SSlmixed.com Forum
Tech discussion => 4K,6K,8K Series => Topic started by: christiancarvin on July 24, 2014, 10:28:38 PM
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hello!!! :)
My ssl4000 recently shown a difference of 0.5dB between left and right.
Is there a way to correct that quickly, or do I have to recalibrate pan of each module?
thanks!!
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How are you measuring the difference? Using the Mix out VU meters, or using an external meter.
Is the difference there if you patch the oscillator into the Pre/Post Master fader VCA patch points?
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Thanks for your reply!
I'm using VU meters of the desk.
The difference is not there if I patch the oscillo in pre and in post fader vca patch point.
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Could still be the 82E26 card. Try swapping the Left and Right cards around and see if the difference moves.
Also, does the difference change with frequency?
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I've never entered in the center part of the desk.
Sorry for that newbie question, but what's the procedure to do that correctly?
Thanks!
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Has your desk had all its capacitors replaced? As fading caps on the 26 cards can cause a level imbalance.
To lift the centre section first turn of the power to the desk.
Then you remove the 2 screws top and bottom and if you have the lifters, and the threads in the panel are still good, you use the lifters to raise the centre until it locks into its raised position on its rails. However, it is often safer to remove the cover panel under the desk, and push it up from below.
This operation is best carried out by 2 people if you have never done it before, as it is heavy and trapped fingers *will* hurt! :'(
Can't remember the exact position of the 26 cards, but they are 4 identical cards around the middle-ish.
Once you find the cards and swap the LF with RF you can re-power the desk with the centre raised to check results......
Hopefully Andy will be along soon to confirm or say "No no no, don't do this...." ;D "try this instead...."
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Could still be the 82E26 card. Try swapping the Left and Right cards around and see if the difference moves.
Also, does the difference change with frequency?
Id try this first aswell, could be a bad bi-cap... just loosen the screews and push it up from under the console until you hear it clicks (hopefully it stays up, the rails can go bad so you might want a freind to help perhaps)
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Yeah, agree with Kevin, two people make this job simple.
The 651 must be powered off when moving up and down.
Hopefully the fault will move with one of the 026 cards, and you can leave two covering LF RF, whist recapping the other two.
Found that new caps, just sort any niggles out, and makes for a nice silent noise floor.
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Thanks everyone!!!!
I'm going to try that!
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The problem stays after exchanging 82E26.
Any other suggestion?
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So if you cross patch the Pre VCA from Left to right, the issue moves with the patch?
Next thing to do is reseat the S5 Y cable, either side of the centre section, and also into the bottom of the 651, assuming you have a 4k here.
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lets check calibration as well before going furthur, use a meter on the output of the cards, not the VU, to make sure there is a difference or if its the meter calibration.
Alan
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I'll do that!
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I took time to make a better test, here is what it says on my 4k:
I use an external calibrated VU on Main output.
Oscillator wired in PRE VCA (on the patch): -0.3 dB on left 0 dB on right
Oscillator wired in POST VCA (on the patch): -0.1dB on left 0 dB on right
Oscillator wired in line input of a module: -0.3 dB on left 0 dB on right
The problem stays when after exchanging 82E26.
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Those results definitely prove the problem is around the 26 card, either the input caps or VCA circuit.
Have they been re-capped? Are you sure you swapped the LF and RF cards, and not the LB and RB? (Grasping at straws now) :)
Try reseating the 27 card and twiddling the Quad compressor controls, and master VCA trim pot.
Does the difference stay the same if you drop the master fader by a few dB, then raise the oscillator level back to match?
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The 82e26 have been fully recapped.
I was unable to make a mistake in the exchange of 82E26, because I have only two in the center section.
I'll try!!
Thanks for the help!
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I've been having similar problem with my SSL 4000E where the the left channel level would be as much as 5db lower than the right channel. My console is fully recapped and the problem doesn't follow the E26 card. If I Send signal from the oscillator to quad I see no difference in the vu's. I found a couple of things to contribute to the problem: One was the ribbon cables underneath the center section. After touching them the left channel went up a couple of Db's but there is still a difference in level. Another problem was that by tilting the E26 card the problem sometimes would go away. My suspicion is that the pins on the edge connector need to be re-soldered. I haven't been able to re-solder due to the hectic schedule in the studio, but will try to do it soon. This problem has been driving me crazy but since I mostly print to 1/2" tape I compensate on the tape machine. I wish that the master fader would be a dual mono like on many neve consoles as opposed to one stereo fader. I would love to hear the source of your problem once you determine what's causing your level drop. Good luck.
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Thanks :)!
I hope I'll find the solution!
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the 26 card is a vca card that sets levels from a DC control voltage, if that voltage is changed in anyway it will have an affect on the output level.
If my memory is correct, the master fader generates the control voltage, it goes to the computer and back again, then to each respective 26 card. You should check all the connectors and clean them in that path, especially after they diverge into separate paths (can't remember if it is separate thru the computer path).
Check the block diagram and find the path! and then clean it.
You might also try measuring the difference of the control voltage at the point it reaches the 26 card. from the edge connector on each card to plus and minus leads on your DMM. Should be the same (ie 0V) or some small value that does not change.
Alan
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Thanks!
I'm going to try that!
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meant to say at the end,
does not change as you change level or fader position.
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I actually use the board with the computer off for the most part. There is a difference in the gain between channels with or without the computer on. Same difference, no changes if I turn the computer on or off. When the computer is off the main fader doesn't work, only the large monitor knob. Voltages are fine in the center section.
I also noticed that this problem is intermittent, so the gain difference between channels vary from time to time. I will confirm once I re-solder the connector related to the left channel.
the 26 card is a vca card that sets levels from a DC control voltage, if that voltage is changed in anyway it will have an affect on the output level.
If my memory is correct, the master fader generates the control voltage, it goes to the computer and back again, then to each respective 26 card. You should check all the connectors and clean them in that path, especially after they diverge into separate paths (can't remember if it is separate thru the computer path).
Check the block diagram and find the path! and then clean it.
You might also try measuring the difference of the control voltage at the point it reaches the 26 card. from the edge connector on each card to plus and minus leads on your DMM. Should be the same (ie 0V) or some small value that does not change.
Alan