John Curl's Blowtorch preamplifier part III

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Diamonds are an amps best friend? :D

Mark seems overly keen on reinforcing your bias that you are not susceptible to expectation bias or confirmation bias and probably others which are evident in your posts.

So let me get this straight......i’m agreeing with a quite logical explanation for what I’m hearing but yet your still arguing that I’m suffering from some expectation delusions?

It must really suckle hind teet to have absolutely no confidence in ones own senses (as you portray), to live without voicing a personal opinion for fear of being wrong.

Hey......if i’m Wrong a hundred times a day and right once, I’m still right once.
 
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How about a headphone driver that draws 100W quiescent?
I just got word they're going to stock the T2 headphone driver (PCB) in the diyAudio store. It runs class-A and draws a whopping 4W per channel, quiescent. Here's a thermal image; the unit is sitting on a plywood board and has been powered up for 90 minutes.

759322d1558993363-single-class-headphone-amp-using-transistors-t2-hpa_thermal_with_y_axis_labels_removed-jpg


There are four transistors, four heatsinks, zero ICs, and zero vacuum tubes inside the box.

_
 
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It must really suckle hind teet to have absolutely no confidence in ones own senses (as you portray), to live without voicing a personal opinion for fear of being wrong.

Hey......if i’m Wrong a hundred times a day and right once, I’m still right once.


I have 5 daughters, so am ALWAYS wrong :)


I think you confuse between personal opinion and engineering accuracy. Opinions are fine and people have preferences. It's only when someone days 'X is better than Y' that it will get questioned if there is no evidence.
 
So let me get this straight......i’m agreeing with a quite logical explanation for what I’m hearing but yet your still arguing that I’m suffering from some expectation delusions?
What is your explanation for the change you perceive when you disconnect the wire then connect it again? Expectation bias is something we all experience, even you, even when you refer to it as a delusion, which is in itself evidence of one of your biases.
 
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Pavel,

Unless I am misreading things the diamond output stage has the capability of more current drive. Which I would not expect there to be much difference as there is a 50 ohm series resistor on the output.

I would be curious to see if darlingtons with emitter to base resistors between devices would not improve performance.

I think we both read the increase in distortion as onset of clipping type behavior. (Not true clipping just beging to run low.)
 
2 PMA

Only hypothesis, what about output DC ofset? DC bias for transformer core..And C25 is really "zero" value?

Yes, there is no C25 there, it was only in a simulation. DC is <50mV, so maybe? Simulation shows nothing. I am trying a 47 ohm res + 9 mH coil as a load, behavior is very, very strange. I will take a wideband scope to check HF stability.
 
What is your explanation for the change you perceive when you disconnect the wire then connect it again? Expectation bias is something we all experience, even you, even when you refer to it as a delusion
The amp cooled off Scott (10 mins)......I was not aware of this exponential cooling factor that mark brought up (I’m assuming it’s a real thing) and it all made perfect sense. I accepted it because it made perfect sense.

Where as your explanation of it is as if I was ‘expecting’ something.......I was not expecting anything when I put it back together exactly as it was, but yet there was the difference.

Was that non expectant, expectancy gone awry?
 
Phsycoacoustics is how we perceive a sound......in your explanation there is no sound in the first place.

Well if the amp was off for 10 min and 60% of the cooling takes place in the first third of the time it takes to heat up (30 min) the math says that it should sound as though it was only on for around 10 minutes from a cool start. Which in fact is how it sounded.......for me there’s no need to waste any more time on it as my curiosity is satisfied, but I will certainly pay more attention later maybe even borrow my buddies laser gun to get some ‘measurements’
 
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Phsycoacoustics is how we perceive a sound......in your explanation there is no sound in the first place.
You said you heard a difference? :confused:

Psychoakustik is a branch of Psychophysik and is solely interested in the question if sound events evoke auditory events, psychological effects are only of interest as potential confounders but are examined in cognitive psychology.
So when you adapt to a sound, like when entering a room or moving position or focusing on a particular person for example, that's not psychoacoustics? Or masking, ignoring reflections etc? I know Wikipedia isn't the be all and end all but this is from the entry on psycho acoustics

"The term "psychoacoustics" also arises in discussions about cognitive psychology and the effects that personal expectations, prejudices, and predispositions may have on listeners' relative evaluations and comparisons of sonic aesthetics and acuity and on listeners' varying determinations about the relative qualities of various musical instruments and performers. The expression that one "hears what one wants (or expects) to hear" may pertain in such discussions."

Sorry Bob, in that case I don't know what you meant by psychobabble BS?
 
for me there’s no need to waste any more time on it as my curiosity is satisfied, but I will certainly pay more attention later maybe even borrow my buddies laser gun to get some ‘measurements’
That's fine, it could be the cause of the change you hear, but it's just as likely not. You did provide that as one example but also said other changes required settling time, I wonder what the other explanations could be.
 
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