# What is the effect on audio of using larger wattage resistor

• Planobilly
In summary: The resistor will only last as long as the component it is installed in. Resistors have a three year warranty.
Planobilly
Hi,
In general 1/2 watt resistors is what I see in tube guitar amps. I built one with 1 watt resistors and can not hear any difference. I assume shot noise will decrease with larger wattage values.

Other than heat dissipation, how is a 1 watt resistor different from a 1/2 watt resistor.

Thanks,

Billy

Planobilly said:
Hi,
In general 1/2 watt resistors is what I see in tube guitar amps. I built one with 1 watt resistors and can not hear any difference. I assume shot noise will decrease with larger wattage values.

Other than heat dissipation, how is a 1 watt resistor different from a 1/2 watt resistor.

Thanks,

Billy
I wouldn't expect any difference

Averagesupernova
Kinda what I thought...thanks

There will be no immediate difference, but the choice of resistor will make a difference over time. It is usually not clearly specified, but many resistors are only rated at 100 volts. They creep towards open circuit if operated on higher voltages. Higher power resistors will usually have higher voltage specifications where the resistance and power rating necessitate that increased voltage. V=√(W*R).

Higher power resistors will also be more reliable than standard due to lower thermal ageing. If you do not know the voltage rating of a resistor, assume 100 volts for axial and 50V for SMC. Use multiple series resistors to make higher voltage resistors.

Baluncore said:
Use multiple series resistors to make higher voltage resistors.
that's an old trick used by those of us that did tv servicing in days gone by

Hi guys,
On schematic I work from I don't think I have seen any notes pertaining to voltage values of resistors. Carbon Composition resistors were almost universally used in guitar amps made in the United States in the 1960s. While failures do occur from time to time, resistor failure in those amps is generally a function of some other component failing. Shorted tubes often take out the plate and grid resistors. There is not a lot of current in those circuits but the voltage is anywhere from 200VDC to 500VDC.

I commonly see 1/2 watt metal film, and carbon film resistors used as plate resistors on output tubes running at 300VDC to 450VDC. Ohmite brand carbon comp resistors use to come in three different series and the series "OA" which was rated at 500V is no longer made as of 2014. Most of the various data sheets I have looked at indicate a voltage rating of 150V to 350V. Metal film datasheets I just looked at have around the same voltages ratings. Perhaps they will function at higher than stated values.

I have not paid much attention to the voltage rating because I have not had any issues along those lines.

As I am building one off custom turret board guitar amps, the cost of resistors is not really an issue. I had in mind to use 1 watt resistors as a general standard if in fact using 1 watt as opposed to 1/2 watt would not add some other negative condition to the build.

In general, I am trying to define type, brand, and values standards of the components I am using. The only real cost issue relates to transformers and I don't yet know if the extra cost of Mercury Magnetics transformers is worth the money or not. The transformer issues I will post in another thread as it is anything but simple.

Thanks,

Billy

Planobilly said:
Perhaps they will function at higher than stated values.
You hope. Design to the component specifications, never beyond them. If there is no specification, do not use the component.

Different construction resistors age at different rates under various conditions.
If you base your choice of component on difference in price, what does that make your reputation worth ?

Commercial and domestic products are now constructed to survive for only a three year warranty period.
How long do you want your reputation to last ?

davenn
Hi,

As I said, price of resistors is not really an issue. Whatever grade of resistor was used in all the mid sixties Fender guitar amps are still working to this day without many issues.

I have not made a serious search but all the 1/2 watt current day stuff I see has a voltage rating of around 350V. Tube amps run at voltages considerably higher than that. Thanks for the heads up and I will key the voltage issues into the search.

Billy

## What is the effect on audio of using larger wattage resistor?

The effect of using a larger wattage resistor on audio depends on the specific circuit and components being used. However, in general, a larger wattage resistor can handle more power without overheating and potentially causing distortion or damage to the audio signal.

## How does a larger wattage resistor affect the quality of audio?

In most cases, a larger wattage resistor will not significantly affect the quality of audio. As long as the resistor is appropriately sized for the circuit and within the recommended tolerance range, the impact on audio quality should be minimal.

## Can using a larger wattage resistor improve audio performance?

In some cases, using a larger wattage resistor can improve audio performance by reducing distortion and allowing for a more accurate representation of the audio signal. However, this improvement may be subtle and is highly dependent on the specific circuit and components being used.

## Are there any potential drawbacks to using a larger wattage resistor in audio circuits?

One potential drawback of using a larger wattage resistor is that it may take up more physical space in the circuit, which can be a concern for compact or densely packed circuits. Additionally, using a larger wattage resistor may also increase the cost of the circuit.

## How can I determine the appropriate wattage for a resistor in an audio circuit?

The appropriate wattage for a resistor in an audio circuit can be determined by calculating the maximum power that will be dissipated by the resistor (using Ohm's law) and then selecting a resistor with a wattage rating that is at least 1.5-2 times higher than this value to ensure safety and avoid potential damage.

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