The M60 OTL's are very load sensitive! They function best with a flat high impedance speaker - of which few exist. The solution is to use an autoformer between the OTL amp and the speakers. That's what I have on my Futterman H3 - a pair of Altec autoformers. The original owner had Julius Futterman add a pair of them to the H3 chassis so he could drive his low impedance (below 4 ohms) speakers. An autoformer presents a uniform higher impedance load to an OTL tube amp without compromising sound quality!
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