John Curl's Blowtorch preamplifier part II

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Yes, and that's your field, your knowledge that may help.

Really, beyond knowing that a charged electrolytic will have a double layer at the electrode surface, there's nothing more to say. If you either force symmetry by back to back connection or you polarize the cap (as it is intended to be used!) so that the AC isn't asymmetrically depolarizing the double layer, the H2 basically goes away. This is obvious to anyone who has ever done a loopback test with a soundcard (there are both input and output electrolytic coupling caps).
 
Likewise increasing the bias, if that's what's used to run the electrolytic properly.

This is more than obvious. But look at most commercial or DIY designs - single coupling electrolytic cap without any DC bias. DC bias was a rule in the times of single supply designs, as a result of the circuit topology. I assume that two back-to-back electrolytic capacitors would increase the production cost, so nobody cares to use it or to properly bias a single el. cap.
 
This is more than obvious. But look at most commercial or DIY designs - single coupling electrolytic cap without any DC bias.

Hard to say since I don't have much commercial gear and haven't surveyed the field. I do have some commercial solid state amps (Adcom, Bryston, and Sunfire), though; they use non-polar electrolytics for coupling and feedback, and those are essentially back-to-back electrolytics. My diy stuff uses polypropylene exclusively for coupling, but I can't speak for others.

But yes, we agree that, whatever its prevalence or non-prevalence, single electrolytic without bias is a poor design practice.
 
jan.didden said:
The model is only tested and found valid to 'model' charge/discharge, because that's where we use it for.
What else does a cap do apart from charge and discharge? You are suggesting a frequency-related nonlinearity, but surely sample-and-hold circuits (where DA can be a problem) sometimes work at quite high speeds and quite high resolution? Any nonlinearity in DA would be seen there first.

Some evidence that DA causes nonlinearity would be nice, or even just that DA is reasonably well correlated with nonlinearity. So far, we have none of the former (just some 'smoking gun' allegations) and perhaps the contrary to the latter?

PS I'm not Doug.
 
I am sorry but I am not able to find harmonic distortion in a standard, 10uF/35V electrolytic capacitor. Two in series, no bias, resistor load, pls see the image with circuit shown. That 0.00042% is a sound card distortion.

P.S.: input AC voltage is 1.55Vrms

Pavel,

I see a lot of fundamental base spreading, is this an increase in noise or just due to the FFT?

ES
 
Pavel,

I see a lot of fundamental base spreading, is this an increase in noise or just due to the FFT?

ES

What exactly do you mean, Ed. Would you please explain in simple English, thanks.

If you speak about width of the 200Hz line spectrum, it reflects FFT resolution + Hanning window shape. At 2kHz, it will be narrow. At 20Hz, it will be even broader ;)
 
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massles field coil Iverson speaker

I did know John Iverson well, and 40 years ago, I listened to his force field speaker. It was very inefficient, but it played Joan Biaz's young voice better than any other speaker that I ever heard. I thought the Mafia did him in for owing them money, but nobody knows for sure. He was a great engineer, better than me, or anyone else I have worked with in audio.

Thanks John for replying. I found nothing except conspiracy theories in the net on this. There was even an Absolute sound article on his disapperance. But are there any pics of this "speaker"? Do you know how it worked? Was it a coil like the Rodin ABHA Nunez thing see the you tube I reference to in my original post. I did not find ANY patents under John G Iverson that could relate to him!!

I liked the sound of the youtube ABHA coil example and figured that even if inefficient in a horn speaker enclosure it would do well. Similarly the Iverson massless speaker has the same potential but need more info on it.
 
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What else does a cap do apart from charge and discharge?

Yes but it does something additional during that process - nobody would dispute that caps DO distort. You wouldn't see that if you only look for charge/discharge. Likewise, if you only look for the link between charge/discharge and DA, that's all you will find.
Bateman found correlation between 2nd and DA, which may or may not be causal.

PS I'm not Doug.

Apologies - my bad.

Jan
 
What exactly do you mean, Ed. Would you please explain in simple English, thanks.

If you speak about width of the 200Hz line spectrum, it reflects FFT resolution + Hanning window shape. At 2kHz, it will be narrow. At 20Hz, it will be even broader ;)

You got it! If you try a film cap under the same conditions and the spreading at the lowest levels of the fundamental do not change, it is the limit of the signal processing. When the skirts widen up a bit at lower levels this can be noise modulation. Often worth doing band limits near the fundamental to look for this.
 
You got it! If you try a film cap under the same conditions and the spreading at the lowest levels of the fundamental do not change, it is the limit of the signal processing.

With all respect Ed, this is a nonsense. Please try to learn about FFT and windowing basics. If I used more points in the FFT record, the line would be more narrow. If i use something like 2K FFT, the width will be over several hundreds of Hz. Please let's not waste time with fundamentals.
 
With all respect Ed, this is a nonsense. Please try to learn about FFT and windowing basics. If I used more points in the FFT record, the line would be more narrow. If i use something like 2K FFT, the width will be over several hundreds of Hz. Please let's not waste time with fundamentals.

Attached is an example of noise induced low level spreading. The first shows the noise, the second is the FFT limit.
 

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Well. Am-i correct saying there is no distortion in a capacitor using air as a dielectric ?
If yes, the distortions we are talking about are obviously due to the dielectric. This hypothesis is enforced by the way distortion ratio varies when we change dielectrics in film caps. (The electrodes in film caps are symmetrical, aren't they ?)

I'm thinking to some properties of the ways distortions are produced by the pressure variations in the air in the compression chamber of a horn at high levels.
 
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Dielectric spectroscopy - Wikipedia, the free encyclopedia

Dielectric - Wikipedia, the free encyclopedia

Permittivity - Wikipedia, the free encyclopedia

Electric susceptibility - Wikipedia, the free encyclopedia

Dielectrics are not necessarily perfectly linear, and with multiple dependencies.
Charging or discharging a capacitor (dielectric assembly) is not simple, certainly not a simple as the spice models proposed.
Dielectric_responses.svg.png
A dielectric permittivity spectrum over a wide range of frequencies. The real and imaginary parts of permittivity are shown, and various processes are depicted: ionic and dipolar relaxation, and atomic and electronic resonances at higher energies. From the Dielectric spectroscopy page of the research group of Dr. Kenneth A. Mauritz.

Dan.
 
Well. Am-i correct saying there is no distortion in a capacitor using air as a dielectric ?
If yes, the distortions we are talking about are obviously due to the dielectric.

No doubt, distortion is due to the dielectric used, in unipolar capacitors like electrolytic capacitors is a function of voltage polarity and amplitude as well, but it again leads to dielectric properties.
 
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