Why no B+ fuse?

[PlinytheWelder]

I'm just wondering why there's no B+ fuse in wrecks or a fuse on the heaters center tap?

I suppose that it goes against the philosophy of these circuits which is to simplify and get to the most direct circuit possible.

I didn't put any in mine and am not particularly worried, but it just seems standard to put them in. I guess in _mass_ production, it would.

[rjgtr]

A lot of older tube amps just had a mains fuse, Fenders being one of the most conspicuous. Marshall has usually had a B+ fuse, except in the 18watt and other smaller amps.

Heater and Center tap fuses are common on Peavey amps, but not on most others.

I almost always add a B+ - it is good insurance against a bad output tube. Better the fuse than the output transformer!

You can always add a fuse after the rectifier. .5 amp for most amps 50 watts and under and 1amp for 100 watters.

[PCollen]

I'm just wondering why there's no B+ fuse in wrecks or a fuse on the heaters center tap?

I suppose that it goes against the philosophy of these circuits which is to simplify and get to the most direct circuit possible.

I didn't put any in mine and am not particularly worried, but it just seems standard to put them in. I guess in _mass_ production, it would.

The c/t of the heater winding is never fused ; at least I've never seen it fused. If you want to add a B+ fuse, and I would recommend doing so,
put it immediately following the rectifier output rather than on the PT secondary HV winding center tap. If on the latter and it blows, your B+ and other voltages will drop, but they may still be present at all DC voltage nodes at reduced levels and you can still get shocked if the amp is powered on for troubleshooting.

The philosophy of the TW circuits is to provide the simplest, shortest, most direct SIGNAL PATH, which has little to do with the power supply. If it did, Fischer would have distributed the pre-amp filter caps to be in closer proximity with the pre-amp tube plate resistors which they are supplying.