Deer Creek Audio EQ901PS  User Guide


The EQ901PS is a direct replacement for existing BOSE 901 equalizers for users with pre/power amplifiers or pre-in/pre-out ports who wish to add a powered subwoofer to their system.  Switchable input levels between 0.9 Vrms and 2 Vrms accommodates use with most preamplifiers/amplifiers. The EQ901PS is based on the miniDSP 2x4 digital signal processor.

Features Included:

•     EQ901PS Equalizer I/II, III/IV or V/VI

•     Precision frequency equalization optimized for each BOSE 901 Series

•     Active Subwoofer Crossover (subwoofer not included)

•     Single or dual monaural subwoofer output(s)

•     Regulated US power supply


Analog audio input and output connections are made directly to the RCA input and output jacks.  When making these connections, make sure that the equipment being connected is powered off.

Connection top view EQ901PS II.jpg


The EQ901PS  does not have a power switch.  We recommend that it be left powered on as power consumption is very low.  When you power the EQ901PS off and on, ensure that you turn the connected equipment off before disconnecting power from the EQ901PS .  Also, connect power to the EQ901PS before turning connected equipment on.

Subwoofer Settings

To begin, your subwoofer should be set at mid level gain, and the crossovers should be set at the highest frequency or disabled.  After you have the system up and running adjust the subwoofer level, phase, and crossover to get the best response.

Tone Controls:

The EQ901PS has been calibrated to provide a neutral and natural sound without tone control adjustments There are no external tone controls on the EQ901PS, your audio/video receiver or amplifier tone controls are used to make fine adjustments. The EQ901B-III/IV includes a 48dB/Octave subsonic (rumble) filter

Setting Input Levels:

The analog audio input levels are switchable between 0.9 Vrms and 2 Vrms to accommodate use with most preamplifiers/amplifiers.  The EQ901PS is shipped with the input level set to 0.9 Vrms.  This EQ901PS equalizer is set to install on your pre amplifier output (input 1, 2) and then connect to your power amplifier input (output 3, 4) and to your powered subwoofer(s) (output 1 and/or 2).

This unit is configured with the 0.9 Vrms input setting.  If you need to reduce the input sensitivity/gain you can change the input level jumpers to the 2.0 Vrms setting.

0.9 Vrms position - The maximum input signal voltage allowed before clipping the A/D converter is 0.9 Vrms. This position is typically used when the EQ901PS  is connected between a preamp and a power amplifier.

2 Vrms position - The maximum input signal voltage allowed before clipping the A/D converter is 2 Vrms. This position is typically used when the EQ901PS is connected in a tape recording loop (REC/in to PB/out).

Accessing the Input Level Switches:


Distortion <1% THD at maximum input

Dynamic range: un-weighted >98dB

Analog Devices ADAU1701 digital signal processor (DSP) Engine

Dimensions: 26h x 107w x 94d mm

Crossover Plot:

Warranty Terms:

This product is warranted to be free from defects in materials and workmanship for a period of one year from the invoice date.  Warranty does not cover failure of the product due to incorrect connection or installation, improper or undocumented use, unauthorized servicing, modification or alteration of the unit in any way, or any usage outside of that recommended in this manual. Return shipping is the responsibility of the customer.

Please contact us with any questions you may have   720.726.9272