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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. 
nightfall

Showing 4 responses by almarg

almarg's avatar
almarg
9,670 posts
 
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
almarg's avatar
almarg
9,670 posts
 
@nightfall

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):

https://www.audiogon.com/listings/lis92fh8-music-reference-rm-10-mkii-tube

Links to the manufacturer’s pages on this amp:

http://www.ramlabs-musicreference.com/rm10mk2.html

http://www.ramlabs-musicreference.com/rm10design.html

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

Regards,
-- Al

almarg's avatar
almarg
9,670 posts
 
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 
almarg's avatar
almarg
9,670 posts
 
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.

Regards,
-- Al
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