I've recently bought a Klark Teknik KT-2A compressor to use with my Warm Audio TB12 preamp and noticed the TB12 has insert input and output sockets. What is the best practice when using outboard compressors with preamps when tracking? Should I daisy‑chain them so that the TB12 output goes into the KT-2A then to converters, or should I connect the KT-2A to the insert of the TB12?
SOS Forum post
SOS Technical Editor Hugh Robjohns replies: In terms of the signal flow, it doesn't really matter; you'll end up with a compressed mic signal either way. However, the first point I'd make is that the TB12's inserts are unbalanced, and so you're more likely to suffer ground-loop hums or interference problems if connecting the compressor as an insert. Perhaps more importantly, the two different configurations may well produce different sound characters — particularly if you like to 'drive' the TB12 (Warm Audio state that the preamp is specifically designed to deliver some character when 'pushed'). A large part of that character typically comes from deliberately 'stressing' the output stage and/or output transformer. If you insert a compressor into the preamp signal path ahead of its output stage — and the insert point is between the input and output stages — you'll typically reduce the signal level going into the output stage, and thus potentially struggle to achieve the desired overdrive effects. Of course, you also have the opportunity to use the compressor's make-up gain control to push even more signal through the output stage, so it could also work to your advantage depending on how you set up the compressor!
Personally, I'd wire the main balanced output from the TB12 into the compressor's balanced input, and perhaps save the preamp's insert point for an outboard EQ... but it really is horses for courses: the two connection arrangements will simply deliver different effects when driven, and neither is categorically better or worse than the other.