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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
hvowell
13 posts
 
Atmasphere,

Thank you very much for your response.

So, if I understand correctly, for the most part an ESL will be as efficent (output approximately the same sound pressure level or volume) at a given amplifier output, say 1W, regardless of the impedance? I assume at the impedance extreme of the ESL (less than say 2ohms) the SPL will be reduced?

I hear reference of "less musical energy" at the upper registers. Effect being these upper frequency sounds are by nature "softer/lower" in volume compared to lower frequencies and less amplifier output is required?

Again my apologies for my simplistic understanding.

Lee
georgehifi's avatar
georgehifi
10,312 posts
 


Sorry guys amp that can't keep it's end up at those 1ohms loads, will not have a flat frequency response from 20hz to 20khz no matter what level it's being played at. It becomes a tone control, end of story.

Cheers George
hvowell
13 posts
 
George,

Would it also be true than that an amp that can't make power into higher impedances is also a "tone control" of sorts?

Respectfully,

Lee
georgehifi's avatar
georgehifi
10,312 posts
 

An amp like say a Krell or similar, will remain almost flat in it's response across the frequency spectrum.
All you need to do is look at the simulated speaker load graphs of amps at 1/3 power on Stereophile to see what happens to them if they have, high'ish output impedance or can't deliver current, many tube amps exhibit this, and even many Mosfets, they are far from the ideal flat.
And the simulated speaker load that Stereophile uses is not as savage as what we're talking about here with the ML's, and things like Wilson Watt/puppy, Alexandria etc.

Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 

Here is an Audio Research Reference 150 considered by many to be a tube amp with better drive than most.

It's only being asked to drive 2.83v hardly taxing.
Look at the black trace in the link, this is Sterophile's simulated (rather easy speaker load), the 150 is having a hard time staying flat.(I can show you an impedance graph of their simulated speaker load, I have it somewhere it's not as nasty as the ML's)

Then look what happens to it when it has to drive a straight 2ohm load (green trace) it's really starting to take a dive in the upper mids/highs. What do you think will happen to the highs into a 1ohm capacitive load of the ML's

http://www.stereophile.com/content/audio-research-reference-150-power-amplifier-measurements#dgk5iym3Akuwqg5H.97

Cheers George
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