When only a steep filter will do. This is a bare unassembled circuit board for an 18 dB/Octave, high and low-pass filter to replace the Neumann HT-75.

Features

• Balanced Inputs and Outputs. The inputs are fully-balanced using THAT 1246 line receivers with THAT 1646 OutSmarts® ICs driving the outputs.
• 18 dB per Octave 40 Hz High-pass and 16 kHz Low-pass at the two most useful frequencies.
• Relay bypass of each filter.
• Optional on-board regulator for the relays.
• Current-limited LED outputs for relay status. (10 mA 2K21Ω/24V)

Mechanical and Power Specifications

• Board Size: 4.3" x 3.0" Mounting holes: M3 0.125" diameter on a 4.0" x 2.7" pattern. Assembled height: Approximately 1" not including stand-offs.
• Power Requirements: ±15 to ±18V (max) approximately 65 mA (no signal current). Relay +24V 40 mA two relays and LEDs. Up to +36V using on-board regulator.

Audio Specifications

• Inputs: THAT1246. Input Impedance 24KΩ differential, 18KΩ common mode. Maximum input level +27 dBu.
• Outputs: THAT1646. Output impedance 50Ω nominal. Maximum output level +27 dBu.

Note: Noise measurements are for a 20-20 kHz bandwidth and are unweighted unless specified. Maximum level specifications are for ±15V supplies.

Additional audio specifications and performance as they become available.

The construction thread for the Transfer Filter is featured in the Pro Audio Design Forum.

The Transfer Filter is sold as either a bare PC board, a "kit" including THAT1246, OPA2134 and THAT1646 ICs, or an assembled and fully-tested module.

A Mouser Electronics Project Manager bill-of-materials is available for DIY builds of the Transfer Filter.