25W 6600 Ohms Ultra Linear Push Pull Output transformer

Description

This transformer is the culmination of many weeks of work to produce an output transformer for the Mullard 5-20 amplifier using EL34 output valves. I wanted something that would give me plenty of bass, down past 20Hz, and perform at the top end past 20KHz.

I have settled on this design as the analysis showed excellent results, giving a flat response less than 20Hz and, due to the winding methodology used, over 30KHz.

May be used in any push-pull design where an anode to anode impedance is 6600 Ohms.

Primary

Multi section winding, for reduced leakage inductance.
6600 Ohms Anode to anode
40% UL taps

Inductance

Inductance approx 50H.
Leakage inductance 16mH

Bandwidth

Wide bandwidth, 20-30KHz. (-1dB)

Secondary

Output impedance 4,8 and 16 Ohms.

Steel

High quality Grain Orientated M6 0.35mm.
Hand laminated for the best stacking factor, and accuracy.

Winding wire

Double coated Grade 2 enamelled copper wire.
Wound using CNC winders for highly accurate wire placement and turns count.

Connecting wire – stand up only

High quality PVC 600V 20 AWG UL1015

Mounting

Stand up, Drop through and frame.

Weight

2Kg

Additional information

Dimensions

Here are dimensional diagrams for this transformer.
Please refer to the relevant key below for the dimensions.

shroud_with_feet.pdf
frame.pdf
drop_through.pdf

Shroud With Feet Drawing Key

Frame Drawing Key

Drop through Drawing Key