yes, of course if you can find them...
with power supplies, safety is your biggest concern, get it right first...
high valued ecaps are simply not common as of yet...
with power supplies, safety is your biggest concern, get it right first...
high valued ecaps are simply not common as of yet...
The PSU's I'm working on are Tube rectified for a tube preamp. For a 274B rectifier it is recommended the first cap is 4uF or less while the second and the first caps should not total more than 24uF. so a Mundorf Supreme 3.9uf 800vdc and a 20uf 750vdc Mundorf Tubecap should work fine.
Is there any reason other than voltage to split the caps? better filtering or less stress on the rectifier tube?
Thanks.
Is there any reason other than voltage to split the caps? better filtering or less stress on the rectifier tube?
Thanks.
none that i know of other than safety. for one the series esr's add up which may not be a good thing...
What is between the caps? If nothing, or not very much, then the two caps are in parallel so the rectifier sees 23.9uF and has a short life. If an appropriate value resistor or choke then the rectifier only sees the first cap and lives long. The choke/resistor plus the second cap act as a low pass filter. I don't know why there is a specified limit on the sum of caps; this would be quite unusual. Have you done any reading on PSU design?AvMania said:
Practicality works for many of us - buying and positioning two 47uF 400V electrolytics is so much easier than your alternative 22uF 1000V poly. If you have those poly's lying around then use them if the chassis is big enough.
If you are fixated on thinking that a poly can do a better job in that situation, then perhaps its worth thinking about how much worse the ESL could be for the poly, and how much longer the cabling is and whether that will couple more dI/dt and dV/dt noise in to the rest of your amp.
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DF96 - I have taken the ratings from Emission Labs 274B spec. Here
I'm trying to adapt the EL 274B circuit number 5 onto a PSU board with a good regulator which normally uses a 5U4G. The original design is fine for the 5U4G as its first cap can be up to 33uF but not for a 274B.
I could put in two 5uf 500v Audio Note Kaisei electrolytic (for C1&C3 on the PSU board) or a single Mundorf Supreme 2.2uF (800v).
Trobbins - The Mundorf Supreme and Tubecap occupy the same area the 4 electrolytic caps use. no extended cables required where as if I was to use a Supreme 22uF it would not fit.
I'm trying to adapt the EL 274B circuit number 5 onto a PSU board with a good regulator which normally uses a 5U4G. The original design is fine for the 5U4G as its first cap can be up to 33uF but not for a 274B.
I could put in two 5uf 500v Audio Note Kaisei electrolytic (for C1&C3 on the PSU board) or a single Mundorf Supreme 2.2uF (800v).
Trobbins - The Mundorf Supreme and Tubecap occupy the same area the 4 electrolytic caps use. no extended cables required where as if I was to use a Supreme 22uF it would not fit.
Be careful with that Emission Lab page's information.
Placing a choke in the negative leg can cause other noise issues:
Note on a cause of residual hum in rectifier filter circuits 1934.pdf
They show a poor connection point location in circuits 2 and 3 of their notes.
They also appear to indicate that 600mA is the peak short duration current limit allowed - you should confirm that your final circuit complies with that using PSUD2, and using a hot start, and using measured power transformer and choke winding resistances, and preferably the capacitance tolerance.
Placing a choke in the negative leg can cause other noise issues:
Note on a cause of residual hum in rectifier filter circuits 1934.pdf
They show a poor connection point location in circuits 2 and 3 of their notes.
They also appear to indicate that 600mA is the peak short duration current limit allowed - you should confirm that your final circuit complies with that using PSUD2, and using a hot start, and using measured power transformer and choke winding resistances, and preferably the capacitance tolerance.
I thought people use these rectifiers because they are beefy, not because they are weedy. I guess that is what you get with 1930s technology! A 10H choke ought to deal with inrush current; I don't know why they think it won't.
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