*** So thrilled to have some Imperials- if you don't have the patience or desire to read my little intro diatribe but have some wisdom to impart re upgrading Imperials, please skip the next 3 paragraphs for the substance of my questions, thank you ***

I know this forum is for Decware stuff, but given the popularity of their Imperial plans and the fact searching google for KT31 and Imperial leads straight here, figured there'd be Imperial savvy folk lurking about.

Scored some 50's Imperial corner horns some time ago- KT31 speaker kits in nicely dressed plywood boxes that I think are Cabinart kits. Build is like this:
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Just last night made space to bring them home and have a listen for the first time. Well, hard to describe my joy. My $3k (in 1989 dollars) Mirage M3 Stereophile "A list" speakers sound lifeless in comparison- the porch doors are hitting their bipolar asses on their way out.

So, think I've read somewhere these can benefit from internal dampening and/or more bracing. I'm thinking adding dampening material would be the easiest thing to address first. What kind? How much/how thick? Along all interior surfaces, or where?

Bracing: Any specific recommendations about what/where to add?

Xover? Think the stock xover is just coils and oil filled caps? Don't think oil filled caps drift much over time, and heck, many audiophiles strive to put paper-in-oil caps in their signal chain. Would there be any sonic benefit to changing caps to polypropylene or some other "modern" cap? Don't want to debate the merits of boutique caps in xovers, just wondering if there's something blatantly wrong or inferior with these stock old oil can caps in an xover vs modern film types.

thanks in advance for any help, suggestions, clarifications,
Ethan

Hi Steve,
Thanks for the welcome. Given the design of the imperial I can understand how the folded horn design can impart something special to low freqs, but the two HF drivers are just suspended in air at the top of the horn. Yes, it has a high quality horn midrange, something I'd never experienced, and I've often heard people sing the praises of them, the sense of breath they can impart, but I'm so baffled how a near 60-year-old Jensen dome tweeter can sound so much better, have such better definition, broader soundstage, and simply sweeter tone than so many high-end modern tweets I've heard. That has nothing to do with the folded horn design, does it? I use tube pre and power amps exclusively, except when using exceptionally inefficient speakers, where I biamp (using tube xover) and power LF drivers with behemoth SS amps. Perhaps the magic I'm hearing is simply due to the fact that for the first time I'm using high-end speakers that were actually designed to be driven by tubes?!