[jwvm]

On Nov 12, 2:46*am, (Don Pearce) wrote:
On 11 Nov 2011 20:44:11 -0500, (Scott Dorsey) wrote:

Don Pearce wrote:

The DC offset vanishes when you apply the low end crud filter. You do
filter the low end crud from every track?

Well, that is the whole subject of the thread. *The original poster
seemed to still have DC offset after doing the low pass filter, which
shouldn't happen.
--Scott

I presume you mean high pass, and yes you are dead right. It sounds
like his high pass isn't entirely so. I have seen this in the past
where the number of bins treated in the FFT is wrong. It tends to
leave a small residue of DC rather than all of it though.

d

Not to mention that the sum of the filter coefficients will be zero in
a properly designed high-pass filter which of course removes DC and is
a necessary condition for any filter that has infinite attenuation at
zero frequency.