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Re: What's the difference between the 5U4, 5U4G, 5U4GA, and 5U4GB tubes?

38.32.10.39

Thanks Robert, that's helpful.

Now, I was thinking of beefing up the power supply in my Mark IIs. If the ST shaped 5U4G is less rugged, will that make it more likely to be damaged if I increase the capacitance and hence the current demands increase? Current inrush at power up is concern enough, but what about when it's playing music and a demanding passage comes along?

While we're at it, any thoughts on about how much I can safely increase the power supply capacitors in the Mark II? As you may know, the original design used a quad electrolytic cap, 30/20/20/20 @500VDC, with the 30uf section between the rectifier and the 50 ohm 10W resistor. Can I safely replace the 30uf @500VDC electrolytic section with a Solen 51uf @1500VDC polypropylene, or will the extra current roast the 5U4G (or 5U4GB)? How much can the total, originally 90uf, be increased to?

Do you think I need to be concerned about the replacement caps rating for high frequency (100KHz region) ripple current? I don't see why since it's not a switching power supply, but there seems to be a lot of discussion about this...

Thanks.
Peter



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