John Curl's Blowtorch preamplifier part II

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SY, I actually more or less agree with you about .05% distortion, ONCE IT IS WEIGHTED, with 2'nd harmonic having a multiplier of one, and 7'th harmonic having a multiplier of 12 or more.
That is WHY the CTC Blowtorch has passed listening tests, with honors, YET it does NOT measure all too well. It is NOT because of ADDED distortion, BUT that the WEIGHTED distortion is low enough to ignore.
Ayre is even MORE cavalier about distortion numbers. Yet they succeed in selling their product.
The Wavac that was put up, was really BAD, but it is based only on a 50Hz sine wave. Maybe, 200Hz might be 10 times better. Who knows?
We all know that loudspeakers have more distortion than most electronics. How could we hear differences in electronics then? Well, 40 years ago, Richard Heyser insisted that it was NEGATIVE FEEDBACK, to Bascom King, Geoff C.(another engineer) and me, that caused the most 'damage' to the audio signal. Speakers don't normally use negative feedback, gee maybe there is something to this? '-)
Bascom's Constellation amp just won an Editor's Choice award in the latest TAS. Maybe Bascom learned something that many here don't believe in.
 
Others think that THEIR hi fi designs are among the best in the world, yet nobody outside their family circle has ever heard them.

If you mean me, I can assure you that neither SY who measured, nor other people who used my vacuum tube Pyramid-V amp on BAF to audition speakers (including ones with complex crossovers) are not my family members. :D

However, if you mean that DIY Audio forum is one big family, I agree with you. :)

Edit: and lots of negative feedbacks did not cause damage to it. So it is not negative feedback that is bad. It is how, and to which topology, it is applied. Masking can explain something, but it is not the full story. Dynamics matter more.
 
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...on second thought, I will be able to close blinds when watching a move, and open when I want it to be light, regulating dispersion according to time of day. UV rays are good; we need UV rays particularly to produce vitamin D that is vital for our body. Also we need sun spectrum because LED lights fooling imagination as if the light is white actually disrupt feedbacks of our natural self-regulating organisms.

Awh... just take a D3 pill. Right now it is 105 outside... no, I want the coolness -- heck with the white light. No UV for me today, thank you.
Closing hot metal blinds/window glass to watch a movie in a hot room? To each his own.
Me, I'm getting in the cool pool :drink:
 
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who will go first?

SY, I actually more or less agree with you about .05% distortion, ONCE IT IS WEIGHTED, with 2'nd harmonic having a multiplier of one, and 7'th harmonic having a multiplier of 12 or more.
That is WHY the CTC Blowtorch has passed listening tests, with honors, YET it does NOT measure all too well. It is NOT because of ADDED distortion, BUT that the WEIGHTED distortion is low enough to ignore.
Ayre is even MORE cavalier about distortion numbers. Yet they succeed in selling their product.
The Wavac that was put up, was really BAD, but it is based only on a 50Hz sine wave. Maybe, 200Hz might be 10 times better. Who knows?
We all know that loudspeakers have more distortion than most electronics. How could we hear differences in electronics then? Well, 40 years ago, Richard Heyser insisted that it was NEGATIVE FEEDBACK, to Bascom King, Geoff C.(another engineer) and me, that caused the most 'damage' to the audio signal. Speakers don't normally use negative feedback, gee maybe there is something to this? '-)
Bascom's Constellation amp just won an Editor's Choice award in the latest TAS. Maybe Bascom learned something that many here don't believe in.

With PC based virtual instruments and ADC/DAC, who will be the first to offer us software plug-ins to do various weighting functions for us??
And, after wieghting, what else to add to the plug-in list of apps?

-RNM
 
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Edit: pointed right now IR thermometer at several surfaces around. 95 degrees maximum. Not bad. However, the notebook is a bit hotter. :)

Inside surfaces are at 95 degrees !! and your window glass temps? Yikes, man! Multiply that by all the surface areas... good luck with cooling the room down ($$). Not bad!?! What is the ceiling temp with that white roof?

I'm not here. I'm in the pool. Pool surface area = big and temp is 68F. Big X 68 = still cooler. (wireless computer is floating next to me in a styrofoam cooler).
 
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got any ideas where we can find those qualities? I nominate you. Will those fit into an instrument app? How, exactly. When can you start?

I started from synthesizing sounds. Guitar effects, analog synth. From scratch, in laboratory. When tried to follow beliefs and fashions could not understand why fully complementary very low distortions and fast power amps sounded worse than tube amps that I thought were lousy. Until much later understood that the experience I gained designing distorted sound is sufficient to design gear which distortions are inaudible. Since then use both tubes and SS devices, with great results.
 
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Measured the roof from inside, 95. Not bad, since my roof has no attic, about 1 feet between the roof and the ceiling. Before it was a nightmare. Under the sun the roof was getting hot, and temperature inside was always higher than outside.

I can't draw PCB in the pool, unfortunately... I don't delegate prototyping to anybody, because during prototyping I often correct design, all the way...
 
SY, I actually more or less agree with you about .05% distortion, ONCE IT IS WEIGHTED, with 2'nd harmonic having a multiplier of one, and 7'th harmonic having a multiplier of 12 or more.
That is WHY the CTC Blowtorch has passed listening tests, with honors, YET it does NOT measure all too well. It is NOT because of ADDED distortion, BUT that the WEIGHTED distortion is low enough to ignore.
Ayre is even MORE cavalier about distortion numbers. Yet they succeed in selling their product.
The Wavac that was put up, was really BAD, but it is based only on a 50Hz sine wave. Maybe, 200Hz might be 10 times better. Who knows?
We all know that loudspeakers have more distortion than most electronics. How could we hear differences in electronics then? Well, 40 years ago, Richard Heyser insisted that it was NEGATIVE FEEDBACK, to Bascom King, Geoff C.(another engineer) and me, that caused the most 'damage' to the audio signal. Speakers don't normally use negative feedback, gee maybe there is something to this? '-)
Bascom's Constellation amp just won an Editor's Choice award in the latest TAS. Maybe Bascom learned something that many here don't believe in.

Three points.

1) Marketing makes all the difference, whether the product is superior or not. Less expensive manufacturers use reverse of bait and switch (discussed this with a federal investigator friend.). Instead of bait and switch, moving the customer to higher priced; marketing/PR is that lower priced, inferior product is as good.

Everyone is after a higher market share of the multibillion dollar market.

2) Low enough distortion and the subject becomes mute. So design with cushion in mind.

3) Global negative feedback can have problems, depending upon the transit time and feedback ratio.

Cheers.
 
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I am OUTSIDE. On backyard, under the tree.

Let me go inside and measure...

83 the hottest surface. I switched on air conditioner at around 3 pm only - not bad! Neighbor's conditioner hums since the morning.

Sure... I know your untreated glass windows are not 83 if its 105 in the shade. Com-mon. Ceiling? List 'em.

Go get the film and do your windows... but get the type to put on the inside of the window glass. Hurry and then get back to me asap with the before and after temps.
-waiting. Holding breath.
:drink:
 
3) Global negative feedback can have problems, depending upon the transit time and feedback ratio.

You really should read Bruno Putzey's article in Linear Audio. The transit time thing is nonsense (unless you're designing video amps), and feedback ratios were solved problems 40 years ago. His analysis is brilliantly simple and clear. To date, no one has contradicted anything he wrote.

To quote Morgan Jones (Valve Amplifiers, 4th edition, p54):

In the late 1970s, when cheap gain became readily available, designers because very excited by the possibilities and implications of the feedback equation, and set out to exploit it by designing amplifiers that were thought to have very high levels of feedback. In practice, these amplifiers did not have high levels of feedback at all frequencies and all power levels, and it was the lack of feedback to linearise these fundamentally flawed circuits that caused their poor sound quality.
 
Sure... I know your untreated glass windows are not 83 if its 105 in the shade. Com-mon. Ceiling? List 'em.

Go get the film and do your windows... but get the type to put on the inside of the window glass. Hurry and then get back to me asap with the before and after temps.
-waiting. Holding breath.
:drink:

Don't hold for too long. In your age it can be fatal, especially when 105 outside, and when you consume pills instead of healthy lifestyle. It was 95 here outside when I measured the table edge (under the tree). Now it is 91 only.
 
You really should read Bruno Putzey's article in Linear Audio. The transit time thing is nonsense (unless you're designing video amps), and feedback ratios were solved problems 40 years ago. His analysis is brilliantly simple and clear. To date, no one has contradicted anything he wrote.

To quote Morgan Jones (Valve Amplifiers, 4th edition, p54):

Jneutron mentioned an article that demonstrated the ear can detect 2us time changes. Dr. Kunchur spent 5 years, used medical experts and other national organizations, and demonstrated 5us was perceived. Transit time of typical amps is between 10-20us or more.

Cheers.
 
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