been interested in these, and this question can apply to any tube preamp, but how are you supposed to know if a tube is going bad, or more specifically which tube is the one causing issues other than trial and error

islp.......This is where a tube tester will come in handy. Small tubes will often show much lower transconductance and higher noise levels as they begin to reach the end of their useful life cycle. A tube tester will also identify tubes that are shorted. Owning or having access to a quality tube tester is essential if you own tube gear, and especially if you do a lot of tube rolling with tubes purchased from unqualified sellers.

Makes sense. It is better than nothing. I always order matched pairs but this one was a hard to find pair so I might have had to settle for not so matched. Decided against them in the end. I would like to try a pair of Mazda/Visseaux 6L6's. Maybe I'll run into them sometime. Meanwhile, I'll be trying a pair of Mullard 6L6 XF2's, as discussed earlier, and a pair of RCA black plate EL34's. Should keep me busy and happy for a while! :thumbsup:

Edit: Rereading, I realize I got that backward - should be Mullard EL34 XF2 and RCA black plate 6L6. :redface-oops-6:

There's a new headphone amplifier design from Dennis available on eBay now. Familiar looking, but with a new twist. Two different versions available.

The TungSol 6550's came in late last week, and I've been giving them a few listening sessions. The bass is noticeably bigger and deeper than the 6V6G/GT bass, but it was almost obscuring the wonderful midrange from the 6V6's. I swapped out the Telefunken E88CC for a mid-70's era Siemens E88CC, and the balance was restored. The midrange came back forward and it sounded less muddied up. I had also tried the big Sovtek 6H30P, but that made the upper ranges brittle and edgy. The Tele was definitely tilting the tone down and augmenting the bass a little too much to my ears. The Tele was perfect with the 6V6's, but less so with the more powerful 6550's. Still experimenting, but getting incrementally closer to audio nirvana...

Spotted the headphone amp as well..... Just emailed to find out if he would offer a headphone stage combined with a preamp.... We shall see.

You might try the 6N1P again - easy swap to see with these 6550's.

I again tried the Tung-Sol 6550 reissue and was very pleased. It will be amazing if I end up staying with a current production after all this!

I never did try KT120's since Dennis talked about the hard clipping they do. I probably should to be thorough though. In my CJ 11A, it was between 6550's and KT120's, but that was at 70wpc, so probably little clipping in that application.

Yesterday I received my pair of RCA blackplate 6L6 and Mullard EL34 XF2. Haven't tried them yet. I'm suspicious of the XF2 however. I'm corresponding with the seller and he will take them back if I so decide. They are single top halo getters, narrow black base, but crimped rather than welded plates. All my reading suggests the crimped plates are XF3/4.

I may try the 6N1P again. I do recall Dennis saying they were preferred over the 6H30P. I've got a couple of the early 80's production Voskhod/rocket logo as well as the Novosibirsk (rhombus logo) manufacturing plant for the 6N1P's. I think the Voskhod/rockets were preferred by most.

I wonder how much the reissue TungSol 6550's really have in common with the 60's/70's US production versions other than appearance? I doubt TungSol would sell them the original tooling to make them in the height of the cold war, so at best they could be considered "reverse engineered"? Dunno, just a guess.

I've got Voskhod/rockets on their way from Ukraine now. Just passing through NY on the way to me in AK. :D Dirt cheap for a desirable tube.

I'm not thinking that the reissue TS6550's are very much like the vintage originals. More that 6550's are an interesting choice in general. It is also interesting to me that, to my ears, the TS reissues are more pleasing than =C= 6550's. Don't think I'm going to spring the big bucks for vintage TS6550's at this point - but I could change my mind at any time! :tears:

:music:

I'm a blues harp player and just love good recordings of great harp playing. Was listening the the first Canned Heat album. Man, Blind Owl Alan Wilson never sounded better! "Goin' Down Slow" :thumbsup:

I love the music suggestions! It's great to discuss and share great recordings. Especially the ones that give you that warm glow as you're relaxing in your listening chair. Steve Earle's release with the Del McCoury Band "The Mountain" sounds great. If you're into the newer/alt music, the new one by The War On Drugs "Lost In The Dream" sounds great. Can't get that one out of the player.

I tried a couple of the 6N1P's I had, but they weren't as extended on the top or bottom compared with the Siemens gold pin E88CC. They sounded a little closed-in by comparison. The Siemens seems to do everything right with the TS6550's, but when the 6V6GT's find their way back into the amp, back in goes the Telefunken E88CC.

I wish I knew more about the design of the driver/power tubes. There definitely seems to be some synergies between certain sets of tubes. The differences between the various rectifiers is a little easier to understand because you're using those to vary the voltage to the rest of the amp, and those differences can lead to audible differences.