These are machine wound and packed using Philips and ROLA NOS winding wire with 200v insulation. The transformers have both the standard 8 ohm impedance and a 4 ohm tap for modern speakers often with a 6 ohm impedance or can be used to drive electrostatics .

ROLA OPT-50 Push Pull Ultralinear Output Transformer                                         

Power: 50W  RMS full bandwidth 65W RMS for guitar amplifier use at 40hz.

They can be used for the rated specifications for Hi-Fi use or approximately up to 25% more power for guitar amplifier use where the lowest frequency of bottom E is 40hz.  The transformers have been insulation tested to 5KV with a Trimax insulation tester.

Primary Impedance: 5KΩ P-P plus 30% screen taps
Output:0-4Ω-8Ω
size: W-96MM  stack-47MM   H-80MM
core Material: Z11(0.35mm lamination)
freq response full bandwidth 20hz to 20khz +/- 2db
Primary inductance: 110H
Weight approximately 2kg

Replacement warranty 12 months when used for Hi-FI use

Suggested tube types 2A3,300B,6L6,5881,EL34,6550,KT88