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Stormy2021

The "phenolic ring" tweeter - where did it come from?

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I was wondering if anyone knew anything this ubiquitous tweeter which in the 70s seemed to be used on dozens of different companies' loudspeakers, from entry-level models to respectable "Buick-level" speakers. I've heard them many times and never thought they sounded *bad* and quite a few times I thought they sounded quite good, if a bit on the beamy side as far as dispersion is concerned.

1) what company designed it?

2) what was the phenolic ring - sometimes black, sometimes reddish brown - specifically used for? Why not plastic or some other material?

3) was KLH's cone tweeter the inspiration for it?

I've seen these with small magnets weighing around only 3oz., and versions in better loudspeakers with heavy 8oz. magnets. I think some later models also included ferrofluid.

Until a year ago or so, I saw this tweeter on the PartsExpress site and it was built by Pioneer.

BTW: any thoughts on why cone tweeters fell out of favor? I realize domes are almost always better in most respects, but for 2-way systems their (relative) drawback is that their crossover frequency is usually much higher than the typical cone tweeter's xover point.*

Did speaker system manufacturers finally decide that the advantages of a dome tweeter outweighed its problems in a 2-way system i.e. being crossed over at a higher frequency, say 2500kHz which could affect the system's midrange output?

* I realize some domes had quite low xover points, like the one with the inverted dome made by Genesis in the late 70s/early 80s. I think it had a xover point at around 1500Hz or so.

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Well I don't have definitive answers but here are some thoughts:

Don't know if they designed it but CTS made a lot (all?) of the originals.

Phenolic IS plastic

DK about any KLH inspiration

PE still has them (by GRS). They "had" some nice buyout specials with metal screen grilles but they had different characteristics.

Don't know about the other questions.

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Regarding the Genesis inverted dome check out Human Speakers web site which puts the crossover at 1800.  I think (speculate) there currently are more dome tweeters available to reach below 2000 than back in the day.

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Here is my CTS phenolic tweeters inserted in Fisher XP6 cabinet.
These tweeters are original USA, dated 75 03, have large ceramic magnet, brick color ring, black paper.
In the photos you see the flange built to adapt the tweeter to the original hole of the XP6 cabinet, the original dome tweeter.
These tweeters, purchased NOS before had been tested in an AR4x cabinet, where they adapt without modification to the original hole.

phenolic1.jpg

phenolic2.jpg

phenolic3.jpg

phenolic4.jpg

phenolic5.jpg

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First time I ever saw one of these was in a Marantz-branded speaker in the early 70s. 

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Earliest instance of which I'm aware is the KLH Model Four tweet, ~1958.

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