Power tubes as drivers -- Line Magnetic


I just purchased a LM 518 IA, which is a 22 watt SET integrated using 845 tubes. The amp uses 2 6L6 as drivers and 12ax7 for input.

I'm picking up the amp this week, and although I haven't seen the user manual yet, From what I can gather, virtually any power tetrode or pentode, including EL-34, KT-88, 6L6 and 6V6 can be used as a driver in this amp. Of course that means I'm getting ready to try a buncha tubes.

My current thought is to pick up decent, but not expensive, current production samples of the various tubes (probably all made by the same manufacturer to maintain some control) so I can get a handle on which sound I prefer most, then move on to more expensive and probably NOS versions of those tubes I like best. Just checking in with the community for reality check on if this makes sense to anyone else.

Also, I've seen on various tube sellers sites reference to "this (noisy/micro phonic) tube is only suitable for use in a driver stage . . . ." Can I infer from this that I can get away with slightly dodgy driver tubes and thus buy really fancy schmancy tubes in low grade and still achieve good results?

Will appreciate your thoughts.

D
dkidknow
Tboooe,
I like your attitude, find a more cooperative dealer. One of the supposed advantages of a brick and mortar dealer is providing equipment for home auditioning.Truemaineiac what increased Tboooe's interest is a review of this very amplifier driving his speakers brilliantly.
Charles,
TB. Looks like you already found the Steve Huff review of the 518 and 219. He's having such success driving your speakers with the LM amps. I haven't heard the 219, but have had similar experience with the 518's "fat" sound. With my Merlins, this is very welcome and I'm happy to have a bit more bass. Mind you, that isn't code for "bloated"-- it's taut and tuneful bass rather than one-note boom. Steve does seem to prefer the 219 with the Sonus Fabers, but I believe that amp is about $3k more than the 518 and those 300b tubes make for expensive tube rolling, especially considering how expensive 845s are.

Steve's experience should give you a lot of comfort. My dealer wouldn't let me bring the amp home either, and bringing my speakers into the shop was definitely a distant second choice, but I did get to spend as much time as I wanted driving my speakers with the 518 and was therefore absolutely sure it was the right choice. It's a bit more hassle, but you get to the same desired place. I also got the benefit of the store's expertise: without their suggestion and blessing I would never have thought/dared to change output taps on the fly to experiment and end up discovering the 16 ohm taps sounded best on 8 ohm nominal and 6.5 ohm minimum speakers.
Dkidknow,
Good post! I had also suggested taking the speakers to the dealer. Tboooe has some reservations about the LM amplifier's ability to drive the Sonus Faber, well this would address that concern. Steve Huff found the 518 to be "very close" to the 219 amp and said both drove his SF speakers effortlessly. For 3000.00 dollars less the 518 seems a terrific buy.
Charles,
I have the 518IA and have experimented with the various power tubes and to my ears the vintage KT66 tubes sound the best. Sweeter and smoother than the 6l6 or EL 34. My second favorite is the 6V6. This amp requires extended break in time before it blossoms.