Hi,
Is Kirchoff dead?
250k Dale
0.47uF/630V MKP
V=72,5v+/- and I=60mA+/- (w22 and MKP/400V)
The amp has “ultra path” cap.
Yes it is.
Yes it is.
Something like: http://home.pacifier.com/~gpimm/56 C4S preamp.gif
Katapum
Is Kirchoff dead?
250k Dale
0.47uF/630V MKP
V=72,5v+/- and I=60mA+/- (w22 and MKP/400V)
The amp has “ultra path” cap.
Yes it is.
Yes it is.
Something like: http://home.pacifier.com/~gpimm/56 C4S preamp.gif
Katapum
Hi,
In your topology, the 5842 heats slower than the 300B. As supply voltage builds up quickly , the current source charges up the coupling cap to the 300B, and this charging current flows almost entirely through the grid of the 300B, because the 5842 doesn't sink current yet. This causes the 300B to operate at slightly positive grid voltage during the entire time the supply voltage rises, and draw excessive current. When the voltage comes up after the 5842 has heated, the tube does sink current and by doing so, it saves your 300B quite some punishment by reducing the speed at which the coupling cap is charged and its ultimate voltage. So to make a long story short: if you make the change you posted in post #17, and make sure you switch on the HT only after the 5842 has heated, you're probably safe. You may also just leave the GZ37 in place. Does the 5824 have a cathode decoupling cap? This also provides extra safety, and a lower driver impedance.
I hope this helps. At least we have a good idea about the cause of the arcing, and how to prevent it.
Jurgen
In your topology, the 5842 heats slower than the 300B. As supply voltage builds up quickly , the current source charges up the coupling cap to the 300B, and this charging current flows almost entirely through the grid of the 300B, because the 5842 doesn't sink current yet. This causes the 300B to operate at slightly positive grid voltage during the entire time the supply voltage rises, and draw excessive current. When the voltage comes up after the 5842 has heated, the tube does sink current and by doing so, it saves your 300B quite some punishment by reducing the speed at which the coupling cap is charged and its ultimate voltage. So to make a long story short: if you make the change you posted in post #17, and make sure you switch on the HT only after the 5842 has heated, you're probably safe. You may also just leave the GZ37 in place. Does the 5824 have a cathode decoupling cap? This also provides extra safety, and a lower driver impedance.
I hope this helps. At least we have a good idea about the cause of the arcing, and how to prevent it.
Jurgen
Hi,
So I have two solutions to solve the amplifier problem.
One as Jurgen refer the amplifier should work with GZ37.
Another is inserts a “bleeder” resistor (tuned to draw 2x10mA like 5842 stages) like I draw in post #22 (not #17). When warm up is finished I will open the switch.
Am I right?
Another problem in my PSU amplifier (and nobody refer) is the last PSU cap. It’s a 100uF but only 400V (and I spent a lot of money… they are Audyn caps). Maybe now is dead (I only have a DMM to measure 40uF caps, nothing more). What do you think?
PS: first and second PSU caps are motor run.
Katapum
So I have two solutions to solve the amplifier problem.
One as Jurgen refer the amplifier should work with GZ37.
Another is inserts a “bleeder” resistor (tuned to draw 2x10mA like 5842 stages) like I draw in post #22 (not #17). When warm up is finished I will open the switch.
Am I right?
Another problem in my PSU amplifier (and nobody refer) is the last PSU cap. It’s a 100uF but only 400V (and I spent a lot of money… they are Audyn caps). Maybe now is dead (I only have a DMM to measure 40uF caps, nothing more). What do you think?
PS: first and second PSU caps are motor run.
Katapum
Hi,
Yes, you have two options: use the GZ37, or install a stand-by switch like post #17. The bleeder from post #22 won't prevent the voltage to rise early, and isn't nearly as effective as the stand-by from post #17.
The audyn caps are polypropylene types, which are self-healing to some degree. If you test them with an ohmmeter and they show no shorts, it should be OK. A momentary overvoltage usually doesn't hurt them. I once put 750 Volts across a 400V one, and it still lives.
As far as improvement goes: if you use the schematic from post #1, and include the stand-by switch from post #17, that would be the best mix of the configurations we have discussed so far. But beware, the possibilities are endless. Motor run caps are very hard to beat sonically, especially at their price level.
My advice would be: complete the amp, check that it works properly, grab yourself a beer and enjoy it...
Jurgen
Yes, you have two options: use the GZ37, or install a stand-by switch like post #17. The bleeder from post #22 won't prevent the voltage to rise early, and isn't nearly as effective as the stand-by from post #17.
The audyn caps are polypropylene types, which are self-healing to some degree. If you test them with an ohmmeter and they show no shorts, it should be OK. A momentary overvoltage usually doesn't hurt them. I once put 750 Volts across a 400V one, and it still lives.
As far as improvement goes: if you use the schematic from post #1, and include the stand-by switch from post #17, that would be the best mix of the configurations we have discussed so far. But beware, the possibilities are endless. Motor run caps are very hard to beat sonically, especially at their price level.
My advice would be: complete the amp, check that it works properly, grab yourself a beer and enjoy it...
Jurgen
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