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March 5, 2011

The Millett DCPP Engineers Amplifier

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.



The Fine Print:
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. 


6 comments:

  1. Nice job HiGHFLYiN9. I am in the proses of building the DCPP amp. Board is stuffed, transformers on there way. But haven't been able to contact Bob Collins to order a top plate!
    His Ebay sales is closed & he appears to be inactive on DIYAudio. Dose anyone know if he is still producing the plates or how to order one? Thanks Randy autotron@frontier.com

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  2. Hi Randy, I'll shoot you his email address.

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  3. Great, great build! I've had one on my bench for about six months, and I've decided to finish it up.

    Did you do the woodwork yourself? I live in DC with no access to a woodshop. Wondering if you'd be interested in building another case on commission. I used the same top plate, so the specs should be identical.

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  4. Thanks Robb! I used a local woodshop to handle the base after giving them dimensions and drawings. I wouldn't recommend them though as I had to return it to them multiple times to fix crooked edges and things they ignored on the directions.

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  5. Nice work... and I love you site... seems you have built many things that I have...
    I do have a question for you... How hot does the heat sink on the Milett Eng Amp get???

    Does it have enough area to do a good job of sinking?
    I am about to fire mine up and set the various adjustments.

    Phil Townsend
    Santa FE, NM

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  6. Thanks very much for the compliment Phil. The heatsink on this unit doesn't get very hot, warm to the touch, that's about it. Congrats on your build!

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