Re: Re: Adding more power supply filtering to Two Stroke?

[Robin]

Near the back of Merlin Blencowe ‘s ” designing power supplies for tube amplifiers” there is an in depth explanation of the mosfet circuit voltage control….London calls it power scaling, 65 amps calls it Master Voltage, etc. An easier method of output power reduction would be to use a simple attenuator. 6db attenuation is about half power, while 12db attenuation would be half of that. The advantage with voltage control or an attenuator over the pentode/ triode switch is that you don’t have the noise and tone shift, just less output. Gerald Weber has a simple DIY 6/12db attenuator chapter in his book “All about vacuum tube guitar amplifiers”. Also 6db & 6/12db versions of his designs were published in Vintage Guitar Magazine a while ago (like maybe 2006-07, I’m guessing).

You could add more filtering as you’ve suggested by putting another cap in parallel with the 40uf cap and see if it does anything for you. 40uf is already plenty of filtering though, many TwoStrokes are using 30uf or even 20uf in that location. I’ve never heard a “triode” mode that sounded very musical to me.