is this true????

[kathodyne]

So, no use in audio for this, and wrong implementation might melt your tubes......
hmmm, tricky article then, as this fellow makes it seem true for those who do not entirely grasp all the matter ivolved with it.....

[Johan Potgieter]

Kathodyne,

I say the following with humility - I am still learning after a half century. (Just a few posts ago Marconi re-juggled my grey matter. So there):

Be v-e-r-y circumspect of what you read on the internet. It contains a wealth of good information, but with respect, I have honestly also read the greatest load of twaddle imaginable there. As the well-known Douglas Self said: It pays to be sceptical in audio.

Regards.

[Shoog]

I was messing about with Ultralinear and I tried this diode trick just to see what result I would get. With the diode the sound is indeed much cleaner and sharper sounding than without. However I didn't like the sound with the diode for exactly those reasons. Without it the sound is more triode like.
A look with the scope at what what was going on on the Ultralinear tap "seemed" to show an unbalanced waveform (the diode seemed to be rectifying it). I therefore would guess that the introduction of the diode introduces some form of distortion.

Shoog

[kathodyne]

@johan.....

Noted and imprinted........

[Johan Potgieter]

Most interesting, Shoog. When I have time again I am also going to look into it, even though it might mean the danger of sacrificing tubes as some predicted. It goes a little against logic, but it can only be informative to have a look. I have done stranger things in my life.

Regards.

[Majestic]

Originally posted by Shoog
I was messing about with Ultralinear and I tried this diode trick just to see what result I would get. With the diode the sound is indeed much cleaner and sharper sounding than without. However I didn't like the sound with the diode for exactly those reasons. Without it the sound is more triode like.
A look with the scope at what what was going on on the Ultralinear tap "seemed" to show an unbalanced waveform (the diode seemed to be rectifying it). I therefore would guess that the introduction of the diode introduces some form of distortion.

Hmm, interesting. So it seems you feel then it's a waveform related distortion and not the "sound" of the diode itself (which a tube-diode might fix)

[Shoog]

I didn't put a sine wave through it, I just used speech. Looking at the waveform on the main primary tap and the UL tap, it looked like the waveform was cropped on the positive side of waveform on UL tap compared to the main tap. Without more controlled testing (which i'am not going to do) I wouldn't like to be absolute about this.
Its interesting to note that the article also advocates including a series resistor to the screen of at least half the plate load. My experiement showed that this softened the sound - taking away some of the diode introduced hardness. It seems as if he got a result with the diode, but found it a bit much and then went looking for a solution.
I took out all series resistance as well as the diode, and it sounds better than with the diode and the series resistance. It was very close to a triode sound with nothing.

My conclusion is that the man found an effect, forced it to work and then concocted some hockum to account for it. The complete absence of any empirical results and wave plots suggests that this man is a fantasist. Not been totally able to follow his reasoning - I fell for it and gave it a try.

Its a very easy thing to try, and my experience with the 807 is that it presents no risk to your valves. I encourage someone else to try this, if for no other reason than to confirm my negative findings. You may of course disagree.

Shoog