EQ901PS User Guide

Introduction 1

1. Features 2

2. Installation 2

3. Subwoofer Settings 3

4. Tone Controls 3

5. Setting Input Levels 4

6. Accessing the Input Level Switches 5

7. Specifications 5

8. Warranty Terms 6

Contact Deer Creek Audio 6


The EQ901PS is a direct replacement for existing BOSE 901 equalizers for users with pre-power amplifiers or pre-out / power-in ports who wish to add a powered subwoofer to their system. Switchable input levels between 0.9 Vrms and 2.0 Vrms accommodates use with most preamplifiers/amplifiers. The EQ901PS is based on the miniDSP 2x4 digital signal processor.

1. Features

  • EQ901PS Equalizer for Series I/II, III/IV or V/VI (series selected at order)

  • Precision frequency equalization optimized for each BOSE 901 Series

  • Active Subwoofer Crossover 

  • Single or dual monaural subwoofer outputs

  • Regulated U.S. power supply included

2. Installation

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.

Figure 2.1

Connection top view EQ901PS II.jpg

Figure 2.2

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.

3. 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.

4. 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 and the subwoofer controls are used to make fine adjustments. The EQ901PS includes a 48dB/Octave subsonic (rumble) filter.

5. Setting Input Levels

The analog audio input levels are switchable between 0.9 Vrms and 2.0 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.

Figure 5.1

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 pre-amplifier and a power-amplifier.

2.0 Vrms position. The maximum input signal voltage allowed before clipping the A/D converter is 2.0 Vrms. This position is typically used when the EQ901PS is connected in a tape recording loop (REC/in to PB/out).


6. Accessing the Input Level Switches

Figure 6.1

7. Specifications

Distortion:   <1% THD at maximum input

Dynamic range:  un-weighted >98dB

Analog Devices:  ADAU1701 Digital Signal Processor (DSP) Engine

Dimensions:  26 h x 107 w x 94 d mm

Crossover Plot:

Figure 7.1

8. 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.

Contact Deer Creek Audio

Please contact us with any questions or comments: