National Horizon 5 User manual

The
National
INSTRUCTION BOOK FOR
The National Horizon 5 preamplifier — controlunit
introduces a new concept in preamp design. When
used in conjunctionwith the National Horizon 20am-
plifier orthe NationalCriteriontuner, no complicated
externalconnections are required. The preamp simply
plugsintoeitherunitthrough an opening inthe front
panel. Once installed, the compensating controls,
selection of inputs andthe individual bass and treble
controlsbecome an integralpart ofthe tuner oram-
plifier. If desired, the Horizon 5 preamplifier maybe
usedwithotherhighquality,highfidelityaudioequip-
ment. Its exceptionallycompactdesign and ease of
mountingmake it adaptable toany custom installa-
tion. The unusualrange ofits controls and compen-
sating circuits make it outstanding among units of
this typeand, when usedwith the Nationaltuner and
amplifier, it affords the ultimate in listening pleasure.
PREAMPLIFIER
-CONTROL UNIT
FEATURES
UNIQUE PLUG-INDESIGN:Preampbecomes an
integralpart of either the Horizon 20 amplifier orthe
Criterion AM-FM tunerpermitting maximum flexibility
of custom installations.
INPUTADAPTABILITY:Accommodates TV, Tape,
Tuner and Phono. When the Selectorswitch isatTV
or Tape, the inputcircuitgain canbe adjusted toac-
commodate levels from 50mv,to5 volts. The Tuner
input is fixed to accept a 1-volt output from the Cri-
terion orthe majority of high-qualitytuners. A switch
atthe Phonoinputprovides for either 10-mv or 30-mv
phonograph cartridges.
OUTPUT IMPEDANCE:About3000ohmswith 30-
db of feedback. The Horizon 5 maybe usedwith
output cables upto50 feet in lengthpermitting a
wide variety of custom layouts.
Please use this manual. It has been prepared with the prime purpose of enabling the user to obtain
full satisfaction from this product.
NATIONAL COMPANY, INC.,
MAIDEN & MELROSE,MASS.

EASE OF MOUNTING: When usedwith the Horizon
20 orthe Criterion the preamp needs only tobe plugged
in.If installed ina customwooden cabinet only one
cutout is required. Its small size permitsmounting
in extremelycompact installations. For remote
operation, an interconnecting cable completewith
mating connectors maybe procured to carry allthe
operating and signal voltages between the preamp
and tuner or amplifier. This cable is available in4
or 15-foot lengths.
HARMONIC DISTORTION: Less than0.2% at1.5V
output,0.6% at10V output and 1.5% at15V output.
(Normal output is1.5 volts).
INTERMODULATION DISTORTION: Less than
0.31% at normaloutput level measuredwith a 4 to1
ratio of400to 7000 cycles.
FREQUENCY RESPONSE: Flat within ±0.25 db
from 20 cycles to30 kilocycles and within ±1dbto
100kc. when Bass and Treblecontrols areinthe
Flat position.
HUM AND NOISE: Hum level is70dbor more below
1.5 voltoutputwhenusing the Tape, TVor Tuner
position and50dbor more below signal level measur-
edatthe10mv phono position.
EQUALIZER CONTROL: Positions 4 to10ofthe
Selector switchprovidesevencombinations of low-
frequency turnover and high-frequencyrolloff to
compensate forthe seven mostpopulartypes ofre-
cording characteristics including the newly estab-
lished RecordIndustry Assoc. of Americastandard
(RIAA).
TONE CONTROLS:Separate Bass and Treble con-
trols are provided. The Bass controlprovides a
maximum of25dbof boost and15db attenuation at
30 cycles per second. The Treblecontrol supplies
12 db boost and25db attenuation at10kc.A special
feature of this control is thatwith low amounts of
boost, the increase takes place near the ends ofthe
audiorange to allowcutting offof recordscratch and
turntable rumble with a minimum effect onthe middle
frequencies. See Figure 1.
LOUDNESS CONTROL: A fully compensated Loud-
ness control is used so that the listener may enjoy
low volume levels without the apparent loss ofthe
low and high frequency ends ofthe spectrum.
LOUDNESS SWITCH: When absolutelyflatresponse
is desired andthe Tonecontrols aresetat their
Flat positions, the compensatingcircuits ofthe Loud-
ness control maybe switched outso that this control
operates asa conventionalvolume control.
PRINTED CIRCUITS:Printedcircuitry is used to
take full advantage ofthe latest electronic tech-
niques,resulting in complete uniformity of manu-
facturing. Figure 2 illustrates the compactdesign
made possible byuseofthe printedcircuitry.
20CPS IOOCPS
FREQUENCY
IOKC
Figure 1. Tone Contra/ Characteristics
-2-

Figure 2. Interior View of Preamplifier
PREPARING TO OPERATE
Examine the preamp immediately after unpacking to
make certainthat no apparentdamage has been in-
curred duringshipment.
A metal mounting strip with two woodscrews is sup-
INSTALLATION INTHE
HORIZON 20
When pluggedintoeither the CriterionTuner orthe
Horizon 20 amplifier the Horizon 5 preamp becomes
an integralpart ofthe unitproviding for selection of
program material, as well asallthe compensation and
tonecontrolfeatures ofthe preamp.Beforeinstalling
the preampintoeither of these units itis first neces-
sary to remove the jumper pluglocated inside the pre-
amp compartmentbehind the removableblank panel.
Loosen the thumbscrews at each endofthe panel and
remove the panel. This procedureautomaticallyactu-
ates the safetyinterlockswitch so that no hazardous
voltages are present atthe plug. Reach into the pre-
amp compartment,remove thetwo Phillips head
screws, and withdraw the jumper plug. In order toas-
sureproperalignmentbetween the plug onthe preamp
and the matingjack onthe tuner or amplifier, itis
plied to facilitatecabinet installation. Make sure
you have these itemsbeforediscarding the packing
material.
CRITERION TUNER OR
AMPLIFIER
necessary to loosen thetwo slotted hex-headscrews
which position the jack onthe tuner or amplifier
whichever is used. The bottomcover ofthe Horizon
20 hastwo cutouts to permit accessibility to these
screws. Onthe tuner, itis necessary to remove the
cabinet. The proper procedure isto loosen thetwo
screwsapproximately 1/2 turn.Now, slip the preamp
into the compartment and secure thetwo thumbscrews.
Thesescrews must be tightened allthewayto insure
closing ofthe interlockswitch.Tighten thetwo align-
ing screws. The multiconnector onthe rear ofthe
preamp distributes allofthe functionalinput and out-
put circuits tothe jacks atthe rear ofthe tuner or
amplifier, asthe case maybe. Inter-unitcabling may
be carried outas outlined inthe instruction manuals
accompanying these equipments.
CABINET
Mounting the Horizon 5 preamp into a wooden cabi-
netor panel is extremely simple. Only one2 by
83/8 inchhorizontalcutout is required. Use care in
laying outthe cutout making surethat the lines are
straight and squarewith the sides ofthe cabinet.
Slide the preampthrough the cutoutuntil the ends of
the thumbscrewstouch the wood.Using the thumbs
press the ends ofthe screwsinto the wood firmly
enough to make a mark onthe wood surface. Remove
the preamp and drill thetwo holes just marked using
INSTALLATION
ano.14 drill.
Refer to figure 3 forthe propermethod of securing
the mounting strip. The stripsupplied is marked
Frontalong one edge. This edgemust be flushwith
the front surface ofthe cabinet. The tabs protruding
from the ends ofthe stripmustpointupwardstoward
thetopofthe cutout.Fourscrewholes are provided.
If the cabinet is constructed of stock 3/8 inch or
thicker, thetwo front holes are used to secure the
strip tothe bottomedge ofthe cutout. Ifthe stock is
-3-

si"
Figure 3. Method of Mounting Preomp in Custom Cab/net
1/4 inchthick or less, a strip of wood at least 1/2
inch thickshould be fastenedalong the inside ofthe
cutout flush with the bottom edge. This willsupply
sufficient thickness to hold the screws andthetwo
rear holes ofthe mounting strip maybe used.
Once the mounting strip is secured tothe cabinet
draw the ends ofthe connecting cable through the
cutout from inside the cabinet and connect tothe
preamp. Slide the preampthrough the cabinetwith
the topofthe paneltiltedtowardyou. When the slots
inthe bottom ofthe tunerengage the studs inthe
mounting strip, release thetopofthe panel. Thetwo
thumbscrews may then be turnedinto theno.14 holes
Turn slowly to allow the screws tocut their own
threads inthe wood.
ELECTRICAL CONNECTIONS
The NationalHorizon 5 preamp is equipped with a
16 contactmulticonnectorwhichcarries all supply
and signal voltages. When pluggedintoeither the
Criteriontuner orthe Horizon 20 amplifier all inter-
connections are madeautomatically. If operation re-
mote from eitherunit is desired a four or fifteen-foot
cable with a matingconnector at either endis avail-
able. Itis onlynecessary to plug oneend into the
preamp andthe otherinto the amplifier or tuner.Con-
nection to other pieces of equipment inthe highfidel-
ity systemshould be made in accordancewith thein-
structions furnishedwith the equipment.
INITIAL ADJUSTMENTS
Two high level inputadjustments anda phono sen-
sitivity slide switch are located onthe bottom ofthe
preamp. These are provided to allow for variations
in output level of different audiodevicesthat maybe
used with the preamp. Ifthe preamp is plugged into
either the CriterionTuner orthe Horizon 20 amplifier
these adjustmentsbecomeavailablethrough holes
provided in these units. With theTV tuner and tape
reproducer connected and operating thetwo input
level adjustments maybesetso that the loudspeaker
output isthe same forTV, Tape and Tunerwithout
resetting the Loudnesscontrol. Volume controls if
any, on theseunits maybe left ata predetermined
setting and program materialswitched at willwithout
changes of output level. R4 sets theTV level andR3
sets the Tape level.
The phonoinput slide switchmakes it possible to
use either a 10 millivolt ora 30 millivoltphonopick-
up with the Horizon 5.Ifthe pickupbeingused hasa
30 mv output (Audak, Pickeringetc.types), slide the
switch toward the front panel. Ifthe pickup isofthe
10-mv. variety (GE reluctancetype) slide the switch
toward the rear ofthe preamp.Setting this switch
provides the propergain and inputimpedance forthe
pickup involved and must be properly setif optimum
phono reproduction is expected. Once the foregoing
adjustments havebeenmade it should notbe neces-
sary to change them unless the associated input
equipment is changed.
Phonopickups ofthe crystal and ceramictypes may
be connected to either theTVor Tape inputs. These
types of cartridgesnormallyhaveoutputsbetween
0.5and1.0 volt. When the abovepickups are used,
the inputlevelshould beset using the level adjust-
ment corresponding tothe input used.
-4-

OPERATING INSTRUCTIONS
Once the Horizon 5 preamp is pluggedintoeither
the tuner or amplifier the operation isthe same for
either case. Assuming that a completeinstallation
will consist ofa TV tuner, a tapereproducer, anAM-
FM tuner anda phonograph asthe audiosource, the
controls ofthe preamp function as follows:
SELECTOR: This switch selects anyofthe four
abovementionedprogram sources. In addition, posi-
tions 4 through 10 provideseven different curves of
record equalization. The Selectorswitchshould be
setatthe positioncorresponding tothe recording
characteristics ofthe recordbeingplayed.
Mfr.
Allegro
American Rec.Society
Angel
Audiophile
Bach Guild
BlueNote
Capitol
Capitol-Soria
Cetra-Soria
Coliseum
Columbia
ConcertHall
Cook
Coral
Decca
Dial
Esoteric
Handel Society
Haydn Society
.ecord
Speed
RPM
33
33
33
78
33
33
33
45
78
33
33
33
33
45
78
33
33
33
78
33
45
78
33
33
33
33
Switch Setting
LP
AES
RIAA
FFRR
LP
AES
AES
RIAA
AES
AES
LP
LP
LP
NARTB
78 Noisy
LP
RIAA
AES
AES
AES
AES
AES
LP
AES
LP
LP
Mfr.
London
Lyrichord
Mercury
MGM
Oceanic
Oxford
Period
Philharmonia
Rachmaninoff Society
RCA Victor
Remington
Renaissance
Telefunken
Tempo
Urania
Vanguard
Vox
Westminister
Record
Speed
RPM
33
33
33
45
78
33
45
78
33
33
33
33
33
33
45
78
33
33
78
33
33 (old)
33 (new
33
33
33
33
Switch Setting
FFRR
LP
AES
AES
AES
NARTB
NARTB
NARTB
LP
LP
NARTB
AES
LP
RIAA
RIAA
RIAA
NARTB
RIAA
FOR
LP
LP
AES
LP
LP
LP
AES
LOUDNESS CONTROL:Once the program material
has been selected the desiredlisteninglevel isset
by means ofthe Loudnesscontrol. When used with
the Loudness switch On, (Out position) the loud-
speakerlevel maybe reduced toa minimum andthe
automatic compensation feature ofthe controlwill
provide the exactamount of bass and treble boost to
maintain listeningpleasure.
LOUDNESS ON-OFFSWITCH:There maybe occa-
sions when it will be desired to reproduce an input
signal with absolutely flat responseregardless of
audio level. Under thesecircumstances the Loud-
ness switch is turned Off (pushed in)andthe tone
controls setat Flat. The compensation circuits of
the Loudnesscontrol are eliminated andthe preamp
output isa completely faithful reproduction ofthein-
put signal.
BASS CONTROL:Starting from the Flat position
thiscontrolwill boost thelow frequencies upto25
db atits maximum clockwiserotation and attenuate
the lows as much as15dbatits maximum counter-
clockwise position. When starting from the Flat posi-
tion,increase in boost or attenuationoccursfirst at
the ends ofthe audiorange to maintainflat response
inthe middle frequency range.
TREBLECONTROL: The Treblecontrolprovides
12-db boost atits maximum clockwiseposition and
25-db attenuation at maximum counterclockwiserota-
tion. Starting from the Flat position, attenuation
occurs first atthe extremehigh frequency endofthe
range. This permitsreduction of surface noise from
old recordings without affecting the range under 10
kc.
-5-

REMOVALFROMCASE
The Horizon 5 is enclosed ina metalenclosure
which serves a two-foldpurpose. It acts asa pro-
tectivedustcoverand, atthe sametime, serves as
a highly effective shield to preventunwantedsignal
pickup. To remove the cover,firstremove the 6-32
off the cover. When placing the preamp backinto its
enclosure,replace the insulatingpaperliner,then
slide onthe metalcover. The cover and paperliner
must be replacedright side upso that thetwo input
input controls andthe phono slide switchline up with
Phillips headscrew atthe rear ofthe cover and slip theircutouts.
MAINTENANCE
The critical circuits employed,plus the extremely
compact design, demand the attention ofa trained
serviceman forany corrective measures other than
changing tubes. Bothtubes are accessible upon re-
moval ofthe cover. The TubeSocketVoltage table
will aidthe serviceman in locating any trouble in
the preampbut, in replacing any components, the
toleranceratingsshould be exactlyduplicated.
INPUTS
TAPE(g
TUNER©
PHONOfQ;
SWIC
TV SWID
INPUT
SELECTION „
FOR
FFRR
SWIF
PHONO
EQUALIZATION
SWIE
GAIN
T~CHANGING
• f-l FEEDBACK
H_r
SWIB
PHONO
COMPENSATION
FEEDBACK
Figure 4. Functional Block Diagram
-6-

TABLE 1. TUBESOCKETVOLTAGES
CONDITIONS
All voltages measured between tube pinand chassis except as noted.
Selector Switch at Tape.
VTVM used forall measurements.
117 VAC, 60 cycleinput.
No input signal.
Tolerance ±10%, all readings DC except as noted.
PIN
TUBE
VI
V2
1
150
130
2
0
0
3
0.9
0.8
4
32 (6.3AC*)
32 (6.3AC*)
5
32 (6.3AC*)
32 (6.3AC*)
6
100
130
7
-1**
0
8
5.6
1.1
9
32 (6.3AC*)
32 (6.3AC*)
*Measured between pin4 or5 and9.
**Measured between pin7 and8.
PARTS LIST
SYMBOL
El
E2
E3
PI
R3
R4
R29
R31
DESCRIPTION
Knob, 1",(4 used)
Knob, (on Push-Pull switch)
PrintedCircuit
Plug, 16 contact, Amphenol
type 26-4100-16P
Variable,500,000ohms, C
taper, IRC type RQ13-133
Variable,500,000ohms, C
taper, IRC typeRQ13-133
Variable, 1 megohm,
special taper, IRC type
Q18-137XX
Variable, 250,000 ohms,
special taper, IRC type
Q18-130XX
NATIONAL CO.
PART NO.
SB:2819
T678-1
T018-1
T448-2
T013-1
T013-1
TO 13-2
T013-3
SYMBOL
R37
SW1
SW2
SW3
SW4
DESCRIPTION
Variable, dual, 2 megohm
each section, special tapers
with SPST switch (SW4)
IRC typeQ18-139XX
Rotary switch, 10 position,
Grigs by- Allison type7945-
4MLW-4
Slide Switch,DPDT, Muter
Co. type4603
Switch,Pushbutton, 4PST,
Oak Mfg. Co. type 170
Switch,part of R37
NATIONAL CO.
PART NO.
T014-1
t
T016-1
T017-1
T015-1
Standard Form Warranty
Adopted bythe Radio Manufacturers Association, Inc.
This equipment is warranted tobe free from defectivematerial and workmanship aad repair or replacement
will be made ofany part which under normal installation, UKand service discloses defect,provided the unit
is delivered bythe owner tothe manufacturer or through the authorizedradiodealer or wholesaler from whom
purchased, intact, for examination, with all transportation chargesprepaid to die factory, within ninety days
from the date of sale to original purchaser, and providedthatsuch examination discloses inthe manufacturer's
judgment that itis thusdefective.
This warranty does not extend toany radioproducts which have been subjected to misuse, neglect,
accident, incorrect wiring, improper installation, ortousein violation of instructions furnished bythe man-
ufacturer, nor extend to units whichhavebeenrepaired or alteredoutside ofthe factory, norto cases where
the serial number thereof has been removed, defaced or changed, norto accessories usedtherewith of other
manufacture.
Any panofa unit approved for remedy or exchange hereunder will be remedied ore
authorized radiodealer or wholesaler withoutcharge tothe owner.
This
authorized t
changed bythe
arranty is io lieu ofall otherwarrantiesexpressed or implied andno representative or person is
o assume forthe manufacturer any otherliability in connection with the sale of their radio products.
NationalCompany,Inc. reserves the right to make any change in design orto make addition to, or im-
provements in,its productswithout imposing any obligations upon itself to install them in its productspre-
viously manufacturered.
-7-

I?
*B
-±-DeSI<SHATES CIRCUIT 6HOUND
CONNECTED TO PIN 7 OF PI ONLY.
NOT COMMON TO PHEAHP FRAHE
NOTES'-
CAPACITOR VALUES' HICROFARAOS EXCEPT AS NOTED
CAPACITORS 5OO VOLTS WORKING EXCEPT AS NOTED
TOLERANCE 1 /OK
RESISTOR VALUES—OHMS
FIXED RESISTORS 1/0*,$ NM7T
K= I.OOO
I,OOO,OOO