Just picked up a beautiful 100 watt Hylight era head; can someone identify this mod with the pot on it?
Thanks!
Paul
‘79 DR103 mod question!
Moderator: Mods
Re: ‘79 DR103 mod question!
Looks like a voltage doubler for the bias - a common and useful mod for older DR103s, which in stock form don't supply enough bias voltage for modern EL34s. The pot is there to adjust the bias to the correct level.
When these amps were made, the original Mullard EL34s Hylight used were very consistent and robust, so they "hard coded" the bias voltage, providing no adjustment.
When these amps were made, the original Mullard EL34s Hylight used were very consistent and robust, so they "hard coded" the bias voltage, providing no adjustment.
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Re: ‘79 DR103 mod question!
Excellent, thank you!