Conrad-johnson design PREMIIER TWO User manual

OWNER'S MANUAL
PREMIER TWO
VACUUM TUBE PREAMPLIFIER
conrad-johnson design, inc.
703-698-8581

Thank you for your considered purchase of a conrad-johnson Premier Two
Preamplifier. In it, you have acquired one of the finest pieces of music reproduction
equipment available today.
The Premier Two preamplifier was designed for the purpose of providing ourselves
(and other members of the community of designers of high fidelity audio equipment
with a reference quality preamplifier. Its unique circuit design embodies the results of
10 man-years of research into the technology of the reproduction of recorded music.
The design has been uncompromisingly executed in the finest available component
parts and each unit painstakingly assembled and tested to insure enduring sonic
excellence and trouble--free operation.
Please take a few minutes to read this manual so that you will better understand the
features and capabilities of your Premier Two preamplifier.

LIMITED WARRANTY FOR THE conrad-johnson PREMIER TWO
1. conrad-johnson design, inc. warrants to the original purchaser that the conrad-
johnson Premier Two will perform to specifications as published in the owner's
manual and that it will be free of defects in materials and workmanship for a
period of three years from the date of original purchase.
2. conrad-johnson will repair defective units without charge for labor or parts with
the exception of the vacuum tubes) subject to the following conditions:
a) The unit must not have been altered or damaged through misuse, abuse,
negligence, accident, or improper operation.
b) The purchaser must provide evidence of purchase at the time service is
requested.
c) All repairs must be undertaken at the factory or other service center
designated by conrad-johnson design, inc. Units submitted for warranty
repairs must be shipped in the factory packing carton to conrad-johnson
design or its designated service center, freight and insurance prepaid by the
owner, and will be returned to the owner, freight and insurance prepaid by
conrad-johnson design. Replacement cartons are available from the factory
for a nominal charge.
d) Normal wear and maintenance are not covered by this warranty.
3. The above warranty may be transferred to subsequent owners provided that the
warranty registration card has been returned to conrad-johnson design, inc. within 30
days of the original purchase and that the registered owner provides the factory with
a signed notice giving the new owner's name and address and the model and serial
number of the unit.
4. Where permitted by law, conrad-johnson design's liability shall be limited to that
set forth in this warranty. No other warranty of any kind, expressed or implied, is
made by conrad-johnson design, inc., and all implied warranties, including
merchantability and fitness for a particular "purpose", which exceed the obligations
and time limits set forth herein are hereby disclaimed. conrad-johnson design, inc.
shall not be liable for incidental or consequential damages. Some states do not allow
the exclusion or limitation of incidental or consequential damages, or limitations on
how long an implied warranty lasts, so the above limitation or exclusion may not
apply to you.
5. This warranty gives you specific legal rights, and you may also have other rights
which vary from state to state. Questions about warranty service should be addressed
to:
CONRAD JOHNSON DESIGN INC
2733 MERRILEE DR.
FAIRFAX, VA 22031

ABOUT conrad-johnson design
We are a small company offering exclusively audiophile products designed for our
own use as well as our customers'. We believe that our commitment to the purchaser
of our products is nearly unique in the industry. The services we offer to conrad-
johnson owners include:
•Information - Registered owners of conrad-johnson equipment will be directly
informed of new equipment we have to offer. They will also be informed of any
significant changes in the design of their equipment resulting from our ongoing
development program.
•Factory updating - Should significant design changes be made, conrad-johnson
design will, whenever practical, offer to update existing equipment. This service
will be offered at a minimal charge to cover parts, labor, and handling.
•Factory service - Any conrad-johnson product may be returned to the factory for
service. All equipment serviced at the factory will perform to its published
specifications when returned. Factory service will be offered at reasonable rates.
•Transferable warranty - conrad-johnson design guarantees its products, not the
owner. Should you decide to sell the product, the warranty may be transferred to
the new owner. (See Registering the Warranty.)
REGISTERING THE WARRANTY
Please return the enclosed card to the factory within 30 days of purchase to register
the warranty. The warranty may be transferred to a new owner if it has been properly
registered initially and if the registered owner sends a signed notice providing the
name and address of the new owner and the model and serial number of the unit.
Proper registration of the warranty is important; Not only will it preserve
transferability of your warranty, it will also enable us to inform you of any alterations
in the design of a given model and of any new products we offer which are likely to
be of interest to you.

CIRCUIT DESIGN
The Premier Two phono stage consists of two stages of cascode triode pairs. This
provides sufficient open loop gain to achieve optimum feedback ratios even at bass
frequencies. The second stage is direct coupled to a cathode follower which drives
the feedback loop as well as the output. Phono equalization is accomplished by R-C
networks in the feedback loop. A unique generalized anode follower configuration on
the second cascode stage tailors the circuits' open loop response to maintain a
constant feedback ratio across the audio spectrum.
The line amplifier stage uses a single triode input amplifier followed by a cascode
triode pair which maintains open loop phase linearity at high frequencies. This
cascode stage is direct coupled to a cathode follower to achieve low output
impedance.
A hybrid rectifier bridge in the plate supply controls turn-on surges to assure
maximum tube life. The plate voltage is controlled by a two stage regulator which
provides exceptional isolation from line voltage fluctuation and vanishingly small
line frequency ripple. Each stage of each channel and each cathode follower is
separately decoupled to its own 90 micro-farad capacitor with poly-propylene bypass.
Filaments are operated at a regulated d.c. voltage to eliminate coupling of subsonic
line voltage disturbances to the audio signal.

INSTALLATION
Because of the number and type of vacuum tubes used, the Premier Two dissipates a
significant amount of heat (approximately 50 watts). It is essential, therefore, that
proper attention be paid to ventilation. The unit should be mounted horizontally on a
flat hard surface so that the ventilation holes in the bottom are un-obstructed. At least
three inches of clearance should be provided above the unit and the cabinet or shelf
should be open at the back. Vertical installation is not recommended.
The front panel of the Premier Two will fit in a standard 19" equipment rack and is
designed to carry the weight of the preamplifier so that the unit may be rack
mounted. Again, it is important that adequate clearance be provided above the
Premier Two so that ventilation is not impeded.
To minimize hum pickup, keep the unit well away from the power amplifier, and
route power cords away from input cables.
THE PREMIER TWO IS TO BE OPERATED ONLY ON AC LINE VOLTAGE OF
108 to 125 VOLTS, 50 or 60 HZ (Can be wired for operation on 100 volt or 220 volt,
50 or 60 Hz, ac lines)
In any system of audio electronics minute leakage currents from the ac line
transformers will flow in the signal ground connections between preamplifier and
amplifier. These currents can intermodulate with the signal and affect the clarity of
sound. Generally, one orientation of the line cord will provide much lower current
flows. When combined with the finest associated equipment this effect is clearly
audible with the Premier Two. After installing the unit try reversing the line cord at
the wall outlet to pick the most satisfactory orientation.

CONNECTION
Inputs:
Phono - 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.
Tuner, Auxiliary, Tape 1, Tape 2 - These are all high level inputs and are
electronically equivalent. The outputs of your tape recorders should be connected to
Tape 1 and Tape 2.
Outputs:
Record 1, Record 2 - Connect these to the inputs of your tape recorders.
Output 1, Output 2 -- Connect to the inputs of amplifiers with impedance of 10k-
ohms or greater.

USE OF EXTERNAL TONE CONTROLS OR OTHER EXTERNAL SIGNAL
PROCESSING DEVICES:
Use Tape 1 and Record 1 for your tape recorder, as described in the preceding two
paragraphs. Connect the output of the tone controls to Tape 2 and the input of the
tone controls to Record 2. The Monitor 2 position of the monitor switch will insert
the tone controls in the circuit; the Source position will provide flat, unprocessed
response. This method of connection will permit the use of tone controls with tape
playback by selecting Tape 1 in conjunction with Monitor 2.
AC OUTLETS
Four ac outlets are provided for your convenience: two, marked unswitched, are
always live; the remaining two are switched by the preamp's power switch. THE
TOTAL CURRENT REQUIRED OF THE SWITCHED OUTLETS MUST NOT
EXCEED 5 AMPERES. This precludes the use of these outlets for high powered
amplifiers. It is preferable not to switch power amplifiers by the preamplifier power
switch in any case.

OPERATION
Turn on: Because of the delayed warm up characteristics of vacuum tube equipment,
a time delay muting circuit is incorporated in this preamplifier. Output 1 and Output
2 are grounded via a relay for approximately 90 seconds after the unit is turned on in
order to suppress warm up transient noises. The relay grounds the outputs again
immediately at turn off or in the event of any power line interruption.
Selector: Use the selector switch to choose an input from Phono, Tuner, Tape 1,
Tape 2 or Auxiliary inputs. The selected source will be available at the source (out)
position of the tape monitor switch and at both Record Outputs. Note that dubbing
between tape decks is possible in both directions. Also, since the selected decks'
output is fed back to its own record input, care must be taken not to select a tape deck
which is in the record mode. Similarly, if one of the tape loops is used for an external
signal processor, that tape loop should never be selected (and, of course, there is no
reason to select it since the external processor is not itself a program source). Failure
to observe these precautions will create an unstable feedback system and may
generate a "howling" sound.
Monitor Switches:Tape monitoring is accomplished via two push-button controls.
The first, labeled Tape 1/Tape 2 selects the tape deck from which you will be
monitoring. The second, labeled Source/Monitor lets you compare the original
program source with the playback from the chosen tape deck. These controls permit
the user to listen to a tape from one deck while recording material from Phono,
Tuner, or Auxiliary inputs on a second tape deck.
Mode: (the setting of this switch does not alter the signal at the record outputs)
Left - Passes the left channel input to both channel outputs
Right - Passes the right channel input to both channel outputs
Stereo - Normal stereo operation
Stereo Reverse -- Passes the left channel input to right channel output and vice
versa
Mono - Passes the sum of left and right inputs to both channel outputs
Balance:Permits continuous control of location of stereo image from left to right. In
the full counterclockwise position only the left channel will be heard. Similarly, the

full clockwise position will reproduce only the right channel. In normal use this
control will be centered.
Volume: The Premier Two volume control is an extremely precise control,
maintaining channel to channel tracking within t 1/2 db throughout its rotation.
Mute:This switch permits the user to manually trigger the relay grounding the
preamps' main outputs after the initial warm up period. This enables the user to
interrupt listening without moving the volume control setting.

TUBES
The audio circuit of the Premier Two uses ten vacuum tubes of four different types;
two 12AX7 (V1 and V2), five 5751 (V3, V4, V6, V7, V8), two 5965 (V5 and V9),
and one 12X4 (V10). Each type has been carefully chosen for its circuit application.
It is well known that tubes of a given type vary sonically depending on the
manufacturer. We have chosen the brands of tubes that we supply based on extensive
auditioning of available brands. The choice of brand has been made solely on the
basis of sonic performance without regard to either cost or prestige. We know of no
vacuum tubes available which will improve the sonic performance of your Premier
Two. Also, the tubes in your preamplifier have been tempered by a controlled burn in
procedure that permits them to perform for a greatly extended period without sonic
degradation. We anticipate two to three years of operation without degradation in
normal use. We highly recommend that, when the time comes to replace the vacuum
tubes, you purchase replacement tube sets from conrad-johnson design.
Please note: The indiscriminate substitution of type 12AX7 tubes for the 5751s will
seriously degrade sonic performance of the unit. Substitution of 12AX7 type for the
type 5965 is likely to damage the 12AX7. Type 12AT7 or ECC81 may be substituted
for the 5965 with only a subtle degradation in performance.

Tube locations:
Tube complement:
V1,V2 12AX7
V3,V4,V6,V7,V8 5751
V5,V9 5965
V10 12X4
Fuse: The AC line is fused to protect the transformer. This fuse will not fail in normal
operation. Failure of the fuse is a symptom of a more serious problem, so the unit
should be taken to a qualified service center. IN NO EVENT SHOULD THE FUSE
BE REPLACED WITH A FUSE OF DIFFERENT TYPE OR RATING THAN
THAT SUPPLIED BY THE FACTORY.
V1 V2
V3 V4
V5 V6
V8 V7
V9
V10

SPECIFICATIONS:
Gain: phono stage 40 db
high level 27 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 t .25db (20-20kHz)
Total hum and noise (20-20kHz):
Phono inputs: 72db below 10mv input
High Level: 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 ¼” x 12 ¼”
Weight: 21 lbs.

SERVICE
In the event your conrad-johnson component requires service, repack it with the
original packing material and ship it to:
Service Department
conrad-johnson design, inc.
2733 Merrilee Drive
Fairfax, VA 22031
For components weighing 90 lbs. or less, we recommend that you ship via United
Parcel Service (UPS). In all cases, be sure to adequately insure your component. Be
sure to enclose a note explaining the problem you are having in as much detail as
possible. If the problem is intermittent please indicate. If you do not have the original
packing material, replacements are available from conrad-johnson design at a
nominal charge. If the unit is under warranty, enclose a copy of your receipt as proof
of purchase.