Conrad-Johnson PV11 User manual

Congratulations on your purchase of the conrad-johnson model PV11
vacuum tube preamplifier. In it, you have acquired one of the finest
pieces of music reproduction equipment available today. It is the result
of more than a decade of research by conrad-johnson design into the
application of vacuum tube devices to the reproduction of recorded
music.
The PV11 was designed to provide audiophiles with a reference quality
preamplifier capable of accurately reproducing the dynamics, tonalities
and textures of a live musical performance. The design and materials
have been carefully selected to yield years of unvarying excellence.
The PV11 is available as a complete phono-preamplifier and control unit
or as the PV11L line stage preamplifier/control unit only.
Please take a few minutes to read this manual so that you will better
understand the features and capabilities of your PV11. NOTE THAT
THE PV11 LINE STAGE IS PHASE INVERTING. See the section
entitled "Getting the most from your PV11" for details on correct hookup
to your system.
PV11 and PV11L Owner’s Manual 1

LIMITED WARRANTY FOR THE conrad-johnson
PV11/PV11L
1. conrad-johnson design, inc. warrants that the conrad-johnson
PV11/PV11L will be free of defects in materials and workmanship for a
period of three years from the date of original purchase.
2. During the warranty period, 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 repair 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. Cartons
are available from the factory for a nominal charge.
d) Normal wear and maintenance are not covered by this warranty.
3.The 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 regis-
tered owner provides the factory with a signed notice giving the new
owner’snameandaddressandthemodelandserialnumberoftheunit.
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 limita-
tions on how long an implied warranty lasts, so the above limitations or
exclusions may not apply to you.
PV11 and PV11L Owner’s Manual 2

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:
Service Department
conrad-johnson design, inc.
2733 Merrilee Drive
Fairfax, VA 22031
REGISTERING THE WARRANTY
Please return the enclosed card to the factory within 30 days of pur-
chasetoregisterthewarranty.Thewarrantymaybetransferredtoanew
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.
PV11 and PV11L Owner’s Manual 3

INSTALLATION
Because of the number and type of vacuum tubes used, the PV11
dissipates a significant amount of heat (approximately 35 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 unobstructed. 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.
To minimize hum pickup, keep the unit well away from the power
amplifier, and route power cords away from input cables.
The PV11 requires an ac power line providing between 108 and 125
volts at 50 to 60 Hz. Alternatively, the PV11 can be reconnected inter-
nally for operation on 220 volt power lines. Consult your dealer for
details about the conversion.
CONNECTION
Aux/ph: On a PV11L, this is an additional line-level input, and is
identical to the other inputs. On a PV11 with phono stage, this input
provides the amplification and equalization required by moving magnet
and high output moving coil cartridges. The phono input impedance is
the industry standard 47,000 ohms shunted by approximately 100 pico-
farads capacitance. This is well suited to nearly all moving magnet and
many high-output moving coil cartridges. If necessary, the input imped-
ance can be lowered by soldering a resistor across (from center pin to
ground) the input jack. To achieve a desired input resistance of RD, use
the following formula to compute the required additional resistance RA:
RA = 47000*RD/(47000-RD)
Some moving magnet cartridges require higher capacitance for opti-
mum performance. Increasing the input capacitance may be achieved
by soldering a suitable value capacitor across the phono input jack. Use
polystyrene capacitors for this purpose.
Tuner, cd, tape 1, tape 2: These are high level inputs and are electri-
cally equivalent. They present a 50k ohm load to the source. The
PV11 and PV11L Owner’s Manual 4

outputs of your tape recorders should be connected to tape 1 and tape
2.
Record output: The two pairs of record outputs connect the selected
signal to your recorders or external processing loop (eg. equalizer). The
output signal is not affected by the level control. Connect "record out" to
the inputs of your tape recorders or external processors.
Output 1, Output 2: Connect this output to the input of your amplifier
(or crossover in a bi-amped system). We recommend the use of an
amplifierwithaninputimpedanceof10kohmsorhigher.SincethePV11
inverts phase, it may be necessary to invert the speaker leads to
maintain correct phase. See the section on "Getting the most out of your
PV11" for an explanation of this.
USE OF EXTERNAL TONE CONTROLS OR OTHER
EXTERNAL SIGNAL PROCESSING DEVICES:
Use Tape 1 and Record 1 for your tape recorder. 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.Thismethod of connectionwillpermit the useoftonecontrols
with tape playback by selecting Tape 1 in conjunction with Monitor 2.
AC OUTLETS
Four AC outlets are provided for your convenience: two, marked un-
switched, 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 pre-
cludes the use of these outlets for high powered amplifiers. It is prefer-
able not to switch power amplifiers by the preamplifier power switch in
any case.
PV11 and PV11L Owner’s Manual 5

CONTROLS
OFF, POWER: Because of the delayed warmup characteristics of vac-
uum tube equipment, a time delay muting circcuit is incorporated in this
preamplifier. Output 1 and output 2 are grounded via a relay for approxi-
mately 90 seconds after the unit is turned on in order to suppress
warm-up transient noises. The relay grounds the outputs again immedi-
ately at turn off or in the event of any power line interruption.
SELECTOR: AUX/PH, TUNER, CD, TAPE 1, TAPE 2. This selector
switch is used to choose an input. The selected source will be available
at the source position of the tape monitor switch and at both record
outputs. Note that each tape deck’s output is fed back to its own record
input - CARE MUST BE TAKEN NOT TO SELECT TAPE 1 OR TAPE 2
WHILE THE TAPE DECK IN QUESTION IS IN RECORD MODE.
Similarly, if tape loop 1 is used for an external signal processor, Tape 1
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.
TAPE 1, TAPE 2, SOURCE, MONITOR. Tape monitoring is accom-
plished via two pushbutton controls. The first, labeled Tape1/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 CD inputs on a second tape deck.
MODE:LEFT, RIGHT, STEREO,REV, MONO.Thesetting of this switch
does not alter the signal at the record outputs except in the mono
position.
Left-Passes the left channel input to both channel outputs.
Right-Passes the right channel input to both channel outputs.
Stereo-Normal stereo operation.
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. This position produces a near mono signal at the record
outputs.
PV11 and PV11L Owner’s Manual 6

BALANCE: This control is an eleven position stepped attenuator, ad-
justing the channel balance in approximately .75 dB steps. The maxi-
mum attenuation is under 4 dB, so both channels will be present even
in the extreme positions. In normal use the control will be centered.
LEVEL: The PV11 volume control is an extremely precise control, main
taining channel to channel accuracy to within 1/2 dB throughout its
rotation.
VACUUM TUBE REPLACEMENT
The audio circuit of the PV11 uses six vacuum tubes of three different
types: two 12AX7 (V1 and V2), one 5751 (V3) and three 12AU7 (V4, V5
and V6). The PV11L uses two type 12AU7 (V5 and V6). 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 we supply based on extensive audi-
tioning of available brands. The choice of brands has been made solely
on the basis of sonic performance without regard for either cost or
prestige. We know of no vacuum tubes available which will improve the
sonic performance of your PV11. 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 with out sonic degrada-
tion. We anticipate two or 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.
Consult the tube location diagram on the next page when replacing
tubes.
Pleasenote:The indiscriminate substitution of type12AX7tubesforthe
5751 will seriously degrade the sonic performance of the unit.
PV11 and PV11L Owner’s Manual 7

PV11 Tube Complement
V1 AND V2 type 12AX7
V3 type 5751
V4 - V6 type 12AU7
NOTE: PV11L uses only tubes V5 and V6
V1 V2
V5 V6
V3
V4
PV11 and PV11L Owner’s Manual 8

GETTING THE MOST FROM YOUR PV11
The conrad-johnson PV11 offers an unparalleled level of sophistication
and refinement in music reproduction, but it cannot transform an inferior
stereo system. Only high quality amplifiers and loudspeaker systems
will be capable of fully revealing the capabilities of this precision instru-
ment.
Given a system of high quality components, there remain a number of
important details which must be attended to.
ABSOLUTE PHASE
Musical notes are heard through the ear’s response to waves of alter-
nating rise and fall of air pressure. Musical transients are exclusively
positive: that is, the initial effect is a rise in pressure. The ear is capable
of distinguishing these positive transients from the musically unnatural
alternative of a negative transient (an initial fall in air pressure). In terms
of your stereo system, these transients are created by your loudspeak-
ers. If the speakers respond to musical transients by first moving out,
they are creating a rise in pressure, and the system is said to be "phase
correct". If they respond by moving in, they create a fall in pressure and
the system is said to be phase inverting. Each component in the stereo
system is either phase correct or phase inverting (including the source
and speakers-these are normally phase correct). It is of no conse-
quence if an individual component is phase inverting, as long as the
system as a whole is phase correct. This will be the case as long as the
number of phase inversions is even (or zero).
THE LINE STAGE OF THE PV11 INVERTS PHASE OF ALL INPUTS
(including phono). If your system has an odd number of inversions, then
youmustaddone phaseinversion. THISIS CONVENIENTLYDONE BY
REVERSING THE POSITIVE AND NEGATIVE CONNECTIONS TO
YOUR SPEAKERS (be sure to reverse both channels).
If you are not sure about the phase of every piece in your system, you
can establish correct absolute phase by careful listening. When the
system is in correct phase, transients will be noticeably cleaner and
more sharply defined. The effect is especially apparent on plucked
string sounds. A final warning-not all recordings are phase correct
PV11 and PV11L Owner’s Manual 9

(including some "audiophile" recordings), so listen to several before
concluding your investigation of absolute phase.
AC LINE POLARITY
Each piece of electronic equipment in your system is subject to minute
ac leakage currents to the chassis. Since the chassis of components in
a system are usually connected via the ground side of the interconnect
wires,theseleakagecurrents aresuper imposedon themusical signals.
It is possible to minimize these current flows by carefully selecting the
way in which each component is plugged into the wall outlet. Because
the power cord on the PV11 is not polarized, it can be plugged in two
ways. It will normally sound better in one orientation than in the other.
The same will be true of any electronic device in your system.
THE IMPORTANCE OF WIRES
Interconnect and speaker wires are an important element in your stereo
system. Interconnects are available which will permit a reference quality
system to blossom and fulfill its promise of musical reality. Others will
strangle the system to the point where it becomes no better than
average. To complicate matters, our experience suggests that the
choiceof interconnects will be system dependent- those that are ranked
first on a given system may be a poor choice for a different system.
Consult your conrad-johnson dealer for recommendations for your spe-
cific system.
TIP
Warm up the PV11 before listening: The sonic performance of the PV11
improvesnoticeablyastheunitwarmsup.Themidrangebecomesmore
lucid, the highs smoother, and the soundstage expands. Most of the
improvement will occur in the first half hour of warm up.
Questions: If you have questions about the installation or function of
your PV11 do not hesitate to call Customer Service at [phone].
PV11 and PV11L Owner’s Manual 10