So it seems we have a couple of issues with some of our 58s. They're a couple of years old, and have been used on hundreds of shows. Lately we've had problems getting a good sound out of them and problems with gain before feedback. So I decided to AB them and take some measurements. Here's what I found: (Expired Link Removed) Unfortunately, I don't have a "working" 58 with me to compare, but seeing the results, I'll get one or two tomorrow for comparison. Until then, I'm open to suggestions as to which one is OK.