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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
georgehifi's avatar
georgehifi
10,312 posts
 
That's because the McIntosh 275 has quite a low output impedance for a tube P/P amp at .57ohms from the 8ohm tap.(probably has a fare amount of negative feedback)

But the Montis would still be a hard load for many amps as John Alexander's measurements state
" The shape of the impedance trace will result in the Montis's top octaves shelving down when the speaker is driven by a tube amplifier having a high source impedance. This is why Robert Deutsch found that his Audiopax amplifier sounded too soft and lacking in definition."

Cheers George
mapman's avatar
mapman
22,698 posts
 
My understanding is low impedance in treble region does not present nearly as much of a challenge as same in bass in that exponentially less power is needed for flat treble response. I think that is the main reason why tube amps can do well with those.
bifwynne
2,206 posts
 
The title of this thread is "Tube Amp for Martin Logan Speakers." The lst couple of posts give me considerable pause. Let's go back to square one basics.

Seems to me the first question that comes to mind is what did the ESL designers have in mind? That is did they design these speakers to be driven by a low output impedance amp (e.g., SS) or a high impedance tube amp. Regardless of whether the amp in question can drive these beasts without shutting down, with or without ZEROs, the impedance plots are so wacko that matching the wrong type of amp may likely cause considerable sonic colorations.

So, does anyone definitively **know** the answer to my question? What did the designers intend?
mapman's avatar
mapman
22,698 posts
 
I don't know what designers intended for certain, but I suspect SS amps all the way. ML is pretty mainstream and tube amps and speakers that work best with them is way more of a niche market.

The best ML demos I have heard was off a Krell integrated amp in one case and a similar Classe amp on another occasion.

I have never seen or heard them with a tube amp.
bifwynne
2,206 posts
 
Well that's kind of an important question Mapman because given the wacko impedance plots of these ESLs, hooking them up to a high'ish impedance tube amp could really color their sonic presentation if indeed these speakers were designed to be driven by an amp whose output impedance is measureable in decimals points.

And while in such cases ZEROs may "trick" a tube amp into thinking it's not driving into a short, the sonic presentation will still be skewed because the ZEROs will not flatten or "normalize" the ESLs impedance plot.
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