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RE: Favorite Caps (Opinion)?

Posted by Eli Duttman on July 31, 2017 at 16:42:21:
If your preamp is to be capable of driving the 10 Kohm IHF "standard" load, the minimum amount of capacitance in the O/P coupler is 3.3 μF.

That amount of capacitance in a "boutique" item is hideously expensive. The "budget" solution is a 4.7 μF. metalized polypropylene part, like SCR (France) makes, bypassed by a 0.47 μF. 716P Orange Drop. The "budget" solution is pretty darned good. Yet more transparent is using a 0.33 μF. PPFX MultiCap to bypass the 4.7 μF. part. The construction of MultiCap parts makes them highly suited to the bypass role. The "better" solution is costly, but not to an obscene level.

BTW, the "low" voltage present at the cathode may prove to be problematic, if PIO or PTFE is used as the O/P coupler's dielectric. "Run in" may be a VERY lengthy process.