Download OUTPUT POWER = 6W CLASS A

T1
1
IEC CONNECTOR
2
F1
SW1
FUSE
POWER SW
1
1
RT1
1
10H 170MA
310V
6
295V ~137mA ->
8
270V .26A
2
KC012L
2
L1
5U4
(OR HAMMOND 270HX OR 370HX)
J1
(OR HAMMOND 159Q)
V1
THORDARSON 26R160
120 OHM
2
4
2
270V .26A
3
8
t
115V
+
3
4
RV1
5V 3A
5
9
V230LA10
C1
+
C2
50UF_500V
50UF_500V
ELNA
CERAFINE
ELNA
CERAFINE
6
6.3V 8A
7
R1
2.7K_1/2W
250V
C3
C4
20UF_400V
20UF_400V
SOLEN POLYPRO
R2
R3
47K_1/2W
295V
C5
20UF_400V
SOLEN POLYPRO
SOLEN POLYPRO
R4
10K_1/2W
150K_1/2W
R5
R6
10K_1/2W
10K_1/2W
C7
.25UF_600V
205V
R7
PAPER/OIL
1K_1/2W
C6
.25UF_600V
.25UF_600V
110V
V2
R8
PAPER/OIL
270K_1/2W
PAPER/OIL
200mV RMS
FOR FULL
OUTPUT
5
C8
INPUT
6B4G
6
184V
BLU/YEL S1 2
4
1
6
3
41V
4
1
6
3
470K_1/2W
8
7
R10
8
7
6.2V
R11
PAPER/OIL
1
RED
9
10 0 BLK
C9
.25UF_600V
BLK
8 0 BLK/YEL
BRN P2 5
3
2
45V
2
4 GRN
7
2
1
6SN7
5
RCA JACK
BRN/YEL S2 4
2
5
5
6SN7
8 OHM OUT
7 4 GRN/YEL
7
V5
2
V4
RED
1
8 YEL
BLU P1 1
RED B+ 3
470K_1/2W
BINDING POST
HAMMOND 1615
2
3
184V
J2
T2
R9
J3
GENERAL NOTES:
1. Use good components, and this amp will sound great.
Use crummy ones, and there's no guarantee.
2. The amp as shown will put out just over 6 watts RMS into
8 ohms (on the 8 ohm tap). If you change the power supply
to deliver 350V instead of 300V, you will get just over 7
watts, and be right at the limit (300V) for plate voltage on
the 6B4's.
3. You can use any ouput transformer you like, with a
primary of between about 5000 and 6600 ohms CT, rated for
at least 7 watts. Higher impedances will give you less
distortion and less output power. Bigger (15 or 25 watt
transfo rmers) will deliver cleaner bass, usually. If the
transforme r has ultra-linear taps, just tie them off and
don't connect them.
4. If you build a stereo version of the amp, you need
seperat e filament windings for each channel, as the output
tube b ias is present on the filament winding, and you don't
want to connect both channels together.
5.Us e matched output tubes for minimum distortion.
6. Capacitor values in general are not critical. Coupling
caps can be anything between 0.1uF and 1uF, at least 300V.
Paper/oil or polypropylene are best, 716P orange drops
work well. Power supply caps can be Elna, Black Gate, LCR,
or whatever you like. Do not exceed 50uF at the front of the
choke or you will exceed the peak current ability of the
rectifier tube. The output capacitor can be made larger if
you wish; it will reduce hum a little. Don't leave out the
polypro caps on the input stage.
7. Resistors should be within 5% of the indicated values,
watta ges at least what's shown. Carbon comp, metal film,
or y our favorite audiophile neurotic resistor is fine.
8. Tubes: I used Sovtek 6B4G's. They sound great, cost
little, and in this circuit have lasted over two years so far
with no degradation. Use your favorite 6SN7 or 5692 (I've
used GE and Sylvania NOS). Rectifier can be 5U4 (Russian is
OK), or if you can find them GZ37's are better.
1K_1/2W
V3
6B4G
5000 CT : 4/8/16
15W
4 OHM OUT
BLK
2
C10
3V
.25UF_600V
R12
PAPER/OIL
R13
1K_1/2W
^3mA
J4
270K_1/2W
A=~3.3
VO=+120/-150
R14
30K_1/2W
VI=+/-45
R15
10K_1/2W
^4.5mA
R16
470K_1/2W
R17
R18
1K_1/2W
1K_1/2W
6B4G
VA =
IC =
VG =
PA =
Q POINT:
250V (295V B+ - 45V VG)
60MA PER TUBE
-45V
15W PER TUBE
A=0.88
OUTPUT POWER = 6W
CLASS A
^12mA
USAGE NOTE:
Th is design is property of Peter Millett and Wheatfield
Audio LLC - Copyright 2001. You are welcome to use this
infor mation as you see fit to build a reasonable number of
amplifiers for your own use. If you want to try and
commercialize this design, please contact me at
[email protected] and I will wish you luck!
CATHODE BIAS 45V
A=16
BINDING POST
A=11
R19
VO=+/-4.6, MAX=+96/-52V
VO=+/-4.1, MAX=+45/-25V
VO=+/-45, MAX=+/-69V
VI=+/-0.29V = 200mV RMS
VI=+/-4.6 = 3.3V RMS
VI=+/4.1, MAX=5.25
1.5K_2W
R20
1.5K_2W
R21
1.5K_2W
R22
1.5K_2W
^120mA
(30mA EACH)
Pete Millett - Wheatfield Audio LLC
Title
6B4G P-P AMPLIFIER
Size
Document Number
Rev
A
PLACE ONE RESISTOR AT EACH 6B4G FILAMENT PIN
Date:
Tuesday, November 13, 2001
Sheet
1
of
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