What hardware preamp was the AP-57 modeled after?

The AP-57 is modeled after a highly modified Ampex 601 tube preamp, part of a suitcase recording system from the late 1950s. The specific hardware unit used for modeling included the optional input transformer, a custom input attenuator and other custom tweaks.

Our AP-57 mic preamp emulation reproduces the complete experience using a 50s tube mic preamp - the larger-than-life sound, the rich harmonics, and the rapid onset of distortion, especially when using high-output large diaphragm condenser microphones!

If you have a 50s tube mic pre, you probably have an in-line attenuator or two just to be able to record with a condenser mic without overloading the mic pre input. Then again, if you’re looking for a warm but present distortion, the 601 preamp gets you there quickly. 

With our AP-57 emulation, you’ve got this choice as well - start with no pad, turn up the gain, and bask in the thick harmonics! If you’re barely cracking the Input gain but getting too much, engage the -20 dB pad - you’ll be able to increase the gain with less distortion. 

Once you’ve determined the pad setting, tap GL (Gain Link) to couple the Input Gain and Output Level controls to work together. The AP-57 emulation offers more extreme sounds than the other mic preamp emulations, so approach it with a creative mindset!