I am proud to be the first customer of a future Infinity amp. Tomas (
@SonicTrance ) & I have been working out the details the last few weeks and mine will be very special customized beast with add-ons I can reveal at a later time. For now I just want to further elaborate on the exciting new feature he mentioned above allowing for tube rolling, and will try & see if I can coax a few basic impressions of the new amp from Tomas.
First off I feel feel compelled to mention what an extraordinary man Tomas seems to be. My experience with him has been truly exemplary, handling my complex requests with not only an open mind but also very insightful and no hint of unpleasantness. I've dealt with plenty hi-fi companies over the years but my experience with him could be the best.
The
trimmer / voltmeter concept was brought up by Tomas after expressing an interest in rolling both the 6L6 series and EL12 Spez as powers (output tubes), the latter being able to work with special adapters, but has a very different plate voltage. It was explained that the Infinity amp uses fixed bias architecture which is the opposite of a cathode biased (auto bias) amp. This means that the amp would bias optimally towards one type of tube, vs. something like a Glenn or Feliks Audio amp that lets you use a wide array of similar tubes - although not necessarily under the correct operating points. To overcome this, the
trimmer / voltmeter concept allows one to fine tune the grid bias by way of adjusting the potentiometer (knob / 'trimmer') to a voltage that is specified for the tube type, according to a level shown on a corresponding meter added onto the amp. Although I had specified for compatibility with a very large array of tube types, I was lucky enough to work something out where only one set of trimmer / voltmeters would be able to adjust them all to the proper operating points by changing the grid voltage for the tubes - not needing another set for plate voltage. For anyone thinking this sounds like just a bunch of gobbelygook, what this means is the non-stock tubes should be able to reveal their true potential and from what I've come to understand, that can make a huge leap in performance. (feel free to add or correct anything to this, Tomas or anyone).
I further went on to add an additional set of trimmer / voltmeters for the input as well as output tubes, now giving me amazing flexibility with the upcoming Infinity amp. It will be based around the 6L6 series for output including sister classes EL34, KT77 and 7581A, and with above grid bias adjustments and/or adapters where needed, also KT66, KT77, KT88 (maybe), EL12, EL12 Spez / Spec, 6BG6, EL3N, EL38 and the mighty EL39. For input tubes I went with two sockets for 6J5 and one socket for 6SN7 that will run in parallel for either two of the single triode 6J5 (or 6C5, L63, CV1101 / MHLD6), or a single of other dual triode or pentodes such as, 6F8G, 6C8G, VT-96 / 6N7, miniatures: 6DJ8 / 6N23P, 12AU7 / E88CC and ECC88. Maybe EL32 and EL11 (which may need to be dual). Topping off the meter design it occurred to us that the amp best have the standard mA meters as well as voltmeters to facilitate warning of any dying tubes, so in all it will have 4x meters - 2 on the front, 2 on top and two small multiturn knobs (trimmers) on the top.