Joshua_G said:
That is quite elementary.
I think JC just mistyped when he wrote 1 kHz.
Stinius
Of course, PMA, 10KHz is better, 40KHz preferred, but my Parasound designs are made stable and we get what we get.
Psychology and the sound of wires
Allow me to tell you a little story of mine.
Many years ago, Jean Hiraga spoke about a wire to replace the internal wiring of a tone arm. He said that it was the best he knew. I don’t remember how, but I managed to have him to sends me a sample. You can imagine how happy I was. I installed this wire and started to listen to my gear of the time.
I heard a difference. How cannot it be so: sensey Jean Hiraga had said it was the best wire available? But guess what? I didn’t like the sound at all. I thought I had ruined something in my tone arm and decided to reinstall the original wire. After this change, all was ok again.
John / Joshua power supply
I do agree, this design offers a poor load line regulation. In a pretty large frequency range, it is equivalent to something like a “perfect” voltage source in series with a 15 ohm resistor. Not really good as a regulator, but look at the context where this psu is used. It powers the one resistor that feeds both the cascoded fet and cascoding mosfet in a folded cascode stage. That means that the whole circuit is equivalent to a voltage source that feeds a slightly higher resistor.
The beauty of this design is that you don’t have to have a low internal resistance in the psu, you just have to have it constant and linear. You also need to have low noise.
I would guess that in the JC2, John use something that has a lower internal resistance.
Just my tow cents.
Philippe (who started many many uaers ago his engineering studies to be an audio designer but catched the IT bug)
Allow me to tell you a little story of mine.
Many years ago, Jean Hiraga spoke about a wire to replace the internal wiring of a tone arm. He said that it was the best he knew. I don’t remember how, but I managed to have him to sends me a sample. You can imagine how happy I was. I installed this wire and started to listen to my gear of the time.
I heard a difference. How cannot it be so: sensey Jean Hiraga had said it was the best wire available? But guess what? I didn’t like the sound at all. I thought I had ruined something in my tone arm and decided to reinstall the original wire. After this change, all was ok again.
John / Joshua power supply
I do agree, this design offers a poor load line regulation. In a pretty large frequency range, it is equivalent to something like a “perfect” voltage source in series with a 15 ohm resistor. Not really good as a regulator, but look at the context where this psu is used. It powers the one resistor that feeds both the cascoded fet and cascoding mosfet in a folded cascode stage. That means that the whole circuit is equivalent to a voltage source that feeds a slightly higher resistor.
The beauty of this design is that you don’t have to have a low internal resistance in the psu, you just have to have it constant and linear. You also need to have low noise.
I would guess that in the JC2, John use something that has a lower internal resistance.
Just my tow cents.
Philippe (who started many many uaers ago his engineering studies to be an audio designer but catched the IT bug)
that's true, but can't be solved.Joshua_G said:
If the regulator behaves well on a dummy, static and dynamicwise, there is still some work and risk left.
regards
I hope your not suggesting long exposure to loud sounds (music included) dosnt harm hearing.
Joshua_G said:
??? I thought this was for a constant current load, so the Zout wouldn't be a problem? A constant current load from a constant voltage is equivalent to a resistor as a dummy load, no?
Jan Didden
john curl said:
That is very good, reliability first. But please teach Atkinson not to get:
---------
"With balanced drive, there were no problems. However, after I'd performed a full set of
balanced tests, I hooked up an unbalanced connection and again started to experiment with grounding. With one configuration—understandably, I didn't note
which it was—the amplifier went into high-level ultrasonic oscillation. In the short span of time it took me to yank loose the AC cord after seeing the oscilloscope screen go crazy, the room had filled with the smell of toasted components."
------------
Do not get me wrong, just responding 😉
This idea that our acoustic memory is very short is often accepted without supporting evidence.Andre Visser said:
I've never tried it, but I suspect I can remember the acoustic difference between a brass horn and a violin for decades. The statement is no less absurd than the one that generalizes all acoustic memory as lasting seconds.
Reality as usual is far more complex than this simplification. So if we don't reveal exactly what it is we are trying to remember, the argument adds nothing to the discussion.
Unfortunately much of this thread is exactly about what it is we are or are not hearing (remembering).
PMA, reality is not always flawless. JA MISSED what you found, because he used an AP floating balanced drive, that essentially ignored the problem. Thanks again for finding the problem that eluded me, Carl Thompsen (who modified the switching logic, initially from the PLD 2000 schematic, Parasound techs, Taiwan techs, and finally JA. I can't test with balanced drive, so I essentially ignore it.
I seriously tried to follow up on the oscillation that JA had. I was told that it seemed to be a ground fault problem concerning the AP, and that it never happened again. I can't fix what isn't apparently broken.
JA is not perfect, and neither am I, and I suspect most of you out there. Keep it real, don't pick and poke at little things that can't be easily followed up. That is just one-upmanship. I mean this in a general sense, and not really toward you, PMA.
I seriously tried to follow up on the oscillation that JA had. I was told that it seemed to be a ground fault problem concerning the AP, and that it never happened again. I can't fix what isn't apparently broken.
JA is not perfect, and neither am I, and I suspect most of you out there. Keep it real, don't pick and poke at little things that can't be easily followed up. That is just one-upmanship. I mean this in a general sense, and not really toward you, PMA.
hermanv said:
Judging by this thread some people's acoustic memories seem to only last milliseconds.
John, thanks for the explanation.
I know very well that reality is not that easy, and even one may think everything is solved and perfect, surprise and problem may arise. I did not mean to insult, anyway, just to remind; as I expected you were pointing at my recent oscillations problem.
I know very well that reality is not that easy, and even one may think everything is solved and perfect, surprise and problem may arise. I did not mean to insult, anyway, just to remind; as I expected you were pointing at my recent oscillations problem.
hermanv said:
There is truth in it, but like most things can't be generalised. I believe on an unknown system and not knowing what to listen for, it can be difficult to detect smaller differences. On a known system, I've detected a small difference after more than six weeks of not listening to the system.
janneman said:
There is a confusion between 2 supply circuits I came up with.
The last one posted here has opamp in the output and is intended for low current, good load regulation.
The previous one has paralleled JFETs in the output, it has lower noise figure but poor load regulation. Only this circuit is useful for a fairly constant current load. Even this circuit cannot be finished by dummy load only, as the actual load may not be purely resistive.
stinius said:
A little lesson in the ear and sound damage:
Maybe some of you already know this, but mayde not everybody.
The middle ear contains two tiny muscles. The tensor tympani muscle is attached to the hammer; it helps to tune and protect the ear. The stapedius muscle is attached to the stirrup and oval window; it contracts in response to a loud noise, making the chain of ossicles more rigid so that less sound is transmitted. This response, called the acoustic reflex, helps protect the delicate inner ear from sound damage.
If the sound engineer knows this and uses the low frequencies to control the muscles in the ear, the sound can be very loud and still don’t damage the inner ear. It is not to low frequencies that damage the ear but the high frequencies. Around 4 kHz is one of the first frequencies that “drop out”.
One of the things that really damage you hearing (inner ear) is if you are jogging / cycling with earphones with loud music. The blood will then go from your head and to your legs (making the ear muscles slower) and thereby let the loud sound enter the inner ear.
The absolute worst case would be to be drunk (puts the ear muscles out of work) and dancing, at a disco with terrible sound.
Hope that this was clear.
Stinius
Congratulations John!
To have a good design on paper or as a dead-bug-style prototype is one thing, but to make a real mass-produced
product is a totally different thing.
Sigurd
To have a good design on paper or as a dead-bug-style prototype is one thing, but to make a real mass-produced
product is a totally different thing.
Sigurd
john curl said:
stinius said:
really interesting.
That 4 KHz notch is prominent in my Significant Other's
hearing, too, but there is much more damage. Working in
a little childen school takes its toll. She has her hearing
checked on a regular base because she holds a pilot license.
Nevertheless it was fun at the Berlin Reichstag with Pink Floyd
and attenuators in the ears. I spent a few minutes in the first
row and the bass sound pressure made my clothes move.
IIRC they had an extra wall of speakers to make sure they could
not be overheard in the then communist part of the town.
regards, Gerhard
gerhard said:
Thank you Gerhard
Working in a children school is a typical place to get hearing damage, also working in a factory with a lot of hard sounds will damage the hearing. Sitting in the middle of an orchestra with a trumpet behind you is also a typical place not to be.
All of this is a lot worse than a very loud concert that makes your clothes move.
I’m sure that the Pink Floyd concert was a big happening. I Wish I was there.
I have spoken with David Gilmour, but never heard Pink Floyd live.
BTW how people react to different sound and frequencies is a very interesting subject.
Stinius
- Status
- Not open for further replies.