ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Hi everyone
I have gathered together 3 sets of S45-2 over the last few months. I noticed a few weeks ago that each set has a different looking tweeter. One set has the clear (slightly yellow looking) tweeter dome, one set has a shiny black dome and another pair has the standard matt black looking dome.
I saw a pic in a thread a while ago which showed the shiny black dome but figured it might be the flash.
I note the shiny black dome and clear dome versions seem to have a little more high end compared to the matt black domes.
Have a look at the pics below of the clear dome and shiny black dome versions. I knew there were 2 versions of the tweeters out there but didnt realise there were three, any ideas?
Another question, in the pic below of the clear dome tweeter there appears a ring around the outside of the dome which looks like glue, would these have been repaired or is this how they come? both have the same marks..
Andrew
I do remember having these Philips dometweeters back in 80's, and they did have differently colored domes.
So I dont think they are repaired.
blah-blah and photographs as needed
Has anyone else seen these shiny black domes?
In the course of history, I've seen all three, clear shiny, black shiny, and dull black. I think I listed them in the order of manufacture too, at least the oldest ones I remember seeing were clear, then I saw black, and it was later I saw the dull black ones in a car system by Philips.
Interesting and widely used tweeter in a lot of speakers. My old DCM Time Window, the original ones, had the clear dome Philips tweeter. The square frame tweeter on the S75 I think is a Peerless, same tweeter used in the original Polk Audio Model 7 and 10 speakers.
Jeff
I'm afraid I'm recovering from the BeoVirus.
I just remembered where else I saw the dull black dome Philips tweeters, in various different McIntosh speakers.
Thanks Jeff
With respect to the s45-2, do you think the different tweeter models would have necessitated different components in the crossover network? From what I have seen all crossovers seem to use 15uf caps, so I would expect there could only be a difference in the resistors used... Any ideas?
Without the drivers to test I can't be sure, but if the crossover cap is the same it's unlikely there's much difference between them. If you can measure the resistor you could tell, but I'm betting there's not any difference. Definitely I would expect the two with glossy, hard poly domes to be the same, the only one I'd even suspect at being different is the dull dome. I'll ask around, I know the old McIntosh speaker designer, I'll email him and see if he has an opinion.
Thanks Jeff :)
I asked a couple of buddies of mine, the McIntosh guy and another speaker designer, and thought I'd post their responses. Not as definitive as we might have liked but useful info hopefully. I think the dull black tweeter may use a soft plastic dome and if so might well have smoother response, even if the efficiency and impedance are the same. I think slight differences in efficiency would be the most probable difference, which would make replacement in pairs the best approach, but I also agree with my friend that differences between two tweeters of the same type may be as great as differences between the types due to production tolerances.
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I had rejected the Philips plastic domes but can't remember why. The textile ones were better and that is what we used. Maybe the dull plastic one you mention is actually the textile one.
The differences you mention in the plastic ones may also have other changes like the cavity behind the dome and/or acoustic material behind the dome. I would expect maybe slight differences in smoothness of response and possibly a difference in Q at resonance.
It may be that the dome subassembly is interchangeable with any of them.
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I suspect there are slight differences in performance among the variants, and even within the variants. The biggest difference will always be impedance. I think the most important thing to do is always replace in pairs. The next thing is probably replace the capacitors in the crossover, as they have probably drifted lower about 1% per year. Matching values is more important than getting the exact value the designer intended, but if he does all three, he should be all right.
Sort of supports the view that almost all B&O speakers need their caps upgraded!
Hope this helps at least a little!