However, the calibration hasn't gone so smooth lol.. Perhaps someone can give me some pointers here. Firstly, when I send out a sinewave and monitor the input of the compressor back in the daw, the levels aren't the same. I calibrated (as instructed) the individual channels so that the level is the same when the unit is bypassed or engaged, but yeah, the level between the two is not exactly the same, a couple of DBS off... It's not the cables, I swapped them, same result. Might check the patch-bay (maybe a solder joint there isn't good explaining why one output is slightly quieter...?)
It
could be an external issue such as the patchbay, but it could also be an internal problem. The best way to determine this before you get too far into your hunt, in my opinion, is this: send your sine wave out to the compressor and measure the AC voltage with your multimeter between pins 2 & 3 on the xlr input jack of each channel. If the channels do not match, then the problem is happening somewhere in your system before the compressor. Now measure the AC voltage between pins 2 & 3 on each xlr output jack (with compressor in but no compression happening). If the inputs matched but the outputs do not, the problem is in the compressor itself -- either calibration still needs tweaking, or there is some misplaced component or something like that. If the VAC on the inputs of both channels matched AND the outputs of both channels matched, but you still have a considerable discrepancy between the channels coming back into your DAW, then the problem is in the system after the compressor.
However, the main issue is, that I'm not getting any voltage reading when measuring TP12.
Could there be an issue with VR7? No matter what way I turn, there is no readable voltage. I'm pretty sure I'm in SSL mode (turbo switch on 1/2 and the button is engaged), so it can't be that, I think (just because the manual specifies there is no voltage if you're not in SSL mode in case that happens).
I adjusted TP11 so it reads the same as TP8 (1.113V). TP 10 reads (0.225V).
Another issue (although I couldn't really proceed with the next step seeing the previous step couldn't be completed, when moving the threshold, there is no reduction of gain, the needle doesn't move at all. If it was wired the wrong way, it would probably move the wrong way (right?) the LED works fine.
I didn't watch the video that you included because I won't be in a position to do so until a little later, but I'm wondering if you have made extra sure that your ICs are all oriented correctly. I've definitely messed that up before and it led to all sorts of incorrect voltage measurements and headaches before I realized what I'd done.
I also noticed how there don't seem to be specific instructions for the trimpots on the quad VCA boards, which I have installed.
The trim pots on the Quad VCA boards are used to calibrate for lowest THD. The info on that is available at the bottom of the first post way back at the beginning of this thread, but I will quote it here as well. However, this step will need to wait until you've sorted out the other issues that you've encountered.
Calibrating for lowest THD with Quad VCA boards:
Easiest way to calibrate THD is feed a 1K test tone into compressor and look at the return signal with a freq analyzer in your DAW. (I recommend to download Blue Cat's Freq analyzer for this.) Distortion node will be seen at 2K, adjust until 2K node is as low as possible.
Engage the "External In" so the sidechain is disabled (Of course be sure there is no external signal being fed to the external input).
Adjust DTRIM Pots (VR3/VR4 on Main Board) for lowest THD. Then turn front panel gain knob to Max (lower the input signal as required so signal doesn't clip). Now adjust the 50K Pots on the VCA boards for lowest THD. Return front panel gain knob to 0. You will need to repeat this process a few times until lowest THD is achieved.
