If you try them post your thoughts, I am going to try them myself.... Here is Bob's spiel ...... We do not care for the yellow jacket adaptors, they will cut the power but they will also make the amp sound less full. Here are some options.
The Lone Star amps are fixed bias at a pretty cold setting but not as cold as the Dual Rec's so any matched quad of 6L6's or EL34 type tubes including the JJ Electronic 6L6GC or JJ E34L's are just plug and play and you also have the option of using a quad of the JJ 6V6's in the Tweed mode. Because of the cold setting I would go with a hotter set of tubes and five of the JJ ECC83S preamp tubes and I would make one of the ECC83S tubes a balanced one for the phase inverter which is in the back row farthest from the input jack. The JJ's have a very deep tight low end, a natural harmonically rich mid and a smooth sweet high end with a nice sparkle that's not brittle.
If you want a little more of a Marshall type tone that has more of a mid and upper mid focus then the E34L’s will do it. The JJ E34L's provide a deeper low end and are more aggressive and punchy than a standard EL34. The E34L is tighter with slightly more headroom and power with a more aggressive crunch, very articulate British tone.
The new KT77's would also be an option. These are not quite as tight as the E34L, but tighter than an EL34. The 77's have even a bit more low end extension than the E34L's and they have a nice sizzle in the top end that is not brittle. The clean tone is very fat and full and the crunch has more of a chunk to it and it's very punchy but not quite as aggressive as the E34L, a great tube for rhythm and solo work.
We can also do Integrated quads with a pair of the 6L6GC’s and a pair of the E34L’s or even the KT77’s. These quads consist of hand picked 6L6GC's and E34L's that all draw the same exact amount of natural plate current which is how tubes are matched. In an amp that has between 470 and 500 plate volts which is what these amps have. These quads can be run with the amp set in the EL34 position. The integrated quads do provide a very cool mixture of tones combining the deep thump and clean smooth highs of the JJ 6L6GC's and the aggressive punch and classic British sound of the JJ E34L's or the KT77’s.
Rectifier tubes are the only tubes that are not directly in the tone circuit, they rectify AC voltage in to DC voltage, they either work or don't work and rectifier tubes will out last power tubes about 20 to 1, so if your 5U4 is working you don't have to replace it. I do have NOS 5U4's for 30.00 and these will give a slight improvement in dynamic response.
Another option if you’re looking for the smoothest richest tone you can get would be to use two of the Gold pin ECC83S’s in V1 and V2, with two standard ECC83S’s in V3 and V4 along with a balanced Gold pin ECC83S for the phase inverter in V5. This option would add 29.50 to the prices below.
The only other option would be if you want any of the preamp tubes premium graded for gain. The high gain ECC83S's have about 10% more gain than standards which adds a bit of bite and a sharper dynamic but does not hurt the clean tone. The other attribute that these tubes have is a faster filament rise time which is great for an EVH, Petrucci or Satriani type style and is also good for fast palm mute styles. If you decide to use these I would use them in V1 and V2 which would add 10.00 to the cost below.
I will give the yellowjacket 6v6 combination a try also
