- Dec 4, 2011
- 2
- 0
- 18,510
Hello,
Has anyone, other than me, ever done the math on the cut off frequencies used in Fisher ST-830 speakers. The tweeter has a 1.5 microF capacitor with a 2.2 ohm resister. Thinking back to simple electronics and high pass filters... I come up with a cutoff frequency of 48,228.8 Hz (human hearing stops at about 20,000 Hz). Why are they (Fisher) limiting the frequencies sent to the tweeter to above human hearing, and above the drivers range?
The same is true for the mid range driver. 10 microF and 2.2 ohm gives a high pass cutoff frequency of 7,234.32 Hz. This frequency is at the upper limit of the replacement mids I was going to buy for my set of ST-830 (family gift... I know they suck, but I think I found out why!). So with the mid range replacement I am going to buy i will only be driving them from approximately 7,200 Hz to 8,000 Hz (the cutoff of the replacement driver).
something there just doesn't add up!
Oh, let me add that if you change the 1.5 to a 15 microF and, or the 10 to a 100 microF you get cutoff frequencies that more closely match the frequencies of typical drivers and the stated crossover frequencies on the speaker cabinets. Did some one miss a decimal place at Fisher? Or am I just missing something?
Thanks
Jason
Has anyone, other than me, ever done the math on the cut off frequencies used in Fisher ST-830 speakers. The tweeter has a 1.5 microF capacitor with a 2.2 ohm resister. Thinking back to simple electronics and high pass filters... I come up with a cutoff frequency of 48,228.8 Hz (human hearing stops at about 20,000 Hz). Why are they (Fisher) limiting the frequencies sent to the tweeter to above human hearing, and above the drivers range?
The same is true for the mid range driver. 10 microF and 2.2 ohm gives a high pass cutoff frequency of 7,234.32 Hz. This frequency is at the upper limit of the replacement mids I was going to buy for my set of ST-830 (family gift... I know they suck, but I think I found out why!). So with the mid range replacement I am going to buy i will only be driving them from approximately 7,200 Hz to 8,000 Hz (the cutoff of the replacement driver).
something there just doesn't add up!Oh, let me add that if you change the 1.5 to a 15 microF and, or the 10 to a 100 microF you get cutoff frequencies that more closely match the frequencies of typical drivers and the stated crossover frequencies on the speaker cabinets. Did some one miss a decimal place at Fisher? Or am I just missing something?
Thanks
Jason
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