Broadstone Hi.
Written bench test results from one review on ML Ethos:
"Measured overall impedance was low at 4 Ohms, in fact surprisingly low considering the bass unit is powered. This is due to the electrostatic panel that comes in hard at 400Hz our impedance analysis shows, careering down to 1 Ohm at 20kHz – ouch!"
I'll look for graphs that back this test statement up.
But from what was said to get the very best from the ML Ethos you need an amp that can that can deliver good current down to at least 2ohms, so it stays flat over the frequency range, and not start behaving like a tone control at different load impedances.
That means "close" to doubling the 8ohm spec wattage to 4ohms and again doubling to 2ohms
EG:
8ohms-50watts
4ohms-100watts
2ohms-200watts
Cheers George
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Beside the tube amp Clio09 came up with Music Reference RM-200, this tube amp also has 1ohm 2ohm 4ohm 8ohm and 16ohm speaker taps, Audio Research VT200, and it has more wattage to start with so volume level may not be as critical as the Music Reference RM-200, I bet there are some more out there as well. http://www.arcdb.ws/VT200/VT200.htmlCheers George |
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Well guys I beg to differ big time, I have Martin Logan Monoliths with the new aluminium vapour deposited panels, and they have a very similar impedance curve that the Ethos have being 1ohm or less in the upper mids/highs.
When ever big tube amps that I have owned or mates have bought around, be it push pull or single ended toplogy are used to power them, yes they sound "nice", but there is a distinct softening in the upper mid/treble region with a big lack of presents and dynamics.
Then swapping over and using my very stable massive high current solid state amps, everyone then hears what's missing during these savage impedance drops, it like someone has opened up a window to the upper ranges and the detail/dynamics that comes with it.
This statement is what a Stereophile reviewer found, with the ML Montis (which have an impedance character almost identical to the OP's ML Ethos speakers) when driven with a highly regarded Audioplax 88 tube amp, .
"This is why Robert Deutsch found that his Audiopax amplifier sounded too soft and lacking in definition."
Cheers George |
Broadstone, look and you can see in the graphs 1 2 & 3 of the new reincarnation of the highly regarded Mcintosh 275. You can see that the black trace is what happens to the frequency response of the amp that can't do current as I've outlined above into a simulated dynamic speaker load. The upper mid/ to highs are considerably rolling off, and the whole amp is acting like a tone control Now into the 1ohm of the Ethos this will be even more rolled off, as it is much more severe. http://www.stereophile.com/content/mcintosh-mc275-power-amplifier-measurementsCheers George |
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I think Clio09 came up with the answer if the OP really wants a tube amp, the Music Reference RM-200.
In that it has 1ohm or 2ohm speaker taps, there is a proviso though, will it still have the watts to get to a reasonable level when driven off these taps, the wattage goes down the lower the impedance tap is used.
Cheers George
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Yes Bruce and Al, I'm trying to find a Phase Angle graph on the OP's Ethos to see if they are even worse for an amp to look at than just the impedance graph shows they are.
Cheers George
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As I said Ralph, I have had a pair of Zero Autoformers given to me, and used them a few times and regarded them as banaid fix for mismatched amp/speakers combiations.
As for your continued accusations of me trolling you (again popycock) and if I were it's better than being a shill.
The OP's wants to buy an amp for his ML Ethos speakers, why would he buy an amp that is not suited and then buy Autoformers as a bandaid fix to make them compatible.
Cheers George
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Please don't accuse me of trolling on these forums Ralph, it's fact and that's that. I'm just keeping things honest here, in that Autoformers are not the magic bullet that you portray they are.
And that your better off saving the $700 odd dollars that they cost and getting the right amp or speakers so things do match up.
Autoformers are at their the most advantageous when used with OTL amps on speakers they can't drive, should ring bells on who's doing what, on these forums.
Quote:
"The most important thing to remember about the Autoformers is: if there is no significant impedance mismatch, then there will be no real benefit to using the Autoformers."
I'll add to that not that the reviewer would say it, there will actually be a detriment to the sound if used in the above situation.
Cheers George
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"If you combine that with an amplifier that can double power as George suggests, the result is brightness"
Popycock Ralph, it is the opposite with not only with ML ESL's but others as well and you get dullness with an amp that can't keep "keep it up" current wise.
Why then advocate the use the Zero as a bandaid fix with your amps on these sort of speakers when getting the right amp is clearly obvious, even a rare tube amp with output taps of 1ohm 2ohm that Clio posted designed to drive this sort of load.
Just listen or read the reviews of ESL's with upper range impedances like the OP's ML Ethos speakers have when driven with amps that "can't get it up" (current wise), dullness or similar are the words used all to often.
Cheers George |
Ralph, please don't assume.
I have had a pair in my house that were given to me, and have tried them on different occasions, and have always said with amps and speakers that are a mismatched they can be made to work together, but are just a bandaid fix, until the right amp is used.
And instead of spending the $600 odd dollars on them as an interim fix, put the money towards the right amp for the speakers being used, or the other way, change the speakers to suit the amp being used. Without having to purchase autoformers and have them in the way.
Cheers George
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Look at Stereophile tests (12 & 13 posts back)on tube amps into their simulated speaker load, and what happens to the frequency response, and then magnify that many times for the OP's Ethos speaker, as they are more severe than the simulated load.
Here is a Parasound amp that can do current, note how with the same simulated load frequency response this amp hardly differs from just an 8ohm resistive load. Compare it now to the tube one and then multiply the difference by quite a few times, because of the OP's speakers more severe load characteristics.
[url]http://www.stereophile.com/content/parasound-halo-jc-1-monoblock-power-amplifier-measurements[/url]
Cheers George |
Looks like Clio09 may have the right tube amp for the OP's Ethos speakers, should work well either off the 1ohm or 2ohm tap and maybe not sound like a fixed tone control, and only one transformer in the way.
And you can see it in the second graph working off the 1ohm tap, only slightly deviates of dead flat when driving the simulated speaker load, maybe it will be a bit worse with the .8ohm of the OP's Ethos.
[url]http://www.stereophile.com/content/music-reference-rm-200-mkii-power-amplifier-measurements[/url]
Whether or not it will have enough watts off the 1 or 2 ohm tap is another story, this will depend on how loud the OP likes to listen, because the lower the tap impedance the less wattage is available, but higher current and lower output impedance (higher damping factor).
Cheers George |
Tomcy6
It's not the power, it's trying to maintain a flat frequency response between 20hz to 20khz, amps with weak current delivery will sag with these wild impedances that the OP's ML Ethos speakers have regardless of listening level.
And to try and fix this by putting basically another output transformer between the speaker and the tube amps own output transformer is just a band-aid fix.
It should be the right amp to handle those .8ohm impedances to start with.
Cheers George |
Sorry Ralph, but Uh, Uh. Autoformers are a band-aid fix only, after the owner has purchased the wrong amp to begin with, they cause more problems than they fix.
Cheers George
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Always best to get the right amp to start with, instead of putting a band-aid fix between it and the speakers.
The most questionable part of a tube amp that uses an output transformer, why put another one in between it and the speaker, if it wasn't the right one to start with.
For the OP's speakers for a tube amp to be a great match, it should have a real 2ohm transformer tap even 1ohm for these. For it not to start behaving like a tone control.
Cheers George
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The Peachtree 220 from what I found can almost double into 4ohm giving 400watt but I can find nothing into 2ohm.
If it gave 600 or 700 into 2ohm then this is the sort of amp that would not whimp out into the 1ohm of the the Ethos.
And at 72 years old you don't want an amp that is going to curtail the upper mid/highs, because it's here where the Ethos are that heavy load of 2 to 1ohm, that will make a whimpy amp sound soft and dull.
Cheers George
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