PWHT05 250V @80mA 6.3V @ 2A Pre-amp RIAA valve transformer


RIAA pre-amp transformer
Primary voltage:  220, 230, 240 and 250V.
Secondary: 250V @ 80mA. 6.3V @ 2A Centre tapped.

Earn up to 71 Points.

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This transformer was inspired by the EAR 834P RIAA pre-amplifier, but may be used in many other designs.

Being a pre-amp the spec on this transformer is very conservative. It is designed with very low flux density, and high quality M6 laminations, meaning the magnetising current is tiny, and the stray flux is very small.
This would normally be enough for a pre-amplifier transformer, but we went further, and added a bright copper flux band, to reduce any stray flux down to almost nothing.
The fact that the magnetising current is so small ensures the mag current waveform is still quite sinusoidal meaning less harmonics to be generated. This is much better than a typical toroidal transformer, where the mag current is high, and is very distorted, generating lots of harmonics.
The copper band makes the transformer look great.

Proudly made in the United Kingdom


European primary voltages, 220V, 230V, 240V and 250V.


A single 250V 80mA secondary for use with a silicon rectifier.
Heater winding 6.3V at 2A centre tapped.


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


Separate primary and secondary sections for safety.

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
Primary and HT : 24AWG UL1015
Secondary LT : 20 AWG UL1015




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

Additional information

Weight 0.95 kg
Mounting type

Clamp, Frame, Stand up, Drop through


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


Clamp Drawing Key

Label Description Dimension (mm)
A Width 76
B Height 64
C Depth 57
D Core depth 29
E Mounting distance 92
F Hole width 5

Shroud With Feet Drawing Key

Label Description Dimension (mm)
A Width 64
B Height 78
C Depth 70
D Mounting depth 48
E Mounting width 48
F Hole width 5

Drop through Drawing Key

Label Description Dimension (mm)
A Width 64
B Length 76
C Height 48
D Cutout width 58
E Cutout length 61
F Fixing length 64
G Fixing width 51
H Mounting hole diameter 4.1

Frame Drawing Key

Label Description Dimension (mm)
A Width 67
B Height 79
C Depth 54
D Mounting height 54
E Mounting width 54
F Mounting depth 41
G Overall depth 57
H Mounting hole width 5


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