Ep. 139: "I'm Going Negative"

It's the 139th episode of the Truth About Vintage Amps podcast, where amp tech Skip Simmons fields your questions on all-things-tube amps!  Want to be a part of our show? Just email us a question or voice memo to [email protected]. Some of the topics discussed this week:  :48 On the bench: A 1974 Alembic pre-amp, a Showman head in disguise 3:58 Webb's Music and a hang gliding pioneer 6:08 Our sponsors: Grez Guitars; Emerald City Guitars and Amplified Parts; the Wood Wire & Volts Show in Anaheim (link); Bruce Harvie of Orcas Island Tonewoods 11:10 Skip has a warning for the TAVA Kegger Facebook group...and others 14:38 A luthiers' pet peeve 16:55 Bias modulating tremolo, intensity pots 20:45 Skip works on a Dan Torres-modded amp 21:35 Jason screens his Ben Harper Dumble film in Seattle; Ben Harper on TAVA (ep. 118) 25:34 When does Skip use his tube tester? 28:17 Should I turn this jukebox amp into a guitar amp? 30:52 A monitor out a la GA17RVT; Quilter amps; full-fat Greek yogurt 36:24 When do we get a Marshall/Vox expert on the show? 37:58 A Kroker Triple Toad amp 40:13 Warming up a Nat Daniel-designed amp; separately mounted pre-amp tubes 42:17 Late '60s Fender biasing (AC568) 43:54 Skip's new guitar: A 1966 Fender Duo-Sonic 49:51 The Fender Files on YouTube (thanks, Larry Chung) 52:17 Using 5V4 rectifier tubes in a Matchless DC-30; Nduja mayonnaise (link) 1:00:17 Recommended reading: "There Are No Electrons: Electronics for Earthlings" (Amazon link); subbing a 6SL7 for a 6SN7 in a Gibson BR9 1:02:42 Transformer Corner: Using US amps overseas   1:11:07 Recommended music: Henry Kaiser & David Lindley's "Sweet Sunny North;" Steve Melkisethian remembered 1:13:01 A cheap and easy output transformer dynamic test; rebuilding reverb tanks 1:19:54 Skip's map collection Hosted by amp tech Skip Simmons and co-hosted/produced by Jason Verlinde of the Fretboard Journal.  Don't forget, we have a Patreon page. Join us to get show updates and get to the front of the question line.