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In the Forum: Off Air Audio
In the Thread: Rohde & Schwarz EU-6201 Tuner
Post Subject: CR vs. LR low-pass filter.Posted by Romy the Cat on: 6/8/2008

The precision of those inductors is very much irrelevant – it would be easy to fine-tine the filter with the value of the resistor. There is a bigger fish to fry – the benefits of LR filter.

If we are taking about high-pass filter then there are no questions that a series cap is way inferior to RL filter. I tested it a LOT on the Melquiades’ MF channel. However, in case of low-pass the picture is not so clear and I did consider it in Melquiades’ bass channel.

We have two options: a cap to ground vs. a series coil. In case the series inductor the used or passed signal flows across the turn of inductor, so we are taking about a few dozen feet of wire. I do not mention all possible alinearity of inductor. Do not forget that it is a series devise. In case of RC filter we have a cap to ground. Well, we presume that a caps are bad because the electro-mechanic problems with dialectic (or whatever) but, there is one but. In our case of low-pass filter the filer-transparent or passed signal flows across a resistor to load. What flows via a cap is the filtered signal that is getting shorted to ground. So, it is hypothetically possible that a CR filter would not be damaging in low-pass context.

I do not know the answer at this point. I was trying to test it in Melquiades’ bass channel but the inductor was large in there and I was not able to shield it properly. In the case of decoder the inductor will be much smaller and the concept would be essay to trail.

The caT

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