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.

Wow interesting design indeed and very powerful as well.
Not really into tubes, but for this one I'd give a try someday to listen out of huge curiosity. Must be a great unit indeed.
give Matthew Rotunda at Perfect Pitch Audio a call ... he sells those amps and is very knowledgeable in all things tube related!
Thanks Jrinker. I'll give Matthew a call.

I love my dealer (In Living Stereo), and they thought my strategy outlined above would be a useful approach, but then I called a very reputable tube guy who thought it would be a complete waste of time. So far, it's been a perfect microcosm of our hobby, with two experts completely at odds with one another! At least it's really fun figuring it all out.

Didn't pick up the amp and already replacing the tubes. You are a true audiophile. Enjoy your new amp.
Dkidknow, what speakers are you driving with the 518?
Sounds like the amplifier operates class A2. Otherwise one would not need such a hefty driver tube.
Chayro: Apparently, I absolutely am that guy! I've been enjoying the amp for a couple days now.

Tb: I'm driving Merlin TSM-MME. I also tried the 15W leben integrated, but it really didn't have the grunt to drive the Merlins. I'm not sure if it's the extra wattage or the current capability of the 845s, but the LM was a much better match for my speakers.

Ralph: I had never heard of class A2 until now. I just did a little reading-- very interesting. Until then, I would have had to use my best Nigel Tufnel accent to say class A2 is "one louder" than typical class A! Thanks for the info.
We operate our amps in A2 mode as well. Fisher in the 1950s that made the first A2 amplifiers that I ever heard of.
Ralph-- you might find it interesting that my Merlin TSMs, which are 8 ohm nominal and 6.5 minimum, are really enjoying being driven off the 16 ohm taps of the Line Magnetic. I'm getting a very open and extended sound but all of the bass definition I could want.
Congratulations with the new amplifier. I get the impression that the Line
Magnetic 845 amplifiers are exceptionally good and possess excellent drive
capabilities. Based on owner reports like yours and also reviews, these LM
SETs are using high quality output transformers coupled with good power
supply design. As Ralph noted, the driver tube/ stage is robust.
I don't think Ralph would be surprised with your results using the 16 ohm
tap, you have to experiment with different speakers to find the best tap
usage. This amp offers much flexibility to tailor your sound with driver tube
choices. Also different brands of 845 offer additional fine tuning, there's
great potential with your amplifier. I believe that it's a true High End bargain.
Dkidknow, yes, the Merlins are an easy to drive speaker. I think that is the most popular speaker used with our M-60 amplifiers.
Thanks for the input Charles. The amp is still breaking in, but I'm confident I'll get to a good place. My dealer was nice enough to let me bring my speakers over to audition them before I bought, and the combination was very engaging. I'm going to let the amp and tubes really settle in and get a handle on the sound before rolling tubes. I do have some mid 1990s Svetlana 6L6s around the house as spares for my guitar amp, so I suppose I can pop those in to see how they sound.

As far as Merlins being easy to drive, they certainly do have that reputation, and I know Atmasphere amps are generally thought of as a very good match for them. However, as I mentioned above, I first paired the Merlins with the Leben CS-300, and the Leben really couldn't drive them in a satisfying manner. This was strange, because the Leben did an amazing job driving a pair of Dynaudio Focus 260s, which at 4 ohms nominal impedance, would theoretically be a harder speaker to drive.

I also think the Line Magnetic is tonally just a better match for my Merlins-- the Leben sounded a bit lean on the Merlins, but fantastic on the Dynaudios. By the same token, the LM/Dynaudio combination yielded some plummy/wooly bass, but through the Merlins produced the best bass I've ever heard from my speakers. It would have been interesting to hear the more powerful Leben CS-600 paired with the Merlins, but that amp was just a bit too expensive.

Truth be told, I was pretty sold on Leben when I went to the store and was just trying to make sure they could drive my speakers. There was really no contest though and I had to change my plans.
Virgin Poster: I am thinking of buying a Line Magnetics 218IA to drive my newly arrived GoldenEar Triton 2's. The GE have their own woofer amp (Class D) and are self-rated at 91 Db efficiency, so they are supposedly "an easy drive."

Does anybody have any experience with this kind of a combo?

I am fantasizing about my high school tube system: single driver speakers (God knows what) in plywood, unfinished cabinets, w/ a small tube Int. Amp. It was my first "stereo" and it sounded fantastic, but I was embarrassed (2 years later) to bring it to my college dorm because it looked "old fashioned" and I wanted a SS system. Got one prior to going off to school and I have been frustrated since.

Is LM the answer to my dreams?
Welcome DRS! I haven't heard the LM 218 or your speakers, so of course I can't form much of an opinion as to their synergy. I am finding that the 518 has a lot more drive than its 22 watts might otherwise suggest. It's always unsatisfying to hear "you need to see for yourself," but here it's really true. Find a dealer and check out the amp. On paper, sounds like a decent match, but you'll never really know until you try. I am a very happy camper though.


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?
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.
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, 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.
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.
Truemaniac, thank you for the perspective. This is definitely a quandary for both the dealer and the customer. I guess my attitude is why have local dealers if they are unwilling to offer this kind of service. Might as well only sell the products online, cut out the dealer margin, and perhaps lower the price a bit to sell more units. Frankly listening to electronics in any system other than your own is a crap shoot. I don't have any ill feelings towards this local dealer. It's his business and he can run it any way he feels is right for him. In this case, there was not a good match between seller and buyer. Happens all the time. I will happily move on and look for a product and dealer better fits my needs.
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.
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.
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.
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.
I own the Line Magnetic 518IA. I have reviewed it on www.wallofsound.ca

First, the stock power tubes are great. They are the Psvane HiFi Series. Good to see that LM didn't just put cheap entry level Shuguangs in. I just bought a pair of HiFi Series from PartsConnexion. They are identical to the stock tubes.

The most important tube to roll is the 12ax7. I have some Psvane Treasure mk2's in right now. These are remarkable tubes--brilliant from top to bottom.
My favorite, though, is the TJ Full Music 12ax7. So warm! The new production Genalex Gold Lions work very well too.

Second, in order of importance, I think, is the rectifier. I would remove the stock Shuguang and replace it with NOS or with a current production Mullard, Genalex or Tung-Sol. I have the current production Mullard. This, plus the Psvane 12ax7s, has eliminated all hum. Plus consider an Emotiva CMX-2 to get rid of hum produced by your line.

Third, the driver tubes. I am a 6L6 freak. I have over a dozen pairs than I use in single ended amps. After rolling all sorts of 6L6s and EL34s, I settled on... wait for it... Shuguang Treasure black bottles. The ones sold about 2 to 3 years ago. They impart a muscular tone and rhythmic drive to the amp that I find compelling.

This amp really is incredible. It is so fast, but so smooth. It has unlimited reserves of power with most dynamic speakers. You won't use it for Maggies, but virtually everything else will work.
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!
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 taste….
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.
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.
The Pxvane 845 II ,12ax7 II and the 6ca7 II sent my 518 line magnetic to heaven
I recently auditioned the LM 518 mated to a pair of Harbeth 7s, the same speaker Tim used in his excellent review. It sounded absolutely horrible. Congested, bloated, dull, slow, and completely devoid of any dynamics. Everything from the lower mids down was a complete mess. The dealer was apologetic and as he said, "embarrassed" that I set a Saturday aside to drive the considerable distance to hear (and not hear) this highly regarded amp that we both agreed was unlistenable. I was really wanting to love this amp and was sorely disappointed when it wasn't even close. The dealer attributed the poor sound to what did seem to be a rather pronounced echo in his listening room, however, it sounded so poorly, I wasn't convinced that could be the primary reason and declined his generous in-home audition offer. As a consequence I've since ordered the Coincident 845 SE and can't say that based on my experience, I could recommend the 518 to anyone.
In my experience Harbeth's sound much better with solid state. When paired with warmer sounding tubes they can sound dull, veiled and congested. IMHO YMMV
My experience with LM 518is driving Daedalus Argos V2s is that it is an exceptional match. Dynamic, transparent, soundstaging, placement, etc. CSwapped in NOS tubes except for supplied 845s which I have not changed; not sure if I will try Shuguang 845bs or Natual Sound 845s. 
If you get a chance you should try a pair of WE845 by psvane. They are a very interesting tube. They make everything subtlely better. They let you listen deeper into the details of the music in all areas. I did have some reliability issues, but once I got a stable pair , they are fantastic. Tried in both the 518ia and a 219ia. Driving 0/96 and some HUGE homemade pioneer TAD based speakers.
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