Conrad-Johnson - Premier Three Tube Preamp with Phono Stage - Fully Serviced

Free Shipping on *ALL* Electronics (Excluding Speakers, Contiguous 48 US States Only)

This is a super warm sounding vintage preamp from CJ. Beautifully built, and working like the day it left the factory.

Includes a very capable built-in phono stage, highly desirable in C-J preamplifiers.

This specific preamp is in amazing survivor condition with no significant blemishes. As you can see from our photos, the faceplate is super clean.

Tube Notes:
All tubes tested on our modern and professional Amplitrex AT-1000 tube tester for performance and microphonics.

• (2) 12AX7 - Current Production Electro Harmonix (Gain Matched Pair).
• (5) 5751 - Vintage GE JAN - 1 Gain matched pair, 1 Gain Matched / Balanced Pair, 1  with balanced sections.
• (2) 5965 - Vintage GE - Both well balanced.

Service Notes:
• All controls cleaned and tested.
• Power on delay relay cleaned.
• All tubes tested and verified - tube placement optimized for peak performance.

Conrad-Johnsons - Premier Three Tube Preamp Manual

From the owners manual regarding the Phono input section:

"The phono inputs provide the additional amplification and RIAA equalization required by most high fidelity cartridges. The input impedance is 47,000 ohms shunted by approximately 100 picofarads capacitance. This is the industry standard load and will work well with most moving magnet cartridges and all pre-preamplifiers for moving coil cartridges. A few moving magnet cartridges perform better with a 10,000 ohm load which may be achieved by having a service technician shunt the phono inputs with 12,000 ohm resistors.

For some moving magnet cartridges, optimum performance requires higher capacitive loads. This may be achieved by soldering suitable value capacitors across the phono input jacks. Polystyrene capacitors are recommended for this purpose."

SPECIFICATIONS:
Gain:
Phono stage 40 db
High level 28 db

Output:
Maximum 25v, rated at 2.5v

Phase:
Phono and high level stages are each phase correct (non-inverting)

Phono overload:
In excess of 500mv at 1kHz

Response:
Bandpass 2Hz to more than 100kHz
RIAA equalization to +/- .25db (20-20kHz)

Total hum and noise (20-20kHz):
Phono inputs: 72db below 10 mv input
High Levels: 84db below 2.5 volt output

Distortion:
THD less than 05%
IM less than .05%

Output impedance:
Less than 200 ohms

Dimensions:
19 x 5-1⁄4 x 12-1⁄4 inches

Weight:
21 lbs.

The SkyFi Testing Process for Preamplifiers:

We start with a visual inspection of all internal components to make sure there are no signs of stress or aging. Capacitors are checked for telltale sings of bulging or leaking, resistors are checked for signs of overheating or cracking, and transistors are checked for signs of stress or damage. Special attention is paid to the power supply which is the most common source of failure for preamps. We then power up the unit and run a simple 1k sine wave while monitoring the low voltage output on an oscilloscope for signs of distortion or noise to get a baseline.

At this point we will lubricate and clean all switches and potentiometers (that are not sealed) with a high quality contact cleaner, and then re-test all functions for any signs of noise or scratching.

Final testing involves putting actual music through the preamplifier We have learned over time that some issues are only noticeable to a trained ear while listening to a familiar source material. Our test bench has reference vintage KEF speakers that we are super familiar with which will quickly reveal any discrepancies. Some preamps will then move into the listening room where they will be tested with our in-house reference system.

Please click here for detailed specifics regarding our specialized packing process that separates us from the rest.