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Op-amp gain trouble

PostPosted: Fri May 22, 2015 2:34 am
by Guitarik
The op amps on the console are weak. Anyone have some positive input about this?

for example I have to max out the gain in order to get a ~(-12) dbfs on a kick drum!!

Re: Op-amp gain trouble

PostPosted: Fri May 22, 2015 1:42 pm
by Crash
Thatn is odd, I have never have had any issue with the pres on the d8b. You don't have anything whacky going on with your digital trim?

Re: Op-amp gain trouble

PostPosted: Sat May 23, 2015 7:26 am
by Guitarik
no that i know of

Re: Op-amp gain trouble

PostPosted: Mon May 25, 2015 7:54 pm
by Guitarik
bump

Re: Op-amp gain trouble

PostPosted: Wed May 27, 2015 6:22 pm
by FrankH
Out of idle curiosity....what kind of mic are you using and is there a pad on it that is being employed? Are you getting low gain across all 12 Mic inputs or just a select few (or one)?

Crash brings up a good point about the digital trim. "Not that I know of" isn't enough info.

What is the setting of the Digital Trim on the channel that's giving you low mic pre gain?
And just to be certain you aren't getting a false reading, exercise the Digital trim up and down back to "0".

And while you're at it, exercise all the Mic pre pots. These things are over 15 years old and have a tendency to go wanky if left untouched for long periods of time.

Re: Op-amp gain trouble

PostPosted: Fri Jun 12, 2015 8:31 pm
by Guitarik
i am using a variety of mics sm 57 58 cad sennheiser neumann etc.. everything on the line inputs 10-24 channels is weak. I can get a guitar amp to -15dbfs if i turn both analog gain pots and digital trim all the way up.

Re: Op-amp gain trouble

PostPosted: Fri Jun 12, 2015 10:27 pm
by Crash
You are running mics into line inputs? That would explain it if that is the case. It is hard to tell by what you wrote up there. Only channels 1-12 have mic preamps.

Re: Op-amp gain trouble

PostPosted: Fri Jun 12, 2015 11:24 pm
by FrankH
everything on the line inputs 10-24 channels is weak.

You are running mics into line inputs? That would explain it if that is the case.

Re: Op-amp gain trouble

PostPosted: Sat Jun 13, 2015 7:44 am
by Guitarik
it was never a problem before. This is a new problem

Re: Op-amp gain trouble

PostPosted: Sun Jun 14, 2015 6:22 am
by High C Double G
Hi,

You will need a microphone preamplifier to run into the line inputs of the d8b, perhaps you missed this step this time.

Dbl G