Re: [fluid-dev] Purpose of dither?

[Edenyard]

	Can somebody please re-assure me that I'm not dreaming all of this: 
I've tried pinching myself and I SEEM to be awake, but....

Mihail Zenkov <address@hidden> wrote, very reasonably:

> :) Where are you read this? I six years do amplifiers (mainly on
> tubes)
> and acoustics. All amplification strongly linear. Otherwise, we have
> big THD and IMD.

        Absolutely right, Mihail.

Z F wrote:

> Well, what can I say, tubes afford huge dynamic range and so they go as
> linear as possible providing good quality. Consumer electronics,
> generally, does not have a huge dynamic range, so to solve the problem,
> speaker output (in other words, the last stages of amplification) are
> non-linear. This causes non-linear distortions in the signal, yes, but
> it is less noticable than clipping.

	I really can't believe I just read that! Trust me: if you put music 
into an amplifier and it has a non-linear transfer characteristic,  what 
comes from the output will sound AWFUL!!!

	Furthermore (just for the record), tube (or 'valve') amplifiers will 
generally have worse linearity than solid-state ones because they need a 
large, lossy, iron-cored transformer at the output to match the high 
impedance of the valve output circuit to the low impedance of the 
speaker coils. In actual fact, tube amplifiers are much more likely to 
provide nolinearity (the so-called 'soft clipping') for high-amplitude 
output signals than solid-state circuits, due to (among other things) 
saturation of the output transformer core.

> when I was little I used to fix analog
> consumer audio/video equivment, but I do not do that anymore. 

	Well - with all due respect, it's probably just as well that you 
stopped when you did. The world doesn't need non-linear audio amplifiers.

	Sorry, readers - I think that we MAY have strayed off the topic of 
adding dither to signals now!

        Cheers,

                Gerald.