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Specs on T33 - SP1265

 
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Dyolf
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Joined: 08 Dec 2014
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Location: Norway

PostPosted: Wed Jan 21, 2015 11:55 pm    Post subject: Specs on T33 - SP1265 Reply with quote

Once again I'm trusting the knowledgeable members in this forum to help with info!
I have found nothing on the web regarding this tweeter, but would be happy just to get the main numbers:
The free air resonance.
The sensitivity.
I know its a 4 ohm unit, but are there any abnormities in the resistive load?
Thanks in advance
Steen
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speakerguru
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Joined: 18 Nov 2005
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Location: Green Hut, Tovil

PostPosted: Thu Jan 22, 2015 10:05 am    Post subject: Re: Specs on T33 - SP1265 Reply with quote

No data was ever published but all KEF soft dome tweeters had a resonance of about 1 kHz. I think you'll have to infer the sensitivity from the sytem specs.

I don't know what you mean by this statement:
Dyolf wrote:
...I know its a 4 ohm unit, but are there any abnormities in the resistive load?...

No moving coil transducer presents a purely resistive load. The mechanical resonance reflects electrically as a rise in impedance (so called back e.m.f.) and at high frequencies the impedance rises due to the voice coil inductance, although not at 6dB/oct like a pure inductor, but at 3dB/oct due to the coil movement and losses in the steelwork.
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Dyolf
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Joined: 08 Dec 2014
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Location: Norway

PostPosted: Thu Jan 22, 2015 5:07 pm    Post subject: Re: Specs on T33 - SP1265 Reply with quote

speakerguru wrote:
........ but all KEF soft dome tweeters had a resonance of about 1 kHz.


The SP1265 is the later aluminium dome tweeter used in 107/2. Is an FS in the 1000Hz region still a good estimate?
Steen
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speakerguru
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PostPosted: Thu Jan 22, 2015 10:23 pm    Post subject: Reply with quote

Yes. Sorry, I should have said KEF 1" tweeters.

I should also have added that, even if you wanted to, it's difficult to move a tweeter resonance, given a particular design and construction. The resonance is proportional to the square root of both the moving mass and surround compliance, so changes of dome material will not make much difference when the total moving mass is dominated by the voice coil.
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Gossy
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PostPosted: Sun Jan 25, 2015 8:15 pm    Post subject: Reply with quote

http://s220.photobucket.com/user/sastusbulbas/media/T33B.jpg.html a different T33 but judging from what Speakerguru said, their characteristics could be very similar.
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