Tommy,
Could you comment a bit on the relationship issues some Class D amps have with highly capacitive ESL speakers. Some amps don't work. Others may. One company even markets a Class D amp for use with their own ESL speakers. There is a topic about this on the solid state forum.
steve
Steve,
Please provide a link to the topic on the solid state forum that you mentioned.
Unfortunately, Class-D is a gross generalization. It means "switching amplifier". A.k.a "digital amplifier" ---- thought by some to be a misnomer, but technically correct if the signal is represented by one or more logic levels. There are MANY ways to make a Class-D amp....
Various architectures handle reactive loads with differing levels of skill. We have a bias toward the preferred solution to handling tough loads. We design the circuits for sonic quality rather than bench performance, although you can see for yourself how well we do with measurements.
The biggest difference in being able to handle "tough loads" (love that phrase), or not, is primarily damping factor, but the number there is over-simplified (or is it "overly-simplified"?). Damping factor is dependent on frequency, and most amp manufacturers only measure this at the "sweet spot", which is typically well below the center of the spectrum. Providing high damping factor (>>100), in conjunction with flat response, and retaining the liquidity of the sound, as the frequency reaches the extremes of the amplifier's working bandwidth (whew, that's a mouthful), is a difficult nut to crack. We believe we've done this better than in any other amplifier with the Maraschino.
With ESLs, the step-up transformer and diaphragm have all sorts of behaviors based on frequency, amplitude, and phase (signal history). These effects make it like a tug-of-war between the amp and speaker, and in a good sounding system, the amp RULES the speaker, taming it like a wild horse!
The error compensation (feedback, also a complicated topic) used to flatten response or provide a high damping factor at the "sweet spot" in some Class-D amps becomes unstable when the load fights the amp too hard, and the amp "gives way".
Pardon the excessive use of quotes!
Thanks for your post. I like this topic.
-Tommy O
