I have just finished my Aleph 3 (test part) and one think surprised me a bit: The rectifier gets rather hot!
PSU: 800VA transformer, 1 bridge (35A) i metal housing, 2x47000uF/40V caps....no hum/noise....
I have mounted the bridge directly on the secondary windings (for shortest possible wiring)so it is not mounted as normal on chassis.
It ran rather hot after few minutes (still touchable), so I fitted it on a small heatsink. After some hours this heatsink is now rather hot too, but still touchable.....
Will this be a problem? If I must rewire it is a major workaround and amplifier works perfect. My concern is reliability....how rough is this rectifier bridge?
PSU: 800VA transformer, 1 bridge (35A) i metal housing, 2x47000uF/40V caps....no hum/noise....
I have mounted the bridge directly on the secondary windings (for shortest possible wiring)so it is not mounted as normal on chassis.
It ran rather hot after few minutes (still touchable), so I fitted it on a small heatsink. After some hours this heatsink is now rather hot too, but still touchable.....
Will this be a problem? If I must rewire it is a major workaround and amplifier works perfect. My concern is reliability....how rough is this rectifier bridge?
The dissipation of the diode bridge rectifier may only be some 3 watts, if you picked the regular bias level.
But 3 watts is still enough to need a 10C/W heatsink if you wish to keep the temperature of the rectifier diodes at 50-55C (20-25C ambient)
The lower the temperature of the rectifier diodes is, the higher their thermal reserve is.
For class A/AB PP amplifiers, that translates into a high thermal reserve, which is necessary for the diodes to pass high peak current levels without choking to death.
Bias on the Aleph/3 is constant, and higher than that it never gets. Means that the temperature of the diodes only affects their life expectancy. At 55C, they may outlive you.
Why anyone would hang a diode rectifier block out in open air, instead of bolting it to the case ? Beats me.
Everything gets hot: cars, women, Aus, class A amps,... rectifiers.
But 3 watts is still enough to need a 10C/W heatsink if you wish to keep the temperature of the rectifier diodes at 50-55C (20-25C ambient)
The lower the temperature of the rectifier diodes is, the higher their thermal reserve is.
For class A/AB PP amplifiers, that translates into a high thermal reserve, which is necessary for the diodes to pass high peak current levels without choking to death.
Bias on the Aleph/3 is constant, and higher than that it never gets. Means that the temperature of the diodes only affects their life expectancy. At 55C, they may outlive you.
Why anyone would hang a diode rectifier block out in open air, instead of bolting it to the case ? Beats me.
Everything gets hot: cars, women, Aus, class A amps,... rectifiers.
And the worst: beerEverything gets hot: cars, women, Aus, class A amps,... rectifiers.
Steen
Skorpio said:
Anybody heard of failing metal housing rectifiers?
Yes, it sounds remarkebly close to a BANG
Magura
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