Willsenton R8: Must do Modification to Bias Boards!

In this video I show in detail the modifications to the Bias Boards, mainly by installing a very important bias "failsafe resistor" that will save the amplifier if the potentiometer goes open for any reason.

I also replace the coupling caps with some Mundorf Alum/oil caps which sound very good. Finally we install some output tube grid stopper 1K resistors. These are shown in the factory schematic, but didn't make it into the amp.

The schematics showing the factory bias board wiring and then my mod wiring are here:

This is a video series about the popular Willsenton R8 KT88 EL34 Push Pull tube audio amplifier. We will go through the repair this amp needs, testing and reviews of the amp as delivered, and then work on modifications to improve the sound quality and durability.

A great book for DIY amp building info!
Morgan Jones: Building Valve Amplifiers.

You can buy this amplifier here

The tools I use in this video include:

Hakko FX888D-23BY Digital Soldering Station
Be the first to comment