EQ901USB User Guide

Introduction

The EQ901USB is an upgrade replacement for existing BOSE 901 Equalizers. The EQ901USB Series features four specifically designed equalization curve sets unique to each Series: I/II, III/IV or V/VI.

The EQ901USB is also a high performance digital pre-amplifier (DAC) intended to drive high quality power amplifiers or integrated amplifiers/receivers. Analog, USB and TOSLINK digital audio inputs are provided.

When used in the digital input mode, the music stream is maintained in the digital domain all the way through the 901 equalization process. This is the purest and highest fidelity way to drive your 901s.

1. Features

USB / TOSLINK Streaming Digital to Analog Converter (DAC) with built-in equalization curves for the 901 Series V/VI
Precise BOSE 901 equalization is performed digitally before the DAC in an Analog Device 400 MHz SHARC DSP processor with 24 bit resolution
The four BOSE 901 tone modes (EQ curves) are available on all four outputs. Two identical stereo pairs outputs are available, allowing for dual active stereo systems (two stereo power amps) or the addition of an active subwoofer(s)
Remote selectable inputs:

Analog
TOSLINK
USB

Remote selectable tonal characteristics settings:

Normal mode
Enhanced mode
Warm mode
Low frequency reduction mode

Remote volume control with 0.5 dB resolution and mute
Ultra low distortion 2.0 Vrms output driver stage
Selectable input sensitivity of 2.0 Vrms or 4.0 Vrms

2. What’s Included

EQ901USB equalizer for your BOSE 901 Series I/II, III/IV or V/VI (series selected at order)

Four precision engineered tone adjustment equalization curves

Two identical stereo pairs outputs are available allowing for dual active stereo systems (two stereo power amps) or the addition of an active subwoofer(s)

Deer Creek Audio USB drive with PC USB audio driver

IR Remote Control

USB cable

U.S. regulated power supply (see option for global supply)

3. Typical Installation Examples

Analog audio input and output connections are made directly to the RCA input and output jacks. For RCA connections, #1 is Left (L) and #2 is Right (R). When making these connections, make sure to power off the equipment being connected.

3.1 Stereo Mode

3.2 Dual Stereo (Quad) Mode

3.3 Active Subwoofer Mode

3.4 Tape / Processor Loop Setup

3.5 Analog Only Preamp / Power Amplifier Setup

This example shows a typical connection between a preamp and power amp.

If you have a receiver or integrated amplifier with a pre-out / main in loop, you can insert the EQ901B as shown below.

4. USB Streaming Music Driver Installation (PC only)

The driver enables USB streaming music from the computer to the EQ901USB. Connect the processor to the computer using the supplied USB cable, and power it on. Navigate to the WinDrivers folder of the software download and double-click on the driver install.

miniDSP_UAC2_v4.82.0_2020-06-09_setup.exe for Windows 7, 8 and 10

(The version number and date embedded in the filename may be different.) We recommend accepting the default installation location. Once driver installation completes, click Finish.

5. Level Setting

Your EQ901USB is being delivered with an internal level (gain) setting of 0db (max, no insertion loss) that you will adjust with the supplied remote control. It has been set with the analog inputs selected. Be sure to turn down your music source to protect your system at turn on. Once you have your inputs connected and all components on, you can adjust all the gain levels for optimal volume midposition control performance.

6. Analog Input Level

The analog audio input levels are switchable between 2.0 Vrms and 4.0 Vrms to accommodate use with most equipment. The EQ901USB is shipped with the analog input level set to 2.0 Vrms.

7. Subwoofer Settings

You may drive an active subwoofer with outputs 3 and 4, however keep in mind these are an exact, full range, stereo match to outputs 1 and 2. To begin, your subwoofer should be set at mid-level gain, and the crossovers should be set at the mid-level setting. After you have the system up and running, adjust the subwoofer level, phase and crossover to get the best response.

8. USB Music Server Volume Setting Warning

If you are streaming digital music via a server such as foobar2000, JRiver, Roon, etc., begin with the server application level set low.

9. Using the EQ901USB Remote Control

The IR remote control provided with the EQ901 controls the following runtime functions.

Mute. Mute and unmute audio output.
Volume. Reduce or increase the volume. Each press changes the volume in 0.5 dB. Holding down a button will accelerate volume change to 3 dB steps.
Source Selection. Cycle through the input sources in order: RCA (unbalanced analog), TOSLINK, USB.
Tone Modes (1 through 4). Switch to the selected tone mode. It takes a few seconds for the preset selection to complete.

10. Setting Tone Modes

Selection of the tone mode is generally a subjective choice based on what sounds best to you. Specifically: Normal mode is the most neutral, Enhanced mode provides a richer sound with more treble and bass, Warm mode adds midrange with slight treble reduction, and Low frequency reduction mode is intended to control bass in smaller rooms or on “boomy” recordings.

11. Specifications

EQ901USB platform base: miniDSP 2x4 HD
Digital Signal Processor Engine: Analog Devices Fixed point DSP SHARC ADSP-21489
USB controller: XMOS xCORE-200
Digital to Analog Converter (DAC): AK4626A
Internal Processing resolution and sample rate: 32 bit / up to 192 kHz
Audio Input Connectivity: RCA, TOSLINK (optical), USB Audio
Audio Output Connectivity: Unbalanced output, RCA
Input / Output Max Levels: In 2.0 Vrms / 4.0 Vrms (jumper-selectable), Out 2.0 Vrms
Input Impedance: 10 k Ω
Output Impedance: 560 Ω
Filtering Technology: FIR + I/IIR
Dimensions: 27 h x 119 w x 107 d mm
Power: 12V DC single supply, 2.1 mm round plug, 2.5 Watt
IR Remote: miniDSP Remote

12. 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:

staff@deercreekaudio.com

720.726.9272