Homemade Tube Audio
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Tom's Foreplay #2

See the rebuilt version here



The layout on this one is quite a bit different from the kit. I followed the schematic, but I made some small standoff boards that sit next to the tube sockets. In fact, I found that 2 of the resistors attach directly to the socket pins. How's that for luck? I had thought these boards would make changing out parts easier, but with everything packed so tight and the el cheapo coupling caps in the way, it's a real pain. I think it turned out pretty well considering. Almost all of the parts were from surplus stores here in Eastern Iowa.

 The pictures are a little misleading...The first one shows a smaller power transformer than the one I started with. The original was a 160 volt DC supply that I found at the surplus store, but I thought it made the linestage sound a little dry and it ran quite warm. I replaced it with a smaller one under the top plate (again) and put in the "dummy" to fill the hole. I'm still on the lookout for a one with the same bolt pattern as the first. The current PT puts out about twice the voltage as is called for, so I used a a fullwave rectifier instead of a bridge and everything is fine.

You might notice the small strip of perfboard in the last picture. That holds the PS caps tight to the top plate by way of the solder joints. Look at my next version to see the solution I came up with for a more rigid way to mount these. I had the same hum problem when touching the volume control as with the first one. A ground lead to the mounting plate cured this again. This time I went with the shunt volume control mod and played around with series and shunt resistors to bring the gain down at the input. The top plate was drilled using a step-bit and the opening for the transformer was cut using a scroll saw. The walnut base was made from some small pieces I had out in the garage. A Scotch-Brite pad made an old knob usable again and polished up the caps.



On to Foreplay #3 Back to index