72 coupe bottom – Kustom 36 coupe User Manual

Page 21

’72 Coupe Bottom

1) Power Cord Receptacle/Fuse Holder: Insert the AC cord (provided) ﬁrmly into

the AC connector. NOTE: Replace the AC power cord if protective jacket is damaged or

ground pin is damaged or removed. The fuse is located in a housing just below the re-

ceptacle. Replace only with same type and size. To remove the fuse, remove AC power

cord and pull out on the tab above the fuse symbol located on the fuse carriage. Place

the new fuse in the carriage clip and re-insert. NOTE: To prevent an electrical hazard,

DO NOT replace fuse without using the fuse carriage. Replace the fuse carriage if lost

or damaged before re-inserting the AC power cord.
2 & 3) Speaker Outputs—These 1⁄4” jacks are provided to connect the internal
and/or external speakers to the Coupe ampliﬁer.

The Coupe ampliﬁer should never

be operated without a speaker plugged into a speaker jack.

4) Impedance Selector—This switch is used to select the appropriate impedance,

and is important in achieving the desired results from the Coupe ampliﬁers. The cor-

rect impedance should be selected using the Impedance Selector Switch as follows:
a. Internal speaker only: 16 ohm setting
b. Internal speaker + external 16 ohm speaker: 8 ohm setting
c. Internal speaker + external 8 ohm speaker: 4 ohm setting, although it’s not

matched
d. External 16 ohm speaker alone: 16 ohm setting
Incorrectly “mismatching” the amp to the speaker should not damage the ampliﬁer,

but would result in lower output powers, and could result in shorter output tube life.

5) 6L6 Output Tubes—These power tubes were selected to provide the best com-

bination of performance and tube life, and shouldn’t require adjustment to their bias.

The amp uses a mixed-bias system which is a combination of ﬁxed and self-bias tech-

niques to give the user the best of both worlds. The result is that the amp will control

its own bias to a certain point, but without the typical reduction in power associated

with normal self-biased amp designs. The ’72 Coupe uses four 6L6s in a “push-pull”

ampliﬁer conﬁguration.
6) Phase Inverter Tube—The phase inverter tube uses a single 12AX7 in what’s

called a long-tail pair conﬁguration. This results in the most signal swing possible for

driving a power amp, and the most symmetrical drive capability, as well.
7) Effects Loop/Boost Tube—The Coupe ampliﬁers use an all-tube effects loop to

preserve the tube sound through the signal path. This single tube is used for both the

Effects Loop Send/Return and the footswitchable Volume Boost circuit.
8) Preamp Tube 2—This 12AX7 is used on both channels, but has the biggest im-

pact to the lead channel since it has the additional stage required for the very large

amount of gain.
9) Preamp Tube 1—This 12AX7 is the input tube, and as such, is the most likely

to cause microphonic problems, especially in the lead channel, and it is also shared

by both channels. If tube feedback occurs, it can usually be corrected by swapping

this 1st tube with one of the other tube locations, since they have less gain following

them and are less prone to feedback. The ﬁrst tube also has the greatest affect on the

“cleaned up” tone of the amp, i.e. the tone when the guitar is turned down.

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This manual is related to the following products:

72 Coupe