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Atma-Sphere amps with Eggleston Andra II's

I own a pair of Atma-Sphere MA2 Mk2.3 OTL monoblocks that are probably the one part of my system that will staying put for a long, long time. Currently, speakers are Dynaudio Confidence C2's. Preamp is an Atma-Sphere MP1 MkIII.

I'm looking to change/upgrade my speakers. As good as the C2's are, i.e., extremely coherent, very natural and detailed, nonfatiguing, they certainly don't have much "slam" factor. Now, I mostly listen to classical, jazz, and female vocals at moderate levels, but once in awhile still throw on some Cream, ZZ Top, Seger, ELP or whatever that demands some volume and presence in the low frequencies. I have been reading that the Andra II's can provide most, if not all, of the C2's traits but also add the missing lower octave and slam.

My question to Andra II owners is this: will 220 watts of OTL power drive the Andra II's properly? The MA2's can handle 4 ohm loads without difficulty as long as there are no crazy phase shifts. I am mainly concerned about running my amps dry.

TIA.

Bill
billspecfoc
audiokinesis
1,872 posts
 
French Fries,

The Atma-Spheres and other output transformerless tube amps roughly approximate a "current source", unlike most amplifiers which approximate a "voltage source". In English, that means the Atma-Sphere amps deliver less than their rated power into a low impedance load, and more than their rated power into a high impedance load. This is just the opposite of the way most amplifiers (especially beefy solid state amps) behave. In addition, OTL amps typically have a high output impedance (low damping factor) which further makes a low impedance speaker less likely to be a good pairing.

Duke
gregm
3,021 posts
 
As Duke notes (twice) and others have confirmed, you will not get superlative results using yr AS with the Andra. I.e., you'll get good sound -- but NOT what you bought the equipment for.
The music will be refined and s/what lacking in ultimate energy (upper -> mid bass will be too "polite").
With yr amps I would strongly recommend high sensitivity hi impedance spkrs wearing powerful drive units (wide-range). Audiokinesis gives a good recommendation above. Tannoy (prestige series), rethm, horn-loaded models etc would be fine.
The sound you'll get will be outstanding
luke72
116 posts
 
The OTL's, as correctly stated, are intended to use with high impedance, especially electrostatics (like Soundlab), speakers. The Dynaudio drivers need current and amps with a good damping factor in order to get the best results. Actually it is strange that your match with the C2's is still good...
Anyway, if you want to keep the AS, why not bringing your amps to the nearest Eggleston dealer and listen for yourself ?
Just a thought by an Eggleston lover.
springbok10
708 posts
 
Don't sell your amps - they are far too good! Think of other speakers - Kharma 3.2 come to mind - that's what I use with AS 2.2s and the sound is remarkable
rushton's avatar
rushton
2,430 posts
 
As an MA-2 owner, I've been quietly reading this thread because I've never heard the MA-2s with the Andra IIs and they may well not be a good match with this particular speaker. However, unlike typical OTL amps, the MA-2s are designed with a low impedance output and are incredibly versatile in the speakers loads they will drive exceptionally well, and with tremendous bass authority.

For example, they have proven to be a great match with Avalon Eidolons (4 ohm nominal load, 3.6 ohm minimum) and with the Magnegpan 3.6 (which will challenge many amps).

I'm not trying to suggest they would be a good match to the Andras, but some very broad statements have been made here that might lead some to think that the Atma-Sphere MA-2s would not be a good match with lower impedance speakers across the board, and this is demonstrably not the case.
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