I review my experience with high-fidelity tube amps in general and, in particular, restoration and modification (resto/mod) of Magnavox stereo console amplifiers from Magnavox's stereo tube era (1958-64). My intention with this video is to give the viewers some ideas about what's possible with these console amps, how they can be used as an entry point into tube amplifiers, and how they can be incorporated into existing systems. I share some of what I know about tube amplifiers, what makes them special, and my approach to modification and redesign.
The video features four different amps, one single-ended and three push-pull (plus a brief visit with a Westinghouse single-ended console amp). Two are based on Dave Gillespie's modifications, which are designed to improve on the original but also preserve its character. One of these is an AMP 185 and uses Gillespie's mods for the 8800 series. The AMP 185, like the 8800, uses 6V6 (or 6V6GT) tubes in the output stage in push-pull configuration. The other Gillespie-inspired amp is the DG-SE1 and uses Gillespie's mods for the 8600 series. I've built three of these so far, two on 8600-series chassis and one on an AMP 196 chassis. Two other amps are based on Morgan Jones's Bevois Valley amplifier. One follows his design nearly exactly and is built on a Magnavox 9300-series chassis with Dynaco output transformers. The other modifies the design to use 6V6 (rather than EL84) tubes in the output stage and is built on a Magnavox AMP 175 chassis with Harman Kardon output transformers.
Sound tests feature "Kiss from a Rose" by Seal.
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00:00 Beginning titles
00:23 Warning: Shameless Self-Promotion Ahead
06:43 Tube Curious?
10:11 A Story About Scoring Vintage Gear
11:56 Build 1: Magnavox AMP 185
17:13 Build 1 Listening Test
17:44 What's so great about tube amps?
18:47 Is it pretty? Aesthetics of tube and solid state amps
22:25 Builds 2, 3, 6 & 8: DG-SE1 single-ended tube amp
23:18 DG-SE1 frequency response graphs
25:58 DG-SE1 Listening Tests
27:05 What's so special about single-ended tube amps?
32:59 DG-SE1 frequency response with bigger output transformers
33:33 Single-ended Westinghouse amp
35:05 Push-Pull Tube Amps
35:52 Build 4: BV-6V6 push-pull tube amp
38:40 Tube Names: WTF?
39:15 Back to the BV-6V6
43:19 BV-6V6 Listening test
43:51 Build 5: Bevois (Beaver) Valley push-pull tube amp
48:00 Beaver Valley frequency response graphs
49:09 Beaver Valley specs vs. Willsenton R8
51:14 Downside to the Beaver Valley?
52:15 Beaver Valley listening tests
53:36 Satisfying My Own Tube Curiosity
54:04 Easy integration of tube power amps into existing systems
56:10 Aren't tube preamps the best way to get that tubey sound?
58:41 Closing
