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Tube Amp for Martin Logan Speakers

Hi, I love tube sound through my Martin Logan Aerius-i fronts and Cinema-i center. I currently have a Butler 5150 which is a hybrid, but it busted on me and would cost $700 to fix. I've had china stereo tube amps that were pretty good and gave true tube sound, but not enough drive for higher volumes. I live in condo, so not like I can blast music anyways but still. I got the Butler because I wanted 5 channel tube sound for home theatre (The piercing sound from my Denon 3801 receiver was not pleasant to my ears). It appears there are only three multi-channel tube amps around, from Mcintosh, Butler 5150, and Dared DV-6C. The latter two are hybrids, and the last one was one of the worst tube amps i've ever heard. I have no clue why 6Moons gave the Dared a 2010 award, but maybe it's because it produces only 65W.

So since multichannel tube amps are hard to come by, and they tend to be hybrid, I was thinking maybe it would be best to get three true tube monoblocks to power my fronts. Thing is I wonder if they will be underpowered for my speakers, and not sure which ones are decent for the price. Maybe China made ones would suffice, and they still go for pretty expensive price. I'm wondering if anybody knows of a decent powerful tube monoblock that is affordable, because I can't pay $3000 per block. or maybe best to just repair my Butler. Thing is, I'm not confident that it is reliable. The tubes are soldered in which is weird, and i've taken it to a couple repair guys who both said that the design is not good, because it's very tight inside and more susceptible to being fried from DC voltage areas. it's too sensitive.

Any suggestions for tube monoblocks, even if china made ones? the holy grail for me would be Mcintosh tube amp, but they are hard to come by. Thanks.

smurfmand70
unsound
7,329 posts
 
Al, thank you. I thought I might have missed something. Still, the last paragraph seems to suggest what I think most could reasonably expect:
"...Figs.5-7 show the measured impedances of the 2Ce, Angelus, and Aerius. Note that the Sonic Frontiers' frequency-response deviations when driving these loudspeakers show the same general trends as the impedance magnitudes of each respective loudspeaker. That is, the peaks and dips in the responses correspond closely to the peaks and dips in the impedance plots. The impedance plot therefore gives a general indication as to just how a given loudspeaker's response will change when used with an amplifier having a high output impedance.—Thomas J. Norton"

Unless there is some sort of internal eq or the impedance actually compensates for the drivers-crossover/speaker systems inherent deviations from flat frequency response (something that has been done to some degree in crossover designs from other manufactures, but something I've yet to hear attributed to ML designs), I'd hazard a guess that it might be reasonable to extrapolate that the sound output to somewhat mimic the impedance/frequency graphs provided.
unsound
7,329 posts
 
Atmasphere, perhaps I'm not seeing the same things you are?

And, Bifwynne's post re: MLs amplifier recommendations seem to suggest amplifier characteristics that are at odds with your post
"...IOW the ML ESLs are a low impedance Power Paradigm loudspeaker."
almarg's avatar
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almarg
9,670 posts
 
04-09-14: Unsound
Unless there is some sort of internal eq or the impedance actually compensates for the drivers-crossover/speaker systems inherent deviations from flat frequency response (something that has been done to some degree in crossover designs from other manufactures, but something I've yet to hear attributed to ML designs), I'd hazard a guess that it might be reasonable to extrapolate that the sound output to somewhat mimic the impedance/frequency graphs provided.
As I indicated I have no specific knowledge of the behavior of Martin-Logan speakers. But keep in mind that application of a voltage which is constant as a function of frequency will result in power delivery which progressively increases as impedance decreases. (In saying that I'm oversimplifying a bit by ignoring phase angle effects).

As you'll realize, what a speaker basically does is to convert some fraction of the electrical power supplied to it into acoustical power. And as Ralph pointed out earlier, the efficiency of an ESL (power out vs. power in) does not decrease in step with impedance as frequency increases, but instead remains pretty much constant as I understand it. So in the absence of specific indications to the contrary I see no reason to expect flat frequency response in (in terms of voltage) to result in flat frequency response out.

As I see it the usefulness of TJN's measurements is that they provide insight into the DIRECTION in which tonality will be affected as a function of amplifier output impedance. But they provide essentially no insight into what output impedance will be optimal.

Best regards,
-- Al
georgehifi's avatar
georgehifi
10,312 posts
 
From the Marin Logan website:

Quote:
However, it is important that the amplifier be stable operating into varying impedance loads: an ideally stable amplifier will typically be able to deliver nearly twice its rated 8 Ohm wattage into 4 Ohms, and should again increase into 2 Ohms. Quote:

Cheers George
mapman's avatar
mapman
22,198 posts
 
Where did ML ever pick up that crazy paradigm?

I guess it's always easier to put the burden on the other guy :-) That's a pretty safe bet no matter which way one thinks technically.
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