Yet another question for electronics guys

[Monkeyleg]

In another thread I said I was replacing capacitors on my guitar amp. There are four resistors on that capacitor board, and I thought I'd replace them as well as long as I was there.

I order four capacitors from Mouser Electronics using the same wattage, resistance and color code as the originals. The ones I received are much smaller than the originals, though. The bodies are about 1/2 the size or less.

The amp is probably five years old. Maybe ten at the oldest. I thought maybe resistor technology has improved like everything else, and they've gotten smaller. I don't want to screw up anything, though.

As far as I know, the original resistors are fine, but guys who know guitar amps said to replace them anyway.

So, do you think there's any difference between the new ones and the originals?

Thanks for any replies.

[CNYCacher]

Resistors made of different materials are different sizes for the same wattage.

How did you determine wattage for the old resistors?

[geronimotwo]

^^^^what he said.  also, the conductors on the resistors should be the same size wire.   

[Monkeyleg]

I used the color code, as well as wattage and resistance spec's from the manufacturer.

I found an article on resistors and such for acoustic equipment. The author made the point that tube amps and such should have resistors that can handle 350 volts, and that the small resistors can't necessarily handle that. I called the online retailer and they weren't sure. I'd have to look at the spec sheets for each resistor to see if voltage is mentioned.

The originals look like traditional carbon resistors, although the spec's call for carbon film or flame proof metallic.