Studio Latest Schematic
D
12AX7 V1a
+180 v.
l
a
m
r
o
N
68K
K
0
0
1
250pf
68K
+1.5 v.
M
1
+
5
2
-
5
2
.022
K
5
.
1
500 pf
320 V
12AT7
Dwell
1M A
V2
2200
25- 25+
Reverb Trans
California Dreamer Plus” v. 2.6
Variation on the California Dreamer by Gino
Iorfida for Ax84.com
http://www.drifteramps.com
Modifications by Dave Zeryck
fenderelectric@yahoo.com
Caps: 400 v min. Resistors: ½ w 10%
Voltages shown are with 272DX and 5Y3 @ 117 VAC
5U4G yielded: Plate 404V, Screens 400V
D
0K
10
ble
Tre
A
0K-
25
l
o
V
ss
A
M
.1
Ba
1
-A
0K
25
Up to 50K ohm can
id
K-A
be sed for some boost
M
10
here
12AX7
V1b
+1.5 v.
+180 v.
K
0
0
1
+
5
2
-
5
2
D
100K
195 V
Reverb
Tank
Pedal
220K
Note A: Fixed Bias: 22 – 27 mV across the 1-ohm resistor
Grid Volts Sugg. mVoltage @ cathode
400 23.8 mV
380 25.0 mV
360 26.5 mV
Cathode Bias with 272DX is not practical; wattage will exceed
max dissipation for 6V6. 300-ohm resistor is max recommended.
Note B: Bias voltage ranges (unloaded) with these resistors,
272DX and 5U4G/5Y3:
15k 14 – 40 volts
22k 28 – 53 volts
47k 55 – 75 volts
.022
K
5
.
1
.0047
12AX7
V3a
+1.5 V
10pF
3.3M
220K
100kL
820
+195 v.
470K
25- 25+
D
.1
12AX7
V3b
25K Lin
K
0
0
1
See note B
220K
A
K
0
5
22K
820
12AT7 V4a
.001
170v
.1
1
r
e
t
s
a
M
47
22K
.1
M
1
470
M
75 v
1
47pF
82K 5%
100K 5%
180v
.1
12AT7 V4b
+282 v.
10-100
320v
20-500
100K 1W
C
+
-
D
10K 1W
+
-
20-500
15K
-
+
-
+
25-100
-+
Sw 1 A/C 117 VAC
-36.5v
5Y3/5U4G/5AR4
328 VAC
328 VAC
6V6 V5
1.5K
220K 5%
1 ohm 1W 5%1 ohm 1W 5%
220K 5%
1.5K
6V6 V6
+392v.
10K 1W
SW 2 Standby.
Bleeds caps to
ground when off
2 Amp Fuse
To all 6.3 v. heaters
Hammond
270EX
(5AR4/SS),
272DX
(5Y3/5U4G)
100 1W
100 1W
DC reference for
heaters reduces noise
392v
Note A
392v
B
20-500
250 mAmp Fuse
Fast Blow
36 v
1K 3W
390v
1K 3W
+394 (5Y3).
+404 (5U4G)
Choke
+
-
1K 3W
1M 1W
272DX:
100K
+ -
100 - 100
Impedance
Yellow: 8ohm
Yellow+Grn: 4-ohm
Black and
black+yellow
Notes on rectifiers:
With a 272DX PT and the 1608, the
amp has plenty of presence. A stiff
rectifier (5U4G) can be a bit harsh. With
a 5Y3, responsiveness is excellent and
A
overdrive is round & musical.
In neither case was there much
headroom – this design has a lot of
gain. Past 3 on the volume is crunch
territory, and maxed out this roars.
The clean sweet spot is narrow. A
12AT7 in V1 would be recommended
for cleaner players.
+
-
40-500
Terminal of 40-20-20-20
500V multisection (JJ Electronics)
SW 5:
Select
(4 or 8
ohms)
Hammond
1608
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