Dropping/sag resistor on negative side of rectifier?

[Bergheim]

I have a non ct pt with a ss bridge rectifier and an Arcol HS series 50W 100R chassis mount resistor between the rectifier and the reservoir cap. The resistor is mounted on top (outside) of the chassis with thermal paste. At idle it's dissipating about 2 watts, and cranked it can dissipate 25 watts @ 500mA at which point the B+ fuse will blow. With the amp cranked for 10 minutes it barely got lukewarm..

I've read numerous places that people are skeptical about chassis mounted power resistors in the case of short circuit to chassis due to the thing being heat cycled every time the amp is used. The resistor is rated at 2.5kVAC max and 1.25kV limiting element voltage. Temperature rating is 200C/392F. So with a B+ of 510V max (before the tubes start conducting) it seems this resistor will be more than adequate for the job in every aspect.

Anyway, I started considering rewiring the resistor to the negative side of the rectifier to minimize the voltage across the resistor element and the insulation/chassis. The ground bus is tied to the chassis at the input jack so the bus won't elevate from ground because of the resistor. The only component that will be elevated above ground is the rectifier itself, at a voltage equal to the voltage drop across the resistor (10-50V depending on amp volume).
I can't see any reason this won't work just as well as having the resistor on the B+ side. As an added bonus the B+ won't short to chassis in the case of insulation failure in the resistor, it simply shorts out of the circuit, perhaps with a ground loop to the input jack. In this case the worst thing that can happen is red plating, which I would greatly prefer instead of 500V on the guitar strings. To this day I've never seen or heard of this implemenation of the sag resistor so I suspect there may be a very good reason which makes me wonder; am I missing something stupidly simple here?

[sluckey]

The resistor is in series with the load (your amp). Makes no difference if you put it in the positive supply lead or the negative supply lead. Or, said another way, makes no difference if the sag resistor occurs before or after the load. In a series circuit the same current flows through the resistor as flows through the load. Voltage drops (sag) will be the same.

Do a google search for back bias. Putting a resistor in the negative lead has been around for a LOOOONG time, although it was a method of developing a negative bias voltage without the need for a separate rectifier diode.

[Bergheim]

The resistor is in series with the load (your amp). Makes no difference if you put it in the positive supply lead or the negative supply lead. Or, said another way, makes no difference if the sag resistor occurs before or after the load. In a series circuit the same current flows through the resistor as flows through the load. Voltage drops (sag) will be the same.

That's what I was thinking. It works like a charm btw and I like this setup a lot better than having the resistor in the high voltage string. It didn't occur to me when I made this thread, but the bridge negative is of course the same as a center tap in this regard, and most people indeed use zeners to back-bias/drop the B+ on the ct.