When someone tells you it's a $40,000 amp, does it sound better?

@sns +1

HiFi separate components, manufactured in very small quantities, have to be priced very high to cover huge R&D cost, internal parts cost more in lower quantities, tooling setup cost, ppl training, sales and marketing travel, exhibitions etc. Internal component quality and overall design of my Accupase amp exceed many, significantly more expensive amps, because it was produced in higher quantities. Second amp I have is a class-A custom made, beast with 40 TO3 metal housing bipolar complimentary transistors, and amp has two separate power supplies with 700VA toroid transformers for each ch., practically same as two mono-blocks. Measurements, including max output current, distortions etc are stellar, but I am not using it much because max power I need is about 15W, for my 89db/m sensitivity speakers.

There can be no crossover distortion because the transistors never turn off.

@larrykell It might interest you to know that most class D amps are inherently incapable of crossover distortion.

@atmasphere How can this be when the turning on and off of output transistors at a rapid rate in Class D amplifiers produces high frequency noise which must be filtered out? There is no such thing as instantaneous switching.

I tried a Class D amplifier the last time my Colosseum was in for repairs and I hated the thing. It sounded harsh and gritty to me. Granted, it was a $1-2k Class D amplifier. I sold the Glass D amplifier as soon as my Colosseum came back to me. 

To me, it’s about having the power to handle the transients in music and those transients can require tremendous amounts of power. I don’t understand how one can be certain that a small amount of power will be sufficient. The more current reserves an amplifier has the more able it is to effortlessly handle transients. 
 

I learned that speaker drivers do not have a magical number at which they fail. It comes down to how well the spider is constructed, its durability, the ability of the driver to dissipate heat, on and on. 
 

So, I don’t worry too much about whether my Cantata speakers to handle the power I throw at them, I think the drivers are well built.

How can this be when the turning on and off of output transistors at a rapid rate in Class D amplifiers produces high frequency noise which must be filtered out? There is no such thing as instantaneous switching.

I tried a Class D amplifier the last time my Colosseum was in for repairs and I hated the thing. It sounded harsh and gritty to me. Granted, it was a $1-2k Class D amplifier. I sold the Glass D amplifier as soon as my Colosseum came back to me.

@larrykell I get that- there is tremendous variance in the sound and technology of class D amps- if you heard the wrong one it can be a big turn off!

How the amp can be immune to crossover distortion has to do with how the audio signal is extracted from the switching of the amp. The output devices turn on and off for differing amounts of time depending on the slope (how steep it is, whether its going up or down) of the incoming audio signal.

This type of analog encoding is called Pulse Width Modulation.

When the switching frequency is filtered out, the audio signal is what remains; there’s no way to generate crossover distortion, inherent in the design. This is a considerably different approach as opposed to traditional Push Pull amplifiers where the output devices have to follow the signal (which is why they can be prone to this problem) in order for it to be amplified.

(Apparently it is possible to build a class D amp that has no output filter; if such an amp were built it could have a problem with crossover distortion. But I know of no such commercially available amp- all I’ve ever seen use output filters.)

Regarding noise, if the class D is designed properly the amount of noise it makes on account of its switching can be less than many tube or solid state amplifiers. They can also have considerably less noise floor in the loudspeakers, making them suitable for driving horn speakers.