why?
the F5 is a ClassA amplifier and it draws continuous current even after the power has been switched off.
Have you measured how long the caps remain fully charged?
the F5 is a ClassA amplifier and it draws continuous current even after the power has been switched off.
Have you measured how long the caps remain fully charged?
No, not yet, I'm in the process of designing one. So, you think I don't need it?
Wouldn't it help with speaker protection when turning off?
Wouldn't it help with speaker protection when turning off?
Is there a problem sir?
My guess was that if on turn off the resistor drains the caps then no power left in the rails.
I asked twice for an explanation, now if you don't want to reply, it's your ***** problem,
but if you do then keep your tone done. You don't know me, as I don't know you.
You imply that I said something REALLY stupid, and this is your brilliant answer that outsmarted me?! Right!
Some time ago I read something that Wavebourn wrote (if I'm not mistaken). He said the "wiser" give their knowledge with open hands to new comers, and then not treated accordingly. That they get a lot of bad reactions. Well this is not what I've seen here, and it happened to me a few times and also read same reactions in past conversations between others.
My guess was that if on turn off the resistor drains the caps then no power left in the rails.
I asked twice for an explanation, now if you don't want to reply, it's your ***** problem,
but if you do then keep your tone done. You don't know me, as I don't know you.
You imply that I said something REALLY stupid, and this is your brilliant answer that outsmarted me?! Right!
Some time ago I read something that Wavebourn wrote (if I'm not mistaken). He said the "wiser" give their knowledge with open hands to new comers, and then not treated accordingly. That they get a lot of bad reactions. Well this is not what I've seen here, and it happened to me a few times and also read same reactions in past conversations between others.
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What is the current draw of the ClassA amplifier?
Now at the instant you pull the mains plug from the mains supply socket, what is the current draw of the ClassA amplifier.
Now take a guess at how slowly, or how quickly the smoothing capacitors will discharge.
Why do you need to add extra resistors to draw more current from the PSU?
Put your thinking cap on.
Now at the instant you pull the mains plug from the mains supply socket, what is the current draw of the ClassA amplifier.
Now take a guess at how slowly, or how quickly the smoothing capacitors will discharge.
Why do you need to add extra resistors to draw more current from the PSU?
Put your thinking cap on.
Bleeders are still a good safety measure. let's say the amp needs trouble shooting? You are not garunteed the supply will discharge it's caps and could get burnt, blinded, etc. It's only a few mA extra draw vs. Amps for the output section.
"I have looked at relay connected discharge resistors that ONLY connect AFTER power down. That is a quite different topology."
Like?
Like?
They don't conduct while the amp is operational.
They don't get warm/hot.
They don't increase current draw.
They do conduct when required.
They do discharge high voltage capacitors in a controlled way.
I even bought lots of 24V tungsten bulbs to gain some advantage in non linear resistance characteristic as the capacitor voltage drops.
They don't get warm/hot.
They don't increase current draw.
They do conduct when required.
They do discharge high voltage capacitors in a controlled way.
I even bought lots of 24V tungsten bulbs to gain some advantage in non linear resistance characteristic as the capacitor voltage drops.
I never thought of it that way but it explains a lot. On my Tube amps with large power supplies or various Class A/B amps, I would always wait a period of time after switching off the power amp before switching off the pre amp. As they would continue to play after switch off otherwise, I always thought this was a good idea for bleeder resistors. With the F-5, I always noted it was "Dead" immediately with switching it off, and immediate switching off of the preamp caused not a sound.
I would imagine it bleeds off almost immediately. I have noted several have noted in F-5 builds these bleeders werent necessary, now I know why.
Russellc
I wouldn't have said it was exactly hard...
Drive the relay with the secondaries of the transformer which switch the caps power to the amp or through the bleed resistors. This gives a much more controlled power down of the amps too and eliminates the possibilities of one rail draining faster than the other.
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