Heathkit AS-105 Installation instructions

PRiCE $2.OO

Dear Customer:
The Heathkit electronic product you have purchased is one of the best performing electronic products in the
world.
Here's how we aim to keep it that way:
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During your first gO days of ownership, any parts which we find are defective, either in materials or
workmanship, will be replaced or repaired free of charge. And we'll pay shipping charges to get those parts to
you - anywhere in the world.
lf we determine a defective part h8 caused your Heathkit el€tronic product to need other repair, through no
fault of yours, we will service it tree - at the factory, at any retail Heathkit Electronic Center, or through any of
ou r authorized overseas d istributors.
This protection is exclusively yours as the original purchaser. Naturally, it doesn't cover damag€by use of
acid€ore solder, incorrect assembly, misuse, fire, flood or acts of God. But, it does insure the performance of
your Heathkit electronic product anywhere in the world - for most any other reason,
After-Warranty Service
What happens after warranty? We won't let you down. It your Heathkit electronic product needs r€pairs or you
need a part, just write or call the factory, your nearest retail Heathkit Electronic Center, or any Heath
authorized overseas distributor. We maintain an inventory of replacement parts for each Heathkit model at most
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We hope you'll never need our repair or replacement s€rvices, but it's nice to know you're protected anyway -
and that cheerful help is nearby.
Sincerely,
HEATH COMPANY
Benton Harbor, Michigan 49022

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INTRODUCTION
The Heathkit Model A9105 Two-Way Bookshelf Speaker
System will accurately reproduce all frequencies from 20 Hz
to 18 kHz. Even at high volume larels this System will
operate properly with negligible distortion.
A 10" acoustic suspension low frequency speaker, and a
3-1 12" high frequency speaker are used in this System. The
low frequency speaker incorporates a one-pound Alnico
magnet and compliant rubber suspension to produce low
distortion bass response over a range of volume levels, The
high frequency speaker is a ring-damped cone unit which
acts like a dome speaker at high frequencies, but uses the
entire cone at midrange frequencies. A control on the rear of
the enclosure allows you to adjust the volume level of the
high frequency speaker.
The low and high frequency speakers are mounted in a
specially designed airtight enclosure that is loosely filled
with acoustic padding. The AS-105W enclosure is enhanced
by its rich, oiled-walnut exterior. The AS-105U enclosure
comes to you unfinished, enabling you to apply a finish that
will match your decor. Both cabinets come with a removable
grille cloth front. These features make the AS-105 Speaker
System a worthy companion for any music system.
Refer to the "Kit Builderc Guide" for complete information
on unpacking, parts identification, tools, wiring, nldering
and step-by-step asembly procdur*.
UNPACKING
This Speaker System is shipped in two separate cartons. The
larger carton contains the enclosure, grille, and acoustic
padding. The other carton contains the electronic
components, hardware, and other miscellaneous parts of the
System. The bass and treble speakers in the smaller carton
are individually packed in separate cartons. To protect these
speakers and the enclosure, do not remove them from their
cartons until they are called for in a step. Unpack the other
parts and check them against the "Parts List" and the "Parts
Pictorial."
PARTS LIST
The key numbers refer to the corresponding numbers on the
Parts Pictorial.
To order replacement parts, use the Parts Order Form
furnished with this kit. lf a Parts OrderForm is not available,
refer to the "Replacement Parts" section in the "Kit
Builders Guide."
KEY PART
No No
DESCRIPTION
Control
8 pF capacitor
Black binding Post cap
Red binding Post cap
Binding post insulator
Binding post base
Low frequencY sPeaker
High frequency speaker
Black wire
Red wire
KEY PART
No. No.
HARDWARE
250-327
DESCRIPTION
6-32 x 114" flat head
screw
8-32x7/8" screw
1*8 x 112" sheet metal
SCrew
6-32 nut
Control nut
Control flat ransher
Flat washer
Small lockwasher
Control lockwasher
Solder lug
Spade lug
PARTS
Per Kit
PRICE
Each
1.00
3.45
.10
.10
.10
.10
16.55
3.05
.05/ft
.05/ft
PARTS
Per Kit
1
12
I
5
1
1
12
3
1
2
2
PRICE
Each
.05
.10
.05
CIRCUIT COMPONENTS
1
2
3
3
4
5
6
7
1
1
1
1
4
2
1
1
1
1
11-122
23-106
100-16-2
100-1 6-1 8
75-17
427-3
401-158
401-141
344-2
344-3
I 250-385
10 250-410
11 252-3
12 252-7
13 253-10
14 25345
15 254-1
16 254-35
17 259-1
18 259-7
.05
.05
.05
.05
.05
.20
.05
.05

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STEP-BY.STEP ASSEMBLY
Deuil 1A
PICTORIAL 1
NOTE: Before you start to assemble this kit,
read the "Kit Builders Guide" for complete
information on wiring, soldering, and
step-by-step assembly procedures.
( ) Position the control plate lettered side
up. Note the position of the
countersunk hole.
( ) Cut four 4" lengths of rubber tape.
NOTE: The following lengths of rubber tape
should be placed on the control plate so
they form a continuous gasket seal' Make
sure there are no gaps between any two
pieces of tape.
( ) Turn the control plate over and press
down on the plate to make sure the
tape strips are securely attached.

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( ) Cut one lead of the 8 pF capacitor to a
length of 1". Then remove 114" ol
insulation from the end of the lead
and twist together the fine wire
strands.
DO NOT CU]
TH I S LEAD
FOR GOOD SOLDERED
CONNECTIONS, YOU MUST
KEEP THE SOLDERING
IRON TIP CLEAN...
WIPE IT OFTEN WITH A
DAMP SPONGEOR CLOTH.
( ) Push the capacitor into the capacitor
. mounting clip with the short lead
toward solder lug A.
( ) Connect the long capacitor lead to lug
1 ofcontrol C (S-1).
( ) Connect the short capacitor lead to
solder lug A (NS).
( ) Connect a 1-1 12" black wire from lug
3 of control C (S-1) to the lower hole
in solder lug B (S-1).
Detaal3A
SHORT
LEAD
PICTORIAL 3
( ) Prepare the following lengths of wire.
Cut each wire to the length indicated;
then remove 1/4" of insulation from
each end of each wire and twist the
fine wire strands.
1-1/2" black 25" black
19" black 25" red
19" red
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( ) Open the remaining shipping carton
and carefully remove the speaker
enclosure. Place it grille side up on a
soft cloth to protect the finish.
( ) Remove the sheets of acoustic padding
from the enclosure. Lay this padding
aside until it is called for.
NOTE: A plastic gasket will be used around
the openings where the speakers will be
mounted. These gaskets provide an airtight
seal between the speaker and the enclosure.
Make sure all the gasket holes are clear.
GRILTE
( ) Pull up on the grille tab to remove the
grille. You may hear a ripping sound as
you pull up on the grille.
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( ) Mount the control ptate in ttre
enclosure. Use eight #B x 1/2,, sheet
metal screws. Be sure the plate is
positioned as shown and the screws are
tight.
( I Place the large plastic gasket around
the large hole.
( ) Place the small plastic aasket around
the small hole.
Detail5A
PICTORIAL 5

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FINAL WIRING GHECK
After the speakers have been installed it would be difficult
to get at the wiring connections if you should encounter
trouble. Therefore, before the acoustic padding and speakers
are installed, recheck your wiring as directed in the
following steps. Refer to Pictorial 7 to mdke sure that each
wire is connected to its proper point and that each
connection is properly soldered. Reheat any connections
that do not appear properly soldered.
D Short capacitor lead to solder lug A.
tr Long capacitor lead to lug 1 of control C.
D Black wiie between lug 3 of control C and solder lug
B.
tr Red wire of long twisted pair to solder lug A.
tr Black wire of long twisted pair to solder lug B.
tr Red wire of short twisted pair to lug 2 of control C.
tr Black wire of short twisted pair to solder lug B.
tr Short twisted pair to the high frequency speaker.
tr Long twisted pair to the low frequency speaker.
tr Red wire of each twisted pair to the marked lug of the
speaker.
Proceed to "Final Assembly."
o 25"
/TW ISTED
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PICTORIAL 9
( ) Carefully position the high frequency
speaker into the small hole. Secure the
speaker to the enclosure with four
8-32 x 7/8" screws and four flat
washers.
( ) Garefully position the low frequency
speaker into the large hole. Secure the
speaker to the enclosure with eight
8-32 x 7/8" screws and eight flat
washers.

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IN CASE OF DIFFICULTY
Perform the following checks to locate any troubles you
may encounter.
1, Make a careful visual check of the complete unit for
any obvious errors, such as improperly soldered
connections, wires connected to the wrong lugs, or
bare wires touching together. Carefully check all
Repeat the "Final Wiring Check" on Page 10.
About 90% of the kits that are returned for repair do
not function properly due to poor solder connections.
Therefore, many troubles can be eliminated by
reheating all of the connections.
2.
FACTORY REPAIR SERVICE
You can return your completed kit to the Heath Company
Service Department to have it repaired for a minimum
service fee. (Kits that have been modified will not be
accepted for repair.) Or, if you wish, you can deliver your
kit to a nearby Heathkit Electronic Center. These centers are
listed in your Heathkit catalog.
To be eligible for replacement parts under the terms of the
warranty, equipment returned for factory repair service, or
delivered to a Heathkit Electronic Center, must be
accompanied by the invoice or the sales slip, or a copy of
either. lf you send the original invoice or sales slip, it will be
returned to you.
lf it is not convenient to deliver your kit to a Heathkit
Electronic Center, please ship it to the factory at Benton
Harbor, Michigan and observe the following shipping
instructions:
Prepare a letter in duplicate, containing the following
information:
o Your name and return address,
o Date of purchase.
r A brief description of the difficulty.
o The invoice or sales slip, or a copy of either.
o Your authorization to ship the repaired unit back to
you C,O.D. for the service and shipping charges, plus
the cost of parts not covered by the warranty.
Attach the envelope containing one copy of this letter
directly to the unit before packaging, so that we do not
overlook this important information. Send the second copy
of the letter by separate mail to Heath Company, Attention:
Service Department, Benton Harbor, Michigan 49022.
Check the equipment to see that all parts and screws are in
place. Then, wrap the equipment in heavy paper. Plaie the
equipment in a strong carton, and put at least THREE
INCHES of resilient packing material (shredded paper,
excelsior, etc.) on all sides, between the equipment and the
carton. Seal the carton with gummed paper tape, and tie it
with a strong cord. Ship it by prepaid express, United Parcel
Service, or insured parcel post to:
Heath Company
Service Department
Benton Harbor, Michigan 49022

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ACOUSTIC SUSPENSION THEORY
The main components in this acoustic suspension System are
the low frequency speaker; a sealed, airtight enclosure; and
sound absorbent padding inside the enclosure. The principle
involved here is that the air in a sealed enclosure makes an
almost perfect spring. To take advantage of this principle, a
speaker with a highly flexible cone suspension must be used.
When this type of speaker is mounted in an airtight
enclosure, the flexible suspension of the speaker cone will
allow the cone the considerable back and forth movement
that is necessary for good bass response.
LOW FREOUENCY SPEAKER (WOOFER)
The cone construction of the low frequency speaker
(woofer) tends to reduce the acoustic output above 1000 Hz
and its impedance begins to increase at the same time. This
is called a "mechanical crossover,,, a crossover method that
is becoming more popular than low-frequency electrical
crossovers because there are less phase problems at the
crossover freguency. Also, since series inductors are not
used, damping problems are reduced and inductor saturation
problems are el iminated.
HIGH FREOUENCY SPEAKER (TWEETER)
The high frequency speaker (tweeter) in this system is a
cone type speaker with a gradual "roll off', at the lower end
of its range. This slow roll-off permits a 6 dB per octave
crossover to be used. This high frequency speaker employs a
single capacitor crossover circu it.
CIRCUIT DESCRIPTION
Refer to the Schematic Diagram while you read the
fol lowing circu it description.
Audio signals are coupled to the Speaker System through
terminals 1 and 2. From term in al 2, the signals are coupled
directly to the low frequency speaker and through capacitor
Cl and High Frequency Level controt Rl to the high
frequency speaker. High frequency audio signals are coupled
through capacitor Cl to the high frequency speaker. The
level of the high frequency signal is controlled by R1.