Acme Audio MTP-66 Motown Tube Preamplifier and DI

Acme Audio MTP-66 Motown Tube Preamplifier and DI is a single-channel tube preamp rebuilt from the original 1966 engineering drawings. Its ancestor was the five-channel Motown input box that guitars and bass ran through in Detroit from 1966 to 1972.

Instrument straight into the tubes, no amplifier

Instead of miking an amp in a booth, bass goes directly into a tube path feeding a Cinemag output transformer. There is no baffling to arrange and no bleed to fight, and the signal arrives with density and compression that a clean direct box does not provide. A quarter-inch through output sends the instrument to an amplifier in parallel.

Drive set at two points in the chain

The original had no input or output control. The MTP-66 has both, so you can push the tubes hard and pull level back at the output, or work cleanly: that is what sets the amount of drive and natural compression. The microphone section is built on a fixed-gain pentode with an Acme Audio/Triad transformer and a 15 dB pad. The unit does not provide phantom power.

KEY FEATURES

• Recreation of the Motown input box from the 1966 schematics
• All-tube signal path with hand-selected tubes
• Cinemag output transformer
• Microphone section with fixed-gain pentode and Acme Audio/Triad transformer
• Independent input and output controls, absent from the original
• Quarter-inch instrument through output
• Custom VU meter in a rugged steel enclosure

TECHNICAL SPECIFICATIONS

• Type: tube microphone preamp and DI, single channel
• Gain: 36 dB
• Tubes: EF86, two 12AT7, 6V6
• Output transformer: Cinemag
• Microphone input transformer: Acme Audio/Triad
• Inputs: 1/4" Hi-Z, XLR microphone
• Outputs: XLR main, 1/4" instrument through
• Microphone input pad: 15 dB
• Phantom power: not provided
• Power: 115/230 V, 50/60 Hz
• Weight: 11.5 lbs (approx. 5.2 kg)