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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

Showing 5 responses by hvowell

hvowell
13 posts
 
This is all well beyond my understanding and wondering can someone comment on a question concerning the voltage vs power model? I believe I read two, perhaps more, points of view?

Concerning an ESL such as the Quad "57" referenced earlier with a SS amp "doubling" the amps output as the impedance is halved (assume)

25W into 8ohms
50W into 4ohms
100W into 2ohms

would not the output be also "halved" as the impedance rises above 8ohms

12.5W into 16ohms
6.25W into 32ohms

If I understand correctly than, for the Quad ESL this means only 6.25W/12.5W in the lower frequencies while 100W into the higher frequencies?

Now is the reason this type of amp works is (assuming the speaker has a sensitivity (SPL) of 85db/1W into 8 ohms)

.25W into 32ohms = 85db
.50W into 16ohms = 85db
1W inot 8 ohms = 85db
2W into 4 ohms = 85db
4W into 2 ohms = 85db

so the SPL remains constant into all impedances?

Thank you everyone for all the previous information, so very informative!

Lee

hvowell
13 posts
 
The quad has an impedance in excess of 32 ohms under 100HZ, with just under 2ohms impedance at about 10KHZ.

Lee
hvowell
13 posts
 
Now is the reason this type of amp works is (assuming the speaker has a sensitivity (SPL) of 85db/1W into 8 ohms)

.25W into 32ohms = 85db
.50W into 16ohms = 85db
1W inot 8 ohms = 85db
2W into 4 ohms = 85db
4W into 2 ohms = 85db

so the SPL remains constant into all impedances?

Can anyone please comment on the above as to its accuracy? If correct, I dont understand this electrical concept as it pertains to how the speaker plays various notes at the intended (recorded) levels?

Considering a very simplistic example, if a bass note and mid range piano note are recorded at the same level and are played at the same moment, and assuming the speakers impedance at the bass note frequency is different from the speakers impedance at the piano note frequency, how then are the level of these two notes played through the speaker at the intended playback level? At the moment these two notes are played, does the speaker draw a constant output, (voltage/cureent) from the amplifier? If so, lets say it is 1W. If the above speaker sensitivity question is true, how can both notes be played at the same level at 1W being drawn from the amplifier?

Thank you, Lee
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
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
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