Allow me to introduce you to "Nothin' Fancy." This is the Dynaco Stereo 70 I recently rebuilt and am now offering for sale. This is NOT an "exotic" amplifier, but rather a careful attempt to preserve the "Vintage" nature of the original. If you would like to learn more about the construction of this particular rebuild, you can read about it here:
http://www.audiocircle.com/index.php?topic=58338.0Here is a picture with the tube cage/cover removed.
Note the original Dynaco transformers. These are the "cloth-covered wire" style transformers and sound simply WONDERFUL!. The NOS Mullard-manufactured, GE-branded GZ34/5AR4 will be included, as will the two NOS RCA 7199's. The Electro-Harmonix EL34EH Output Tubes are just one of several options. You can see the longer shafts of the Spectrol 10-turn potentiometers and the "upgraded" multi-section can capacitor. The Driver Board has been completely rebuilt using Allen-Bradley NOS carbon-composition resistors. All resistors are matched within 0.1%! All tube sockets (other than the "biaset" sockets) are genuine Cinch "Micanol" sockets for increased long-term reliability.
Here is a picture of the under side of the amplifier.
Note the new Filter Choke. Also note the routing of the wiring to minimize hum around the grids of the 7199's. The wiring is arranged the way Dynaco wired their units at the factory. This is especially noticeable with the "grid stopper" resistors. Also note that the Power Take-off sockets are unwired (except for the "biaset" connections) in order to minimize hum and noise still further.
Here is a closer look at the connections to the Driver Board.
Also note the replacement of the selenium rectifier with a silicon diode. The bias is rock-solid!
Here is a picture of the top of the driver board.
All 1/2 Watt resistors have been replaced with NOS Allen-Bradley carbon-composition resistors; hand-selected to be matched within 0.1%! The large coupling capacitors are simple NTE replacements rated at 0.56 uF, in order to improve the bass somewhat. The .047 uF capacitors are Illinois Capacitor MWR series - in other words, simple, reliable and cheap. The 390 pF and 82 pF capacitors are originals. They were VERY closely matched, so I kept them!
And finally, here is a picture of the back of the amplifier.
Note the original Dynaco Power Cord. It has been restored. The Output terminal strips are NOS original style parts. The fuse holder is new. Even the rubber grommet for the Power Cord is new. Also, the small fasteners have all been replaced as well.
In this configuration, the cost for the tubes alone is over $250.00! Add a very reasonable $250.00 for the actual amplifier and that brings us to a nice even $500.00! (plus shipping!) If you would rather have a NOS matched quad of Mullard EL34's, add another $300.00 for a total of $800.00 (plus shipping).
If you have wanted to get into "tube amplification", the Dynaco Stereo 70 is the least expensive way to sample all that "tube goodness" for yourself. By the way, in case you happen to have all the tubes you will ever need, the bare amplifier (without any tubes included) will sell for $350.00.
This has been a MOST enjoyable project. The end result is a beautifully quiet amplifier. The sound quality is simply SUPERB! This should be an EXTREMELY reliable amplifier for years to come.
Contact me at
nostubesforyourdynaco@gmail.com and we'll work out the payment and shipping details. Thanks for taking the time to read this ad, as well as the construction "chronicles."
Sincerely,
Bill Thomas
8/18/2008 Note: "Nothin' Fancy" has been sold. I will have a very similar amplifier available for sale by Wednesday. A third Stereo 70 rebuild should be available by the end of next week.
Coming up soon: How about a REAL PAS-3X preamplifier complete with "improved" green-glas circuit boards, those "special" tone controls and a re-plated cadmium-plated chassis? I am checking my stock of "suitable donors" and NOS parts and *should* have a timetable for construction during the next week.
Stay tuned!
Sincerely,
Bill Thomas
