Horn driver adaptor

[Sootshe]

I've been doing some experimenting here with my Klipsch K55 mid range drivers mounted to an ALK Trachorn. I first removed the bug screen & noticed a considerable improvement in detail, then I removed the rubber washer between the driver & the horn...again a noticeable improvement. On closer inspection I notice that the Selenium Adaptors (APT 25-25) have a length of 25mm in the neck of the adaptor, whilst the threading on the K55 is only 13-14mm, leaving a nominal distance of 11mm of extra length before the sound actually enters the horn flare. I could hear a difference when I removed the washer in this area so I'm wondering what it would sound like with the driver feeding directly into the horn flare. Does anybody know where you can get adaptors for the K55 (1 3/8 inch - 18 TPI) that are only 12-14mm long in the threaded neck, so that when you screw the driver on ......the exit from the driver feeds direct into the horn flare? :cheers:

[jcrobso]

I've been doing some experimenting here with my Klipsch K55 mid range drivers mounted to an ALK Trachorn. I first removed the bug screen & noticed a considerable improvement in detail, then I removed the rubber washer between the driver & the horn...again a noticeable improvement. On closer inspection I notice that the Selenium Adapters (APT 25-25) have a length of 25mm in the neck of the adapter, whilst the threading on the K55 is only 13-14mm, leaving a nominal distance of 11mm of extra length before the sound actually enters the horn flare. I could hear a difference when I removed the washer in this area so I'm wondering what it would sound like with the driver feeding directly into the horn flare. Does anybody know where you can get adapters for the K55 (1 3/8 inch - 18 TPI) that are only 12-14mm long in the threaded neck, so that when you screw the driver on ......the exit from the driver feeds direct into the horn flare? :cheers:
Yes "K" uses a washer of slightly smaller diameter, I saw this on a pair of Cornwall. Not sure exactly why, but this reduction in diameter would act as a low pass filter and reduce the high frequency response of the driver.
As for the extra length of 11mm, I wouldn't worry about it since it is linear.

But the adapter only cost 6.35 at PE, just but an extra one and shorten it by 11mm. Lets us know how it turns out.;)
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-323

[Sootshe]

Yes, that would be the trick if you could just cut the excess length off, but the adaptor isn't threaded all the way in. I used to have some aluminium ones many moons ago that are long gone that were only 10mm length in the threaded neck & were perfect. :(