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Matching SCA Mic Pre Output Level .. help Single-Channel Preamps
Old 5th September 2011
  #1
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Matching SCA Mic Pre Output Level .. help

Hello everybody,

We've got two API and four Neve modules in a Seventh Circle box here at the studio. Were exporting some ITB mixes today, and as an experiment to add some analog mojo, I wanted to attempt to run our stereo mix out through two of the neve clones.

Problem is, when I match the gain and output settings on the pres, the levels don't exactly match. I'm not sure if this is do to the way the power supply is wired or something.

The input gain is stepped, so logic would tell me I should set them both the same, but I'm concerned about using varying levels of the output transformers. Usually when we do matched pairs here we use a rented 3124, so I haven't noticed this issue before.

Any SCA owners / users here that could chime in some advice?

TIA for any help. I tried to search around but to no avail.

--adam
Old 5th September 2011
  #2
After you finished soldering, did you bias them? For some reason SCA says it is optional, but i don't see how it isn't a mandatory step.

I have 8 of the N72's and all is well!
Old 6th September 2011
  #3
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We actually got them used so I'm not sure, but the output level appears to decend preamp to preamp which is why I thought it might be a power supply thing?

They are also plugged into a power strip?

The dude we got them from was a pretty serious DIYer, so I imagine he biased them, but should this be the first thing I check? Never done it before.. difficult?

Thanks for the reply!

Sent from my SGH-T959 using Gearslutz.com App
Old 6th September 2011
  #4
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Tubthumper's Avatar
 

Adam, not sure if you've posted this question over at the SCA website forum, Tim is usually quick to reply.

I have a couple of N72s that I run mixes through, no problem with level match. I had my builder (Codeman015) calibrate and all is good. I pad down the 2 buss and get the impedance right with a pair of Avedis Line PadZ.
Old 6th September 2011
  #5
Quote:
Originally Posted by nosleepPDX View Post
We actually got them used so I'm not sure, but the output level appears to decend preamp to preamp which is why I thought it might be a power supply thing?

They are also plugged into a power strip?

The dude we got them from was a pretty serious DIYer, so I imagine he biased them, but should this be the first thing I check? Never done it before.. difficult?

Thanks for the reply!

Sent from my SGH-T959 using Gearslutz.com App
You would need a good DMM and an oscilloscope of some sorts, hardware or software, to 100% calibrate/bias these guys.

There is a really good video I saw somewhere on the Internet of someone doing this process with the N72's. Also download the build instructions and it is in print there. Very detailed instructions.
Old 6th September 2011
  #6
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Cool, sounds like this should solve the problem. Thanks guys!
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