Of course it sounds like a telephone you nitwit.
Your using a 3KHz filter to listen to a 10KHz signal.

The key here is selectivity between a R75 and 800 in AM mode not what filter
your using - d'oh!

"David" wrote

I'm using my R-75 for MW bedside listening and it's MW performance in
the SSB mode is rock solid, but it sounds like a telephone.