Ok, nailed my problems. I went through the board several times checking voltages, all was good. Went through the calibration procedure a ridiculous amount of times and it still sounded dodgy. Went over all the solder joints, look fine. Checked most of the resistors, all in the right places.
The two issues that had me stumped which may be handy for others were:
* The cheap audio interface between my Mac and the 1176 caused me the biggest issue. I was sending a test tone through it and when checking the pins on the lead with the DMM, it was reading .775. Perfect. However, as soon as I plugged it into the input of the 1176, it this dropped to around .130! I didn't notice this straight away so when going through the calibration, it all wasn't really working right. And when finished, everything didn't sound right (see my last post). However, once I found this out, I had to go out of the Audio Interface into another unit to get the gain back up and once I had that going, calibration was much smoother.
* I had viewed the Mnats calibration videos before, but used a PDF from this thread (UREI KIT CALIBRATION 1176 V.A.pdf) which I downloaded and printed off, just to save having to pause the vid whilst calibrating. However, this document was incorrect (or correct for a different version) and had me stumped until I watched the Mnats video again. For the last calibration step (meter tracking), for the first half, it incorrectly states that once you've adjusted the input level to -10dB with compression on, turn the compression back off and adjust R55 (R71) to get the meter back to 0VU. Of course, you should actually adjust the Output level and not R71 at all!
Anyway, that aside, I'm totally chuffed I managed to get this compressor built in my 1st go. It's the first big project I've done in a very long while, so took my time.
It's sounding really great, I've run it through all sorts and so far, I'm liking the sound on room mics/overheads. Vocals sound great. And bass guitar.
Thanks everyone
The two issues that had me stumped which may be handy for others were:
* The cheap audio interface between my Mac and the 1176 caused me the biggest issue. I was sending a test tone through it and when checking the pins on the lead with the DMM, it was reading .775. Perfect. However, as soon as I plugged it into the input of the 1176, it this dropped to around .130! I didn't notice this straight away so when going through the calibration, it all wasn't really working right. And when finished, everything didn't sound right (see my last post). However, once I found this out, I had to go out of the Audio Interface into another unit to get the gain back up and once I had that going, calibration was much smoother.
* I had viewed the Mnats calibration videos before, but used a PDF from this thread (UREI KIT CALIBRATION 1176 V.A.pdf) which I downloaded and printed off, just to save having to pause the vid whilst calibrating. However, this document was incorrect (or correct for a different version) and had me stumped until I watched the Mnats video again. For the last calibration step (meter tracking), for the first half, it incorrectly states that once you've adjusted the input level to -10dB with compression on, turn the compression back off and adjust R55 (R71) to get the meter back to 0VU. Of course, you should actually adjust the Output level and not R71 at all!
Anyway, that aside, I'm totally chuffed I managed to get this compressor built in my 1st go. It's the first big project I've done in a very long while, so took my time.
It's sounding really great, I've run it through all sorts and so far, I'm liking the sound on room mics/overheads. Vocals sound great. And bass guitar.
Thanks everyone