Hi, to change the power valves of my JVM 410, do I need a matched quartet or I can use two matched pairs? The bias is set by two separate trimmers, one for every pair, so maybe two matched pairs will be enough?
We would always recommend matching all valves as closely as possible, but feel free to contact firstname.lastname@example.org for more information.
i reccomend getting a matched quad...
valves are not only matched by the amount of plate current draw at a given bias voltage on pin 5
they should also be matched for transconductance
TAD in germany does a fantastic job at this in my experience... if i remember correctly, marshall used their KT66's for the vintage modern series