Install a GZ34 in place of the EZ81
The GZ34 provides more solid dynamics creating less
“sag”. With an octal socket you can also experimentation with
many types of rectifier tubes such as 5Y3, 5V4, 5R4, etc.
Step 1
– Cut a hole in the chassis (in place of the original 9
pin hole) large enough to accommodate an octal socket. Drill
the two mounting holes and install the octal socket.
Step 2
– Connect the yellow with white stripe and the yellow
wires (filament wires) from the power transformer to pins 8
and 2 of the octal socket (photo 11a). Tape off the unused
white wire.
Step 3
– Connect the two red wires (HV) from the power
transformer to pins 4 and 6 of the octal socket.
Step 4
– Connect the B+ wire from the standby switch
to pin 8 of the octal socket.
Step 5
– Install your octal rectifier of choice.
Upgrade the normal channel input
tube from a 12AX7 to an EF86 -
An EF86 gives a more transparent high end and
tighter low end … very “VOX AC15” sounding.
The wiring layout at right (drawing 11b) shows the
proper components and wiring diagram for the
conversion from 12AX7 to EF86.
Rx1 and Rx2 (attached to the input jack) work well
as 33K each. Two 68K resistors will function too but
with a slight reduction in sensitivity gain.
The EF86 adds a very “shimmering” high end quality
to the tone where as the 12AX7 has a very “vocal”
midrange quality.
TubeDepot.com 55
photo 11a
11
Cool Modifications
drawing 11b
