Warm Audio TB12 Tonebeast Mic Preamp

90 out of 100. Incorporating 90+ ratings and reviews.
Warm Audio

Gearank High Notes

Gearank Recommendation

The TB12 Tonebeast appeared on our recommended list for Microphone Preamps in our first edition back in February 2017 where it remained until February 2018 when it was out-ranked by other preamps.


Warm Audio describes the TB12 as a clone of the API 312 preamp, complete with premium Cinemag input-output balancing transformer. This distinct feature was normally found on more expensive units, but it is now more accessible, thanks to the increased efficiency of today’s raw materials and production.

This preamp also houses multiple discrete signal paths that let you choose between two op-amps, be it the Jensen 918 (which is more transparent) op-amp or the Melcor 1731 (which is more colored).

Controls include a tone switch that changes mic impedance, 80Hz highpass filter, 20dB pad, and output attenuation. There’s also a Hi-Z switch in case you want to plug-in electric guitars and basses.


  • Channels: 1
  • Mic Preamps: 1 Solid State 312 preamp with Cinemag Transformers
  • Frequency Response: 10Hz – 50kHz
  • OP-Amp: Swappable/Socketed
  • Input Connectors: 1 x XLR, 1 x TRS (with Hi-Z Switch), 1 x TRS (Receive)
  • Output Connectors: 1 x XLR, 1 x TRS, 1 x TRS (Send)
  • Controls: 20dB pad, 80Hz highpas filter, Output attenuation, Tone switch, Transformer bypass, Phantom Power, Phase Switch, Compressor
  • Dimensions : 1.75″ x 5.5″ x 19″
  • Weight: 5 lbs.
Unfortunately it’s very hard to find one in stores these days, so if you’re looking for a new preamp then check out our guide to The Best Microphone Preamps.