Triode or Ultralinear, again

[Haselsh1]

Sussed out Class D yet Shaun?

Geoff I have only just found out that it has nothing at all to do with 'digital'

[Haselsh1]

Just been checking it out on Wikipedia. May as well have been bloody Chinese.

[walpurgis]

If you can understand how AM radio works, you'll understand Class D amps, there are similarities.

[Haselsh1]

I got the impression that it may be something to do with PWM but all I know about that is from analogue synths and square waves.

[anthonyTD]

Cross over distortion is caused by two halves of the signal being reproduced by two or more devices in a push-pull arrangment not joining, or coming together properly at the cross-over point, [how bad will depend on how hard each output device in each half of the push-pull is switched on] if you take an example of a sign wave in a class B output stage, you would likely see a misalignment half way down where the two halves of each half of the signal come together, this sometimes looks like a kink. its a bit like cutting two eggs in roughly half, and trying to put each half of the diffrent egg together, they will look ok, until you look really close, The variation of how bad this miss-alignment is will depend on how far into class B the amp is biased, eg; CLASS A, CLASS AB1, CLASS AB, CLASS B. As for single ended, as stated, conventional single ended is inherently Class A, due to the single device having to draw all the necessary current needed for a specific power output ALL of the time.
again hope this helps.

A...

So I take it that crossover distortion is caused by the devices switching between the positive and negative cycles..? So from that, if the amp is single ended there will be no switching and hence no crossover distortion due to there being only one device per channel..? So class A and AB can be single ended..? However only Class A is permanently 'switched on' and amplifying..? Still does my 'ead in

[Haselsh1]

OK, so why does a directly heated triode win out over so many others in terms of sound quality..? And why, even in push pull mode, does it still sound superior..?

I'm guessing but I reckon my perfect amplifier would probably be a single ended 300B in parallel for a bit more power.

[anthonyTD]

Hi Shaun,
There is a lot to be said for simplicity, especialy when simplicity works! with directly heated triodes, they are the simplest in terms of parts count per valve, ie; Anode, or Plate, Control grid, and Heater which doubles as Cathode too! As for them having superior sound quality,. well that is a very subjective, but I supose if your describing them from a simplisitic view, then I agree, to a point.
Horses for courses, I don't paticularly like that saying, but in this case it is very apt.

OK, so why does a directly heated triode win out over so many others in terms of sound quality..? And why, even in push pull mode, does it still sound superior..?

I'm guessing but I reckon my perfect amplifier would probably be a single ended 300B in parallel for a bit more power.

[Haselsh1]

OK, point taken. Maybe I should say 'distinctive' sound.

[Haselsh1]

Back in 1997 I was using an Audion 300B SE amplifier with Klipsch KG3.5 loudspeakers and the combination was really good with the 300B amplifier taming the sting in the Klipsch horn unit. I remember at the time being really impressed with the sound of Hugh Cornwell's album 'Guilty' and the amount of information that was being displayed by the amp. It didn't have anywhere near the level of realism that I currently have and nowhere near the huge stereo effect but it was a good stepup to where I am now.