Kustom 36 coupe, 72 Coupe 36 Coupe Bottom

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’36 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 oper-

ated 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 correct

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 combina-

tion 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 techniques

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 nor-

mal self-biased amp designs. The ’36 Coupe uses two 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 impact

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 ﬁrst

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.