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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
atmasphere's avatar
atmasphere
11,778 posts
 
on this very forum speaker builders have suggested that with a lower impedance they can more easily achieve deeper bass response (extended frequency response), a more linear impedance (improve linearity of frequency response)and as you've said a lower impedance can make a speaker play louder (increase dynamic range)(am I really putting words in your mouth?). To that let me add that I've yet to see an impedance plot from a speaker that claims to provide waveform fidelity and can back it up with an appropriate square wave response that doesn't also demonstrate an impedance plot that drops below 8 Ohms.

You are indeed putting words in my mouth. What I said was that a lower impedance can sometimes get you more power out of some transistor amps. That is a long way from saying that is is increased dynamic range! For example the speakers I have at home are 98 db, go down to 20Hz, and are 16 ohms. They tend to have dynamic range because of their efficiency, which is where dynamic range actually comes from.

Regarding the other point you made in the quote above, a link would be nice. I can't think of a mechanism that would give a speaker with lower impedance an advantage of better LF response. The two are unrelated: you can get exactly the same LF response from a speaker that is 16 ohms or 24- impedance has nothing to do with it.

George, unlike Unsound, you are a troll. Your comments are unwarranted, without merit and uncalled for.
unsound
7,329 posts
 
^Let's start with these links 1st:

"If sound quality is your goal, it will be best served by a speaker that is 8 ohms or more, all other things being equal." If you want greater **sound pressure** there is a slight argument for 4 ohms if you have a transistor amp. IOW, there is no argument in support of four ohm speakers in high end audio.

FWIW these days there is little argument for 4 ohm speakers in high end audio. This because regardless of the amplifier technology (transistor, tube or class D), the amplifier will sound better and perform better on higher impedances. Of course, if you are unconcerned about sound quality, and more interested in sound pressure, than 4 ohm speakers will be more attractive if you also own a solid state amplifier. The other argument against 4 ohms is the speaker cable- they are extremely critical for best results on 4 ohms, while at 16 ohms they are not nearly so. Making a speaker to be higher impedance, all other things being equal, is an easy way to make the speaker appear that it is smoother with greater detail, always a desirable combination.
Atmasphere (Threads | Answers | This Thread)


http://forum.audiogon.com/cgi-bin/fr.pl?
cspkr&1356668050&openusid&zzAtmasphere&4&5#Atmasphere

The point is; speaker designers have to make many considerations when designing speakers and sometimes for the greater good compromises have to be made, and rarely is it so black and white that a design choice is either good or bad. Even what might appear to be a less than ideal choice might actually have some positive attributes.

BTW, I don't agree with your assessment of George either. Like most of us here, he's shared his experience and his points and advice seem to have merit.
mapman's avatar
mapman
22,152 posts
 
"Im shocked at how much tube monoblocks go for new."

Its a reasonable response I think.

Especially in the case of low power tube amps like SETs costing 5 digits. These use only a few tubes, and often claim to keep circuitry simple towards the end of good sound. Granted, high quality parts cost more and there is some intellectual value associated with design, but nothing hugely innovative going on here.

OF course, more tube power = more tubes, so understandable how cost goes up in that case.

If you buy into the concept that a couple of watts can be made better than if more, then that helps with the justification. But then it often requires very expensive and large speakers to complete the deal for TAS.

I tend to think you get a better deal with quantity, including watts, and those additional watts are not as detrimental as some purists might portray them to be on the grand scale of all the things that go into good sound, especially when modern SS amps like Class Ds are more efficient and cost effective than ever before.
georgehifi's avatar
georgehifi
10,312 posts
 
03-21-14: Atmasphere:George, you are a troll. Your comments are unwarranted, without merit and uncalled for.


There is only one reason for you calling me a troll, that is you have to stick up for the Zero Transformers, because they are the only way your OTL's will drive many semi difficult speaker loads that are out there.

And I stand by my comments about them, they are a bandaid fix for amps that cannot drive difficult loads, and the owner is better off getting the right amp, or an easier load impedance speaker.

I have actually praised your OTL amps, when they are mated to the right speaker, but to put a Zero Transformer on them is just defeating the fact they are OTL in the first place.
http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1304533364&openfrom&23&4#23

Then your suggestion of putting a Zero on a tube amp that already has an output transformer is just plain stupid, instead of getting the right amp or speakers. And then to infer to putting them on a good quality solid state amp is just ****************

Cheers George
unsound
7,329 posts
 
Atamsphere, here's another link:

12-28-09: Audiokinesis
Unsound, obviously I should have
made it clear which part of my
response was about things an owner
of existing speakers could do, and
which referred to something that
would have to be done during the
design stage.

In my opinion using an autoformer is
something a speaker owner would do
to make his speakers more compatible
with OTL amps.

If we're just looking at the design
stage, then yes it is easier to
smooth the impedance curve by
lowering it. But if the end goal is
compatibility with OTL amps, for
example, lowering the impedance
curve can be counter-productive.
Some of the design choices that lead
to a medium to high, and smooth,
impedance curve need to be made
before the crossover design stage.
For example, I can't expect to build
a 2.5-way system using two 8-ohm
6" woofers and end up with an
OTL-friendly design.
Audiokinesis (Threads | Answers |
This Thread

I'll try to find more as my time
permits.
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