Using the cranesong as an analogue limiter to avoid clipping the Mytek AD convertors
When recording a mix, some of you may have been having problems with clipping when moving from the analogue into the digital domain, i.e. when mixing on the SSL or processing with the analogue outboard before going back into the computer via the Mytek AD convertors. Of course you could just drop the gain slider on the desk, amongst other things, but if you’re looking to do analogue mastering, you may want to use the Cranesong–which has extremely fast attack times–to peak limit and avoid clipping the convertors. In order to do this you’ll need to make sure the Cranesong is set up and calibrated properly. During a mastering session yesterday, Martin, Lauren, and I proceeded as follows
- Using the audiotester app (located on the Mac desktop at present but this may move to the app directory at some point), set up a one second noise burst. This needs to be attacks rather than a constant tone because we’re looking to limit peaks. We actually had to set this software’s output at +5db (not its default -20db), in order to get enough gain from the app to the DAC (i.e. to output just below digital full scale).
- On the patchbay, we routed through the Cranesong as a mix insert on the AWS900. This means that you can then enable and disable the Cransong via the main stereo busses on the bottom right of the mixer. You could also set up an external insert in your DAW if you prefer.
- We set the Cranesong so that we’re not using a preset and can therefore set the attack and threshold etc. manually. To do this, set the preset knob to the V at the bottom (see image below).
- Then set the attack and release to 10 and threshold to 0 so that the compressor isn’t working at all. This way we’re only using the Cranesong as a peak limiter, but of course you could use the compressor circuitry too.
- Make sure stereo link is enabled and adjust the gain. Bear in mind that even in stereo link mode the two gain pots work independently so that you can adjust the stereo image.
- Then it is a matter of setting the peak threshold to the right level so that it is not clipping the Mytek ADC (when you look at the ADC meters on the Mytek). On the Cransesong this is set to 19db. We’ve marked this on the Cranesong for reference.
- Set the meters to GR (Gain Reduction). You should be able to see the amount of gain reduction that you’re getting from the PEAK limiter. A rule of thumb is perhaps not to exceed 2db or so.