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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
almarg's avatar
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almarg
9,670 posts
 
Hi Unsound,

The Manley Snapper has a single output tap, which is described as having been optimized for a 5 ohm load. Its output impedance is specified as 1.5 ohms, as George indicated. Its specified damping factor of 4.7 is slightly inconsistent with that (8 ohms/4.7 = 1.7 ohms; 5 ohms/4.7 = 1.06 ohms), but is in the same rough ballpark.

You might be recalling having read something in which the author confused the output impedance of a tap with the load impedance the tap is optimized for. A not uncommon error.

Best regards,
-- Al
unsound
7,329 posts
 
Thanks Al. You are too generous, the error was probably all mine.:-)
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georgehifi
10,312 posts
 
Almarg/Unsound/Bifwyne: Looking at these figures again the Snapper's speaker termianls are a 7ohm tap to be pedantic about it.

Cheers George
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almarg
9,670 posts
 
George, if I may be a bit pedantic as well, although multiplying the 1.5 ohm specified and measured output impedance by the specified damping factor of 4.7 ohms equals 7 ohms, both the manual and this page at the Manley website clearly state that the output is optimized for a 5 ohm load.

As I indicated the numbers are not quite consistent, but I would be inclined to think it more likely that the damping factor spec is inaccurate than the 5 ohm figure. In part because I note that the damping factor number does not appear in the manual, but the 5 ohm figure does. And also because maximum power ratings are provided only for 5 ohms and 8 ohms, not 7 ohms, with the 5 ohm capability being higher than the 8 ohm capability.

Regards,
-- Al
bifwynne
2,206 posts
 
Thanks George. I looked at the review and picked up the following concluding statement that "[t]he Manley's output impedance [1.5 ohms], while not unusually high for a tube amp, is still high compared with typical solid-state designs, and may therefore have some effect on the frequency response of the speaker-amp combination.—Thomas J. Norton"

The reason I asked the Q is because Capdek said that the Manley does a good job with his ML ESLs. I'm sure Capdek has good reason to be happy with his Manley/ML combo. But I suspect that the treble may be a tad shelved and the bass a bit augmented -- just based on what Thomas Norton said above.

Obviously, unless one measured the ML's frequency response in a controlled environment, it's difficult to know what's really going on with Capdek's rig. So, I'll leave it there. If Capdek is happy -- then that's all that matters.

This has been an interesting thread. I think all of us have leaned a lot.
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