Anyone try Townshend Super Tweeters?

my own speaker is ruler flat(plus/or minus 1.5 db)to 25khz

If you're -3db @ 20-25kHz the only reason to boost your hi freq is if the room is damped: the wavelength at 20kHz is very short, so average thickness material will absorb...
Assuming you want a HF spl boost, use a 1st order & cut higher rather than lower. The good thing is that the s-tweet's upper resonance will be too high (~100Khz) to be significant in the audible spectrum as its effects daisy-chain downward.
But there, you'll need a Murata or a Tad (or Townshend/Tannoy -- but they're very expensive). There is also a FOuntek s-tweet that's priced logically. The Fountek mentioned above is a normal tweet (37kHz) and will only boost your audible hi-frequencies.
Measure yr main spkrs' power rating & make sure you equalise the s-tweet accordingly. Also make sure you place it correctly on the same vertical acoustic plane as the tweet while you're at it -- or you'll be out of phase with the tweet!
Cheers

So,Gregm--Based on my set-up,in a dedicated room,with some acoustical damping(only to cut out any glare,and the room does have a wonderful,natural sound),do you think my idea is overkill.I,personally have NO problems with my current high freq presentation,but thought that if I added a super tweeter,it would level the playing field,with the "berylium/diamond dome" crowd.If there really is an audible advantage,to them.

Any thoughts would be appreciated!

Jtgofish. Hmmmmmmm.... .5uf or 1uf cap? Are you using an inductor in series with the cap?

I've been using Tonian Supertweeters (ribbon) with Harbeth C7s for a number of months. They've added openess, air, sparkle(the good kind - like finer musical nuance) along with extended highs. Tonian matched them for my speakers specifially and sent along extra resistors to adjust the output level if needed - didn't have to. I've also, for fun, tried them with Spendor 3/5s and got the same result. I'd have to say that anyone with Harbeths, Spendors, or (based on my listening in stores only) some models of Sonus Fabers would really like these tweeters.

I can't say whether they'd be useful with speakers that claim to go to 25khz anyway but Tonian claims they have output to 40,000hz. Tonian offers a home trial but they are expensive. However, I find them indespensible.

Sirspeedy- I'm not sure it's overkill, I'm just wary of the cost-benefit.
Yr room treatment obviously addresses reflections (you mention "glare"). By adding a s-tweet you'll be adding HF sp on axis & (assuming a ~30degrees dispersion) and some reverberant sound as well (you'll effectively overcome part of the room treatment): so, you might perceive more "air" and HF harmonics will be more pronounced, even at low volumes. From yr description, you don't need a s-tweet for high volume listening.

This may be useful for cd as there typical response peters out after 10kHz or so -- the energy level falls.

TO put things plainly, the advantage of a s-tweet is that its response limit is so high up that the audible HF are well within its linear region. The disadvantage is that it won't play as low as a regular tweet... Most spkrs start dropping in room, around 10kHz or so, & a s-tweet will cover +10Khz easily (and that's audible).
Best thing would be to borrow one -- possible? Try at low AND high spl. Cheers