2. amps-preamps
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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's avatar
tboooe
1,009 posts
 
I am dying to try the 518 with my very inefficient Sonus Faber Evolution monitors but my local dealer will not allow an in home demo. Anyone in the Southern California area want to let me borrow theirs for a few days?? :). Pretty please?
truemaineiac's avatar
truemaineiac
249 posts
 
I had the LM218 and was recommended genelex KT77 tubes from my dealer. I agree that this powers way beyond its rating and is a great value in tube audio.
charles1dad's avatar
charles1dad
6,996 posts
 
Hi Tboooe,
It's unfortunate your dealer is that rigid with you as a very interested customer.
Why not just take your speakers to him. At the very least you'll be able to assess amp drive capability with the speakers.
Charles,
tboooe's avatar
tboooe
1,009 posts
 
Charles, I thought of that. Frankly I don't want to handle my speakers too much for fear of scratching them. Besides, for this kind of money I would expect a bit more flexibility from the dealer. Unfortunately his stance was very firm and unequivocal. On well. There are plenty of other products and dealers out there who are willing to earn my business.
truemaineiac's avatar
truemaineiac
249 posts
 
Tbooe, I can see a little of the dealers perspective on this approach, these are very heavy amps to deal with taking in and out of systems. If you are worried about scratching your speakers, you can imagine his worry about having the amp messed up. Also, I would be hesitant about someone off-site testing with my low watt SET amp on inefficient speakers and driving the daylights out of the amp. It is not as unreasonable as it might seem but at the same time, spending this type of money without an audition is also tough too. Given it is not likely a good match on paper, I wouldn't buy without an audition either.

I have heard stories of a manufacturer not allowing an amp to be sold to someone unless they have suitable speakers for the amp. Reminds me of my days dealing with rare hunting dog breeds and you would have to sign a contract agreeing to a training, testing, and breeding program if you were allowed to buy the dog.
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