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I recently decided to change the coupling capacitors in my tube dac to better quality ones. It was recommended to me that I could play around with different values ranging from 1.5uf to 4.5uf. The stock caps are 2.7uf. What sonic changes could I expect with a low value or with a high value? Is there any danger in deviating from the stock value.
Follow Ups:
The coupling cap value is chosen based on the load it must drive. wit ha value of 2.7uF it is likely the output cap. The output cap is typically sized to drive the minimum recommended load and still have good low frequency response. If you are using the DAC with a single load (preamp) and don't expect to change it soon you might be able to use a smaller cap. You will need to determine the input impedance of the preamp. Now calculate the necessary capacitor value for the desired low frequency response using the following formula:
C = 1 / (2 * Pi * F * X)
C = capacitance in farads
F = frequency
X = impedance
If you use a value that is too small the bass will be reduced. An overly large value will not cause a specific sonic problem unless it is of a different construction. If the value becomes too large it can cause problems during turn-on due to the long time required to charge up and stabilize the circuit.
I think this is one of those situations where it is necessary to see what your gear is, especially your dac and preamp. It's possible that you don't need that much capacitance, but without knowing what you are using its hard to say. (BTW, you don't say what brand of capacitor is in there now. How do we know you don't already have a good one?)
I also like a good paper in oil for coupling, just make sure they are not sitting right next to a heat source. Also, look at the phisical dimensions as they tend to be bigger than a film cap.
Not much difference. Stay with present value, but buy the best you can afford. But the quality of that capacitor will have a greater say on your DAC output. The ideal capacitance will depend much on the kind of load your amp and/or pre-amp presents to the DAC. Cheers
I agree with the first part ...but a lot depends on the quality of the original caps.
I've used paper in oil in many amps and output stages and I've not heard anything that tops them [yet]
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