EQ901B Series User Guide
The Deer Creek Audio EQ901B Series is a direct replacement for existing BOSE 901 equalizers. The EQ901B features dual output equalization (EQ) curves, Normal and Enhanced, either of which will accommodate your 901 Series and can be selected based on personal preference. See below for instructions on using this feature.
The EQ901B installs in your tape monitor loop, pre-out/pre-in loop or between your preamp and power amp. Switchable input levels between 0.9 Vrms and 2.0 Vrms accommodate use with most preamplifiers, amplifiers or receivers. The EQ901B series is based on the miniDSP 2x4 digital signal processor.
Precision engineered 901 Series model-specific EQ curves
Dual output EQ curves Normal and Enhanced
Simple drop-in replacement
High fidelity and low noise
2. What’s Included
Frequency equalization curves for your 901 Series
Regulated power 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 Tape Monitor Loop Setup
3.2 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.
3.3 Connecting a Power Subwoofer
The two unused outputs connect to your subwoofer L and R line inputs. The subwoofer controls can then be adjusted to your preference.
3.4 Typical Setup I/O
3.5 AC Power Connection
The EQ901B does not have a power switch and can be left powered on, as power consumption is very low. You also may power your EQ901B from a switched outlet on your receiver.
4. 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 or receivers. If you are experiencing excessive signal level or distortion, you may need to switch the unit to the 2.0 Vrms setting.
The EQ901B model is shipped with the input levels preset to 0.9 Vrms.
0.9 Vrms position. With this setting, the maximum input signal voltage allowed before clipping the A/D convertor is 0.9 Vrms. This position is typically used when the EQ901B is connected between a preamp and a power amplifier.
2.0 Vrms position. With this setting, the maximum input signal voltage allowed before clipping the A/D convertor is 2.0 Vrms. This position is typically used when the EQ901B is connected in a tape recording loop (REC/in to PB/out).
5. Accessing the Input Level Switches
6. Using the Dual Output EQ Curves
The EQ901B is equipped with two equalizer (EQ) curves. The Normal EQ curve is available on outputs 1 and 2, and the Enhanced EQ curve is on outputs 3 and 4.
If you're using an amplifier or receiver with two tape monitor loops, you can connect the EQ901B outputs 1 and 2 to tape playback inputs 1, and outputs 3 and 4 to tape playback inputs 2. Then you will be able to switch easily between the two equalizer curves. If your configuration is a pre-amplifier out / main amplifier in setup, you'll need to manually move the cables from outputs 1 and 2 to outputs 3 and 4. Be sure to power off all equipment before making these adjustments.
Distortion: < 1% THD at maximum input
Maximum input voltage: 2.0 Vrms or 0.9 Vrms - jumper settable
Dynamic range: un-weighted > 98dB
Analog Devices: ADAU1701 Digital Signal Processor Engine
Dimensions: 26 h x 107 w x 94 d mm
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.
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