The Fine Things are Always Hand Made
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Dave:
Your suggestion about grille cloth below receiver is a good one, and I can do it. Also just discovered that the pigtail recep that the phono used to plug into is switched when unit turns on. That would allow me to install a silent fan as well.
I strongly recommend more than 3 inches - say 5 inches minimum. The transformer and all the other tubes and the speaker field coil (or hidden power resistor in the bell cover of later production 800B PM speakers) all produce heat, too. The receiver is probably well enough shielded to be that close and still avoid magnetic effects of the power transformer and speaker field coil. Do orient the amp like the instruction manual shows with the 6L6's at the rear opposite the receiver front panel. Maybe drill some 1 inch holes in the bottom for air intake to aid heat ventilation.
Coffee filter paper has been recommended by others, too. For glue, an old hand recommended to me DEVCON, a rubber adhesive in a squeeze tube - at your local hardware. I have used it. Stays flexible. Apply with an acid brush - which is suitable & inexpensive, so discard after use. I trim the acid brush a bit shorter to achieve my desired degree of flexibility. It sets fairly fast but not too fast. Practice on something else before turning to your speaker cone. I have also used a thin coat of DEVCON to coat the flexible edge of a old weakened speaker cone.
I can do all of these things with minor changes to the dimensions. I'll drill some holes in the bottom of the cabinet to the front side of the amp, and mount a PC fan behind the amp, in order to pull air across those output tubes.
Have an old speaker for a Magnavox that needs fixing, and I'll practice on that. Do you know of sources for these paper cones? Most of these speaker cones appear to have deteriorated over the years, as one would expect.
By the way, I received the Collector's Guide, 2nd ed., and am enjoying it very much. Now just have to find a good example of one of these units.
Many thanks indeed for your suggestions.
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