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100 Watt Speakers: What Size AMP? (Updated 2022 Guide)

Size AMP For 100 Watt Speakers

You’re excited to blast your favorite tunes on your 100-watt speakers.

But you still can’t find the right AMP for them. 

No worries. I’m here to help. 

Just follow this guide, and you’ll finish your audio setup in no time.

Continue reading to find out:

  • What a 100-watt amplifier means.
  • What size AMP is best for 100-watt speakers.
  • 5 simple steps to match your speakers with an amplifier. 
  • And this is just the beginning… 

What size AMP for 100-watt speakers?

For 100-watt speakers, you should use a 150-watt AMP. Using an amplifier that’s more powerful than your speakers is always better. Because this ensures that you won’t overpower your AMP. Your audio devices should also have the same impedance. Otherwise, you’ll ruin 1 of them.

What does 100-watt AMP mean?

A 100-watt AMP means your device can give your speakers 100 watts of electricity.  

See, passive speakers can’t produce sound on their own. 

So, they need an AMP with enough watts to give them power. 

“Do my 100-watt speakers also need a 100-watt amplifier?”

Not necessarily. 

It’s a common misconception that an AMP must match the speakers’ watt value. 

But audio devices can’t function efficiently in this type of setup. 

That’s because if your amplifier is only as powerful as your speakers…

Your AMP will have difficulty providing enough electricity to the latter. 

Think of it this way:

Your 100-watt speakers need 100 watts to run efficiently.

And your amplifier can only provide 100 watts at its full capacity. 

Now, this setup will work. 

However, you’ll risk overworking your amplifier in the long run. That’s because your AMP will always need to use all of its energy to power speakers.

This leads to the big question… 


How do I match my speakers to my AMP?


To match your speakers to your AMP, multiply your speakers’ power capacity by 1.5. Then, find an amplifier with the same watt value as the product you get. After that, ensure that your audio devices have the same impedance. And your audio setup will be good to go.

For a more detailed guide, here are the… 

5 simple steps to match your speakers with an AMP

#1: Know your speakers’ power capacity 

This refers to the amount of electricity your speakers can handle. 

And you need to know this value to calculate how many watts your AMP needs.

“Where can I find my speakers’ power capacity?”

You’ll see it in your speakers’ user manual or specifications sheet. 

Note: In some models, this is called program watts or RMS.

Warning: Don’t confuse power capacity with peak power capacity. The latter refers to the maximum power your speakers can withstand. So, if you use it for the equation later, you’ll risk blowing out your speakers

#2: Find your speakers’ nominal impedance

Find Your Speakers' Nominal Impedance

This measures your speakers’ resistance to electricity.

I’ll explain why this value is crucial later in step 4.

But for now, just check your speakers’ user manual.

And find their nominal impedance, which is measured in ohms.

You might also be interested: 2 Ways To Wire A 4-Channel Amp To 6 Speakers (How-To)

#3: Calculate how many watts your AMP needs

Here’s all you need to do:

  1. Take your speakers’ power capacity.
  2. Multiply it by 1.5.
  3. The product you get is how many watts your amplifier needs. 

For example, if you have 100-watt speakers…

Just multiply 100 x 1.5. 

And since the product is 150, you’d need a 150-watt amplifier.

By getting an AMP that’s 50% more powerful than your speakers, you’ll ensure that:

  • You won’t overwork your amplifier.
  • Your speakers won’t have audio clippings.
  • Your AMP can play for long durations with ease. 

So once you know how powerful your amplifier needs to be…

#4: Match the nominal impedance of your devices

As mentioned, this refers to your devices’ resistance to electricity.

And simply speaking, if the impedance is low, power travels fast.

But if the ohms value is high…

Electricity will travel slowly because there’ll be more resistance. 

“Why is matching the impedance of my audio devices important?”

That’s because you’ll risk ruining your devices if you don’t.

To be specific…

If your speakers’ have a lower impedance than your AMP…

You’ll fry the internal components of 1 or both devices.

“Does this also happen if my speakers’ impedance is higher than my amplifier?” 

No, it doesn’t. In that scenario, you won’t destroy any of your audio devices.

However, your AMP will have difficulty giving enough power to your speakers.

After all, the latter will have a higher resistance to electricity.

As a result, your speakers won’t be able to play loudly. So, your setup will still be running inefficiently. 

See, it’s crucial to match the nominal impedance of your audio devices.

So, if you have 100-watt speakers with 4 ohms… 

You should get a 150-watt AMP with the same nominal impedance.

Note: Some speakers will have an impedance range. For these models, get an AMP that matches the lowest ohm value of your speakers. 

If you want to know more about speakers’ nominal impedance, watch this video:

#5: Buy the right AMP 

As a review, the right amplifier for your audio setup should have:

  • The same nominal impedance (in ohms).
  • 50% more power (in watts) than your speakers.

That said, once you have an AMP, you should…

Bonus: Test your speakers and amplifier

Step 1: Find the power and ground wires of your speakers.

These 2 wires will be in black and red, respectively. 

Step 2: Attach both wires to your speakers.

Step 3: Connect the speaker’s RCA cables to your AMP.

Note: These are the 3 wires with the colors (red, yellow, and white).

Step 4: Try playing any music through your speakers. 

Pro tip: Reconnect the wires between your audio devices if you hear distorted or fuzzy sounds. Because this is the easiest way to fix crackling speakers.

Step 5: Enjoy your new audio setup.

You’ve matched your speakers to an appropriate amplifier. So, rest assured, this setup will keep your devices safe and running efficiently.