Passive Crossover for Fostex 208ez and T90A

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WayneAudio

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Joined 2016
Hi guys. I've ordered some cheap caps so that I can test before investing in some really decent ones, but I've been looking at the crossover frequency for the 2 different cap ratings Fostex recommend and I can't work out why they've recommended them as it makes the crossover point very high indeed....although i know it's a super-tweeter, it doesn't make sense to me given a) the lower end frequency capability of the T90a super-tweeter (5khz) and b) the range of human hearing (especially my 40 year old ears). Can anyone help me understand? Images attached to support my confusion (apologies.... I'm still new to all this! )...
 

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WayneAudio

Member
Joined 2016
Keruskerfuerst said:
For the low pass:
coil and capacitor
For the high pass:
capacitor and coil
Click to expand...

Sorry, I still don't know what you mean, but aren't you suggesting something different to what Fostex are recommending (my first attached image)? They are showing no coils or caps for the full range driver, and an attenuator and capacitor for the super tweeter...
 
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Ron E

Ron E

Member
Joined 2002
WayneAudio said:
I can't work out why they've recommended them as it makes the crossover point very high indeed....
Click to expand...

Just try it and take the super tweeter in and out of circuit. There is a bit of a religion among fullrange addicts, one where they desire a supertweeter but cross it over above audibility. The low 6dB rolloff assures that some of the tweeter output will be audible.
 
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WayneAudio

Member
Joined 2016
Keruskerfuerst said:
The problem is, that the datasheet of the horn tweeter does not show the resonance frequency.
I would not use the attenuator, but an voltage divider.
Click to expand...

I don't mean this to sound rude, but why are all of your suggestions against the manufacturers recommendations? I acknowledge that you clearly know a lot about all this, but to my novice mind, it's almost as if you're trying to find a solution to a problem which doesn't exist?

In this particular example, why not use the attenuator?

Thanks.
 
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