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Capacitors for HP filters in tube amps recommendations?

I’ll soon be installing a capacitor on each of the input jacks of two tube power amps, to create passive 1st-order high-pass filters. Cap values are 19.9uF (20uF will do) and 30.33uF (let’s say 30uF). I’ll need two of the former and four of the latter (balanced/XLR input jacks), and I don’t want to spend more on the caps than the amps cost me ;-) .

I’m all ears for nominees. I don’t need or want any flavoring, "just" neutral transparency. The amps are powering fairly transparent loudspeakers (ESL’s, and Magnetic-Planars with Ribbon tweeters), which will pretty well reveal the character of the caps. In spite of that fact, "most-bang-for-the-buck" nominees are of particular interest, not cost-no-object ones. Thanks y’all.

128x128bdp24
pragmasi
212 posts
 
100k and 80Hz requires .02uF, 30k and 175Hz .03uF.
 You parallel up .01uF caps (for caps in parallel you just sum the values), so five for each channel means $4.20 in capacitors.

erik_squires
16,057 posts
 
On the inexpensive, I like Cornel Dubelier a great deal.

If you want to try pricey ... both Audyn (True Copper Max) and the 600V versions of Jansen copper foil caps come in 0.01 values.

Best,

Erik
bdp24's avatar
bdp24 OP
9,788 posts
 
Ah yes @pragmasi, you explained that above and I missed it. And the caps you speak of are small enough to fit side-by-side on the input jacks. Thanks, mate. @Erik, I’ll have to look inside the amps to see exactly how much room I have for the caps. Those Jansen’s are huge!
erik_squires
16,057 posts
 
BDP24 - You know, you can easily make yourself an interconnect cable with a cap in line, no reason to mod your existing pre. :)


But good for you for catching the size problem with those! :) I forgot to mention it.
bdp24's avatar
bdp24 OP
9,788 posts
 
Actually Erik, the caps are going into the two power amps rather than the output jacks of the pre, as each amp is used with a specific loudspeaker. But I take your point---the caps could be incorporated into the interconnect going to each amp. Not soldered onto the outside of each cable’s RCA or XLR plugs, of course, and they won’t fit inside them. Modjeski lays out his amps (RM-10 Mk.2 and RM-200 Mk.2) pretty sparsely, so there should be plenty of room inside for caps.
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