nik--

SSL Clone Question? fault in my clone?
« on: June 10, 2004, 03:19:41 PM »
I have buildt a SSL Clone from Gyraf audio during the last weeks and mounted it in a case the last days and checked it in the studio.

first of all thanks to Jakob for making this possible !


and now my first question, my unit works perfectly and sounds good on drums etc...  but in Auto release mode with Ratio swith at 10 I get heavy distortion (when treshold is adjusted) before the meter shows compression, but there is still some gainreduction 0-  minus 10db on my consoles meter but nothing to see on the ssl clone. I used the sifam meter. It works for all other release positions right. ?? ? is this normal ?? or do I have a fault ?

second question:


I get more gainreduction with Ratio on 2 than with Ratio on 10 (all other settings are the same) is this also normal ??


If somebody who has also built the unit can help me, this would be great.

Nik


matthias

SSL Clone Question? fault in my clone?
« Reply #1 on: June 10, 2004, 03:33:11 PM »
1st:   this is not normal...  check all values at the autorelease of the small pcb

2nd:  your switch isn't configured alright...  
        did you set the nut correct to limit the positions to 3 ??
       
        did you soldered it directly on the pcb or did you use some cables ??


cheers,
matthias

nik--

SSL Clone Question? fault in my clone?
« Reply #2 on: June 10, 2004, 05:59:37 PM »
hi matthias,

thanx for your reply, I will check the values on the small PCB but I think that they are right, because no parts were left and I ordered the exact amaount and measured all before soldering...

2 what can be the fault with the switch ?? I soldered It on the PCB and limited it to 3 Pos.???

I works for all three positions but on Ratio 2 the meter shows more (not much more) compression than on Ratio 10.  (nothing changed on the unit exept of the ratio switch )

Nik

gyraf

SSL Clone Question? fault in my clone?
« Reply #3 on: June 11, 2004, 04:41:29 AM »
This sort of questions should preferably be in the "SSL help thread?" thread: http://www.groupdiy.com/index.php?topic=47

But:

The Ratio switch acts completely normal - this is a question often asked.

The thing is that the ratio switch not only controls compression ratio, but it also modifies the threshold setting in order to keep the same average gain reduction regardless of ratio - if levels are like at the SSL mixbus.

So at low ratio it lowers threshold, and at high ratios it uses a higher threshold. If you're working on a relatively low level, there would be more gainreduction at lower ratios.

But the actual ratio follows the selection on the switch as it should..

--

Your "Auto" setting on the release seems to have a problem though. My guess is that the two capacitors and two resistors that makes up the auto-release timing circuit is not working. There is a 6u8 tant and a 0.47u tant in series to ground on the release switch. These makes a double-time-constant that is your "auto" setting. If some parts here are missing, or it's not referred to ground, there will be no "holding" function for your GR controlling voltage, and the VCA's will be fed a full-wave rectified AC signal in stead of a nice varying DC control voltage. This distorts the audio.

Look for problems around the release switch on the control PCB.

Jakob E.
..note to self: don't let Harman run your company..

nik--

SSL Clone Question? fault in my clone?
« Reply #4 on: June 11, 2004, 06:48:21 AM »
Hi Jakob,

sorry for not posting in the correct thread (have not seen that there is a meta thread on the new forum)

I was able to solve the release problem last night -- It was so simple that I checked everything and found no problem, but I had set the switch to 6 Positions and so in the last position (auto realease I thought because of not having the frontpanel made) there was heavy distortion because of nothing connected to the release circuit. have not checked it yet but I think it will be ok now.

If you think that the Ratio problem is normal and is no problem thats good news  :grin:  :guinness:

 I checked Ratio Switch and found for Ratio 1:10 connection via the 1M2 Resistor , Ratio 1:4 via 1M8 and Ratio 2 via 3M9 ---- is this also correct ?
I cant see it in the circuit diagram because 1:10, 1:4 .... are not labeled there.

but I have a short question to the Tantalums in the release circuit, is it possible to parallel two 3,3u to get aprox the 6u8 because my supplier does not have them ?


many thanks for your great reply

Nik

gyraf

SSL Clone Question? fault in my clone?
« Reply #5 on: June 11, 2004, 07:42:03 AM »
Quote
I checked Ratio Switch and found for Ratio 1:10 connection via the 1M2 Resistor , Ratio 1:4 via 1M8 and Ratio 2 via 3M9 ---- is this also correct ?
I cant see it in the circuit diagram because 1:10, 1:4 .... are not labeled there


That's correct. They're labeled 1:2-4-10 in the schematic (but not very clearly)

Quote
but I have a short question to the Tantalums in the release circuit, is it possible to parallel two 3,3u to get aprox the 6u8 because my supplier does not have them ?


That would do just fine..

Jakob E.
..note to self: don't let Harman run your company..

ChrisA

SSL Clone Question? fault in my clone?
« Reply #6 on: June 12, 2004, 02:26:18 AM »
curious about a couple things...

why specifically tantalums in the release section?

would it react differently with a different type of capacitor?

how does the 6.8u cap affect the auto release...If that was changed to a higher or lower value, what would be the result?

nik--

SSL Clone Question? fault in my clone?
« Reply #7 on: June 12, 2004, 10:24:08 AM »
yust wanted to tell that now everything is working well  :grin:  :guinness: (it was only the not limeted switch) and now I will make the frontpanel - if I get the digi Cam of my friend I will post a few pics.... in a few weeks...


thanks to all guys helping me out with my stupid questions  :thumb:


Nik


 

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