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In Reply to: Calculating preamp output cap value posted by sherod on April 4, 2007 at 22:47:19:
The output cap is typically sized to yield the desired bass cut-off point driving the lowest load impedance the preamp can drive properly. The output impedance (600 ohms in your case) is not part of this calculation. The best cut-off point is a point of discussion but 10 Hertz is the highest frequency for good sound.The formula to calculate the capacitance required is:
C = 1/(2 x Pi x F x X)
where
Pi ~ 3.14159
F = Desired cut-off point in Hertz
X = Load impedance
C = capacitance in Farads
For your particular situation:
F = 10
X = 100,000
so:
C = 1/ 2 x Pi x 10 x 100,000
C = 1/ 6281835
C = 0.000000159
or 0.16 uF
This will work fine in your system but if you ever want to use an amplifier that has a lower input impedance you will have a problem with the bass response.
You can use about 1.5uF or 2 uF and get good bass response with a 10k load. With your 100k load the cut-off will be about 1 Hz.
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Follow Ups
- Re: Calculating preamp output cap value - beermanpete@socal.rr.com 23:40:46 04/04/07 (2)
- Re: Calculating preamp output cap value - sherod 08:00:20 04/05/07 (1)
- I'd advise - Russ57 10:17:19 04/05/07 (0)