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In the Forum: Melquiades Amplifier
In the Thread: Planning my DSET
Post Subject: It does not matter.Posted by Romy the Cat on: 8/10/2015
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 anthony wrote:
I am calculating crossover scenarios for the HF Channel (Channel F) and am hoping that you can remember a reasoning for using a 20K LPad instead of a larger value such as 30K or even 50K?  As the larger impedance is used the value of the capacitors reduces and the size of the inductor increases, which I would have thought to be a good thing in terms of the actual performance of the inductor compared to its design specifications.  Unless your aim was to minimise the inductor size or you were just using the LPad that you had available?

I am not sure how increasing the LPad from 20k to 50k would affect the operation of the filters in the other channels.
  
There is no aspects of minimization of the inductor size. You can go to 30K, or 50K, or 100K input LPAD. The LPAD (which is not inductive switched attenuators with good resistors) anyhow sites behind the filter, so the input impedance of the attenuators will be “visible” by other channels only at HF, so the value of the attenuators is semi-irrelevant. The reasons why I went with 20K is because I would like to keep the value of the resistors that formed the attenuators lower. If I use S102 resistors that have no inductance of any kind then the value of the resistors would be absolutely irrelevant. I use very good resistors for attenuator (RN/CMF55/60), they are metal film and non-indicative but they still have “some” residual inductance and my presumption was that higher value the more inductance. I warn you that this is such an irrelevant minor thins that we can talk about it but I very confident that it has no practical impact to the sound you will get out of it. So, in term of the input attenuators for HF you can do anything you want.

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