does the dust cap do anything?

[JKent]

...other than keep the dust out?

I have a KLH Model 21 I'm trying to restore. It has a few problems, the least of which being a pushed-in dust cap. Does it matter? I've been trying to think of ways to un-bash it (vacuum cleaner? pin? leave it alone?). It's about 1" diameter.

[joelongwood]

As far as affecting the audible sound quality, I honestly don't think it matters. If it bothers you (it would bother me), you may want to try a vacuum with just the round nozzle. I've had good success pulling out dented dust caps using this method. Good luck.

[Guest bruhl]

Hello Kent,

First, I should say I really don't know the factual answer to your question.

However, I am in the process of replacing the surrounds on a pair of old Fisher speakers. One of the options when you are doing that is to cut out the whole dust cap to shim, and then replace the cap with a new larger one. Seems to me if there was anything super critical they wouldn't want you to cut that cap.

If it were me, I would leave it alone. However, if it is something you would rather "make right", I would try the vac idea first. That is a good idea, and certainly non-invasive.

Failing that I would poke the cap with something like the pin you mentioned, or an exacto knife and then gently pull the cap up to original position. Perhaps a paper clip bent like a golf club would be good to pull the cap up once you have the small hole in place.

Then I would seal the small pin hole with something like xl-49 speaker glue. That goes on white and dries clear. There are glues that are used to repair small tears in cones. They should also be fine to repair for your small pin hole.

That is only what I would try. There are real knowledgeable folks here who can help more than I.

Best regards, Kent.

Mike

[JKent]

thanks guys

[Andy]

I agree with the two previous comments, it may be best to leave it alone but if you feel compelled to pull the dust cap out, the vacume or pin idea are good ones.

A few comments on the great little model 21 speaker; The performance of this 3 inch speaker is nothing short of amazing, having a 3/8" cone excurion which is controled by the highest ratio of magnet power to cone weight ever embodied in a speaker. It has a flawless upper range and a lower frequency response of about 60 cps (never seen in such a small speaker).

A little history; Back in 1959 the audio consultants Bolt, Baranek & Newman had a project to equip the Senate chambers with high quality idividual speakers for each Senator. So BB&N went to KLH and Kloss designed a speaker but the project fell through, so the speaker ended up in the model 8 radio in 1960. Then it was used in the model 11, 14,15,19,50 speakers as well as the mid-range drivers for the high end model 5 speaker and of course the model 21 radio in 1966. Also of importance, KLH was vitically intigrated, making their own cones, winding their own voice coils as well as having access to the MIT magnet lab for sophisticated testing.

Thats probably everything you may not have wanted to know about best small loudspeaker ever made !

[Guest bruhl]

Well tonight my wife and I found that one of my Model Twenty speakers had a sunken dust cap. My wife suggested that we fix it. So we did.

She poked thru the dust cap with a small tipped crochet hook and very easily rounded out the cap.

I then covered the tiny hole with xl49 surround glue that I had available.

"Problem" solved.

Mike