Fender musicmaster amp transformer12/26/2023 I'd appreciate someone chiming in to confirm I've got the V-reference correct.Īlso, I have it wired with an artificial center tap and elevated heater reference voltage. This is what I have right now with tubes in. whether they should be pin to ground, or pin to pin in some cases. I'm just not sure if I am measuring correctly. Chopped stick-ed around a little bit - no obvious loose connections, no smoke or pops. Still fair amount of 120 cycle hum, but not as bad as before rebuild. I finished soldering and installed the power cord this morning. I’d appreciate a go-over of the schematic and layout to make sure I haven’t missed anything corrections and suggestions always welcome. I am waiting for a few more components to come in from AES, so it’ll be a week before I can start putting things back into the chassis. FWIW, I’m using 22 AWG topcoat wire from AES. If noise is still a problem, I’ll have to get some shielded wire. Regarding the signal wire run from the volume pot back to V1B, I am going to run it under the eyelet backer board – of which I am going to cover the underside with copper tape and mount it with metal washer standoffs, so the shielding is grounded to the chassis. Also, one of the original 7-pin wafer sockets was replaced with a ceramic socket – ugly … I have found wafer sockets on eBay, but the mounting hole centers are way off. I’ve not found a replacement that is dimensionally suitable … excepting there are Richey GOLDS at that might work they’re expensive to risk them not fitting, and the being vertical mounts, the all the connections are on the same end. The original amp had a 20uf-20uf firecracker-type combo cap for B+1&2 filtering. I am not happy with where the fuse holder was installed, so I may mount a block fuse holder where the power cord comes in. Splitting pre-amp section and power amp section groundingĪttached is the layout and schematic, plus a pic of the eyelet board with pre-install components soldered on schematic of original amp included, too. Adding artificial center tap and heater elevationĨ. Increasing first filter cap from 20mf to 30mfħ. Changing tone control to bass frequency weighted tone tilt stack ala Blencoweĥ. Reducing noise and making it useable as a bass practice amp are the top priorities. The amp came with a replacement speaker and had some updates already done to it, including drilling the chassis to add a fuse holder – so I am not worried about keeping it stock with original components. I have a 1973 Fender Musicmaster Bass amp that was very noisy – I’ve taken it on as a rebuild and mod platform, with some add-ons that are getting some talk on this forum. If you’re enjoying this podcast, please leave us a brief review on iTunes and don’t forget to share it with friends.This is my first amp R&R/mod project. This episode is sponsored by Grez Guitars and Mono Cases. Some of the many topics discussed on this episode:Ģ:05 Skip works on a barn-find 1960 Fender Tweed Bassmanħ:50 Jason confesses to Skip that he got a Stew-Mac Champ kit DIY amp tipsġ6:05 Building a tube stereo amp (Dynaco Stereo 70, for music playback) versus a guitar ampġ9:39 A synth repairman gets a contact high thanks to LSD residueĢ0:33 Disgusting things found in old amplifiersĢ1:16 Last week’s Baffler (a noisy Princeton Reverb, listen to episode 11) responses and answerĢ7:37 This week’s Baffler is the image above (and on our new Instagram page): What is the thing used for?Ģ8:45 A listener in a hurry fixes his Les Paul thanks to Skip’s tube amp adviceģ0:34 Preserving (sloppy) originality on a CBS-era Fender or making it better than originalģ5:13 A non-reverb Silverface Fender Princeton with a weak vibratoĤ0:48 A reissue ‘63 Fender Vibroverb that needs more clean headroomĥ1:06 What to do with a ‘70s Silverface Champ with no maintenance historyĥ4:14 A ‘66 Ampeg Reverberocket with an unusual distortion soundġ:01:18 A ’69 Fender Bassman with both fixed and cathode biasġ:05:20 Rebuilding an amp found in a Hammond M-3 organ and melted wax on power transformersġ:07:52 A glimpse at the Fender Musicmaster Bass ampsġ:11:40 Differences between an amp schematic and layoutġ:13:24 A bargain Ampeg cabinet with four Altec 417 speakersġ:15:28 Sleeper pedal steel amp recommendationsġ:17:00 An ‘80s Mesa Boogie SOB amp with a red-plating 6L6BC tubeġ:20:01 Alternatives to the 6C10 tube on a ’82 Fender Super Champġ:22:40 Negative feedback: What is it? Adjusting it.ġ:29:21 A 1963 Gibson Discoverer Tremolo (GA-8T) amp with too much trebleġ:32:01 Skip’s brief tutorial on speaker efficiency Submit your guitar amp questions to Skip here: or by leaving us a voicemail or text at 50. Co-hosted by the Fretboard Journal’s Jason Verlinde. Twice a month, guitar amp guru Skip Simmons fields your questions on tube amp buying, restoration and repair.
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