bloom into feedback....

[JD0x0]

low mids is the key IMO. most guitar's resonant freq is in the low mids which will cause endless feedback and bloom. Take a parametric EQ pedal and set it to boost. Play with the frequency until it starts blooming and feeding back, you'll notice it's somewhere in the low mids. This is why the "jazz" setting exsists on dumbles. IMO there is less bloom due to less lower mids, this is usually used to accomodate jazzboxes which can be especially prone to feedback.

[WhopperPlate]

great thread topic!