Conrad Johnson ET5 Enhanced Triode Preamplifier - Award Winning

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General:

2016 and 2017 Absolute Sound Editors Choice Award Winner.

Line stage preamp only meaning you just need an outboard phono preamp to connect your 'table. Also Includes a new RC-10 remote fresh from the factory.

Tube Notes:
This preamplifier is fitted with a single vintage Philips JAN 6922 which tests very strong for both emission and Gm.

ET5 Enhanced Triode Preamplifier
Introduced in 2009, the GAT Preamplifier continues conrad-johnson’s dominant position atop the rankings of reference preamplifiers.

An important benefit of pursuing state-of-the-art designs is that the circuits and techniques developed in our flagship products are frequently directly applicable to our entire line of products. In this instance, we have embodied the technology of the GAT Preamplifier in the more cost effective ET5 enhanced triode line-stage preamplifier at a more affordable price.

The circuitry of the ET5 follows closely that of the GAT line-stage preamplifier.
The audio circuit is elegant in its simplicity.

An audio amplifier stage consisting of a single-ended triode amplifier provides the voltage gain. This amplifier stage is connected to the preamplifier outputs through a high-current MOSFET buffer, which achieves a very low output impedance, making the ET5 extremely flexible in the choice of interconnect cables and amplifiers.

DC voltage is supplied to the circuit by our latest discrete voltage regulator that isolates the audio circuit from the power line by maintaining negligible impedance across the audio frequency band. Infra-sonic noise is minimized by operating the tube filaments (heaters) on a dc voltage supplied by a separate regulated power supply. The ET5 is also notable for convenience and ease of use. The unit features input selection and level adjustment by microprocessor-controlled relays, with controls available both at the front panel and via a full-function remote.

All control functions of the ET5 operate through microprocessor-controlled relays. For the level control, the relays select combinations from a network of precision, low-noise metal foil resistors to effect loudness and balance changes in 100 steps of approximately .7dB per step. All switching and adjustment can be controlled by the unit’s remote control. A Theater Mode, which passes the input signal through at unity gain, makes it simple to incorporate the ET5 into a high quality home theater system without compromising its two-channel performance.
Like its bigger brother, the GAT, the ET5 is constructed from the highest quality, carefully selected parts for unrivaled sonic performance and reliability.

Tubes have been carefully hand selected for minimum noise and microphonics. The same CJD Teflon capacitors that distinguish the GAT are used in the ET5 for output coupling and post-regulator power supply storage. All other capacitors in the audio circuits and related power supplies are polypropylene or polystyrene – there are no electrolytic capacitors in the audio related circuits. The resistors in these circuits (including the two dozen level control resistors) are special low inductance, high-precision laser-trimmed metal foil resistors. Switches are sealed relays with gold-plated silver contacts. Input and output connectors are premium quality custom machined parts.

For more than three decades, we at conrad-johnson have been dedicated to creating audio components that do credit to music performances.

Through meticulous engineering, careful specification of only the finest available component parts, and a painstaking attention to construction, we have created what we feel is a line-stage without rival in its class. We invite you to arrange an audition of the ET5 with your conrad-johnson dealer to experience the extraordinary musical performance of this remarkable preamplifier."

Brand Background:

Our design philosophy is the culmination of more than 40 years of research and development. conrad-johnson products are executed with simple circuits, constructed with the highest-quality custom components.

Our products benefit from the use of proprietary components (CJD film capacitors, audio and power transformers), military-grade parts (precision audio resistors), and in-house designed elements (circuit boards, chassis and dress metal)—all sourced from North American vendors.

Ownership:

Single Owner

Connections:

RCA single-ended inputs and outputs. Removable IEC power cord. 

General Sound:

Accurate to the recording

Cosmetic Condition:

8 - Very Slight Signs of Use

https://skyfiaudio.com/pages/our-rating-scale

• Side panels show some minor scuffs.
• Small chip on top of faceplate above volume meter.

Working Condition:

Working perfectly and tested in our lab.

Included:

Just the unit and power cord

Packing:

Original Manufacturers Packing

Original MSRP:

$9,500

Dimensions:

15.375" D x 19" W x 4.94" H 

Weight:

28 lbs.

Age:

2015

Reviews:

https://www.tonepublications.com/review/conrad-johnson-et5-preamplifier/

Link to Manual:

https://conradjohnson.com/owners-manuals/et5man.pdf

Recommended Cables:

Kimber Kable - RCA Interconnects - Better

Kimber Kable - RCA Interconnects - Best

Kimber Kable - Phono Interconnects - Better

Kimber Kable - Flagship Tonearm Interconnects - Best

Testing Process:

We start with a visual inspection of all internal components to make sure that there are no signs of heat stress or damage. Capacitors are checked for telltale signs of predictive failure including bulging, shrunken wrappers, or physical leakage. We also inspect the PCBs for discoloration from resistors or transistors that may have been running hot. On vintage units we often spot check select capacitors for value and ESR.

When we first power on a preamplifier we connect its RCA output to a Sencore PA81 Power Analyzer which simulates real world loading conditions and gives us an oscilloscope interface. The first order of business is checking that the volume control works smoothly throughout its entire range with acceptable channel balance. This is accomplished by feeding a 1KHz sine wave into one of the preamp’s line level inputs while monitoring the preamp’s output on an oscilloscope. We then switch to a 1KHz square wave to test the tone controls, loudness function, and filters where applicable. During this step we are watching for equal alteration of the test signal by both channels. This also helps us identify dirty controls that will need treatment. Once the basic line stage functions are verified, we test each input individually. This is especially important for devices that use relays to select their sources. If the preamp is equipped with a phono stage we test that as well. We use an inverse RIAA filter which allows us to feed a reference test signal into the phono input with the proper RIAA equalization and level. A square wave or sine sweep is used to verify that the device’s phono stage is faithfully reproducing the RIAA curve. If the preamp under test has balanced inputs and/or outputs these are tested as well.

We finish up our bench testing with a listening test with our bench amplifier and reference speakers. During this test we check for hum or hiss that may not have shown up in earlier testing. We also check that all of the tone controls and filters perform as expected. If the preamplifier has remote control functions these are also tested. Preamps with tube circuits or complicated power supply topologies are connected at our long term test rig for extended stress testing under real world conditions.

Specs:

Gain:
25 dB

Maximum Output:
20V rms

Bandpass:
2Hz to more than 100kHz

Hum and Noise:
100 dB below 2.5V output

Distortion at 1.0 V output:
Less than .15% THD or IMD 

Phase:
Inverts phase of all inputs at main out

Output Impedance:
100 ohms