John Curl's Blowtorch preamplifier part II

Status
Not open for further replies.
Abraxilito,

Kind of, but also consider learning from others mistakes so that we don't have
to make them too, otherwise we don't get ahead much.

AND

If we can learn from the mistakes of others we live.
an example...Madaam Curie with her plutonium in her pocket.
perhaps war time strategy or tactics...very costly to make a mistake
which is why training is so important, make them there not on the
battlefield.

Sadly, in politics...they seem to make the same ones over and over again.

Cheers,
 
If you do a traditional sine wave test on a capacitor and say drop 50% of the voltage across it and the distortion increases.... as I understand it does.... what else is there but the dielectric... it wouldnt be the plate, the leads, the solder? That just leaves the dielectric and I think it is characterized by the DA value. The distortion increased and decreases in lock step with increased or decreased DA.... it correlates. Just what about the dielectric would make the distortion increase? Possibly something about the materials hysterysis (related to DA).

Sine wave test?

If you have to apply a DC voltage to a cap for a relatively long time, then short it for a relatively short time, then go open circuit in order to get DA to even raise its head, then how is a steady state sign wave ever going to even bring DA into the picture?

You should do the test again and see what you find. I could be wrong about DA being an important factor in how people were describing the sound of various caps.... remember the 'sound' of caps came first and was being discussed. I was asked what could make caps sound different and DA was my best guess.. I think I found a mechanism which closely matched the descriptions being given to the various cap types. DA seems to correlate best with what people said they heard. So witch hunters...burn me at the stake if I am wrong.

The big mistake here was assuming the caps were producing actual audible differences. You're putting the cart before the horse. First you establish actual audible differences. If you can't do that, then you can never know if you're just chasing your tail.

se
 
The big mistake here was assuming the caps were producing actual audible differences. You're putting the cart before the horse. First you establish actual audible differences. If you can't do that, then you can never know if you're just chasing your tail.

The notion of 'actual audible difference' is just dogma. If not, let's have a rigorous description of what it is.
 
Disabled Account
Joined 2012
That's how you collect distortion data, but the question is, how do you assign the distortion to DA rather than some other phenomenon or phenomena?

There is a problem here --- models. Why assume the model is completely accurate?

We have learned to not believe some transistor models when we use them in SIM .... for good reason... they dont give the result you expect when you measure.

Here is an example of using your model of capacitor from formula -- you should get a straight line for Xc and Xl according to the standard model (see fig A) but when we measure this cap, it measures like in (B). You will see it at #66100 www there as well with no explanation for it via the model. It isnt in the model... the cap models are not complete.

View attachment cap model of Z.pdf

This doesnt prove anything except the models are not complete or fully accurate. So I would not stake my life on models... rather measurements are closer to the truth. Now its just a matter of interpretation after that.

THx-RNMarsh
 
Last edited:
AX tech editor
Joined 2002
Paid Member
The fuzzy distortion stuff was very speculative, fuzzy thinking IMHO.

I memory serves he himself later acknowledged that '....although
there was a degree of speculation in it, I stand behind the major conclusions to
this day. If I write something like that I always try to indicate what is fact, as we electronic engineers understand it, and what is more of a gut feeling.'

See here and here.
And here is his (in)famous cable article.

Jan
 
Last edited:
diyAudio Member RIP
Joined 2005
You mean in a peer reviewed journal?

Yeah, that can make it difficult. Did he make tenure?
Was he at a tier 1 university? AAU Research university?
National Laboratory?

Malcolm was at U of Essex (UK) and wrote peer-reviewed material, but also held forth in a column called the Essex Echo, where I think he could indulge his more speculative tendencies.
EDIT: I sometimes reply before reading all the water under the bridge, so I see that this was addressed now.
 
Last edited:
diyAudio Member RIP
Joined 2005
The fracpoles, that is interesting, the initial figure shows a
multiplicity of capacitors and series resistors but no exemplar
values.

It has a parallel capacitance and resistance also with the other circuits.
Or is the whole thing considersidered the circuit?
That partial pole-zero cancellation in a lumped network, a special case of it, is the technique by which pink noise is made out of white over a specified bandwidth. I used it in another form in a simulated surround matrix which for marketing purposes was dubbed Fractal Expansion. :eek:
 
Disabled Account
Joined 2012
I just did a quick preliminary 1 KHz thd test of Dadod's nice 200W CFA amp. Looking real good. Until I have a larger heat sink attached to it, I just looked at 1w and 10W levels approximately. There is residual 2H but thd is below -100dB re 1-10W output level. These are important levels to test as we spend a lot of time in that region when listening. Noise is quit low as well.

congrates!



DSC01692.JPG



THx- RNMarsh
 
Last edited:
I don't know that DA is linear.... the simple models show it that way. I figure it isnt purely linear due to the FFT result.

How do you figure that? How have you determined that what you're seeing is due to DA rather than something else? That was the question and still is.

Why assume the model is completely accurate?

Because, as Scott showed, it accurately predicts the recovery behavior?
 
How do you figure that? How have you determined that what you're seeing is due to DA rather than something else? That was the question and still is.
Please, if you have better explanations or hypothesis, can-you give-it to us ? And justify in what they are closer to reality !

Anyway, as i'm not a cap manufacturer, the only things that interest-me are the distortions of the various technologies. I don't care too much of their causes, as i cannot modify them. The only interesting thing, for DIYers and designers, is how and where to use them, and how to chose the best ones or combinations of them for each purpose.
 
Last edited:
I didn't make the claim. I am trying to understand the claim that Dick made, how he eliminated other possibilities, and how he arrived at his conclusion.
So just looking for trouble ?
The only way to demonstrate an hypothesis is wrong is to prove it don't give results in accordance with what we can observe from experiments.
Do you feel asking to Albert Einstein "how he eliminated other possibilities, and how he arrived at his conclusion" ?
(Not to say Mr Jung is Albert Einstein ;-)
Mr Marsh said exactly the same thing: "rather measurements are closer to the truth".
 
Last edited:
Status
Not open for further replies.