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Op-amp gain trouble

Discussion board for Mackie's d8b Digital Console users.

Op-amp gain trouble

Postby Guitarik » Fri May 22, 2015 2:34 am

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!!
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Re: Op-amp gain trouble

Postby Crash » Fri May 22, 2015 1:42 pm

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?
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Re: Op-amp gain trouble

Postby Guitarik » Sat May 23, 2015 7:26 am

no that i know of
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Re: Op-amp gain trouble

Postby Guitarik » Mon May 25, 2015 7:54 pm

bump
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Re: Op-amp gain trouble

Postby FrankH » Wed May 27, 2015 6:22 pm

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.
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Re: Op-amp gain trouble

Postby Guitarik » Fri Jun 12, 2015 8:31 pm

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.
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Re: Op-amp gain trouble

Postby Crash » Fri Jun 12, 2015 10:27 pm

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.
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Re: Op-amp gain trouble

Postby FrankH » Fri Jun 12, 2015 11:24 pm

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.
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Re: Op-amp gain trouble

Postby Guitarik » Sat Jun 13, 2015 7:44 am

it was never a problem before. This is a new problem
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Re: Op-amp gain trouble

Postby High C Double G » Sun Jun 14, 2015 6:22 am

Hi,

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

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