Well, it's been a little while--been busy lately. Cool to be back though--love this site.
On with it. I recently got a nice batch of Randall Aiken's killer "mojofied" 2Watt Carbon Film resistors. I still have a few of his incredibly quiet and good sounding 100K metal films that I have been using for the last few years and these new resistors are quite nice--being able to handle 750VDC like the sweet sounding metal films. Usually I like to design around parts that I want to use. Well, I think that my AC-18
[haha--like this?] would be a great springboard to a Trainwreck Rocket EL-84 design--especially since these resistors would be excellent performers in this type of design. I am thinking of doing a combination of qualities from both of these amps in a standard 18 Watt cabinet. I had a nice conversation with Ken a few months ago regarding the Mill Hill "Truth" amp, the Marshall 18 Watt, and his Rocket. The first Rocket was built strictly for Ken. In case you guys didn't know, Ken modeled a lot of his amp designs [Liverpool and Rocket] around the sonics of a particularly great sounding Selmer [not sure whether it was a Zodiac or Treble and Bass 50, etc. though]. His Rocket was designed to be the ultimate AC-30. According to Ken, there were 2 different rocket topologies. One had it's first gain stage biased in Class A1 and the other had it biased in Class A2. According to him, he would parallel in a resistor or snip it out depending on what the customer preferred. As he put it, the A1 [drawing no grid current] sounded as if you were "peeling off a few layers of harmonics" compared to the A2 [drawing grid current] preamp. Now, after a few posts on Ampage, and some responses from some very respectable dudes with far better technical chops than I posess, I also find the A2 thing a bit difficult to swallow. However, I think that Ken was implying that he uses a larger bias resistance on the first stage--which would bring that stage closer to cutoff and asymmetrical clipping if nailed hard--say with some nice P-90's, hot singles, or Buckers.
So, here is what I was thinking. Any ideas/comments welcome--as always.
Funky first stage ala Ken
Beefed up PT and possibly beefed up OT--Graydon's Heyboer is quite excellent though for EL-84 duets--so is the EMC--I run mine in my 5E3--great with a set of Brimar 6V6's!!
2XEL-84's
1XGZ-34 [beefed up PT secondary will serve to sag less in conjunctin with this--using a 6CA4 would be fine also].
Stock Heyboer is 130ma secondary ICAS--I think a bit more like 160-175 ma ICAS would give more of the Rocket vibe--a stiffer power supply
3X12AX7's
5 stage power supply--40uF [or 32uF can] plates, 40uF [or 32uF can] screens, 20uF PI, 20uF Cathode follower, 20uF preamp--possibly a choke in there as well!
18 Watt Trem--the nicest I have heard/played yet. Never did like Fender Trem all that much
.Jason
