[Harp-L] Re: blues jr mods

[Greg Heumann <greg@xxxxxxxxxxx>]

Hi, Mike - It has been a long time since I had my Blues Jr, but I can  
answer your question "Will the tube swaps recommended in previous  
postings address feedback, or just improve the sound?" - and the  
answer is an emphatic "yes, it will reduce feedback." Guitars a) put  
out less signal than decent harp mics and b) are MUCH less  
susceptible to feedback. The Blues Jr is setup by the factory for  
guitar.  If you lower the preamp gain stages (sub in a 12AU for an  
AX, a 12AT for another AX, for example) will allow you to turn the  
amp up much louder, hence getting the desired overdriven power amp  
distortion, without running into feedback near as quick. With a  
520DX, or ANY mic/volume control combination, you should set up to  
solo with the control at FULL VOLUME without feedback. Roll the  
control back a little when you comp/fill. If you have to set the  
mic's control at 3, you're probably losing a good deal of your  
element's tone.

Hope that helps.

/Greg

http://www.blowsmeaway.com
http://www.bluestateband.net