Peavey Bandit 65 speaker noise on low end

[nukham]

I have a Peavey Bandit 65 with the reverb diconnected and when I use the amp it makes a loud distorted noise thru the speaker on the low end only . High end remains clean. I thought the speaker was going but it does the same thing with a new speaker. Any thoughts on what to check to resolve it.

[J M Fahey]

Try the speaker mounted in another cabinet, preferrably a closed one.
(Your own speaker or just use your Bandit as a "head", into another cabinet).
Everyday I see guys trying to pull too much bass from a relatively small, single speaker open back cabinet.
Don't mean it's your case, but can't discard it either, since you already switched speakers to no avail.
Post your results.
PS: are you plugging straight into your Bandit or going through a simulation pedal?
Because it can simulate anything ... but physics can't be beaten, your speaker can't produce chest thumping bass like a 4x12", no matter what the pedal says.