What is that class XD we can find into Cambridge amplifiers

[destroyer X]

I could read, into their site, that operates class A and class B...and now they are saying AB is not good anymore!

It seems to me another automatic bias adjustment... some new dinamic bias adjustment.. from class A, going to AB and supressing bias into peaks of power.

Can someone explain how this works?

Thank you in advance by your kindness.

http://www.cambridgeaudio.com/summar...s+XD+amplifier

regards,

Carlos

[sreten]

http://www.cambridgeaudio.com/assets...r8-2-06web.pdf

/sreten.

[destroyer X]

I hope the papers are low in level, to allow me to understand...two problems to read...my english and possible Engineering level explanations.

Thank you very much.

Also Rabbitz have bougth one of that, and i will listen what he will say about...also i have a nephew that will come to Brazil very soon, and i will buy one of them to listen to the XD operation.

regards,

Carlos

[SpittinLLama]

I really wish they would have come up with a better term than Class XD. It makes one think they are talking about some form of Class D, as in switching amplifiers. I think they used XD to mean crossover distortion. But they could have done something else. Lame choise on creating a new marketing class (like Class T and Class I).

I believe Douglas Self talks about this in his book (some of the graphs in the white paper looks like they were taken right out of the book).

-SL

[destroyer X]

A crossover point displacement system is the idea as i could understand.... XD as Extra Displacement, or axel X displacement is fine....not "class" in my point of view... this amplifier has not a class...not B, not AB and not A, as i could see.... will depend of the volume... a Variable Class Amplifier.

I remember Graham Maynard have made that with the GEM some years ago...and this was published...not too much different.

And the GEM i have built and sounded great.

The diferences obtained, into the distortion is something i cannot listen to something more difficult to listen.... i cannot listen both levels of distortion...smaller than Class AB distortion into good amplifiers that i cannot listen too.

Very interesting..i have to listen the sound to evaluate if i can perceive something.

Thank you folks...i am satisfied...now i will wait Rabbitz to make the review i have asked him and will ask Graham to explain to me the advantages or disadvantages this system has compared to his amplifier.

Doctor Self is usually very good.... now a days i am addicted to Doctor Self, despite he worries with some distortion i am unable to listen.....maybe other folks can listen.

regards.

Carlos

[destroyer X]

by the white pappers....so... if you want to continue to discuss the subject go ahead... i will be out from the discussion because i think this is something i have to listen to evaluate by myself.

regards,

Carlos

[taj]

Originally posted by destroyer X

....not "class" in my point of view... this amplifier has not a class...not B, not AB and not A, as i could see....

It's just marketing, Carlos. You could just as easily use CLASS DX.

..Todd

[destroyer X]

I will prepare one DXD very soon... i have some ideas boiling in my liquid mind (melted sh--).... Graham idea controled by DC obtained from audio output, alike AGC.


ahahahahah!

Carlos

[Nelson Pass]

The notion of applying single-ended bias to the output of a power
amp has been around for quite a while. Take a look at the Aleph 0
from 1991.

Modulating that bias has also been done, but I found it much more
useful to modulate it against output current than voltage, as
it makes the effect independent of the reactance of the load. If you
modulate the SE bias by output voltage, it is optimum only for
resistive loads.

And while I'm at it, I think the technique of a SE current source on
the output is best used with a Class AB bias on the push-pull
portion of the output stage. If it is Class B, there is a significant
crossover distortion that is there unnecessarily.

[destroyer X]

Now a days i have a lot of FETs here.... will construct something from you Nelson.

The evolution of that one that you have used Lamps...nice amplifier that one...and them you made with CCS and other good ideas that made it more efficient.

Sorry, english continue awfull.

regards,

Carlos