SOWTER AUDIO TRANSFORMERS
PUSH-PULL OUTPUT TRANSFORMERS

FEATURES Our power output transformers use the best grade (M6) low-loss grain oriented silicon iron laminations. This ensures minimal distortion and low insertion loss. We wind our push-pull output transformers on two chamber bobbins which ensures full capacity and resistance balance. All larger types use 14 interleaved primary / secondary sections for the best possible coupling factor and hence excellent high frequency response. The smaller types, where the leakage inductance is lower use 7 sections in a single chamber.

OPTIONS We normally provide a single 8 ohm secondary or 4 separate secondary windings which can be arranged for loads of 16, 8, 4 or 1 ohms as shown in the tables below. Alternatively we can provide a single 4, or 16 ohms or 8 tapped at 4 ohms. Also we can provide twin 4 ohm windings which can be connected in series for 16 ohms or in parallel for 4 ohms. Tapped secondary windings will have somewhat increased losses, reduced HF response and reduced damping when the load is connected to a tap.  This is particularly true when a 4 ohm tap on a 16 ohm winding is used.  Please be sure to specify your preferred option if you wish to have a non-standard secondary option or a screen tap %.

CUSTOM DESIGN Please let us know your proposed valve type and circuit configuration and we will design a transformer for you. We also make replacements for classic amplifiers and circuits. If we do not list the type you need we will design it. The price normally depends on the size. Please see  price/size info. There is no extra charge for design.

PUSH-PULL OUTPUT TRANSFORMERS
By valve type and configuration
CLICK HERE FOR DIMENSIONS

Quote TYPE click for spec VALVE
T YPE
Configuration RLa-a

ohms

P

Watts

Lowest
full power
frequency
dc per
side
mA
LF -3dB Hz HF -3dB kHz SIZE
Buy U058 EL34 Fixed bias (Guitar) 3k5 65 50 130 5 100 L
Buy UA21 EL34 UL 43% 6k6 40 20 120 5 50 N
Buy U057 EL34 Taps for Triode or UL 10k0 or 6k6 20 20 100 20 30 M
Buy U059 EL34 2 pairs fixed bias 1k75 100 20 250 5 70 P
Buy U060 EL34 3 pairs 3k7 200 20 275 10 40 T
Buy U061 EL34 3 pairs UL 43% 2k2 100 20 300 10 50 P
Buy U062 EL34 6 pairs UL 43% 1k7 150 20 400 10 40 Q
Buy U082 EL84, 6CA7,
KT66
Triode or UL 43% Very high performance 8k0 40 20 200 10 80 P
Buy U063 EL34 EL84 Triode 15k 4 20 40 20 30 F
Buy U064 EL84 Pentode or UL 43% 8k0 10 30 80 25 30 F
Buy U065 EL84 2 pairs Pentode or UL 43% 4k0 30 20 100 20 30 M
Buy U066 5881, EL34,
6550, 6L6,
KT66 etc.
Multi Purpose with cathode feedback winding 10k, 5k0, 2k5 +NFB 20 20 150 20 30 L
Buy U067 UCL82 43% UL taps 9k0 10 20 60 20 30 J
Buy UA23 KT66,
EL84
UL or Tetrode Cathode bias 8k0 30 15 125 20 30 N
Buy UA31 KT66 UL Fixed bias 8k0 50 20 120 20 30 P
Buy U069 6550 KT88 Cathode bias 6600 50 20 150 10 55 P
Buy U027 6550 KT88 Fixed bias 5000 50 20 180 10 50 N
Buy U070 6550 KT88 Fixed bias 40% taps 4500 100 25 200 10 50 P
Buy 8950 6550 KT88 Williamson 10000 30 20 150 10 70 P
Buy U071 6550 KT88 2 pairs Fixed Bias 2250 200 20 250 20 40 Q
Buy U072 6550 KT88 5 pairs Fixed Bias 1000 400 40 300 20 40 Q
Buy U073 6L6 Guitar amp 3800 30 50 100 30 30 J
Buy U074 SV811-10 Class A 10000 50 20 100 20 40 Q
Buy U075 SV811-10 2 pairs Class AB2 5000 120 20 320 10 40 Q
Buy U076 813 UL 43% taps 7000 80 25 200 10 40 P
Buy U077 6C33C-B Class A 1200 75 20 200 10 50 P
Buy U078 6C33C-B Class A 600 100 20 300 10 50 P
Buy U079 300B Class A 5000 30 20 150 10 40 M
Buy 9092 300B Class A
V. Low loss
7000 50 10 100 4 50 R
Buy U080 6V6 Guitar 8000 15 50 100 30 30 F
Buy U081 211 (VT-4-C) Class A 20000 50 20 200 10 30 R
Buy U083 805 Class A 7000 100 20 200 10 40 Q
MODULATION TRANSFORMERS (Ham Radio)
  TYPE Suggested Valve Ratio Pry Z
Ohms
Sec Z
Ohms
Lp
(H)
Max D
C
mA
Max AC at 50Hz SIZE
Buy 8997 PP 6L6 1CT:1 5000 5000 12 200 1500 Vp-p   M
SECONDARY CONFIGURATION OPTIONS
STANDARD 16/8/4 ohms
4 separate
1 ohm windings
SINGLE 4,6,8,16 ohms
TAPPED 8/4 ohms
TWIN 4 ohms
Series = 16 ohms,
Parallel = 4 ohms
Secondary configuration options Secondary configuration options Secondary configuration options Secondary configuration options