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Q. How do I set the gain on my preamp and interface?

Published June 2013
By Matt Houghton

Just where should you set the gain knob on your audio interface if you're also using an external mic preamp? First, tweak your external preamp settings to achieve the desired sound and a healthy level, and then use the interface's gain control to set the right level running into your DAW.Just where should you set the gain knob on your audio interface if you're also using an external mic preamp? First, tweak your external preamp settings to achieve the desired sound and a healthy level, and then use the interface's gain control to set the right level running into your DAW.

I could really use some advice! I've got a Shure SM7b mic, a Golden Age Project Pre 73 MkII preamp and an M-Audio Fast Track Pro interface that I use when recording vocals. The preamp has two different knobs: one is gain (labelled 'mic/line'), the other is output. Then this signal goes to the interface, which also has a signal level knob. I know that different settings will change the sound on the preamp, but I was wondering how I should set the interface to get as good and balanced a sound as possible. Can you give me any advice?

Via SOS Facebook page

SOS Reviews Editor Matt Houghton replies: The Shure mic and GAP Pre 73 should be a good match, given the Neve 1073-style high-impedance input on the preamp, which should get the best out of a dynamic mic such as this, so I'd stick with that combo. The harder you drive the gain knob on the preamp, the more 'colour' you'll get from the transformers. So, while aiming for the same overall level coming out of the preamp, a low gain setting combined with a high-output level setting will sound more neutral, whereas a high gain with a lower output will sound a bit more rich/distorted (and even more so if the input signal is very 'hot').

Then feed the line-level output of the preamp to one of the Fast Track Pro's inputs, making sure that the input is set to 'line'. You should set the gain control on the interface as low as possible, while still making sure that you're seeing the right sort of level on the meters in your DAW software or your audio interface (and without the M-Audio's clip light showing!).

If you're recording at 24-bit, the noise floor will be low enough that you don't need your meters going anywhere near to red; you can safely raise the level later on without noise being an issue. If you're recording at 16-bit (try not to, but you may have good reason!), you're looking for as high a level as you can get without clipping, which is trickier to set up, but should give perfectly good results too.  

Published June 2013