Hafler DH-160 Operation and maintenance manual

THE
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GRAPHIC EQUALIZER
INSTRUCTIONS
for OPERATION
aNd KIT ASSEMBLY
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5910 Crescent Boulevard, Pennsauken, New Jersey 08109
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WARNING: Tb prevent fire or shock hazard, do not expose this equipment to rain or moisture.
SPECIFICATIONS
(measured with all controls flat)
Equalizer Range: -r12 dB (t0.5 dB) at octave intervals from 32 Hz to 16kHz -r5vo
Level Control: -r8 dB (*0.5 dB)
Maximum Output: 8 volts rms
Frequency Response: fo3ih?L#ffi"rrrarered with 1000 pr
Rise/Fall Time: 2.5 psec to 10 volts peak to peak
Ttrtal Harmonic Distortion: More than 88 dB below 3 volts rms (less than0.004%)
IHF Intermodulation Distortion: More than 90 dB below 8 volts rms 0ess than0.003%)
Input Impedance: 68 Kohms in parallel with 300 pf
Output Impedance: Less than 600 ohms to 25 kHz
Hum and Noise: 115 dB below 8 volts rms with'A weighting
Channel Separation: Greater than 80 Db @ 1 kHz;
Greater than 55 dB @ 20 kHz.
Meter Display Range: -20 dB to +3 dB; 0 dB level adjustable with rear panel level control
Meter Frequency Response: @ 0 dB, 20 Hz to 20 kflz +0, - I dB
Microphone Input Sensitivity: *0, .-0.5 dB from 20Hz to 20 kHz
Microphone Input Sensitivity: 1.8 mV rms for 0 dB meter indication with microphone gain at maximum
Line Monitor Sensitivity: Adjustable, 80 mV to beyond 8 V rms for 0 dB meter indication
CONTENTS
lnstallation ......
Operation
Assembly lnstructions
BuildingtheKit .....:
4
5
7
9
10
14
Overseas AC Line Connections 15
15
16
18
Kit Parts List
Schematic Diagram
Component Values
PC16 Diagrams Service and Warranty 19
Additional lnformation Pictorial Diagram lnsert

INTRODUCTION
An equalizer may be thought of as a very definitive set of
tone controls, enabling you to make selective corrections
or adjustments to the frequency response of your music
system at virtually any point on the scale. The Model 160
raises the performance of such a creative component to a
high art, providing wide versatility with exceptionally low
noise and vanishing distortion. It assures outstanding
freedom from tonal coloration, provides a true "straight
wire" bypass for comparison, and with an optional acces-
sory package, it affords easy setup for its most common
application: improving the overall linearity of the repro-
ducing system.
As an aid to the critical listener, the David Hafler Com-
pany will make available an optional electret microphone
of known response, together with a calibration record of
band-limited pink noise. The microphone plugs into the
back panel of the DH-160. As each band of the record is
played, the front panel LED display meters the sound level
at the microphone, enabling you to make the appropriate
adjustment of the slide control for that frequency to
achieve uniform response. These settings will provide a
semi-permanent indication of the optimum overall (flat)
response at that listening position, taking into account
your phono cartridge, the amplification system, speakers
and room conditions. It is its performance in this most de-
manding of tasks that distinguishes the DH-160 from the
others.
The attentive ear is still one of the most critical
evaluators of system performance, however, and there is
nothing wrong with allowing its reactions to override or
supplant instrument settings. Changes in listening posi-
tion, placement of furniture, or just adding a few guests
can alter the 'standard settings,' to say nothing ofthe vag-
aries of individual recordings.
The goal of a fine music system is to afford pleasure in
listening. Do not be hampered by undue adherence to 'tru-
ly flat' settings. The audiophile's concern with 'locking
out' tone controls stems not from a lack of need for correc-
tion, but from a frustration at their limitations, with con-
sequent error introduction. Any alteration of the signal
demands a very high order of excellence in the design if it is
not to introduce more problems than it cures. Perhaps
even more attention is required than for designs which
achieve the linear accuracy for which all good amplifiers
are noted.
You may be able to enhance your listening pleasure by
employing the DH-160 to improve your system in the fol-
lowing ways:
o Correcting room acoustics by compensating for exces-
sive absorption or reflection at certain frequencies. Par-
ticularly reducing 'boom' in the mid-bass region (64 Hz or
125 Hz), or softening strident highs (4 kHz or 8 kHz).
o Helping to make a fine speaker system even better, by
extending the range of its linear response (often through
some boost of the 32 Hzor 16 kHz sliders, but sometimes a
cut instead); and by smoothing crossover point variations
between drivers.
o As an effective rumble or high frequency filter system, it
will intrude much less on the music than such filters built
into preamplifiers.
. To correct the balance of specific recordings or programs
which have suffered from thoughtless engineering. Older
recordings which mpy not have followed the RIAA stan-
dard playback curve are not the only culprits here. \4rtual-
ly every modern disc is equalized in the recording process,
and the recording engineer's choice may not agree with
your taste. FM broadcasts often suffer from a sense of a
lack of immediacy or 'liveness' which an equalizer can
sometimes help to restore. :
o When transferring records to tape, you can often re-
create much of the original brilliance of older recordings,
and minimize the background or transfer noise levels.
o Live recordings made in locations which are acoustically
less than ideal may be able to be improved.
o Individual instruments or vocalists can be accentuated,
or you can move the apparent source ofthe sound further
away.
o The apparent definition of high frequency transients can
be heightened.
o Shrillness or harshness can be reduced.
o Some of the nasal or boxy characteristics of some
loudspeakers can be minimized.
o Improve the stability of the stereo image.
o In professional inStallations, as for sound reinforcement,
the DH-160 can help to eliminate acoustic feedback and
obtain higher output level.
For an equalizer to be exceptional, it must be designed
for the audio neutrality demanded of the finest
preamplifiers. Then it must be able to make the desired
alterations without reducing headroom, causing shifts of
balance, or adversely affecting imaging. Great care has
been taken in the selection of individual components for
the DH- 160 to preserve its exceptionally low noise and dis-
tortion. In addition, a true center-out detent on each slider
enables you to remove any unneeded circuitry from the
signal path. Since corrections in a fine music system usual-
ly require only small deviations from the center'flat' posi-
tion, the DH-160 provides expanded resolution in this
range for maximum precision.
In combination with other components noted for sonic
accuracy, you should expect atine equalizerto facilitate an
exact reproduction of the input signal. The perfectionist,
who has in the past often found fault with other equalizer
designs, will be especially conscious of the following char-
acteristics of the DH-160:
o The natural quality of the best vocals.
. A sense of 'space' around the instruments in the best
disks.
. Accurate re-creation of the acoustical characteristics of
the original environment.
o Clear, sharp transients, separated by silence from the re-
sidual sounds.
It is in these aspects in particular that we believe you
will find the Hafler Equalizer exemplary as you enjoy its
capabilities.

INSTALLATION
The DH-160 is supplied with accessory Rack Mount end
caps, in addition to the standard end caps installed on the
front panel. These accessory caps extend the width ofthe
front panel to that of a standard 19" rack, with appropriate
mounting holes. Installation instructions are detailed later
in this manual under Additional Information.
POWER CONNECTIONS
As assembled, units are normally wired for 120 VAC,
50160 Hz, as in the USA, unless they are specifically iden-
tified for another voltage on the cafton. Later in this man-
ual you will find diagrams of alternate wiring of the power
transformer to conform to other line voltages.
The power regulation of the DH-160 will provide full
performance with line voltages which may vary substan-
tially from the standard. Units wired for 120 volts, for in-
stance, will work properly with line voltages between 95
and 140 volts.
Accessory AC outlets are provided on the back panel for
the connection of other equipment. These outlets are not
switched by the front panel power switch, but remain 'on'
at all times. If the DH-160's power cord is connected to a
switched outlet on the preamplifier, however, these AC
outlets will also be switched by the preamp power switch.
You must be careful not to overload the switch capacity in
such a case. Note that the maximum safe capacity for
these outlets, determined by the line cord, is 90 watts.
AUDIO CONNECTIONS
Four pairs of audio jacks are provided for signal inputs
and outputs on the back panel. The top row is intended for
the left channel. A separate single input jack is identified
'Mic,' and is for connection of the accessory calibrating
microphone.
EQ Out
This pair ofjacks provides the normal output signal from
the equalizer, and connects to the 'EPL Return' jacks on
the Hafler DH- I l0 preamplifier, or to the 'External Patch
From' jacks on the Hafler DH-101 preamplifier. Other
preamplifiers which do not have a designated input for an
equalizer or other signal processor may utilize the Thpe
Input on the preamplifier which is selected by the Tape
Monitor Switch. Selecting the Tape Monitor switch, or the
EPL switch, includes the equalizer in the signal path.
If you have a receiver which lacks a tape monitor facili-
ty, but includes a 'preamp out-amp in' set of jacks, the
equalizer may connect to them. Then the EQ Out connects
to 'Amp In,' and EQ In connects to 'Preamp Out.' This
connection between the preamp and the amplifier may not
provide the optimum signal to noise ratio of the preferred
Tape Monitor or EPL connection, however.
EQ In
These signal inputs connect to the 'EPL Send'jacks on
the DH-110, or to the 'Ext Patch To' outputs of the DH-
101. Preamplifiers which do not have an external proces-
sor loop separate from the tape monitor loop provide the
equalizer's signal at the Record Output or Thpe Output
jacks.
Thpe I In
A tape recorder which had previously been connected to
the Thpe Monitor loop of the preamplifier now connects to
the equalizer. The Output, or playback from the recorder
connects to the Thpe I In jacks. If your system includes
more than one tape recorder, it will be most useful if the
machine on which you do the most recording is connected
to this input, for the DH-160 enables you to equalize dur-
ing the recording process without changing connections, if
the occasion demands.
Rec Out
Connect the same recorder's Line Input ('High Level'
or'Radio' or'Amplifier') to this high level output from the
equalizer. This is a constant level output, like the tape out-
put on the preamp, so it is not normally affected by level or
tone controls, etc. However, it will be affected by the
equalizer's slide controls if the Record button on the front
panel is pushed in.
Mic
The accessory calibration microphone connects to this
jack, and is employed in conjunction with its test record
for the purpose of establishing slider positions for uniform
response levels.
Microphones other than those supplied by the David
Hafler Company may possibly be used at your risk. The
jack is connected to the internal16.2 VDC power supply
through 11 Kohms, and the DC voltage is used to power
the electret device. The built-in microphone preamplifier
has an input impedance of 10 Kohms.

OPERATION
A red LED below the power switch willbe lighted when
you turn the DH-160 on. The back panel Function Select
slide switch should normally be kept in the Line position.
If it is in the Mic position when the power is turned on, the
front panel LED meter display will briefly be fully illumi-
nated, before settling down to normal operation.
Conventional operation of the equalizer will have only
the Power switch depressed. If it is used in conjunction
with the DH- I l0 preamp, you must depress the EPL but-
ton on the DH- I 10. With most other preamps, or receivers,
where the equalizer has been connected to the Thpe
Monitor loop, it is necessary to engage the Tape Monitor
switch to activate the equalizer. If you are using a Hafler
DH-101 preamplifier, and the DH-160 is connected to the
External Patch connections, the equalizer is always in the
circuit unless its Bypass switch is engaged.
Delayed Thrn-On
An internal muting circuit prevents voltage transients
from causing damage or noise when the equalizer is turned
on or off while the preamp volume control is advanced.
However, it is good practice to turn the preamplifier vol-
ume control down before switching afly component on or
off.
At turn-on, the EQ Out lines are held 30 dB below input
levels for about 3 seconds. Only a faint signal will be
noticed at this time. At turn-off, either by operating the
DH-160 power switch, or by AC line failure, the muting
circuit will instantaneously attenuate the output signal to
prevent injurious transients. Following any power inter-
ruption, the muting circuit will delay full signal at the out-
puts for a few seconds when power is restored.
Monitor Switch
This switch replaces the tape monitor switch on your
preamplifier, if the equalizer has been connected to the
tape monitor loop, and that switch must now be left in the
tape selection mode to operate the equalizer. A tape recor-
derwhich is connected to the Thpe 1 Injacks on the back of
the equalizer will have its playback signal selected when
this switch is depressed. If the recorder has separate re-
cord and playback heads with independent monitoring fa-
cility (known as 3-head decks), this switch enables you to
compare the signal going to the recorder (source) when the
button is out, with the signal played back from the tape a
fraction of a second later. If no recorder is connected, or if
it is turned off, no signal will be heard when this switch
button is in.
Ifthe equalizer is connected through other than the tape
monitor loop (EPL or Patch connections) this facility sim-
ply provides an additional tape monitor loop, with the
added advantage that the recorder connected here can
benefit from the equalization facility during the recording
process, if so desired.
Record Switch
This button makes it possible for the recording en-
thusiast to equalize the signal going to the record head of
the machine, rather than being limited solely to eqtaliza-
tion during playback, without the need to switch cables. It
is traditional that equalization be employed only on
playback, because you are then always working from a
'normal' signal. However, in such cases as when re-
recording a known work, the experienced recordist may
choose to inseft some overall correction with an equalizer.
Then, when it is played back'flat,' it will include the added
tonal correction. Care must be taken, however, not to
overload the recording circuitry or to exceed the tape's
saturation limit, especially at high frequencies, through
excessive boost with the equalizer.
This facility of '.pre-equalization' during recording can
only be employed with the tape recorder which is con-
nected to the back panel of the DH-160. Therefore, if you
have more than one recorder in your system, the one on
which you do the most recording should be the one con-
nected here.
Bypass Switch
A true 'straight wire' bypass of the equalizer is pro-
vided, which eliminates all active circuitry from the signal
path, enabling an accurate comparison between 'equalizer
in' and 'equalizer out' conditions. A separate IED is pro-
vided as a status indicator when in the bypass mode.
Level Controls
On either side of the LED front panel meter are separate
slide controls which provide up to 8 dB of boost or cut in
overall gain for each channel. They are tapered so that ac-
tion is more gradual just offthe center detent, making pre-
cise adjustment easier when comparing signals with and
without the equalizer. Note that the marked graduations
for these controls are different in scale from the rest of the
slide controls.
While some other equalizer designs may introduce dis-
tortion if the gain is not set so that there is uniform output
when switching the equalizer in and out of the system, this
is not a concern with the DH-160. Its unusually high input
acceptance levels, and output capability before distortion
rises, avoids this need for what is called sonic unity gain.
However, logic would suggest that the level controls be at
'0' before adjusting the octave controls, and when equali-
zation has been determined, then the level controls may be
used in conjunction with the bypass switch to set equiva-
lent overall gain.
Octave Controls
The 10 slide controls on the left control the left channel,
and increase the effect as the control is moved upwards
from the center detent, where they arc out of the circuit, or
'flat.' The response is reduced, or cut, below center. The
designations above each slide control indicate the center
frequency of the band affected by that adjustment. As the
control is moved from center, the bandwidth affected
broadens so that there is some overlapping of response
with the next octaves. The action of these controls is much
more gradual close to the center detent, with the first
graduation designated as 1 dB, and the second as 4 dB.
This enables more precise adjustment in the area where it
is most likely needed. At the extremes, 12 dB of boost or
cut is available.
Do not position all the slide controls at full boost in an
attempt to obtain l2 dB of additional gain-to compensate
for a phono cartridge with low output, for instance. In their
extreme positions, the overall frequency response is not
flat, but rather scalloped shaped with a peak at each oc-
tave's center frequency.

LED Meter
The front panel LED metering system provides l0 in-
crements from -20 dB to +3 dB. The red LEDs simply
indicate operation above the 0 dB level as set by the back
panel level control. Their illumination is r?o, an indication
of clipping. Tb make optimum use of the dynamic range of
the display, use the meter gain control to set the level so
that peaks occasionally light the +2 dB indicator, but not
the topmost one.
In the 'Line' position of the slide switch on the back
panel, the meter monitors the sum of the left and right
channel signals at the 'EQ Out' jacks, representing aver-
age program levels. In the 'Mic' switch position, the meter
monitors the output of the internal microphone
preamplifier. When the 'Bypass' switch is depressed the
meter will not provide any level indication, as all circuitry
is switched out of the signal path.
The meter gain control is actually two independent con-
trol sections on a common shaft. It may therefore be nec-
essary to readjust the gain control when switching from
program monitoring (Line) to the 'Mic' position.
Getting the Most from the Controls
To become familiar with the effect of each frequency
range on the sound, begin by using a wide range program
source, and set all the slide controls at their zero center.
You may find that the changes will be easier to hear if only
one channel is operated. Just put yourprcamp in the Mono
mode (so you will combine the channels, and thus not miss
part of the music) and turn the Balance control fully to one
side. Perhaps you will note that the same program does not
really sound the same from the left and right speakers,
played separately. One of the reasons good equalizers pro-
vide independent controls for each channel is to enable
you to overcome such disparities.
Speaking of tone controls, take the time to compare the
effects of even a well-designed tone c.ontrol circuit on your
preamplifier with the equalizer's real sense of control. If
your preamplifier provides a switch for disabling, or de-
feating its tone control circuit, you'll probably switch them
out of the signal path for good. If not, put them in the 'flat'
position, and make it a point to check them occasionally, to
see that they have not been inadvertently engaged. Tone
controls and the corrections of octave controls are
cumulative-they do not complement one another-and
you might try to push excessive amounts of power into the
speakers without realizing it (especially at the extremes, if
the program material was not so wide-range as to make it
obvious) if both systems provided boost. A few dB of
boost on a slide control, and a few more from an advanced
treble control might drive a tweeter very hard. This might
not be so evident in casual listening if an adjacent slide
control was reduced, for instance. Ten dB of boost de-
mands that the amplifier deliver 10 times its normal 'flat'
power output at that frequency, and if it 'clips' because of
excessive demand, that puts an even greater strain on a
tweeter. Woofers can take more punishment than tweet-
ers, as a rule, and we are also inclined to notice bass over-
load effects more quickly. Sometimes it's as obvious as a
flapping grille cloth.
While it is easy to hear the effect of an octave control
that has been fully advanced, you should learn to recog-
nize the effect of small changes in each slider. The ear is a
6
remarkably critical evaluation device, but it sometimes
needs training. It can perceive relative changes in level,
response and balance, but it is not good at measuringcb.so-
/are sound pressure levels. The ear can complement the
measuring capability of the DH-160 and its microphone,
and, in the final q.nalysis, you should let your ear be the
judge. You will find that unless you wish to deliberately
create an effect which did not occur in the original record-
ing, the octave controls will rarely be set beyond the 4 dB
markings, except when used as a filter. One or two dB cor-
rections will be the norm.
Following are some general observations which may
help you to effectively use this new tool for more realistic
sound.
32Hz
This control may be the most used if your speakers are
capable of truly effective deep bass response. Even the
best speakers fall offnoticeably in this last octave because
of normal room and placement limitations, but if they can
handle the increased power, a 2 to 4 dB boost will add
marked realism. If this introduces boom, or definition is
lost, you may have a problem with acoustic feedback. In
that case, try isolating the turntable from the speakers, but
if necessary, back offon the boost, since definition is more
important to accuracy. Very few speakers will have the re-
serve to accomodate more than a few dB of boost this low,
and your amplifier may also reach its output limit, which
will then produce sharply higher distortion. Remember,
each 3 dB of boost doubles the required amplifier power.
If background noise or rumble intrudes, cutting this
slider back may noticeably improve the clairty of the
music. A lot of programming has very little useful informa-
tion in this region. If very high sound levels are desired,
cutting this octave off may avoid needless amplifier over-
load from extraneous subsonic noise. For maximum filter-
ing with the least disturbance to the music, you may want
to couple a sharp ct;i"at32 Hz with aVzdB or l dB boost at
64 Hz.
64 and 125 Hz
It is not uncommon for woofers to show a rise in this
'apparent bass' region, because this is where they reso-
nate. Systems with multiple woofers are more prone to ex-
cessive output near resonance. Start by cutting only the 64
Hz control; then try just the 125; then a combination. One
dB or so may be all that is needed.
250 and 500 Hz
A dB or two change in this range may have a decided
effect on the character of instruments such as the cello or
trombone. This is the range where many speakers have
their crossovers from one driver to the other. It is also
where the size and shape of the listening room may have its
greatest effect on the sound.
lk and 2kHz
This range most affects vocal quality. Some speaker sys-
tems have crossovers between drivers around lkHz. Tty
adjusting these controls separately for each channel with a
monophonic source, because so much energy is projected
in this region.
4kHz
This will likely be the second most used control in your
system, for it controls the 'presence' range, where the ear

is most sensitive. This is also the part of the spectrum most
affected by room furnishings, the number of people, and
sometimes by speaker positioning. This control can cause
a soloist to move closer, or to recede. This slider, too, is
best adjusted for each channel separately using a mono
source.
8k and l6k Hz
The 8k control affects most of the obvious 'high end',
and if you have excessively noisy material, it, as well as
the l6k slideq must be cut for effective filtering. Boosting
the l6k control will put more edge on transients, without
the obvious harshness which a boost one octave lower
might introduce. Three or four dB boost at the top might
restore the natural rolloffof many tweeters, but you might
want to combine that.with a small amount of reduction at
8k Hz. Conversely, if you have a problem with RF interfer-
ence, or noise, a sharp l6k rolloffmight best be combined
with a small boost at 8k to avoid reducing the significant
high frequencies in the program material any more than
necessary.
K!T ASSEMBLY INSTRUCTIO NS
There are three basic rules for success in electronic kit
building:
1. Read the instructions carefully, and follow them in or-
der.
2. Make secure solder connections which are bright and
smooth.
3. Check your work carefully after each step.
The DH-160 Equalizer is a versatile component with
sophisticated circuitry which has been made remarkably
easy to build by individuals with many years of experience
in the design and engineering of the finest performing
audio kits, and in the preparation of their manuals.
Kit building should be fun, and we are certain you will
find this to be so. Fatigue increases the risk of error, so
take a break rather than push to early completion. There
are relatively few separate components in this design, to
make it easy to pack everything away, if need be.
Yourwork area should have good lighting and the proper
tools. The tools should include:
1. A 40 to 60 watt pencil soldering iron with a 3116" or
smaller tip which reaches 700'E
2. 601 40 (60% tin) ROSIN CORE solder, 1/16" diameter or
smaller.
3. A damp sponge orcloth to wipe the hottip ofthe iron.
4. A wire stripping tool for removing insulation. This can
be asingle-edge razor blade, but inexpensive stripping
tools are safer, faster and easier.
5. A medium-blade screwdriver (about ll4" wide).
6. Needle-nose pliers (a long, narrow tip).
7. Diagonal or side-cutting small pliers.
8. Large "gas" or "slip-joint" pliers.
9. A #l Phillips head screwdriver.
10. All4" "Spin-tite" nut driver may be helpful, but is not
necessary.
A soldering "gun" is rol recommended. The unfamiliar
user is more likely to damage the etched circuit boards
with its higher heat potential and unbalanced weight. Also,
because he may not wait long enough for it to reach operat-
ing temperature each time it is switched on, poor solder
connections are more likely. Pencil irons are much lighter
and easier to use, and there is no waiting time when solder
connections follow in sequence, as in kit building. Make
sure you have a holder for it, though, and always unplug it
when you take a break.
Proper Soldering
There are four steps to make a good solder connection:
l. Make a good mechanical connection to hold the wire in
position while heat and solder is applied.
2. Heat the junction of the wire and lug, or connecting
hole, with the bright, shiny tip of the iron.
3. After heating for a couple of seconds, apply solder to
the junction. It should melt immediately and flow
smoothly around both surfaces.
4. Allow the connection to cool undisturbed.
Remember that the connection is made by the soldet
not by mechanically attaching the wire to the terminal.
Usually the wire is looped through the lug and crimped in
place, but some prefer to just place it through the hole and
rely on the stiffness of the wire to hold it while soldering.
Circuit board connections, of course, are handled this way.
Good solder connections are essentiol for trouble-free.
noise-free operation. A good solder joint does not require
much solder around the conductors. Never "butter" par-
tially melted solder on the joint, as it is useless. A good
connection looks smooth and bright because the solder
flows into every crevice when the parts are hot enough.
The iron must have a bright, shiny tip to transfer heat easi-
ly to the junction. That's why the damp sponge should be
used frequently to wipe the tip, and occasionally you must
add a small amount of solder to the tip, too. If a connection
is difficult to heat, "wet" the tip with a small blob of solder
to provide a bigger contact surface to the joint. Once the

solder flows around the conductors, any movement must
be avoided for a few seconds to allow a good bond. When
cool, check the connection by wiggling the wire. If in
doubt, or ifthe connection is not shiny, re-heat the joint.
Excess solder may be removed from a connection by heat-
ing it and allowing the solderto flow onto the iron, which is
then wiped on the sponge.
ALL SOLDER USED MUST BE ROSIN CORE
Never use acid core solder or any separate flux in elec-
tronic work. Silver solder is also not suitable. If in doubt
about unmarked solder, always obtain a fresh supply of
rosin core solder. We recommend 60/40 for easiest use. Do
not confuse it with 40/60, which is harder to melt.
The general procedure is to use a hot iron for a short time
to heat a connection, then add solder with the iron still in
eontact. Remove the solder once it flows, and then nemove
the iron. A cooler iron applied for a longer time is more
likely to damage components, or lift the copper circuit pat-
tern from the boards. A break in the etched circuit can be
mended by simply soldering a small piece of wire across it.
Do not allow much build-up of solder on the tip of the iron,
or it may fall onto adjacent circuitry and cause a short cir-
cuit.
When soldering to a hole on the board, insert the wire
and apply the iron, leaving some bare wire exposed so that
you can see that the hole is then filled with solder for a
secure bond. A round wooden toothpick is suggested so
that you can heat and clear the hole of solder if it hinders
your inserling the wire. If the wire has first been "tinned,"
usually no additional solder is necessary, but it is a good
practice to push the wire through, and then back it up a bit,
to be sure solder fills the hole. On the bottom of the board,
make certain a bright, shiny flow is evident from the wire
onto the circuit pattern on the board.
"Tinning" refers to the process of applying a light coat-
ing of solder to the bared wire end. This keeps all the
strands secured, and also makes a good connection easier.
Simply touch the wire with the iron for a couple seconds,
and apply solder. Allow the excess to flow away onto the
iron. When properly done, the wire is uniformly bright,
and no larger than before. The hookup wire supplied with
this kit does not normally need tinning, for it is pre-tinned.
Wlrlng th€ Klt
If any components are unfamiliar to you, checking thc
pictorial diagrarn should quickly identify them. Or, the
quantities, and the process of elimination as you check the
parts list, will help. The pictorial diagram is necessarily
distorted to some extent for clarity, so that you can trace
every wire in a single overall view for verification as you
work.
To "prepare" a wire means to cut the designated length
from the length ofthat color, and strip about U4" ofinsula-
tion from each end. The wire supplied in the kit is #22, so
you can set adjustable wire-strippers accordingly. The
transformer leads are #22, and the line cord is #18. Be
careful that you do not nick the wire when you strip it (that
can happen more easily if you do not use wire strippers) for
that weakens it. The wire supplied in this kit is "bonded
stranded," which provides exceptional flexibility with re-
sistance to breakage for easier use.
Whenever a connection is to be soldered, the instruc-
tions will so state, or indicate by the symbol (S). If more
than one wire is to be soldered to the same point, they will
be indicated by (S-2), (S-3), etc. If soldering is not called
for, other connections have yet to be made to that termi-
nal. They would be more diffrcult if the connection was
already soldered. Every connection in the kit will be sol-
dered when it is complete. After soldering a connection, it
is best to clip off any excess lead length to minimize the
possibility of a short circuit, and for neatness.
Be sure that uninsulated wires cannot touch adjacent
terminals or the chassis metalwork.
When the instructions call for twisting two or three
wires together, the length of wire indicated anticipates a
fairly tight, uniform twist by hand, of three full turns every
two inches. If you find the wires too short, loosening the
twist will gain some needed length.
Take the time to be accurate and neat, and you can be
sure that your completed preamplifier will meet the per-
formance of a factory assembled unit, and can continue to
perform properly for years to come. Check your work, and
make sure the entire step has been completed before plac-
ing a check mark in the space provided, and continuing on
to the next step.

BUILDING THE KIT
When you unpack your kit, you will find that it appears
to be largely assembled, because this is the best way to
protect.major components in shipment. Partial disassem-
bly will be necessary as you proceed to completion, and
will be indicated in the instructions. The count of hardware
in the parts list in the back of this manual does not include
those items already installed as part bf the assembly. We
recommend that you check offall the components against
the parts list as you unpack the kit, to make sure that you
have everything, and to enable you to identify any unfamil-
iar items by comparing the quantities involved. An egg
carton is ideal for keeping hardware items separated.
You will also find that most of the wiring in this kit has
been completed, because all of the front panel slide con-
trols have been connected. This was the only practical way
for us to verify the performance of each control, and thus
provide_a full checkout of the equalizer's active circuitry.
t ffiisengage the back panel from the side pieces which
are to be left attached to the main circuit board as-
sembly. There is no need to remove the powertrans-
former. Set the back panel aside.
2 ffselect the main circuit board assembly with the at-
tached front panel. Install the small Phillips head
screws to secure all of the slide controls at the top
and bottom. Make sure the existing scrcws are all
tieht.
3 ffinset the 3 rubber grommets in the rear bracket
which supports the circuit board.
4 CSebct the LED meter module, two metal spacers,
two 5/8" #4 screws and nuts, and the two small fiber
washers. Slide the washers onto the screwsllirst,
then the circuit side of the LED module, followed by
the spacers. Tighten the spacers, and mount the as-
sembly on the front panel with the plug pins project-
ing through the hole. Be sure the mounting nuts are
tight. The threaded spacer makes it impractical to
tighten these with a screwdriver.
S fisinethe large L-shaped Allen wrench, loosen the
bolt which secures the front panel to the right side
piece, near the switches. Now remove the sheet
metal screw which secures the rear circuit board
bsacket, and disengage the side piece.
6 y'Remove the screw and nylon spacer securing the
switch end of the circuit board to the front panel.
This will allow the end of the board to project
through the front panel when the assembly is stood
upright on its back corner and left side, with the slide
cy'ntrols uppermost.
7 fiebctthe two red LEDs. Note that there is a flat on
the red body adjacent to one lead. This flat must be
towards the right edge of the board when the LEDs
are mounted from the top side of the board in the
pairs of holes at the front edge, just below each
switch. The lead length from the back of the red plas-
tic to a right angle bend should be exactly ll2 inch.
When the flat is toward you, and the leads project to
the right, bend the leads downward. Install these on
the top surfacc of the board with the leads flush
against the board. Solder both leads of each LED on
the bottom of the boad and cut offall the excess.
8 ffielect the two ll2" piecesof heat-shrink plastic tub-
ing. Their purpose is to obscure stray illumination
from the back of the LEDs. Slip one over each LED
so that the front edge is even with the front surface of
the thick body, allowing just the tip to project. Light
a match about ll2" below the tubing, and it will
shrink into position. Be careful the match does not
d4mage the switch assemblies.
9 fielecttwo of the 3/8" screws, and two nylon spacers,
and secure the switch assembly to the front panel.
The spacers go between the panel and the switch
mounting bracket.
10 [ Select the remaining two switch mounting screws
and the nylon spacers, and the PC-18 circuit board.
Check to make sure that the 6 upright pins beside the
switches on the main board are straight, so that they
will properly engage the 6 sockets on the underside
of PC-18. Mount the PC-18 to the front panel with
the spacers behind the panel. Check again to make
sure all 6 pins are engaged. Set this assembly aside
te_pporarily.
1l Efselect the back panel, the AC line cord, and the plas-
tic strain relief. Seven inches from the cut end of the
line cord, make a sharp "V" in the cord by bending it
sharply back on itself. Install the strain relief as
shown, with the small end of the strain relief nearest

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the cut end of the line cord. Crimp the two halves of
the strain relief around the cord at the "V" with
heavy pliers, to partially form it before insertion into
the back panel. Then grip the larger portion of the
strain relief with the tips of the pliers, squeeze it
tightly, and insert the end of the cord and the relief
through the back panel hole AC from the outside.
Note that the hole is shaped to engage flat sides of
the strain relief to keep it from twisting. It snaps into
position when fully inserted.
0 fiebctthe two AC outlets, and snap them into the
holes PS from the outside ofthe panel.
l3 ffielect the control potentiometer, the large washer
and nut, and install the control at location MG on the
inside of the back panel, with the washer under the
nut On the outside of the panel. The control's locat-
ing lug engages the small panel hole.
ru {selectthe slide switch and the 2 small Phillips head
screws. Install the switch at location MS. Nuts are
not required.
s 6t""tthe four #4 screws which are
5l8"long, the 4
separate lockwashers, and the 4 metal spacers. In-
stall the screws from the outside at the center of the
panel, and place a lockwasher on each screw before
the spacer is installed. It is important that the spacer
located nearest the control MG be tight, as the
lockwasher must provide a good ground connection
to the chassis, cutting through the paint.
16 #elect the PC-17 circuit board, and the 11,000 ohm
resistor (brown, brown, black, red, brown). The in-
side of this circuit board is the side which will be
towards'the back panel when installed, and it has
very little nomenclature printed on it. Install the re-
sistor on the inside at R45. Solder both leads on the
outside, and cut offthe excess leads.
l7 ffselect the 1 mfd capacitor, and note that the positive
( +) lead is longer than the other. The + connection is
marked on the board at C30. Allow enough lead
length so that the capacitor can be laid on its side
towards the row of holes P9, and install it on the ir-
side of the board. Solder both leads on the outside,
and remove the excess.
ft fielect the l0 pin right angle plug. Install it on the
inside of the board at P9 so that the bent pins point
toward the top edge of the board. Be sure the socket
is tight against the board, and that every pin is sol-
dered on the outside.
D ffineproper wty to install the 9 phono input sockets
on the inside (the same side as the previous parts) of
PC17 is to first insert a phono plug (on the end of one
of the audio connecting cables supplied with the kit)
so that the center contact of the socket will not be
deformed in the mounting process. Install each soc-
ket so that the center m6unting tab is adjacent to the
widest part of the circuitry ontheoutside (soldering)
side of the board. Leave the phono plug in the socket
while bending and soldering of the tab is completed.
If you do not bend the center tab quite flat against
the board, it is easier for solder to flow under the tab
for a good connection. Solder both outer socket lugs
first. Thev do not need to be bent over.
ZO &l"rttt " tong flat cable interconnecting assembly.
Plug one end ofthe cable onto the pin plug at the top
of the board so that the cable extends over the top
edge. Select the four #4 nuts, and fasten the PC17
assembly to the back panel, with the cable project-
ing from the top.
2l l*{eparate the two ends of the AC line cord for 2",'and
strip I - 1/4" of in sulation from each. Tlvist the strands
of each conductor tightly together, and "tin" them
with solder. TWist PS lugs 3 and 4 90'. Pass one bared
lead through PS lug #3 and connect it to PS htg #1.
(S). Pass the other bared conductor through PS lug
#4 and connect it to PS hte #2. (S). Be sure all
strands are securely soldered.
22 frPrepare two l l"green wires, and twist them together
throughout their length. Connect one end of one
wire to PS lug #4. (S-2). Connect the corresponding
errd of the other wire to PS lug #3. (S-2).
Zl {W"pure a l-314" black wire, but strip 3/8" of insula-
tion from one end. Pass the longer bared end through
MS lug #6, andconnect it to MS ltg #3. Solder both
lugs. Connect the other end of the wire to MG lug
#l. (S). Lugs 1, ?and3 on the control anj nearest the
Banel.
Zq {Prepare a9-112" red wire andag-ll2"black wire, and
twist these together thoughout their length. Connect
one end of the black wire to MG lug #2. (S). Connect
the corresponding end of the red wire to MG lug #3.
(S). Check very carefully to make sure that none of
these wires can touch the back panel or the body of
f control, but only its proper lug.
25 [Preparea9-112" redwire andag-112" greenwire, but
strip 3/8" of insulation from one end of each wire.
Starting with the two longer bared ends together,
twist these wires throughout their length. Pass the
longer bared end of the green wire through MS lug
#5, and connect it to MS lq #2. Solder both lugs.
Pass the red wire through MS lug #4, and connect it
to MS lug #1. Solder both lugs.
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Ze .dWe.pary led, black and green wires, eachT-ll2,,long.
T\vist this group of wires together throughout their
Iength. At one end, separate the red wire for the last
inch. Connect the red wire to hole #4on pC-17. (S).
Connect the green wire to MG lug #6. Connect the
,9Jack wire to MG lug #5. (S).
27 @ Prepare a 2" Iength of green wire, and a 2,, length of
black wire. Connect one end of the green wire to MG
lug #6. (S-2). Connect one end of the black wire to
MG lug #4. (S). Tlvist these two wires together, and
connect the green wire to hole #3 on pC-17. (S).
Connect the black wire to hole #2. (S).
28 frelect two #6screws and nuts, and place the back
panel assembly in its approximate pbsition behind
the main circuit board assembly. Ttvilt togetherthe 3
red transformer leads and thread them through the
adjacent grommet in the circuit board rear bricket,
and insert the twisted groups of wires through the i
grommets at the otherend of the bracket. Attach the
back panel to the left side piece, but do not install the
right side piece at this time.
29 ffiebct the green pair of twisted wires from the AC
outlets PS, and connect one wire to hole Z behind
the switch at the front of the circuit board. (S). Con_
nect the other green wire to hole V, alongside the
switch. (S). Do not confuse it with the hole marked
"Y", which is towards the inside.
30 delect the right side piece with its large Allen head
bolt, two #6 screws and nuts, and a sheet metal
screw. Fasten the side piece inside the rear circuit
board bracket and to the back panel, and temporari_
ly secure the front panel to it.
^ The-following connections describe appropriate wiring
for 120 volts AC power lines, as are found in ttre Unitei
States. Alternative connections to utilize other supply
voltages will be found elsewhere in this manual. Tr;d
former leads may be shortened for a neat appearance, but
in the event a different line voltage may be employed in the
future, be sure you do not cut any leadi too short for such a
change.
. For a neat appearance, we suggest twisting the 3 brown
leads together, and twisting the j black leadi together.
3l fu{onnect the brown/white lead to hole D, alongside
the fuse clip. (S). Connect the brown/red lead to hole
E (S). Connect the brown lead to hole R. (S). Con_
nect the black/white lead to hole E. (S). Connect the
black/red lead to hole M. (S). Connect the black lead
to hole S. (S).
y W{ne 3 red transformer leads are wired the same for
all voltages. They too may be shortened for a neat
appearance if you choose. The designation of the
connecting holes for these leads is marked on the top
surface of the main circuit board at the center rear.
The leads connect to the underside. The red/yellow
lead connects to one of the two holes markeO ..a".
(S). One red lead connects to hole ,,B". (S). The
other red lead connects to hole .,C,'. (S).
T ffilectthe red/black/green triad of wires through the
grommet. Connect the red wire to hole U. (S). Con_
nect the black wire to hole L. (S). Connect the green
wire to hole I. (S). Make sure you do not confuse
\b t *;tn hole L.
34 ffselect the red and black pairof wires. Connect the
black wire to hole O. (S). Be sure you do not confuse
hole Q with hole O. Connect the red wire to hole p.
(s).
y ffilectthe red and green pair of wires, and connect
the red wire to hole N. (S). Connect the green wire to
hole Q. (S). This completes the need for a soldering
iron in the construction.
36 #elect a sheet metal screw and secure the small
angle bracket at the left front of the main circuit
board to the left side piece. The screw is installed
from the outside of the side piece.
37 W{electthe short interconnecting cable assembly and
connect it between the LED meter assembly on the
front panel, and the plug in the center of tire main
circuit board. The top pin on the meter unit should
connect to the front pin on the circuit board. Thus
the cable should exit from the meter plug toward the
right, against the adjacent slide contiol. Be sure this
cable is installed correctly. Reversing the connec_
tions will blow out the meter assembly, requiring its
replacement at your expense.
38 dect to be sure the six wire connecting cable on the
main circuit board is firmly plugged in on each end,
and that all 6 pins are engaged.
9 W{ry.in the long cable assembly from the back panel
to the plug on the top switch circuit board. The front
pin on the switch board corresponds to the #l pin on
the rear panel board, which ls nearest the iower
transformer. Make a right angle fold in the cable.
+O ffiectthe grey finish front plate, two strips of dou-
ble sided tape, and the plastic meter face. We
suggest removingjust the brown backing, and apply_
ing the double sided tape to the insidJof tne iiont
plate first, with the white backing still attached.
These strips should be placed along each edge of the
large center opening. To make it easier to tift tne
white backing after the tape is installed on the metal,
press it firmly to the metal at the corners so they will
adhere when you lift the corner of the backing. Then
remove the white backing. Make sure that the meter
face is correctly oriented, and press it into position
from the inside.
4l ffi Select the remaining strips of double sided tape, and
the two felt perforated strips. These strips will be
applied to the inside of the front plate to improve the
appearance of the slide control openings. Note that
at one end of each felt strip, the first two slits are
spaced farther apart than the rest. These slits are to
be placed adjacent to the meter opening in the cen_
ter. We believe it is easiest to install all the strips
l3

first, leaving the white backing in place. The dia-
gram shows suggested placement of the tapes, at
every-other-slot intervals. Then lift and fold back a
corner on each of the white backings. A business
card, or a similar 2" width of light cardboard slipped
through each slit in the felt in turn, makes it easy to
centerthem accurately on the slots in the front plate
as the white tape backing is removed and the felt
presSed firmly in position.
qZ 6ecta pair of end caps (either the standard ones, or
those for rack mounting), the front plate, and the
two remaining cap screws and nuts. The end caps fit
into slots at the ends of the front plate. Remove the
two temporary cap screws holding the front panel,
and install the front plate, being careful to position
the 2 LEDs through the small holes in the plate.
Align the assembly, making sure that the switch
shafts are centered, and tighten the cap screws.
$ Edelectthe 4 buttons and the knob. Press the buttons
r onto the switch shafts, and install the knob on the
back panel meter gain control shaft so that the index
aligns with the marked limits on the panel when it is
rotated fully.
/'
44 EKelect the 22 slider buttons and install them on the
shafts. They are designed fora simple press fit, but if
you find one that is loose, a bit of almost any adhe-
sive will secure the button.
U ffihreeplastic wire ties are included with the kit so
that you can bundle the transformer leads, line cord,
etc. for a neat appearance. These ties can be used
only once, and lock securely when the tail is pushed
through the head end from the flat side. Cut offthe
exce-ss after pulling it tight.
,/
46 Wfiake sure that the fuse is installed on the circuit
board, and that all connections are soldered. Check
particularly that no strands of the line cord or the
transformer leads are unsoldered.
ql Qdt6 sheet metal screws, install the bottom plate.
$ fficethe 4 rubber feet in the corners of the bottom
plate. They are self adhesive when you remove the
baqking.
qg W4ia"one piece of the long U-shaped plastic grom-
met onto the upper front panel flange. The other
piece slips over the rear panel flange.
SO gfSUae the cover on from the rear, and fasten it with
the 4 sheet metal screws. Affix the self adhesive se-
rial number label to the bottom.
ADDITIONAL IN FORMATION
Rack Mounting
To accommodate standard l9" mounting racks, a separate
pair of end caps is included which replace those presently
installed. To make the change, first remove all power and
signal connections to the DH-160. Place the unit upside
down on a soft protective surface, and remove the two
cover screws on each side of the bottom. Slide the cover
back. Wth the large L-Shaped Allen wrench supplied, re-
move the screws in each corner of the front panel. The end
caps slide outward. If you are careful, you will not dislodge
the LEDs from the front panel. Replace the cap screws and
nuts just finger tight at flrrst. Check the alignment of the
panel before tightening them fully. Then replace and secure
the cover.
Slide Control Care
Much time was spent in the design of the DH-160 evaluat-
ing the quality of component parts to assure long term reli-
ability, freedom from noise, and sonic accuracy. The con-
trol choices were particularly scrutinized, since there can
be substantial differences between apparently similar con-
figurations. Used thoughtfully and deliberately, these
superior quality slide controls should last the life of the
product. Do not use any cleaning chemicals on these slid-
ers, as the lubricant may be worked away, destroying their
smooth action.
Minimizing System Noise
Careful interwiring practice helps to ensure that RFI (radio
frequency interference) and ground loop hum is kept to a
minimum. It pays to use high quality interconnecting ca-
bles with good shielding. Never remove a cable by pulling
on the wire-grasp it at the connector body. Special con-
nector platings are of secondary importance to clean con-
nector surfaces, free of contamination. Make sure the
ground tabs of phono pin plugs grip the socket tightly.
Reversing line cord plugs one at a time, listening to the
hum level after each reversal, will minimize the likelihood
of hum. Signal cables should not run parallel to AC line
cords-they should be kept separated, insofar as practi-
cal. It is good practice to bundle excess length of individu-
al signal cables, and secure them with a twist tie or rubber
band. This makes the installation neat, and lessens the
chance of noise pickup.
It does not usually reduce noise to connect the entire sys-,
tem to an'earth' ground. In some instances, this may even
aggravate a ground loop problem by providing an addition-
al ground path.
Caution: Do not indiscriminately connect or disconnect
any cables in the system without first turning off
the power amplifier.
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ALL SWITCHES SHOWN IN THE NON-DEPRESSED STATE FYNTNT S'
PC-18 PC-16
RIGHT
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EOUALIZEF IN
TAPE IN
TAPE OUT
LEFT
EQUALIZER OUT
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TAPE OUT
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NOTE : LEFT CHANNEL ELECTRONTCS NOT SHOWN
ADD 1OO TO RIGHT CHANNEL DESIGNATOR
EXCEPT PC CONNECTIONS
f eoslrrve powER suppLy
$ Hecnrrve powER supply
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LEFT SHIELD GROUND
BIGHT SHIELO GROUND
METER CIRCUIT GROUND
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POWEB TRANSFORMER WIRING
PRIMARY VOLTS 100 't20 220 240
BR/W FDFD
BR /R DFDF
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BK/R EMMM
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FUSE lug eire 1/19 AMe @COPYRIGHT 1982, ALL BIGHTS RESERVED
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EQUALIZER AMP

COMPONENT VALUES
Rlght channel correspondlng yaluea have designatlons above 100.
All resistors arc th wall l % metal film unless otheMise noted. All capacitors are film, minimum 50 volls, unless otheMise noted
B 1 1 megohms
R2 4,&0 ohms
R 3 68,100 ohms
R 4 6,810 ohms
R 5 68,100 ohms
R 6 1,000 ohms
R 7 1,000 ohms
R I 3,320 ohms
R 9 3,320 ohms
R 10 562 ohms
R 11 100,000 ohms
R 12 4,640 ohms
R 13 562 ohms
R 14 392 ohms
R 15 68,100 ohms
R 16 475 ohms
R 17 68,100 ohms
R 18 475 ohms
H 19 61,900 ohms
R 20 475 ohms
R21 68,100 ohms
R22 475 ohms
R 23 61,900 ohms
R24 475 ohms
R 25 68,100 ohms
R 26 475 ohms
R27 68,100 ohms
R 28 475 ohms
R 29 61,900 ohms
R 30 475 ohms
R 31 68,100 ohms
R 32 392 ohms
R 33 61,900 ohms
R34to
A 44 20,000 ohms slide potentiometer
R 45 11,000 ohms
R 46 100,000 ohms potentiometer
R47 100,000ohms
R 48 475 ohms
R 49 100,000 ohms
R 50 100,000 ohms potentiometer
R 51 475 ohms
R 52 22,100 ohms
R 53 22,100 ohms
R 54 22,100 ohms
R 55 22,100 ohms
R 56 22,100 ohms
R 57 1 1,000 ohms
R 58 100,000 ohms
R59 100ohms,1/2w,51"catbon
R 60 1,000 ohms
R 61 2,700 ohms, l/qw,S"/"carbon
R 62 10 megohms, Ya w, 57o cabon
R 63 470,000 ohms, 1/4 w, 51" catfun
R 64 470,000 ohms, Y4 w, 57o carbon
R65 39,000ohms, 1/4w,5"kcatbon
H66 10,000ohms, 1/4w,sY"catbon
R 68 220,000 ohms, l/a w, 5o/o carbon
R 69 47,000 ohms, Y4 w, 57o carbon
R 70 4,700 ohms, 1/4 w, 5"k catbon
R71 47,000 ohms, 1/4 w, s"/ocarhn
R72 10 megohms, Y4w,5locarbpn
R 73 4,700 ohms, % w, 57o carbon
R74 1,800 ohms, l/qw,So/"catbon
R 75 1,000 ohms, l/a w, So/ocarlton
R 76 1,000 ohms, Y4w,s"/"catbon
' R77 270 ohms, thw,sl"cabon
R 78 270 ohms, l/q w, 5o/o cdtbon
R 79 '1,800 ohms, Y4 w, 57o carbon
F 1 Fuse, 1/8 amp Slo-Blo, AGC
M 1 Meter assembly NSM39169
Q 1 J112 JFET transistor
31, 54 Power/Bypass swrtch assembly
52, 53 SPDT-4PDT swnch assembly
Ss DPDT slid€ switch
T 1 Transformer, Power
C 1 330 pF, 3%
C 2 1.5 mfd, 5%
C 3 150 pF,3%
C5 330pE3%
CO 150pE3%
C 7 330 pE 3olo
C 8 47 mfd, 16v, NP electrolytic
C I 0.015 mfd, 3%
C 10 4.7 mld,5Y"
C 11 0.22 mld, 5o/"
C 12 3.3 mfd, 5%
C 13 0.056 mfd, 5%
C 14 1.5 mfd, 5%
C 15 0.033 mfd, 3olo
C 16 O.82mld,5y"
C 17 0.015 mfd, 3%
C 18 0.39 mld, 5%
C 19 82OOpF,3"k
C 20 O.22 mld, 5o/o
C 21 3900 pE 3%
C 22' 0.1 mfd, 5olo
C23 2OOOpF,sok
C 24 0.056 mtd, 5%
C 25 1100 pF, 3%
C 26 O.O22mId,31o
C 27 510 pE 3%
C 28 0.015 mfd, 3%
C n 330 pE 3olo
C 30 1 mfd, 50v NP electrolytic
C 31 47 mfd, 16v NP electrolytic
C 32 22 pF,so/q dipped mica
C 33 22 pF, sYq dipped mica
C 34 1 mfd, SOv, NP electrolytic
C 35 4.7 mtd,25v, NP electrolytic
C 36 22 mfd, 50v NP electrolytic
C 37 0.056 mfd, 5olo
C 38 4.7 mld, 25v, NP eleclrolytic
C 39 4.7 mld,25v, NP electrolytic
C 40 1000 mfd, 35v, electrolytic
C 41 1000 mfd, 35v, electrolytic
C 42 4.7 mld,25v, NP eleclrolytic
C 43 4.7 mtd,25v, NP electrolYtic
C 44 470 mfd, 25v, electrolytic
c 45 470 mfd, 25v electrolytic
C 216 0.056 mfd, 5%
C 47 0.056 mld, 5%
C € 470 mfd, 25v eleclrolytic
C 49 470 mfd, 25v electrolytic
C 50 0.056 mld, 5%
C 51 0.056 mfd, 5%
C 52 0.056 mfd, 5%
C 53 0.056 mfd, 5%
C 54 0.056 mfd, 5%
C 55 0.056 mld, 5%
C 56 0.056 mfd, 5%
C 57 1 mld, 50V NP electrclytic
C 58 0.005 mfd, 1 KV 10% ceramic
D1 LED
D2 LED
D 3 1N4148
D 4 1N4148
D 8 lN,lO03
D I 1N4003
D 10 1N4003
D 11 1N4003
o 12 1N4003
D 13 1N4003
D 14 1N5245F, 15v,|ok,1/z w, zener
D 15 1N5245F,15v,1oh,V2 w, zener
D 16 tN4003
IC 1 LM411CN
tc 2 xR5532
tc 3 xR5532
tc 4 xR5532
tc 5 xR5532
tc 6 xR5s32
lc 7 xR5532
lc 8 xR5532
rc I xR5532
IC 10 LM393N
lC 11 LM317 positi\€ ragulator
lC 12 LM337 n€gatiw rBgulator
Part No.
RMO44
RMO34
RMO39
RMO47
RMO39
RMO21
RM021
RMO33
RMO33
RMO19
RMO42
RMO34
RMO19
RM016
RMO39
RMO17
RMO39
RMO17
RMO36
RMO17
RMO39
RMO17
RM036
RMO17
BMO39
RMO17
RMO39
RMO17
RMO36
RMO17
RMO39
RMO16
RMO36
RPO17
RMO24
RPO18
RMO42
RMO17
FtM042
RPOl8
FtM017
RMO35
RMO35
RMO35
BMO35
RMO35
RMO24
RMO42
8D121
RM02l
RCo31
RC108
RC044
RC044
RC038
RC016
RCO27
8C043
8C042
RCO43
RC108
RC042
RC023
RC015
RC01s
RCO29
RC029
RC023
SFO23
AH315
QN131
SA1 15
S4114
szl 15
TA119
Part No.
cP134
cE122
cP133
cP134
cP133
cP134
cN119
cP124
cE124
cc117
cEl23
ccla
cEl22
cP127
cc122
cP124
cc118
cP132
cc117
cP128
cc116
cP125
cc121
cP123
cPlm
cP129
cP124
cP134
cN114
cNl19
cM113
cM113
cN114
cN118
CN116
cc121
cN118
cN118
CL116
c1116
cN118
CN118
cL111
CL111
cc121
cc121
cL111
c1111
cc121
cc121
cc121
cc121
ccl21
cc121
ccl21
cNl14
c2113
QD119
QD119
oDl16
oD116
QD115
QD115
QD115
QD115
oD115
QDl15
QD112
QDl12 -
QD115
oB119
Q8118
Q8118
o8118
Q8118
QB118
Q8118
o8118
Q8118
Q8116
o8113
Q8114
18

SERVICE POLICY AND LIMTTED WARRANTY
it
Your DH-160 Equalizer has been carefully engineered to
provide many years of use without maintenance or ser-
vice. Factory assembled units undergo many physical and
electrical tests before shipment. Virtually the entire circuit
in kits is similarly tested to meet specifications before it is
packed. Nevertheless, shipping damage can occur, or
human error may intervene to make service necessary.
Because many of the components in this refined design
are not readily available, and because substitution of
apparently similar parts can easily compromise its per-
formance, we strongly recommend that you make use of
our complete factory service facilities, or order exact re-
placement parts from the factory.
It is the owner's responsibility to return the unit, freight
prepaid, to the factory service facility. Units shippecl
Jreight colle<'t v'ill not be accepted. Shipment should be
made via United Parcel Service whenever possible. We
will not be responsible for damage caused by parcel post
shipment: repairs in this case will be made solely at the
owner's expense. Be sure you insure forthe full value of an
assembled unit.
Use the original cafton and packing materials, and en-
close all of the following:
1. Complete shipping address (Post Office Box numbers
are not acceptable for UPS return)
2. Serial number (if not on the unit).
3. Copy of dated bill of sale (for service under warranty)
4. Description of malfunction. If it is intermittent, please
indicate this.
5. You may also wish to attach your address directly to the
unit, or to the line cord.
All service work is guaranteed for 90 days.
Warranties apply only to the original purchaser, and are
void if the Equalizer has been modified without factory
authorization, or if parts have been substituted which, in
the factory's opinion, are not suitable, or if the Equalizer
has been physically or electrically abused or used for some
purpose for which it was not designed or intended.
Technical assistance to help you locate the source of a
problem may be obtained by calling or writing the Hafler
Company Tbchnical Service Department. It will be helpful
to know the serial number, and the results of any tests you
have performed. However we do not recommend that you
attempt your own servicing unless you are knowledgeable
in this regard. If you return a properly functioning
Equalizer for service or a checkout, a charge will be made
for.the checkout time required, as well as for packing and
shipping.
WARRANTY FOR EACTORY ASSEMBLED UNITS
The assembled DH-160 is warranted for a full year from
the purchase date, including parts,.labor and normal return
shipping costs from the factory to the owner within the
continental United States. The owner is responsible for
shipment to the factory and must submit a copy of the
dated bill of sale.
WARRANTY FOR KIT-BUILT UNITS
The parts in a DH-160 kit are warranted for a full year
from the purchase date. If a defective component is found
on a circuit board or in the kit, simply return the individual
part to the factory prepaid, together with the serial number
and the date of purchase. It will be replaced at no charge.
If you cannot locate the cause of a problem in your DH-
160, return it to the factory along with a copy of the dated
bill of sale, and a check for $30. If the diffrculty is solely a
defective part, the unit will be returned to you prepaid, and
your $30 less shipping and packing charges will be re-
turned to you. If the problem is found to be an error in your
assembly of the kit, the unit will be put in proper working
order and returned to you prepaid.
This warranty is void if the kit has not been completely
assembled, or if other than rosin core solder has been
used. Units assembled with acid core or silver solder, or
paste flux, will be returned unserviced.
This warranty gives you certain rights. You may also
have other rights which vary from state to state.
P9
TO FROM MA IN
TAPE TA PE IN
PC-17 rssuE [tT
A
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19

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'l
@ Copyright 1982. AU rights reserved.
hinted in USA
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