MICROPHONE PREAMP

This design is centered around a copy of the venerable Quad-Eight AM10 discrete opamp and features high quality Sowter input and output transformers. Gain is variable from 0-66dB in 3dB steps on gold-contact Elma A4 rotary switches. The high impedance balanced direct input on the front automatically routes the signal through the mic transformer when a 1/4" cable is inserted. Three options for input impedance ensure that you can interface properly with any source, including line outputs. The entire signal path is DC coupled and extremely short with just a single opamp and a JFET input buffer. +/- 24V rails provide high headroom.

These mic pres are currently built to order and the price is $1,600 for two channels with an internal PSU. Up to 4 channels can fit into a 1 RU case with an external PSU. Please contact me for more information.

SPECIFICATIONS

  • Noise: -100dBu @ 0dB Gain, -54dBu @ +66dB Gain (10Hz - 30kHz Un-Weighted)
  • Frequency Response: +/- 0.2dB 16hz - 31kHz @ 51dB Gain
  • THD+N: < 0.012% @ 1kHz with 66dB Gain, +26dBu Output (10Hz - 30kHz Un-Weighted)

Below you can download a zip containing multi-track audio files from a test session recorded simultaneously with Squarewave pres, vintage Neve 1073s, and an API 3124. It's a short section of a full band song with drums, DI bass, acoustic and electric guitar, vocals and piano. Each mic was multed out to all three preamps and all of the files have been gain matched for each source. The zip includes a Pro Tools session or you can import the audio files into your software of choice.

Mic Pre Test Session (Zip)

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