Electrical Audio EApreq500, the 500-series version of the EAPreQ preamp and EQ that Electrical Audio has built in Chicago since 2011. Hand-built, transformer-based, simple to use, and very quiet.

About the maker: The EApreq500 was designed by Greg Norman, longtime engineer and co-operator at Steve Albini's Electrical Audio in Chicago, and hand-built by the studio's crew. It's the 500-series version of the EAPreQ that Norman created in 2011 for use at Electrical, and it has been in use there ever since. It pairs a Lundahl input transformer with a low-noise FET gain stage, and the idea is to let the transformer add subtle color without adding noise or distortion. Tape Op reviewed it and called it a studio workhorse.

Condition: Like new. I’ve owned it for about 2 years. It has lived in the original box and packing since. No wear, no marks. Comes with the original box and info card.

Features:

• Lundahl’s best microphone input transformer
• -20dB input pad switch - sealed gold contact relay
• Polarity reverse switch - sealed gold contact relay across the output for quietest operation
• 48v phantom power switch - standard application
• 16-position, gold contact rotary gain switch, ranging from 20 to 65 dB of gain, with 3 dB per step
• Low and high-frequency shelf boost EQ - Controlled with a solid multi-section gold contact switch, with 5 gain positions.  A sealed relay bypasses the EQ circuit when not in use.
• DC servo for both preamp gain and shelf EQ make-up gain amplifiers. This ensures long-term predictable operation and sound quality, avoiding the gradual decline associated with electrolytic capacitor-coupled circuitry
• Ground-sensing solid-state balanced output amplifier, capable of driving 600Ω loads with ease, balanced or unbalanced
• Clear green LEDs indicating which shelf band is engaged.
• Bright, amber colored "peak" LED signal just before clipping.

TECHNICAL SPECIFICATIONS

FREQUENCY RESPONSE

± .5dB from 7 Hz to 102 kHz (3dB down @120kHz)

MAXIMUM OUTPUT LEVEL=

+27dBu Balanced 10kΩ Termination (typical modern equipment inputs)

+26.5dBu Balanced 600Ω Termination (“vintage” input impedance standard)

+21dBu Unbalanced 10kΩ Termination

NOISE AND DISTORTION

THD+N (1kHz, 35dB gain) ≤ .003%

THD+N (30Hz, 35dB gain) ≤ .012%

IMD (50Hz/7KHz) ≤ .0015%

Noise floor (22- 22kHz unweighted, lowest gain setting) ≤ -99dBu

Noise floor (22- 22kHz unweighted, EQ engaged) ≤ -86dBu

Equivalent Input Noise = (44dB gain, 150Ω input source, no EQ) ≤ -128dB

Power Consumption is typically < 50mA per 16 volt rail, and < 100mA per rail in the extreme (1kHz sine wave @26dBu into a 600Ω load, all relays on).  

Ships insured in its original box. Reasonable and respectful offers welcome.