a ton just by reading stuff on here.  Thanks for all the great info guys!  I just finished my first GSSL last night.  I have not  been able to listen to it yet because Digikey didn't send me enough of the 5534's but I was able to power it up.  I tested the voltages and I was getting 15v and 12v in the right places but the toroidal transformer is getting super hot super fast when I power it up. I did a quick wiring check and everything looks fine.  I have not seen anything about this problem before and couldn't find any info when I did a search.  Any ideas what it could be?

 

[MikeFFG]

Hey guys!  Just finished my GSSL with the Super SSC board and it seems to be working almost perfectly...However, in bypass mode, or not in bypass but with no Gain reduction happening, I am getting an increase in the signal by about .3 db on one side and .4db on the other.  In regular use I'm sure this would never make a difference, but I'm wondering if anyone knows what the issue would be with this?  It's probably not even worth messing around with, but just thought I'd ask.  Thanks people!  I'm so excited to be pretty much done!  Thanks for everyone's help.  This forum rocks!

 

[wahfreak]

Hi all,
I have a dumb question. Can I share a single heat sink with two voltage regulators like the photo shows? It's pretty cramped for space right around there and if I can get away with using one rather than two it would be worth it.


Thanks

 

[isophase]

Hi all,
I have a dumb question. Can I share a single heat sink with two voltage regulators like the photo shows? It's pretty cramped for space right around there and if I can get away with using one rather than two it would be worth it.


Thanks

best if they are individual heat sink
you could cut this one in half and bend the regulators apart a little bit ?

 

[Harpo]

..but the toroidal transformer is getting super hot super fast..

You are probably using a dual secondary transformer and have connected both in-phase or both out-of-phase wires from your secondaries as your center tap. Exchanging the wire connections from one secondary should fix it. A link to the data of the transformer from YOUR build might help. Every manufacturer uses a different colour scheme.

...However, in bypass mode, or not in bypass but with no Gain reduction happening, I am getting an increase in the signal by about .3 db on one side and .4db on the other...

Exchange the 15K feedback resistor of the audio-VCA following op-amp with a 12K in series with a 5K trimmer to dial in the 0dB bypass condition. (With other parts being perfect value and 27K in front of the audio-VCA, this prementioned series string resistor will measure 13K5.)

I have a dumb question. Can I share a single heat sink with two voltage regulators like the photo shows? ..

Of course you can, but make sure there is no conductance between heatsink and regulator by using isolation kits. The metal sheets of these regulators have different potentials connected for the 78xx and 79xx regulators and you don't want to blow them by such silly mistake.

 

[lukev]

The transformer heat problem turned out to be a very tiny short between the + and the 0 on the PCB.  It was so small that I couldn't see it without getting really close to the PCB.  Unfortunately my poor compressor is still not working correctly.  It sounds fine in bypass, so I know the balancing and unbalancing circuits are fine.  When I turn on the compression I do not hear compression happening but the audio signal sounds terrible.  When changing between different attack and release settings it sounds like I am switching between random eq settings with a serious lack of any bass.  When I turn the threshold down, the audio signal gets much quitter and the audio degradation increases.  I spent a few hours checking for any shorts, loose connections, or bad component values.  Couldn't find anything wrong.  Any suggestions on this one? Could that short between the + and 0 have damaged the 2180s somehow?

 

[mac]

Hey Lukev,
double check the orientation of all the IC's and go back over all your wiring connections to ensure that it is hooked up correctly (switch pcb - mainboard, and threshold and makeup pots. Remember your NE5534's are oriented 180 degrees to the input and output op amps.

If you are worried about damaged components (and you dont have any spares), try swapping out VCA's and op amps to see if behaviour changes or follows the swapping.

take your time - good luck..
Mac

 

[MikeClev]

Hello Chaps!

I have just finished putting my GSSL in a box, (after many many problems and about 18 months of on-and-off work) and commenced testing. It compresses fine, sounds great, I have a turbo and CRC boards fitted and everything seemed and sounds perfect. Then I spotted a problem.

When I have no signal running through (inputs still connected, no sound output coming from GSSL either), and lower the threshold to just below halfway (0dbu?) compression shows on the meter! Sometimes it seems almost random. Sometimes I can tweak the threshold so its stays constant, then if I tweak it a little more the meter bounces up to full scale and back down to 0 and tweaking the threshold affects the rate of its bouncing.

I put the lid on the box and it was no better.
I loaded up a webpage on my mobile phone right next to the box and it got worse.
I disconnected my led circuit and that made no difference.
I disconnected the turbo board and that made no difference.
Playing with the attack / release / ratio controls affects the meter bouncing / steadiness
Breaking the 0v to case ground connection makes no difference.
I swapped TL072 and 074s just in case, no change there.

So my instinct tells me this either some kind of unwanted feedback of the timing circuit signal back into earlier stages of the sidechain, or oscillation in a sidechain opamp causing it to pick up RF interference.

I have read this thread literally from start to finish, finished it last week, before I noticed this problem. I don't recall seeing this problem in there. I will flick through again to see if I missed anything.

Thanks in advance for any help! I'm so close to finishing this....!

 

[MikeClev]

Success!

I have spent the last 3 hours or so trying all sorts of things. I rewired the Turbo board- that didn't fix it, but it stopped the bouncing needle problem and turned it into a steady needle problem. Meaning that gain reduction showing when there was no signal present when the threshold was tweaked. I reflowed the solder on every solder point on the control board and sidechain. Some of this soldering was done as long ago as 18 months. This didn't help.

So I checked voltages on the TL074 and 072 against some earlier in this thread and found some were out on the TL072, which got me looking at the schematic. I was drawn to the 220k resistor (just after the threshold pot) and I suddenly thought that must be the wrong value. I measured it, and it was a 220 ohm resistor! Gotcha!

I'm a very happy DIYer!

 

[regularjohn]

Hi all,
I have a dumb question. Can I share a single heat sink with two voltage regulators like the photo shows? It's pretty cramped for space right around there and if I can get away with using one rather than two it would be worth it.

you really don't need heatsinks with the gssl at all.  at max draw, the gssl pulls between 100 and 150 mA.  that's between 10 and 15% of the 7815 and 7915 max rating of 1A.  I've never used heatsinks in gssl's and have never had issues.  don't waste your time trying to squeeze them in.

 

[mitsos]

Hi all, just wired a stock GSSL. Without any chips installed I was getting all the right supply voltages but I was also getting some weird ones, like really high DC on the output pins of the input opamps, for example.  So I installed the input 5534s first, DC was ok, output pin now at 0V. good. Installed 5532s and still OK, so I jumpered the audio VCAs and went to see if I had audio. So far so good.

BUT, I am getting -15V on pin 1 of all the VCA sockets (did the prescribed modifications for 2180s, but haven't installed yet...)... -15V at input seems odd? Just want to double check with you guys before I install and potentially fry these things. They're hard to get where I'm at.

Thanks in advance!

 

[MikeClev]

@mitsos
-15v on pin 1 sounds very odd. I can't imagine its a solder bridge.. the same identical bridge on every VCA! Also strange to find it exactly the negative supply voltage. Especially because pin 8 goes straight to an inverting opamp input which should be a virtual ground. How are you measuring this voltage? Do you have a pin 1 to pin 8 wire link inserted? Try it with that removed, and test pin 8 too. Black probe of meter to ground (pin 2 and pin 6 of the VCAs are grounded, use them perhaps?) and Red probe to test point. If you had one of the probes on a 15v power rail that would explain everything! Sorry if this is blindingly obvious and an avenue you have already explored...

 

[mitsos]

Hi, thanks, that's what I was thinking at first... I'm sure I'm measuring correctly. I will test again when I get home later, but these numbers were with no ICs installed, and again with the in/out 5534/5532s installed.  Then again, I had similar weird voltages in the input 5534s when I had those uninstalled, but I said "screw it, they're cheap,"  installed them, and the voltages went to normal. (I had something like 12V or -12V on the outputs and inverting inputs of both 5534 which went to 0 when I put the opamps in).  I'm wondering if something similar will happen with the VCAs.  Off the top of my head, I 'm pretty sure pin 8 was at 0V.

I had this voltage at all VCA pin 1s, but since the in/out opamps were normal, I jumpered the audio VCAs pins 1+8 (with only the input/output ICs installed) and it passed audio cleanly.  The fact that the weird voltages on the input 5534s went away when I plugged in the opamps makes me wonder if it might be normal when you don't have the VCAs installed?  Maybe someone with a known working SSL could unplug some chips and let me know what voltages they get at the VCA pin 1s?

thanks!

 

[Harpo]

Hi, thanks, that's what I was thinking at first... I'm sure I'm measuring correctly. I will test again when I get home later, but these numbers were with no ICs installed, and again with the in/out 5534/5532s installed.  Then again, I had similar weird voltages in the input 5534s when I had those uninstalled, but I said "screw it, they're cheap,"  installed them, and the voltages went to normal. (I had something like 12V or -12V on the outputs and inverting inputs of both 5534 which went to 0 when I put the opamps in).  I'm wondering if something similar will happen with the VCAs.  Off the top of my head, I 'm pretty sure pin 8 was at 0V.

I had this voltage at all VCA pin 1s, but since the in/out opamps were normal, I jumpered the audio VCAs pins 1+8 (with only the input/output ICs installed) and it passed audio cleanly.  The fact that the weird voltages on the input 5534s went away when I plugged in the opamps makes me wonder if it might be normal when you don't have the VCAs installed?  Maybe someone with a known working SSL could unplug some chips and let me know what voltages they get at the VCA pin 1s?

Hi Dimitri, why do you measure voltages in this spot? These VCAs are current in/current out devices. VCA pin1s measured 0V on mine, but that doesn't mean that much. Memory effect of a charged coupling cap from a previous test with one leg left floating (no VCA in) might give funny readings. Your VCA pin8 at 0V indicates normal behaviour, as the VCA following opamp tries to keep both inverting and non-inverting inputs at same potential. Sure you have 5534s in the substitution circuit?

 

[mitsos]

Hey harpo, thanks for chiming in.  I know they are current in, but when I measured those pins the first time I powered up (with no ICs), I did not have the 2180 pinout in front of me so I measured all the pins to find the +/- supply pins.  I haven't plugged in the 5534s following the VCAs yet, just the ones in the input section and the 5532s in the output section. So 4 ICs total.  Guess I'll just plug the rest in and see what happens! I'll post back later!

thanks again!

 

[mitsos]

OK, I took another look at the bottom of the PCB and what did I see? A tiny-ass solder bridge between one of the two 47K resistors and the jumper wire next to it. Took that out and checked for any more with a magnifying glass... no more seen so I just plugged everything in and so far it works... except for makeup gain, but that's probably something stupid I did (or didn't) do.
Eventually I'll check to make sure it's working properly, but I'm glad to be getting clean audio out of it!

thanks to everyone here, especially jakob, gustav, matt and matthias for the 2180 info, and harpo, who probably has written half the posts in this thread! Finally getting around to building these after having the parts for a while... it's good to have all this info here!

cheers!