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Atma-Sphere M60 monoblocks + ML ESL 11 = Inferior combo

Hi guys,

Today I borrowed home a pair of pure OTL-Tube M60 mononblocks to combine with my ML ESL 11s (which base are partially driven by a Class-D amplifer of 275 watts) with very poor results. Unfortunately, although the M60s where only to cater for the diaphragm panels (at least in theory), when combined with the speakers, the soundstage collapsed, vocals felt muffled and absent deep into the sound picture, almost hidden away, and the base went out of control (got larger and louder in a negative way). I also lost details. The Monos are a pair of brand new demos and shined this morning together with a pair of smaller Vivid monitors.

My current SS - a Bryston 4B3 delivers so much better combined with the ML ESL 11s. Someone that can explain what I did just experience? I thought that OTL tubes and High sensitive Martin Logans of todays generation where to be a marriage in heaven.

Kind regards 

 

  

128x128andy_wonderwall
rsf507
2,367 posts
 

Looking at ML website it shows the ML11's have an impedance of 4 ohms, 0.6 at 20kHz. Way to low for any OTL amp. OTL's like to see a high impedance of 8-26 ohms without dipping much below 6 if possible. That's why they did not match. Maybe Ralph of Atmasphere can chime in for his thoughts.

russ69's avatar
russ69
3,554 posts
 

Not a total surprise. That OTL amp starts dropping power big time as the impedance drops. Your ears told the story, it happens.

decooney
2,271 posts
 

@andy_wonderwall Look here, Agon 2016, a partially related thread and replies.  

 

tomcy6's avatar
tomcy6
2,612 posts
 

It’s not that the atma-spheres are bad amps, it’s just that they were not designed to power speakers like MLs. They are designed for easy to drive speakers and many people find they do very well in that situation.  This has been discussed many times on these forums.

gdnrbob
4,471 posts
 

I wonder why you didn't call Ralph (atmasphere) and discuss this with him? He often answers the phone.

He is very open and provides honest information with regard to his equipment.

Atmashphere amps can work with difficult loads, but you can overtax them- to the detriment of sound quality. Perhaps his new Class D amps would be a better fit.

Bob

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