Tube biasing

[bikewhisper]

I was reviewing earlier posts about swapping and/or changing out valves and I just wanted to know if anyone has 'tuned' the biasing on these valves to achieve the correct voltages? The info I acquired about my Laney PTL50 states that correct valve biasing gives the advantage to the amp for reproducing the best tone. Does the Vx allow for this or is it 'plug and pray?' All valves differ in some degree from each other even if they came from the same batch run and all have a lifespan that varies as well. When changing valves in the Vx, are the replacements a matched set or one from the '80's and another from yesterday's batch run. Does anyone really mix new and old valves?

[Paragon]

Biasing is only for true power tubes that are not cathode biased. It does not pertain to a valvetronix amp where you are hardly putting any power out through the tube and also, this uses a typical preamp tube. These are like any other tube amp where you can swap the preamp tubes as you wish and not have to adjust anything.

[bikewhisper]

That clears up a lot of questions regarding the Vx. Maybe unrelated: Tweaking the tone on Vx amps involves changing out caps to either shunt or increase voltage to the valves rather than using trim pots for adjustments. My AD120VT sounds really good--right now--so no new mods are needed at this time. Will re-read the mods when necessary. Thanks for clarifying. The Laney may need a tune up in the next 6 months and I will attempt the re-bias.

Some thoughts for DIY'ers:

YAMV - Your Amp May Vary
SHIK - Stupid Hurts, Ignorance Kills
WYSIYM - What You See Is Your Mistake

[Matthewop]

good topic.. i am not be familiar with it. i learned a lot from you!