Octal-Noval chassis adapters

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crgfrench
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Octal-Noval chassis adapters

Post by crgfrench »

Say you have a chassis with some octal holes in it. Being the good faithful 18Watt religious type, you can't use that gaping hole. You could make an adapter out of some sheet steel or aluminum, (or titanium, carbon composite, whatev...) or you could buy an adapter. Tubeface sells one, Mojotone sells one, and Tube Depot sells one -- model 829, made by Burriss amps.

They are all different.

The Mojotone adapter is $3.50; it's shaped like a dog tag and has a 3/4" inner hole which a 9-pin socket fits into perfectly.
Screen Shot 2019-09-16 at 2.40.41 PM.png
The Tubeface one is $3.49; it's shaped like a doughnut, with an outer circular diameter of 1 7/8" and a concentric inner hole that's 7/8".
Screen Shot 2019-09-16 at 2.40.26 PM.png
The Burriss one is $9.95; it's shaped like an eccentric cam (football shaped), and has a centered inner hole that's, I dunno, way bigger than 3/4" but I'm not sure the exact diameter since I have never purchased one.
Screen Shot 2019-09-16 at 2.11.34 PM.png
It seems like the overbored models from Tubeface and Tube Depot must be designed for "through-chassis" mounting, where the tube slides through the chassis and into a board-mounted socket. The only points of physical contact on these are the mounting bolts. 12AX7s, EL84s, EZ81s, even the slightly fatter bottle Mullard CV4004s all slide easily completely through these overbored holes.

On the Mojotone adapter, the entire socket shoulder circumference rests against the adapter and so this seems to be the only one appropriate for properly supporting a chassis-mounted noval socket.
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