Some more OTLs that have been popular recently... (I haven't heard them)
https://www.lineartubeaudio.com/new-page-1/
https://www.lineartubeaudio.com/new-page-1/
OTL Tube Amps and Full Range Electrostatic Speakers
Some more OTLs that have been popular recently... (I haven't heard them) https://www.lineartubeaudio.com/new-page-1/ |
We have a number of customers using the RM-200 with their ML speakers. It's an excellent amp for the job. OTLs can also sound great, if Atma-Sphere I would recommend the MA-1 which is 100 watts. I'd recommend putting the autoformer in between the amp and speaker, but it may not be necessary. Ralph could advise as well. There is some debate on whether the Berning patent for his design and that is now used in the LTA amps is actually an OTL circuit. IIRC there is a high frequency transformer that follows the tubes in the circuit. Therefore, some feel that technically it can't be an OTL and I believe Berning more accurately refers to the design as Zero hysteresis since that high frequency transformer does not behave like a traditional output transformer. So the other side of the argument is if it doesn't behave as an output transformer it is still an OTL (output transformer less). |
Power increases into lower impedances!@roberjerman One thing about ESLs is their impedance curve is not also a map of its efficiency, like it is for most box speakers. Instead, its impedance curve is a result of being largely a capacitor. For this reason, what is desired is the ability to put out constant power over the range of impedances presented by the speaker rather than constant voltage (which results in increased power into lower impedances per the quote above). Of course, no amplifier really does make constant power but they can come pretty close, especially if assisted by a set of ZEROs (www.zeroimpedance.com) since any tube amp that is designed to make constant power (like ours are) will tend to have a higher output impedance. For more on this topic, seehttp://www.atma-sphere.com/Resources/Paradigms_in_Amplifier_Design.php |
Ralph, would the solid state McIntosh amplifiers with autoformers qualify as constant power sources? Their specs indicate the same power from any of the speakers taps, e.g., 2, 4, or 8 ohm, but with different levels for the output impedance. If so, that might explain the general tendency to pair these amplifiers with Martin Logan ESLs. My MC2200 model does seem to do quite well with my ML Aerius i. |