I'm having some trouble with sound quality on the phone related to DSL filters. The Sonic-provided filter doesn't seem to attenuate the DSL-band signal enough, leaving an audible hiss in the background of every call. I tried some other models I had lying around as well, with various results. Mostly they leave the hiss. One removes it completely, but the frequency rolloff starts too early on that one, creating voiceband distortion. Before I build my own, does anyone have recommendations for any particularly high-quality commercial filters?
I had a similar problem with filters. There's a simple fix.
I'm using a business phone system in the house which converts all incoming analog lines to a digital form first. The remaining DSL signal that got through the filter mixed in the codec to product really weird harmonics.
I resolved the issue by putting two filters in series on the analog line to the phone system. The attenuation through each filter is additive, so the result was sufficient to remove the harmonics.
