Categories: Custom Fabrication

Sound From A Glass Box

This design project began with the goal of crafting an entire amplifier that echoed the form of a vacuum tube itself.  See here for example of the intial execution.  Thanks to cabinet-maker N.N. for the beautiful walnut frames.

The 22277 is a two-channel audio amplifier for home music-listening.  Power output is approximately seven watts per channel.  Each channel uses 1/2 of a 6SL7 twin triode and one 6L6.  The rectifier used is a 6AX5.

Volume control is provided.  Inputs are via twin RCA jacks and speaker outputs are via 1/4″ jacks.  The relatively high gain of the 6SL7 tube allows the unit to be driven to full output from any line-level source (E.G., radio tuner, DVD player, iPod, etc).

chris

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  • It would be cool to build one in a circle form and cover it with a bell jar like an old ticker tape machine. Stereopile had one a few years ago that used 4CX250s or some similar blower cooled tubes that was in a cylinder and filled with a clear oil for coolant. It looked like an embalming machine to me, and I never saw a picture of it again. An oil leak would be a domestic disaster because you'd never get it out of the carpet.

    //www.ebay.de/itm/Rohde-Schwarz-QAO-Quarz-Oszillator-Baugruppe-Modul-fur-Ballempfanger-/320656732935?pt=Radio_TV_Musik&hash=item4aa8a17307

    See the picture for an idea.....just bigger and with a flat base. Atwater Kent made a radio like this too IIRC.

    • I know what you are thinking. Heat retention.

      But the glass has a lot of surface area. For a low power amp it would be fine. You could also put a quiet low power fan in the base and put in some holes for forced circulation. The bell jar can go through the dishwasher once in a whole if dust builds up.

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