• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Progress on my JE Labs 300B

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Walton amp

When you turn it off, does it say "Goodnight John-boy"?

Sorry, couldn't resist.

It's looking good, and you work pretty fast. Thanks for showing us how it's going.
One comment would be, if you're going to mount the trannys on rubber grommets, use a grommet, or small O ring top and bottom of the chassis plate, with a bolt that runs right through (brass is nice). Then get a crimp/solder connector in an O shape (like a table tennis bat) and attach it to one of the bolts with a wire taken to your earth (do it from underneath). This way vibration from the trans is not mechanically shorted to the chassis by the screw you mentioned you were planning to use in the mount. The top of the bolt should be on to the trans' foot. Make sure there is an electrical connection to the transformer, ie no paint in the way.

Looking forward to seeing more of it as it comes along.

Hello CK,

Very nice indeed ! I am building the same amp. Still collecting some parts, tranny's are done, ( electraprints ) and are on thier way here.

I like the circle cutter idea. I am/was? going to use copper plate for the tops ( 1/8 =.125 ). How thick is your aluminium plate? What are the L x W dimensions of the plate? whole base?

Also, would it be possible to see the bottom sides of your chassis?
Just more information.

Please keep me informed and I WILL! keep you informed of my progress.


Thanks for the comments. I had seen your earlier posts and know what you are going through. I have been gathering parts most of this year and am now starting to see this thing come together. I still lack some of the resistors and caps of which I plan on ording sometime next week.

The chassis top is .09 inch thick and measures 10" x 16". Here is a link to the site with more specifics; I purchased two #3 chassis.

Welborne Labs Chassis

Yes, the circle cutter worked out better than I had expected. Perfect holes. Just remember to run the drill press at a very slow speed (350 rpm) and to have the chuck as tight as possible. Also, find some scrap and cut a few practice holes.

I plan on doing more pictures this week, I spent today working on one of my Fishers and ran out of time :)

More later.
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