V:90 Resonance in 90W mode

[rarebitusa]

So I like running the V, Ch 1 Fat in 90W mode for the clean headroom. I have noticed there is this major bass resonance (low A down to E) that sounds/feels like a compressor on with alot of sustain. To compensate, rolling down the bass has been one solution or going to 45W mode or EQ'ng the signal before with a 250Hz cut. Much less noticeable with Clean voicing, but Tweed does it too. Also more noticeable with the EVM, other cabs V30s or C90s seem to behave better. Since Ch2/Ch3 is typically set to 45W or 10W they don't get it there.

Anyway, I do work around it, but was just curious why the 90W mode would appear to exhibit this?