Another great project from the man himself, Pete Millett. The Engineer's Amplifier is a distortion canceling push-pull amplifier that makes use of low-cost TV tubes, namely four 6JM6s and 6CB6s. If you prefer the top cap look, you can substitute 6JN6s for the 6JM6s. The amplifier puts out about 18 watts in stock configuration, or well over a hundred with some tweaking (take a look at TubeLab posts especially). As seems to be the recent tradition from Pete, the board is large and bright red, and makes use of a compliment of Edcor transformers. The audio path is pure tube except for the CCS in the LTP tail, a few tube purists may take issue with that but they'd be missing out on a great amp ;)
 |
| There they are! Fairchild FQPF8N60C |
Some nice concessions to us vintage parts lovers are the lovely green Koa Speers carbon film and traditional carbon comp resistors, the latter being used as grid stoppers. There's also some good old silver mica caps in there. I decided that I wanted this build to be unique, and had some interesting ideas in mind, including a nice Zebrawood wood base with an illuminated slot for the logo and a copper / antique copper powdercoat scheme.
 |
| Board top with ceramic tube sockets |
 |
| Board bottom with resistors populated |
I initially build this amp with Russian paper in oil caps:
 |
| Russian PIO |
But eventually settled on AmpOhm aluminum paper in Oil.
 |
| AmpOhm aluminum foil paper in oil capacitors |
Here's some final photos of the build:
 |
| Orangey Red LCDs |
 |
| Cardas copper binding posts and Vampire RCAs |
The illuminated logo was achieved by using a piece of perforated powdercoated metal as the base, then fastening the "Millett" brass logo I designed on the front. Lighting the logo from behind is a small circuit featuring 16 diffused orange LEDs that runs at 6.3V off the heater. The nice top plate with cool little perforations around the MOSFETs was made by Bob Collins (DIYAudio member PPP6l6gc)
for a very reasonable price.
Some other fun little upgrades from the stock build were:
- Cardas Copper Binding Posts
- Vampire RCAs
- Kimber and Oyaide Wiring
- AmpOhm Paper in Oil Aluminum Capacitors
The sound is very detailed and engaging. Quite the opposite from the lush Dynaco ST70. Another recommended build from Pete Millett.
Wondering where I got all my parts for this build? Check out a list of my favorite online vendors here.
Please remember that building circuits and performing circuit modifications can be dangerous to you and/or your surroundings and should only be performed by a certified technician. The owner of this blog and all associated parties can not / will not be held responsible if you attempt a build or modification posted above and cause physical harm to yourself or your surroundings. Many electronics contain high voltages that can kill, and mods, if performed improperly, can be a fire hazard. Please keep this in mind.
