John Curl's Blowtorch preamplifier part II

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But that doesn't mean that those who don't make their living at this don't know how to do it.

Some amateurs even get paid for it (quoting a line from a classic Italian movie : to sweeten the mouth).

One of my cars refused to start time and again, usually after it had rained or when it was damp.
It spent 5 days at the service car shop, they even contacted the factory through the web, after which they told I needed new car keys (at >$100 each) and handed me a $1k bill.
On the highway, roadside assistance had to be called twice after a breakdown. On the second attempt, the mechanic said a module of the remote ignition system was faulty and had to be exchanged.(mounted on the underside of the vehicle)

A month later I looked under the car and noticed the earth wire between chassis and engine was damaged. Exchanged it for a $10 new one, Voila.
 
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I've always understood an Amature as one who does not receive compensation, as uposed to a professional being one who receives pay for the same endevor.

Many Amature Radio operators are very professional although they work only as a hobby.

If I wish to insult, I would use the term "Rank Amature" rather than Amature.
 
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Some amateurs even get paid for it (quoting a line from a classic Italian movie : to sweeten the mouth).

One of my cars refused to start time and again, usually after it had rained or when it was damp.
It spent 5 days at the service car shop, they even contacted the factory through the web, after which they told I needed new car keys (at >$100 each) and handed me a $1k bill.
On the highway, roadside assistance had to be called twice after a breakdown. On the second attempt, the mechanic said a module of the remote ignition system was faulty and had to be exchanged.(mounted on the underside of the vehicle)

A month later I looked under the car and noticed the earth wire between chassis and engine was damaged. Exchanged it for a $10 new one, Voila.

Moral of the story: look under the car first :D

Jan
 
I have just bought a new washing machine. My old one, still working after 25 years, was simply too small now there is a lady living in my house.

About 15 years ago the old one developed a fault, which was consistent with the drive belt having broken. I was told by 'professionals' that it could not be repaired, no parts were available etc. etc. I took the back off and found that the motor had shifted in position and the drive belt had simply come off the pulley. 10 mins with a spanner had it fixed and it has worked fine every since (albeit rather noisily in recent years). I now keep it as a spare, as I expect the new one to become unusable and unrepairable in rather less than 25 years!

Many years ago I took my car for an annual service to a franchised dealer. I said to the professional mechanic "Please check the shock absorbers, as it seems to roll a bit on corners." When I picked it up they said they were fine, no need to change. The following year I took it to the same garage again, but said nothing. I received a phone call "Your shock absorbers have gone and need to be replaced. Will cost you £X; OK to proceed?". So who is the true 'professional'? PS I don't know much about modern cars, but I do know a bit of physics.
 
Thanks for the input, many of you. You are right, I am trying to 'push the envelope' in audio design, and pass it on to everybody. At the same time, my approach is abrupt, and actually considered rude by the majority here. I regret that.
Now, please consider my position:
I design a number of audio products that are still made today, and several of my previous designs from previous decades are considered 'collectable' causing their price today the same or more than what they sold for originally. What did I do to get in this position?
Now, I have been studying audio design seriously, almost fanatically, for the last 50 years. Even when I worked on designing other products, my heart was in audio design, and I spent at least an hour every day, on studying the subject. This for the last 50 years. Is it surprising that I might consider myself as experienced in audio design to the point where many here seem to be 'amateurs'?
I am an amateur automobile tuner and re-builder. Or at least I was, starting from 50 years ago, as well. YET, I have found myself embarrassed at times by my ignorance of the subject, yet I read a number of books on the subject and even did rebuild and modify my own engines.
I found that people who were too polite to 'correct' me in these matters did me a disservice by keeping me in ignorance. I feel the same way about audio, in reverse. That is why I provoke, rather than just smile.
Now, PMA is a notable exception: He is correct about DA. It was known about, but normally ignored, except for sample and hold circuits, and previously, analog computers. I had the equations and references available in the early 1970's, BUT I did not connect them to audio. So, I was where we are mostly today on this thread, why NOT use Mylar, or even aluminum electrolytics, perhaps with a little voltage bias? People do it all the time. Parasound does it all the time with products that I do not design. What is the harm? Why don't we now go on to discuss DA, how to measure differences in different caps, and what we think it does to the sound quality?
 
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That is decidedly untrue. A pro in the fashion audio market is judged on how well he moves boxes. Period. He operates under constraints that "amateurs" don't. So it's not surprising that "amateurs" can achieve better results much of the time.
Well I did say needs not does perform to a higher standard. Sy your example is a govenment aproach if we throw enough money at it we can make it better. One off carefully selected and executed designs can beat the pro design because of cost in materials and time to build. So we are not judging the same thing here . The most prized bits of automoblia are often rare and from failed company I see the same thing here so to speak.
 
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Thanks for the input, many of you. You are right, I am trying to 'push the envelope' in audio design, and pass it on to everybody. At the same time, my approach is abrupt, and actually considered rude by the majority here. I regret that.

Regret what, that others consider you rude, or that you are rude? It sounds like the thief who was sorry he was caught.

You should be apologizing.

I found that people who were too polite to 'correct' me in these matters did me a disservice by keeping me in ignorance.
All here are trying not to do you the disservice.

You should be thanking them instead of being rude and condescending.

jn
 
Now, let us proceed to DA in caps: A bit of history. DA was found VERY IMPORTANT in analog computer performance, so they carefully analyzed it perhaps 70 years ago. Some of the early papers from the 1950's are still informative and useful. However, what does it do to audio signals?
Why there is a question is that CONSTANT tones do not easily show any problem with DA. So both harmonic and IM distortion do not show DA directly, so it could be easily overlooked. Therefore, what do we need as a test signal to bring out DA, and its effects? Well, actually music or voice does a pretty good job, but these sources are so random and variable that they don't make the best test signal.
Then, what we need is a consistent and repeatable test signal, and a repeatable way of detecting DA. This is where we were in the early '80's or only 30 years ago. '-)
(more later)
 
jihn curl said:
So, I was where we are mostly today on this thread, why NOT use Mylar, or even aluminum electrolytics, perhaps with a little voltage bias?
Sigh. Can we put Mylar caps with 741 opamps? Something you keep mentioning as though we use them all the time, yet we don't and haven't for some years - even though they are fine when used well within their limitations.

jc said:
Now, let us proceed to DA in caps: A bit of history. DA was found VERY IMPORTANT in analog computer performance, so they carefully analyzed it perhaps 70 years ago.
DA is very important for analogue computers, as it affects the very low frequency behaviour of capacitors.

However, what does it do to audio signals?
DA is irrelevant for audio, as it only affects the very low frequency behaviour of capacitors. There remains a faint possibility that high DA correlates with some other dielectric issue which does affect audio in some unspecified way, but I suspect that the main effect of DA in audio is the fact that it can confuse people who look at waveforms (by changing very low frequencies) so analogous to the effect of a low pass filter (which changes very high frequencies) on waveforms - those who regard any change as "distortion" even when no new frequency components are introduced.
 
Regret what, that others consider you rude, or that you are rude? It sounds like the thief who was sorry he was caught.

You should be apologizing.


All here are trying not to do you the disservice.

You should be thanking them instead of being rude and condescending.

jn

Pretty simple and straight forward really , you guys need to stop interrupting john when he's being rhetorical ..:)



Gives him a chance to tell his story ........ :drink:
 
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