diyAudio (
-   Tubes / Valves (
-   -   Mullard 5-20/Maplin 4-20 modification to NON-Ultra Linear mode???? (

vinyvamos 23rd January 2006 10:39 AM

Mullard 5-20/Maplin 4-20 modification to NON-Ultra Linear mode????
I recently built a Maplin 4-20 Valve Amplifier and I was wondering has ANYONE tried to modify one of these to work in NON-Ultra-Linear mode?
I want to do this because I intend using it for guitar and the Ultra-Linear is too clean. From searching I understand that it's heavily based on the MULLARD 5-20 design so any info on that would be great! Cheers! :-)

harwoodspark 28th January 2006 04:07 PM

Triode mode.
Hi. In the first instance I would contact the designer of the amp for details.His name is Mike Holmes and his web site is at He's a sound bloke and is always willing to help. I have a pair of these amps and if I was going to triode them this is what I'd do. I'd remove the resistor that connects the screen of each output valve ( pin 4 ) to the output transformer. The screen of each valve is then connected to its anode via a 100 ohm resistor.I would run the resistor from pin 4 of each valve base to the output transformer rather the straight to pin 3 as it leaves more room around the valve base.
Good luck, Si.

All times are GMT. The time now is 05:39 AM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2