Monday, October 12, 2015

Tweed Super On The Cheap

While trolling my usual places on fleabay (the "Why pay more?" store), I ran across a trio of partially built tweed amps that consisted of Weber chasses, pots, knobs, and Mercury Magnetics iron but not much else. There were a 5E7 Pro, a 5F6A Bassman, and a high power tweed twin.

Since I'd already built a couple of 5E7 Bandmaster kits I opted to snag the 5E5 Pro and build it as a 5F4 Super. All three of these amps are pretty much the same with some very minor differences.

Once the partially constructed chassis arrived I made an eyelet board for it and loaded it with F&T electrolytics, Mojo Dijon capacitors and mostly metal film resistors. At about the same time I bargained with Dirk Newton for a pair of Weber Ferromax 10 inch speakers and contracted with J.D. Newell for a lacquered tweed cabinet.

Looking through my stash I came up with a trio of new old stock Cinch shielded 9 pin sockets for the preamp tubes and a trio of new-ish Chinese ceramic top loading sockets. For glassware I used new old stock RCA preamp tubes, blackplate power tubes, and a Mullard 5AR4 rectifier tube.

The chassis went together easily as this was my third one, and everything else went together when the cabinet arrived, and it is a beauty. I mostly wired it with 22 gauge pre tinned cloth pushback wire from Stewart MacDonald.

There's a lot of controversy about  what sort of wire and gauge to use for general hookup and filament service but I think it is a relatively simple matter to determine what the current load is and wire accordingly. For instance the total current draw for the preamp and power tubes is about three amps total once the initial inrush is over. At that point we see that 21 awg chassis mounted wire maximum load is 9 amps so that should be well above the margin of safety. Some folks think that they have to use 18 gauge single strand for the filament wiring and there's simply no need for anything that heavy.

Here's the breakdown on prices which includes shipping:

$375.00 chassis
$260.00 cabinet
$  75.00 speakers

Glassware and other components were from stock

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