So a fast PSU is only something that affects how quick you can start up Enzo?
Is there no use for a fast stabilizing PSU during the use of the amp after startup?
I wonder why DHTRob seems to be happy with a faster PSU at page 19 here: https://www.dhtrob.com/overige/pdf/dhtrob_psu.pdf
Is there no use for a fast stabilizing PSU during the use of the amp after startup?
I wonder why DHTRob seems to be happy with a faster PSU at page 19 here: https://www.dhtrob.com/overige/pdf/dhtrob_psu.pdf
I think there is confusion about the word 'fast'. You seem to mean 'quick to stabilise output voltage'; I think DHTROB means 'low output impedance across the audio spectrum'. These two meanings are not necessarily the same; in some cases they could be opposite. Mind you, he also seems to use 'fast' to mean underdamped which is yet another option.
So, you decide what you mean by 'speed' or 'fast' and then design accordingly. Better still, avoid such vague terms (and avoid others who use them?) and say what you mean.
So, you decide what you mean by 'speed' or 'fast' and then design accordingly. Better still, avoid such vague terms (and avoid others who use them?) and say what you mean.
The power supply design was for golden ears audio reproduction, they live in a different planet. Mind you so do we. But that aside, as long as your capacitors are rated for the voltage the rectifiers will be putting out then there will be no concern about fast and slow, especially if you are feeding preamp tubes that are in Class A all the time and do not call for different amounts of current while in use. With an output section the idea of a slow or fast power supply can have some merit.
I think you are spot on DF96, my terminology regarding my question is vague and this is causing confusion. What I wanted to know is if the behaviour ( time vs voltage) at startup of a psu also tells us something about how an amp will perform while playing audio.
"Low impedance across audio spectrum" huh .. I will try to find what that is.
Printer2 your answer helps me with the actual preamp I am working on. Seems that with class A once the psu is stabilized it will remain so because of the constant current draw. Thanks.
"Low impedance across audio spectrum" huh .. I will try to find what that is.
Printer2 your answer helps me with the actual preamp I am working on. Seems that with class A once the psu is stabilized it will remain so because of the constant current draw. Thanks.
The start up time will not define how the power supply will perform whilst playing audio. That will be defined by how much energy the supply can deliver for rapid current demands. The article even says that the slower starting supply performs better. If you look at the circuits, the 'slower' supply has more capacitor storage closer to the output.
The author of the article is attempting to achieve clean start up. This alludes to clean charging of the supply when it gets depleted by the load which is dynamic. All currents return through the ground so clean charge of the supply implies less ground disturbance.
The author of the article is attempting to achieve clean start up. This alludes to clean charging of the supply when it gets depleted by the load which is dynamic. All currents return through the ground so clean charge of the supply implies less ground disturbance.
Thank you all very much for your answers. Things are getting clearer.
I have indeed noticed that adding capacitance makes the psu "slower".
When I have several crc rc rc filters in cascade I tend to get the message by psu2 saying "a current sink has pulled the voltage below zero for more then 5 mains cycles, at ( time)".
The psu's always seem to spend time below zero but a "slower" supply makes this warning message go off.
This happends with a 240v secondary and low current draw ( 4ma), constant current.
Is there a guideline that 5 mains cycles is an acceptable limit for a psu to be below 0?
I have indeed noticed that adding capacitance makes the psu "slower".
When I have several crc rc rc filters in cascade I tend to get the message by psu2 saying "a current sink has pulled the voltage below zero for more then 5 mains cycles, at ( time)".
The psu's always seem to spend time below zero but a "slower" supply makes this warning message go off.
This happends with a 240v secondary and low current draw ( 4ma), constant current.
Is there a guideline that 5 mains cycles is an acceptable limit for a psu to be below 0?
Hi Max999,
I read the linked article by DHT Rob. He keeps referring to the various power supplies coming up to voltage in milliseconds but on the graphics window the horizonal (X) line is seconds, not milliseconds. e.g. on page 4, figure 5 the power supply "comes up" in 2 seconds, not milliseconds.
Redd
I read the linked article by DHT Rob. He keeps referring to the various power supplies coming up to voltage in milliseconds but on the graphics window the horizonal (X) line is seconds, not milliseconds. e.g. on page 4, figure 5 the power supply "comes up" in 2 seconds, not milliseconds.
Redd
there is an r-c time constant formed by the filter caps and the psu traffo dc resistance, their values will determine the time it takes to come up to the right B+....
and if using tube rectifiers, the time it takes the filament to heat up and start emitting electrons is added to the build up time...
and if using tube rectifiers, the time it takes the filament to heat up and start emitting electrons is added to the build up time...
Your amplifier is usually NOT a current sink, but a variable resistance. (There are of course many-many experimental variations, especially here in DIYAudio.)
If the tube is cathode-biased and already hot when the B+ AC is turned on, it is pretty nearly a constant resistance.
This completely changes the concept of "damping". A true current sink is NO damping, a resistor will typically be significant damping.
And a real tube (UN-like a current sink) will NOT pull the rail below zero.
Agree that the cited paper says "mS" but the graphs are in Seconds.
I have _NO_ idea why we care about power rail bopping around for a second or so when it takes 11 seconds for an indirect heater to hot-up, and it takes me minutes to select a disk and put it on the turntable.
Perhaps the result of watching too much bad science-fiction on NetFlix? Or too many press-releases from a certain cult figure who thinks people can happily live on the bleak, barren, and quite deadly surface of Mars?
I bet we could start a golden-ears cult of SLOW if we wanted to. All frequencies above 1 kHz are harsh and unpleasant, the purest recorded sounds of all time came from Edison tinfoil-on-cylinder phonographs circa 1880, and no good audio amplifier or speaker should reproduce anything above 1 kHz. SLOW is better than FAST!
-Gnobuddy
Some twenty years ago, baffled by world events, I coined the oxymoron "Common sense is remarkably uncommon."
Since then, I see more and more support for this hypothesis all around me, and on the news every week.
Perhaps common sense decays exponentially with time, and we only got a one-time supply of it, given to us early in the history of the human species?
The good thing is, we have exponentially growing amounts of bureaucracy, red-tape, selfies, and utterly meaningless tweets. Who needs common sense when you have endless selfies?
-Gnobuddy
Perhaps there is a limited supply and it has to be shared out unequally for us to have a hope in hell. Not so much that it decays exponentially more that the demand grows. Although I don't see much evidence of that.....
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