Mangler - 1/2 watt carbon comp resistors or 1/4 watt

[avidgrim]

Should I use 1/2 watt or 1/4 watt resistors? I've read that 1/2 watt may produce more noise/hum. Was the pcb designed to fit 1/2 watt?

Thanks in advance.

[jimilee]

1/2 watt are huge, 1/4 watt ate pretty much standard for pedal pedal unless its a mini.

[avidgrim]

Thanks. I actually ended up buying both from mouser in each value just to check them out.

[jkokura]

The main issue you face with different size is different heat disappation issues. For instance, in amps 1/2 watt is a minimum and it's common to find 1W or higher in the preamp. 3w is becoming standard in the power section.

In pedals however, you don't need to worry about heat as much, considering we're dealing with at most a 9V voltage swing.

Composition of the resistor makes more of a difference on noise, with the common agreement that metal film are the 'least noisy' and carbon comp being the 'noisiest' we use. Carbon Film are in the middle. I can hear a noise difference between carbon comp and metal film in a circuit with 10 or more resistors. Less than that, it's hard to hear a difference, and it's also hard to hear the difference between carbon and metal film.

Jacob

[madbean]

The only time I would recommend 1/2W resistors in pedals (barring tube-based ones) is for making supply voltages. For instance, sometimes you will see a small resistor like 100R in line with the power supply. This creates a low pass filter with the subsequent filtering cap to reduce noise. It is beneficial to use 1/2W resistors in those cases (metal or carbon film), but generally not a requirement. This is especially true when you have a effect that has a high current draw. If the circuit tries to drain a lot of the current available from the supply, that filter resistor will start to heat up. I've smoked a few out on occasion. But, replacing that resistor with 1/2W almost always solves the problem.