I did a power valve comparison a few years ago using my '88 2205. And what I heard was quite interesting to say the least. I will eventually try this with my re-worked DSL100 as well, and with a few other brands of EL34's mixed into the sound test. Quite a few people have been asking about the new JJ 6CA7's, and they were not on the market at the time I did this sound test. But I am huge fan of these new JJ 6CA7's, and I want to compare them to the power valves I tried in this test as well. And lately I have been running the GT EL34M's in quite a few different amp models with excellent results - they actually have become my favorite flavor lately. Mostly in my DSL100. And when I can swing the $$ I am going to treat myself to a set of RFT EL34's and run them in my DSL100 sound test as well. Here's my post for the Split Channel users out there. I am curious to hear from any of you 2205/2210 users out there regarding your power valve preferences as well. Here's what I had posted: RickyLee » Mon Feb 23, 2009 6:01 pm New Production EL34s Tone Test with '88 2205 !! Well, here it is - I have been yearning to do this for oh so long. I finally gathered together a mix of different EL34's of my liking and threw them into the Fire that is the Beast: a 1988 Marshall 2205. I used my homemade SuperStrat that is loaded with older Carvin PUP's: A M22SD hot humbucker in the bridge, which is their highest output humbucker with a lot of bass response. Single coils in the middle and neck. Straight into the amp, with no pedals. Just primarily used the humbucker with lot's of the 2205 Dirt! Amps Boost Channel controls were: PRESENCE 4 MASTER VOL 4 REVERB 2 BASS 5.5 MIDDLE 6 TREBLE 7 VOLUME 8 GAIN 8 This testing was primarily on the Boost channel, the Clean channel sounded excellent on all the various tubes I tried. The 2205's preamp tube config. is: V1 Mullard ECC83 I61 V2 NOS 5751 V3 Mullard ECC83 I61 V4 JJ ECC83S V5 JJ ECC83S I used my 1936 cab loaded with HELLATONE 60L's. Here is the order and the tubes I ran thru her: JJ E34L's were already in it, so I started there. The B+ is 484V and I biased all the tubes at aprox, 31mA. JJ E34L, Ruby EL34BSTR, ELECTRO HARMONIX 6CA7, SVETLANA EL34, JJ KT77, GROOVE TUBE EL34M Rated 4, SED EL34 WING C. I put the JJ E34L's back in at the end for one more listen. Here is the order I rate them at, and to be honest here, with these split channel amp's, I noticed there is not that much of a tonal difference after all between all these brands of tubes. The other critical element here is the room I was in is very "lively". They all sounded awesome. On a SAD note - I stuck a pair of Valve Art KT66's in, and the lowest I could get the idle at was 54mA I am extremely sad about this as I wanted to see how the 66's sounded in this amp. I will leave that for another day, as I will need to tweak the bias circuit 1) EH 6CA7. There is something special going on with these tubes, and maybe it has to do with my tastes in tone, but these tubes have it going on in all area's. This is the second amp I have run these thru - the other being my TSL 100 with good results. The bottom end is huge and tight, and there is an overall punch that is 3D. The mids are sweet and crunchy, and the treble is just right for this model of amp. The dynamics of this tube is probably what has me hooked, as well as the overall harmonics. Sustained notes would blend into sweet controlled feedback. I think I feel the wood comin' on again just thinking about it. I have to add the Clean channel was incredible with these as well. I can not wait to try these in my 2204. They are physically a huge tube as well. 2) SED EL34 WING C. I know I am probably disappointing a few people out there that swear by these tubes. But for this model of amp, the difference between all these tubes was very minimal. It was a close decision on putting these second. These tubes do have the overall best mids - sweet and crunchy - of all the tubes I have heard to date. They are extremely tight on the low end as well, which is what these amps need. Basically, what I heard on the EH 6CA7's was a better punch and bottom end, maybe just a bit more dynamics. But the WING C's have it going on in all area's as well. 3) GROOVE TUBE EL34M Rated 4. These tubes sound almost identical to me as the WING C's. The WING C's crunch and mids was just a bit more organic "there", if that makes any sense. The GTM's do have excellent harmonics that jump off the fret board as well. Good tight bottom end as well. 4) RUBY EL34BSTR. These tubes were the biggest surprise to me of all, except for the shocker of what came in last place . . . It was actually almost a tie for 3rd with the GT M's. The thing is they both bring a different flavor to the table. These Ruby's have a bigger bottom end than the JJ E34L's, and the bass response is a bit tighter than the JJ's without the slight bit of fizz I noticed the JJ's having after hearing these Ruby's. The mids seem to be a bit less pronounced to me than the other's as well. These also have a huge punch and roar to them as well. Here is where the separation in placing these tubes in order was easier for me - more evident. As these were a bit behind the top 4. 5) JJ E34L. I have always been a huge fan of these tubes. I did notice a slight fizz to these on high gain palm muted rhythm playing. It might have a lot to do with 2205's diode clipping circuit as well. The bottom end on these tubes is excellent as everyone already knows. Actually, my 2205 has excellent bottom end anyway, which is probably why the other tubes with the more refined mids made the difference on this amp. 6) SVETLANA EL34. For the price of these tubes, you can not go wrong. And with the design of the 2205/2210 amps, these tubes sound real close to the Wing C's. Being this is the other duet of a quad I bought that had a red plating tube, I am not too happy with these and I was extremely biased in my sound judgement of these as well compared to the others . . . Just kidding. Actually, I do like these tubes. They are tonally similiar to the Wing C except the sweet mid crunch is just a bit less in your face, if that makes any sense? Reliability ?? 7) JJ KT77. This was the biggest shock, and disappointment to me overall. It is hard for me to put a finger on what I was hearing - they were brand new out of the box, as with most of the others. They seemed to be stuffy - like a tight suit that is just not comfortable. I did not play them long enough maybe? I just was not feeling these tubes in this amp. It might of had something to do with the dynamics? Probably more to do with the 2205 - just might not mesh with this amp overall? I would love to hear back from anyone who has tried these in their 2205/2210. I have these in my SL-X, and they sound excellent. I might have to dig the SL-X out and do a little comparison on that as well. All comments, feedback, opinions, abusive putdowns, are welcome as always. That's what this Forum is all about. Remember, this is MY take with my worn out abused ears! Don't let my tastes in tone stear you wrong on choosing tubes! Let YOUR EARS DECIDE! Let me know if I left YOUR favorite tube out of my tone test.