Line Magnetic 518ia - How Much Heat Does It Produce?

Hello, and thanks for any help with this. I'm helping a very dear friend, who loves music, and good audio equipment, put together a system. He has suffered some very serious personal setbacks of late, and one of the key things he has turned to, is putting together an audio system as a means to attempt to move forward. He is trying to put together a nice audio system in what he has available, a small room.

He travels a fair bit for work, and has had two recent experiences listening to the exceptional Line Magnetic 518ia, and was blown away by it. I can guarantee you that he has heard some very good audio components, but has been captivated by the 518ia. If you have heard it, or read the reviews, you understand, as I do. That's a truly amazing piece of gear, especially for the price.

Here is my concern, Because of serious budget deficits related to his other problems,  he can only afford one of these wonderful integrated amps, used. Okay, they are available  in his price range. I have him set up with speakers and everything else to maximize the quality of his system. But, this is a Class A amp, even if relatively low wattage. He would be using this in a 10x10 room, with the integrated amp only 2.5 feet away from where he sits. There is no other available placement. Is this going to overheat him, and/or the room? 

Any input would be appreciated. If he cannot make use of this amp he loves so much, it could get very difficult to find anything else, given it's price performance capabilities. 
Wish I could better answer your question, I have the 518 but in a 28x20 room and find that I only "feel" heat when I walk right up to the amp. 

(BTW I dropped in some NOS 5751s, 6L6GC and 5AR4 rectifier and the ytake the amp to an entirely new level). 
I had an ARC D115 MKII that idled at 400 W, same as the 518ia. The 10 x 13 room was uncomfortable within an hour (door closed). I had to sell it. 

It could work depending on where you live.  In the northern part of the country, in the spring/fall/winter months, a touch of tube warmth is welcomed.  In the summer, the heat could be problematic.
I live just outside of Memphis, summers are hot as hell and humid , the amp makes no difference , ac runs regardless and not anymore because of the amp
Wait for a 502IA used
47W Single Ended
about same price

Even with AC, some heat will be noticeable.
Maybe move the integrated by or in
between one of the speakers on an amp stand and run a longer interconnect from the source to the integrated amp.  I am assuming he is sitting at lease 6-8 feet from 
I have a 518ia in a fairly large room and I love it. Yes, it gets hot, but so do all tube amps.

IMHO, this is a ridiculous concern as long as you don't live in a shack out in the woods. Most modern homes have what we call "air conditioning". Works like a charm. I don't notice the heat no matter the season of the year.

Unless the thermostat is in the 10 x 10 room, ac vs. 400 W space heater is a no-go.  Been there, done that.

Thanks for everyone's input. Some of you clearly understand where I am coming from, others apparently do not. Yes, all tube amps put out heat. But dependent on design, tubes, and class there is a very wide variation. For example, I was out of town recently for three weeks and loaned him my office systems PrimaLuna tube amp. He had no heat issues whatever, but felt the amp, while very nice, was not in the league of the 518 (which I agree with him on). 

The Line Magnetic is Class A, and uses some tubes that run extremely hot. Thats a very different situation than normal in the tube world. I once had the experience of using an 845 based amp, with heat output not even quite to the level of the 518ia. I used that in my office, which is 10x11, and even with the door open, and the ac running it was too hot to work in the room. I did use it for a couple months the next winter, and after an hour of use, it had raised the temperature of the entire upstairs of the house by 5 degrees. 

I'm going to have to agree that the advice from wlutke, testpilot and others. This solution won't work. Now my problem is that, given that he loves the sound of that Line Magnetic amp, how do I possibly find something comparable to it in the same price range :(
I will respectfully disagree with ozzy62 as I don’t consider this a "ridiculous " concern. Given the very small room size and close proximity to the amplifier heat output is a legitimate concern. A 300b SET amplifier (such as mine) wouldn’t be a major issue. However the 845 output tubes are an entirely different matter. These large transmission tubes generate considerable heat that will be quite noticeable in close quarters.

I certainly understand the desire to own this amplifier. 845 tubed class A SET will provide difficult to equal beautiful, palpable and natural sound.
Bottom line, significant amplifier heat output in very tight surroundings.
There are numerous very good sounding tube push pull amplifiers using indirectly heated tubes, KT 150,129,88,el 34 etc. The DHT SET amplifiers such as The LM 518a are as your friend heard just different and sound fantastic. I know how he feels. Prima Luna is nice sounding but not the same.
Post removed 
I agree with the conclusion that "this solution won’t work."

For a class A amp the calculation is simple. The amp is spec’d as consuming 320 watts, and given that it operates in class A virtually all of that power will be converted to heat and radiated into the room whenever the amp is powered up, regardless of whether music is being played or not. And in this case into a 10 x 10 room at a distance of only 2.5 feet from the listener. That seems to me to be completely untenable.

A small handful of those 320 watts will be sent to the speakers when music is playing, but the great majority of even those few watts will then be converted to heat by the speakers. The rest of the 320 watts will be radiated into the room by the amp.

Also, based on the specs I’ve seen for various Line Magnetic models their power consumption generally seems to be particularly high relative to their output power ratings and class of operation. In the case of the 518ia, for example, 320 watts input divided by 44 max watts of output for the two channels is a ratio of 7.3, very high even for class A operation.  Or putting it another way, 44/320 = 13.7% efficiency, very low even for class A operation.

What speakers are being used? Perhaps less power than 22 watts per channel is necessary, especially since the listening distance will be minimal?

Best of luck in this endeavor.

-- Al
I find it rather strange (bizarre?) that some are discounting the close sitting proximity to amplifiers dissipating 320 watts!!! (Essentially a room heater in a tiny space). As Al mentioned regarding speakers, more efficient models could possibly mate with a 300b SET. Far less heat generated compared to the 845.
Thanks again for everyones thoughts. Now the struggle is finding any integrated amps that will satisfy my friend (based on his loving the sound of the 518ia). It clearly needs to be something  that won't overheat him, and the room, is available for  $3-3500.00, used, and is somehow comparable to the sound of the Line Magnetics.

I've already discussed it with several audiophile friends that are familiar with the sound of the 518ia, and they too, are having difficulty coming up with something that meets all of the above. One initially suggested a Unison S6, which does sound like a real possibility, but I think that might  also present a heating issue. Its a Class A amp, only moderately powered, but in the Stereophile review, John Marks notes that, " The S6 performed flawlessly, though it did throw off a lot of heat.". That surprises me since it uses EL34 tubes. 
The Unison S6 has a specified power consumption of "265 VA max." Given that it is a class A design that probably means a continuous draw of not a great deal less than 265 watts, which in turn is not greatly less than the 320 watts drawn by the LM-518ia.

An EL34 requires close to 10 watts just to heat the filament, and I'm guessing that in this design each of the six EL34's consumes something like 25 watts in total. So that's 150 watts just for the power tubes, plus additional consumption by the power supply, the small signal tubes, and other circuitry.

I don't have a solution to propose, but as Charles and I stated earlier perhaps the answer involves going to a less powerful amp than the ones that have been mentioned.

Good luck. Regards,
-- Al 
Unison Research is an Italian company that has a reputation for good sounding tube amplifiers. My suspicion is that it will fall in somewhere between the Prima Luna (class A/B push pull) and the LM 518a (class A SET) . The S6 model is class A and parallel SET with 3 el 34 per channel.

I bet this amplifier sounds really good given the design, circuit and topology. Don’t know if it will equal what your friend heard with the 518a but you never know until you’ve actually listened . As Al noted heat output is still a concern. I sympathize with your fiend, he has good taste/ears but limiting circumstances.
Even el 34s will generate noticeable heat if they’re operating in class A. Just goes with the territory if the amplifier is rated at say 20 watts and higher. I had a borrowed First Watt S.I.T push pull amplifier (35 watts class A) for several weeks and if ran hotter than my 8 watt  300b SET mono blocks.

Class D amplifiers would be an obvious solution if your fiend can find one with sound he could live with. Not sure if he’ll find one that mimics the LM 518a. Well executed class A is hard to match let alone beat.
Al, and Charles, thanks to both of you for the input. I agree with everything you both had to say. The Unison is an intriguing option, but I suspect may still be too hot to be placed so close to my friends seating area, etc. 

He needs 25-35wpc, ideally. An amp that puts out a bit less but plays above its level, in terms of delivering power might also work. 

Charles, I find it very interesting that the First Watt S.I.T.  ran that hot. Was it the fabled S.I.T. 1, or the S.I.T. 2? Granted, some of Nelson's designs, despite being solid state, can get seriously, seriously hot. I was auditioning several sets of speakers for about 90 minutes last year with a friend. The dealer had us in a huge showroom (literally 100x50. He was using  a pair of Pass X600.8's, which aren't even pure class A, except for the first 100 watts or so (or something like that). Even in a room that large, by the end of the audition, we were sitting there with our shirts completely stuck to us,and sweating liberally from our heads! My friend actually had to go home to shower before meeting a group of us for dinner! 
A I sit here listening to my LM 518 driving a pair of klipschorns in all their musical glory, I feel sorry for your friend that he has to pass up such a great amp.

Respect Al's and Charles' views and maybe the amp is too much for a smaller room. That said, I can assure you that this amp isn't going to heat and entire upper floor , nor in a room such as mine 28x20 going to cause sweat to be dripping nor the ac not to normal shutoff ala some other "apparent experiences" with other amps. Unless I get within a foot of the amp I don't feel any heat. Best of luck to your friend finding an amp that won't cause these exaggerated experiences.
The First Watt S,I,T. amplifier loaned to me was a "push pull" version (Nelson Pass D.I.Y. using the same static induction transitors) that has more power than the single ended versions you cited. It’s still a pure class A circuit with about 35 to 40 watts. It generate more heat than my 8 watt SET which is only 1/5 the power output so less heat is dissipated.

Yes I agree too bad he’s unable to use the excellent LM 518a. Keep in mind he has far less cubic space than you have. 28x20 versus 10x10 (substantial difference and factor in ceiling height). That small room will heat up quite rapidly and become very uncomfortable. It’s going to be difficult to find a comparable sounding amplifier that also runs cool, just my opinion.
I looked at your system page, very nice!!
Your room has a 10 foot ceiling. 28x20x10 that’s a lot of open cubic space to handle amplifier heat. No doubt that the LM 518a driving the Daedalus speakers is a pure sonic joy. Do you alternate the LM with your Modwright components?
Thanks Charles. I haven't updated the photo as I pulled the turntable out (not enought smooth jazz available on vinyl, have it in my 2nd system) and inserted a Finale Audio 7189 MK2 (EL 84 based ) 22wpc integrated on that bottom shelf. I rotate between the Line Magnetic, the Modwright pre/power, and the Finale every 2 weeks to change things up. I enjoy them all with the Daedalus

While I can’t speak to how its sonics would compare to those of the LM-518ia, an approach that you may want to consider would be the combination of a Music Reference RM-10 MkII power amplifier, purchased used, with a relatively inexpensive passive preamp. The RM-10 MkII, designed by the very accomplished and well regarded designer Roger Modjeski, utilizes a push-pull pair of the highly respected but low powered 6BQ5/EL84 tube, in a cleverly designed circuit providing 35 watts per channel (significantly more than the power capability of any other EL84 amp I am aware of), while consuming a total of only 70 watts at idle. And its 100K input impedance and 0.95 volt sensitivity make it well suited for use with a passive preamp.

One of these amps has just appeared for sale here. It is stated to have been purchased new only 9 months ago, and has an asking price of $2950. (The list price for a new RM-10MkII is indicated at the manufacturer’s website as $5K):

Links to the manufacturer’s pages on this amp:

On another note, @facten , as a fellow owner of Daedalus speakers I certainly second Charles’ praise of your outstanding system :-)

-- Al


Once again, thanks for your thoughts. I have great admiration for Roger Modjeski and his products, and I happen to think his RM-200 is one of the truly great values out there. The problem is that his amps are designed and optimized for fully balanced operation, per my relatively recent discussion with him. Good luck finding a truly good, balanced preamp affordably! 
nightfall---while the RM-200 is a fully balanced amp with XLR input jacks only (I agree with you about it, owning a Mk.2 myself), the RM-10 is not. It has RCA input jacks, and is a great little amp (THE best for old Quads, for which it was designed). An excellent suggestion by the always-dependable Al! Roger Modjeski is also offering numerous low-power single-ended amps and passive pre’s. He is also making ESL speakers with dedicated direct-drive (no input transformer on the panels!) OTL amps. Not trendy or expensive enough for most audiophiles apparently, Music Reference is the best kept secret in hi-fi. Along with Eminent Technology, of course!
The RM 10 is a wonderful amp.  I used to own two mk2's and powered both Quad 63's and Merlin's. I think you'll  find it to be very different than the 518 though. It's much more transparent.  But holy cow, whats happened to the pricing at Music Reference?  Not that long ago retail for the RM10 mkII was about 1/2 current retail.
Nightfall...I have never heard any of their offerings..but they seem to get great reviews.

Triode Corporation of Japan
I would recommend two integrated / amps from Decware
I have listed below some links to reference material.
Both amps use EL34 / KT66 and similar tubes and operate in pure class "A" with no feed back. Both are guaranteed for life. 

I am considering The mystery, Line Magnetic 502ia, or Audio research
VSI 75.

Brad do you mean the LM 508ia ? What is the 502ia tube complement?
@ almarg

Txs Al for the compliment on my system. Also, txs for all of the insightful information you impart in many threads
I cannot find a Line Magnetic 502ia model offered for sale in here in the US. 
Brad, Interesting that you brought up Decware. I've honestly never heard their stuff but have read many glowing reviews and they fascinate me as a possible option. The Mystery a,mp is beyond my friends budget, but the Zen Torii MKIV would qualify. I had just finished reading that review by Jeff Dorgay of Tone Audio when I came across your message here. It may only have two inputs, but honestly, that is all my friend needs. 

Built in the USA, lifetime warranty, and free home trial  on their products are other great reasons to support Decware 
In looking at the description and specs of the Torii IV I see one major potential issue. Assuming the specs on sensitivity and maximum power capability are accurate, it can be calculated that its gain is extremely low, even for a power amplifier much less one that could and would be used as an integrated amplifier. Specifically, I calculate a gain of about 17 db into 8 ohms, and even less into lower impedances. Typical power amp gains are in the mid to upper twenties, and typical integrated amp gains are in the mid to upper thirties.

If an active preamp providing substantial gain is not used ahead of this amp, with most vinyl and other analog sources the consequence of that will be that even with the volume control at max a substantial fraction of the amp’s power capability will not be able to be utilized. Probably well over half of that capability in most cases, and perhaps 3/4 of it or even more in many cases.

With digital sources that would be less of a concern, but I would still expect that without an active preamp there would be some recordings, especially some of those having wide dynamic range, for which the volume control would not be able to be turned up high enough to satisfy.

Finally, while the heat issue may very well not be a concern with this amp, given that it is a class A amp it would be good if a spec on power consumption could be obtained from the manufacturer.

Eric (bdp24) and Facten, thank you kindly for the nice words :-)

Best regards,
-- Al
Al, thank you for your always valuable advice and expertise. That gain concern is a real issue if intending to use it as an integrated, as you wisely pointed out. You saved me from potentially making a mistake in recommending the Torii MkIV. I truly appreciate the input.
My little Dennis Had Firebottle HO (it's a HO...says so right there) has only 4 tubes and ties you to efficient speakers for ultimate enjoyment (it's a 12WPC class A SEP meaning Serious Enjoyment Product), so there's that. However, it runs hot as hell and I mean all over the damn thing, which is how it's designed...less overall heat than a power amp with more tubes running, but And utterly worth it as it sounds fabulous...I give a lot of air of course, and fully expect it to melt into a pile someday, but after daily use for a year and a half it hasn't. Yet.
The Line Magnetic would definitely put out too much heat in that size room.  My recommendation would be a Leben CS 300XS.  It’s compact and produces minimal heat as current draw is listed as 82W.  It sounds killer on Devores and Proac’s.  Don’t underestimate the 15W rating.  It plays much bigger than you could imagine.  Plus it’s retro cool looking and artisan quality build.
I just upgraded from a Jolida JD302CRC (50 Watts) I used EL34,and KTT7 power tubes (matched quartet) and in my normal sized living room it was not a problem. Watchful with pets and children as it was open chassis with pretty tubes glowing.
My new amp a Jolida 1000 BRC (100 watts or 150 watts with 6550 tubes) It has 8 power tubes EL34’s so far, and it puts out a tremendous amount of heat. I live in Fresno, CA the last day day it was not in triple digits was a month ago and I am using a cooling fan on it. It has tubes covered behind glass and surface temp was 143F, with fan about 101F. I have it in a salamander archetype rack I hope it don’t bake the component above it. My last Jolida has lasted 12 years with only tube changes, and pot cleanings. Simple-Perfection. My Preamp is a Cambridge 851N [network streamer/preamp/dac]. I run Amp in bypass mode for all but vinyl for that I use Vincent PHO 8 phono amp VPI Scout Jr. Grado Platinum Reference MM.
Can the tube cover be removed from the 1000? I wondered about that when I considered replacing a great sounding Jolida 502P I used for 5 or 6 years...I went in the direction of the single ended Had amp, but have nothing but respect for modern Jolida stuff and enjoyed talking to the MD Jolida people when researching the tube amp possibilities.
Two possible suggestions.  One is go for a mosfet based power amp, and a tube based pre-amp.  You will a good tube sound out of that.

Second, given the room is small you can probably get by with a less powerful amp.  If you have sensitive speakers then two watts should be plenty.
Recently acquired a Manley Stingray II. Uses 4 EL84 tubes per channel and runs pretty cool. Have it in a smallish room. I favor triode mode with 18 watts output. No heat issues whatsoever. Sounds great with efficient floorstanding speakers. 
This may be a possible solution for your friend.
Is this amp good at timing?
Thank you.