[Elecraft] K3 FM filter required for full AM receive width

[KM5Q]

My widest filter is 2.8. I am allowed to widen the DSP to 4. So why  
not in AM, for BC receiving, be allowed wide enough for high fidelity,  
without a roofing (or xmit) filter? (AM can be widened to "10", but it  
sounds narrow and muffled)

I get much better bandwidth (fidelity) now using SSB to receive AMl,  
but it makes noisy band-browsing because of all the heterodyne noise.

Windy KM5Q  K3 764

> How can you have an IF bandwidth wider than 6KHz without using a  
> filter
> that's wider than 6KHz?
>
> -----
> Julian, G4ILO  K3 s/n: 222 K2 s/n: 392