Thursday, September 14, 2017

6418 headphone amp.

My friend on TRB said the 6418 was a good tube to have on hand and 'cheap'. When a bottom feeder hear cheap and good in the same sentence the ears perk up. I ordered a box of them and Andy is correct in his analysis. The little amp is on the cedar block to the left. I took two connectors from dead 9 volt batteries and made the connector on the left of the pine block. The little oak block is bored to fit a AA battery with a blind hole that stops about 3/8" from the end. Then it is drilled with a 1/8" bit the rest of the way through. I inserted a ball point pen spring through the 1/8" hole and screwed a little strip of metal for it to attach to. A drop of solder to secure the spring and that end is done. I screwed a flat plate on the other end and it was ready for the battery. Flip the end plate up insert battery and flip the end plate back down. the spring hold everything in contact.

The two terminal blocks on the amp are for filament supply voltages. I will use some speaker wire to connect the filament and some lamp cord to connect the B+ supply. Using different wires it should make it easier to not cross them.

I'm thinking I need a box for the battery pack and set the amp on top?  Another project!
My hearing aid amp has been my go to AF amp but this little jewel just may be my new first choice.

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