Amp Maker PWAM01 275V-190V@ 160mA 6.3V@3A


Amp Maker PWAM01 power transformer
Now Mark 2 allowing cooler long term running, and also now vacuum impregnated.

Earn up to 46 Points.

SKU: PWAM01D Categories: , ,


The 0-190V winding produces around 260V when rectified – great for EL84-based amps. There’s the full 160mA available, so you can run a pair in push-pull, parallel SE or even in stereo.
The 0-275V winding gives typically 360V when rectified – designed for octal power valves (EL34, 6L6, etc) in more powerful SE amps (15W or so). This also has 160mA available, so it’s also perfect for push-pull amps with lower-power valves, such as the EL84 and 6V6.
The 190-275V winding is also available, and gives around 115V when rectified. This is a ‘freebie’ – a side effect of the two main values I chose – but it adds a really useful option to use in amp projects…

…Switchable B+!

With these asymmetrical windings, there are three combinations available to run into the rectifier bridge. This means you can use a 3-position rotary switch to get a switchable B+ supply in your amp. With the ratios given you get:
Full power from the 0-275V winding
Half-power from the 0-190V winding
1/10th power from the 190-275V winding
It’s like an ultra-simple version of Power Scaling (seeKevin O’Connor’s London Power Website for the cost of a switch! With 3A at 6.3V available for heaters, this is a very flexible transformer for amps up to 18W or so in output.

Dimensions & info

It’s 78mm wide, 70mm deep and 64mm tall, with standard solder lugs for all primary and secondary connections. It’s available in a lay-down style, to drop through a rectangular cut-out in the chassis (such as that on AC04 small and AC02 medium chassis). The rectangular cut-out should be 54x49mm, and the four 4mm mounting bolts are on 64x51mm centres. This type has a dual 120/240V primary winding.


2 x 120V


0 – 190V – 275V @ 160mA
Heater winding 6.3V at 3A centre tapped.


High quality silicon steel
Hand laminated for the best stacking factor, and accuracy.


Separate primary and secondary sections for safety.

Winding wire

High quality enamelled copper wire.
Wound using CNC winders for highly accurate wire placement and turns count.




Built and tested to safety standard BS EN 61558-1 2005

Additional information

Weight 1.3 kg
Mounting type

Drop through, Clamp, Frame

Primary Voltage

European, US


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


Drop through Drawing Key

Label Description Dimension (mm)
A Width 64
B Length 76
C Height 55
D Cutout width 46
E Cutout length 53
F Fixing length 64
G Fixing width 51
H Mounting hole diameter 4


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