2. amps-preamps
  3. 1392024857

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
dkidknow OP
61 posts
 
I've read your review Tim and have shared a lot of your observations. Kudos on a well written review that really captures the soul of this amp!

Although you and my dealer both suggested the preamp tubes would make a lot of difference, I've found them to make a more subtle difference, although I haven't done a proper shoot out with all my tubes on hand. I'm liking a pair of 1960's Mullard CV4004 best so far. Agree the rectifier is very important. I'm using a '60s Mullard there too, and it widened the soundstage considerably. I haven't experimented with many 6L6 or 5881 types, but looking for a nice pair of KT66 to try. So far, my favorite drivers have been a pair of 1950s RCA Greyglass 6V6 tubes I pulled out of a non-working RCA console radio I bought at a consignment shop, and an original pair of Genelex Gold Lion KT88 I happened upon on another tube hunting excursion. I must say I think the drivers are important too. It's probably more a case of making sure it's not a bad fit-- the good ones all work well, but a pair of EL-34s (and they we're pretty good ones) made the amp sound almost broken to my ears.

Agreed its a fantastic amp. Looking forward to adding an analog source quite soon!
tim_smith
8 posts
 
I have had the amp since the spring. It amazes me day after day. Try some NOS Philips Miniwatt 12ax7s. I have those Mullards you mention; they're great. But I like the Philips better because they produce a fatter tone. That's just down to personal tasteĀ….
rleff
1,065 posts
 
What is the return policy on those dealers that would not allow a home audition?
If they would allow a return if the match was not what you wanted along with a refund and not store credit I might go for the purchase and give it a try.
I can't believe dealers that would not allow a home audition of higher end gear; to me the wrong business model.
These amps look very interesting to me as well.
jslateiv
64 posts
 
I have found that the 5751 (GE, JG5751 Blackplate '57) is a phenomenal input tube in this amp. Very smooth, great extension, none of the 'glassiness' that I heard with the stock tube. I also tried a JAN Sylvania 12ax7 that was better than stock but not near as good as the 5751. So far I am preferring 6L6 & 6V6 types over EL34 or 6P3P. I fing the 6L6 and 6V6 to be very similar with the 6L6 to have a little better bass presence. The stock 6P3P was a bit veiled across the entire freq. spectrum compared to these other 2 types.
dodger4
61 posts
 
The Pxvane 845 II ,12ax7 II and the 6ca7 II sent my 518 line magnetic to heaven
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