SOWTER AUDIO TRANSFORMERS
SINGLE ENDED OUTPUT TRANSFORMERS
FEATURES All our Single-Ended 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 Single-Ended output transformers on two chamber bobbins which enables us to provide multiple interleaved winding sections to maximize coupling without excessive inter-winding capacitance. All larger types use 14 interleaved primary / secondary sections for the lowest possible leakage inductance and hence excellent high frequency response. The smaller types, where the leakage inductance is lower we use 7 sections in a single chamber. Single-ended output transformers use a gap in the magnetic circuit. This is needed so that the dc anode current does not cause saturation of the core. Our design process ensures that the specified dc and maximum ac power at the lowest frequency applied together do not saturate the core. The gap is factory adjusted as part of the set-up process.

OPTIONS We can supply 43% screen taps (or any other percentage) for Single-Ended types on request at a small extra charge. All output transformers have 4 individual secondary windings which can be arranged for loads of 16, 8, 4 or 1 ohms. The connection arrangements are shown below. Alternatively we can provide a single 4, 8, 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. When ordering please be sure to quote the type number, package style and your preferred option for secondary windings and screen tap % as required. For size information note the size code letter and see Package Options. (Note style "T" not available for SE types)

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

(No dc permitted)
SINGLE-ENDED OUTPUT TRANSFORMERS
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TYPE
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for
spec
Suggested
Valve
PRY

Z ohms

dc mA P

Watts

Lowest freq
for
full power
rp

ohms

LF

-3 dB

HF

-3 dB

SIZE Weight

(Kg)

Buy SA01 EL84 5k 45 5 40 Hz 3K 20 Hz 60 kHz D 0.9
Buy SA02 EL84 5k 45 5 20 Hz 3K 15 Hz 30 kHz F 1.2
Buy SE04 EL34 3k 90 10 20 Hz 3K 8 Hz 50 kHz N 4.6
Buy SE05 2A3 2.5k 120 15 30 Hz 800 8 Hz 70 kHz L 2.6
Buy SA07 300B/2A3 2.5k 100 20 20 Hz 700 10 Hz 70 kHz N 4.6
Buy SA08 300B 3.5k 100 20 15 Hz 700 8 Hz 70 kHz P 6.4
Buy SE09 845 5k 95 20 30 Hz 1700 8 Hz 70 kHz M 3.4
Buy SA11 211 10k 70 25 20 Hz 3600 8 Hz 50 kHz P 6.4
Buy SE18 2 x 211 5k 150 50 30 Hz 1800 15 Hz 40 kHz Q 9.4
Buy SE15 2 x KT88 or EL34 1.5k 180 30 25 Hz 1500 10 Hz 100 kHz N 4.6
Buy SE12 2 x 300B 1.75k 150 30 20 Hz 350 8 Hz 40 kHz P 6.4
Buy SE14 20 x 6BX7 65 ohms 600 120 20 Hz 60 10 Hz 40 kHz Q 9.4
Buy SE17 SV572-10 5k0 140 40 30 Hz 1500 10 Hz 65 kHz P 6.4
Buy SE19 PX25 5k5 50 10 20 Hz 1265 10 Hz 50 kHz P 6.4
Buy 8983 30% Mumetal   5k0 5 20 Hz   10 Hz 60 kHz D 0.8
Buy 8995 30%
Mumetal
2A3 2k5 5 30 Hz   5 Hz 120 kHz D 0.8
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
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