I have used Futterman H3aa mono OTL tube amps successfully with KLH Nines and Quad 57's. These both have an average impedance close to 16 ohms. The CLX is only about 4 ohms. Any OTL amp will need an autoformer to work well with the CLX. My Futterman Harvard Music stereo amp (6HB5 output tubes) with built-in Altec autoformers could do it! The original owner used it with a multiple dynamic speaker (low impedance) set up.
OTL Tube Amps and Full Range Electrostatic Speakers
I have Martin Logan CLX speakers which have a nasty impedance curve in the treble with a minimum of 0.7 ohms at about 18 to 20 kHz - or so I have read. The impedance of the CLX is, as many know, largely capacitive. Over the years I have preferred tube amps and have heard OTL amps driving various Quad speakers with great results. My own experience with the CLX's has been more positive with high quality solid state amps; I am currently using a Krell 402e which has no trouble driving this speaker well. An ARC Ref 150 did not provide the control, particularly in the treble, which this speaker needs and did not provide the level of transparency which this speaker can provide. I would appreciate hearing if anyone has experience with other tube amps with the CLX's or Sound Labs, particularly OTL's and whether autoformers provided a significant benefit. Thanks for any insights.
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- 18 posts total
- 18 posts total