A monoblock amplifier is a one-channel amp (mono means 1) that provides superior power amplification and can be used to power single or multiple subwoofers. Monoblock amplifiers are popular for car stereo systems and so they need tuning. In this article, we discuss how to tune a monoblock amplifier.
Before we get into it, you can check out our article on what is a monoblock amp and why we use them. You should also understand why it is important to tune monoblock amps in certain situations, for example when you want to wire two subwoofers to your monoblock amplifier.
How Do You Tune Your Monoblock Manually?
Manually tuning your monoblock is the easiest and most affordable method, as you don’t require any special tools or skills. However, it requires you to do due diligence to minimize the failure to capture some distortions.
If you don’t have the time to opt for the most accurate way to tune your monoblock amplifier, here are the simple steps that you should follow:
- Turn the gain setting down and turn off any special settings and filters.
- Turn up your car stereo gently until you start hearing distortions. After that, back the stereo down until you find the sweet spot.
- Use the same principle applied in point number two above to adjust the gain. Crank it up gently and carefully. When you start hearing distortions, back it off and ensure the gain is no more than 80% to avoid putting too much pressure on your speakers.
- Turn the special settings and filters that you need on.
- Repeat steps two and three above until you find the sweet spot. (If you’ve successfully tuned your monoblock amp, you’ll most likely hit the 80% volume without noticing the slightest sign of distortions).
- If you hear any distortion, single out the speakers that are the culprits and turn down their respective gains until you start receiving high-quality sound.
How to Tune a Monoblock Amp with a Multimeter
If the manual method, which involves listening to what sounds best, doesn’t serve your needs, you should opt for this advanced alternative. Here are the steps you should follow to tune your monoblock amp successfully with your multimeter:
1. Use a digital multimeter to measure your speaker’s impedance. To do this, you should follow these specific steps:
2. Disconnect the speaker power supply.
3. Determine the negative and positive terminals.
4. Connect the digital multimeter’s black probe to the negative terminal and the red probe to the positive.
5. Read and record the impedance (Ohms) displayed in the multimeter.
6. Compare the amplifier’s recommend wattage output against the impedance. Here’s the right way to do this:
- Consult your amp’s user manual for the recommended wattage output.
- Compare the figure against the recorded speaker resistance.
7. Find the target AC voltage
It would be best to use this formula, V = √ (P multiplied by R), to calculate the output voltage you require to set the amp’s gain. ‘P’ stands for the Wattage and ‘R’ for the speaker impedance.
8. How exactly should you calculate this?
Let’s say your user manual provides that the amp is 400 Watts. The multimeter also displays 4 Ohms as the speaker impedance/resistance. To find the output voltage (V), multiply 400 Watts with 4 Ohms to get 1,600. You then get the square root of this figure. It’s 40. So, since you have a single gain control, your output voltage is 40V.
9. Unplug all accessories
Unplug the speakers, subwoofers, and other additional accessories. You can only disconnect the positive terminals to make your work easy.
10. Set the equalizer setting to zero
Turn off all the equalizer settings to zero. Alternatively, turn the equalizer off.
11. Set gain to zero
For most monoblock amplifiers, you can achieve this by turning the dial in the counter-clockwise direction.
At this stage, your amp should only be connected to the power source.
12. Set the maximum volume to 80%
You should turn the head unit to roughly 80% of the maximum volume
13. Play a test tone CD
It would help if you played a 60 Hz test tone CD on the stereo by doing this:
- Adjust the amp’s gain knob( keep an eye on the multimeter while doing this)
- Once the multimeter reads the output voltage that you found through your calculations, stop adjusting the knob (it’s 40V in the above example).
- You’ve now correctly set the amp’s gain.
14. Plug everything back
Now you’re almost ready to start playing your music. Follow these steps before switching the unit on:
- Once you’ve reduced the volume to zero, turn the audio system off
- Reconnect all the accessories that you removed
- Ensure you’ve reconnected all the wires correctly
15. Enjoy the music
Play your favorite music. Enjoy the added booming bass.
Is a Tuned Monoblock Amp Good?
Yes, a monoblock amp can give you the desired entertainment experience if you know how to tune it properly.
The ability to add booming bass to your car audio system makes the amp good. However, to get the best experience, you should choose a monoblock that can handle the power without overheating. Moreover, it would be best if you used the right tips to tune it.
Is a Monoblock Amp 2 Channel?
While a monoblock amp has two outputs, it doesn’t have two channels. The amplifier has only one channel. The purpose of the two outputs is to help you connect multiple subwoofers easily. Remember, this difference affects how you calculate the amp’s output voltage.
In this case, you don’t use complicated calculations. You need this formula, V = √ (P multiplied by R), to find the voltage. If you have amps with multiple gain controls, you must treat each separately when calculating the voltage.
Should I Tune a Monoblock Amplifier With A Multimeter?
Not necessarily. You can tune it manually by listening to the sound as you adjust the gain. If you are keen enough, you’ll find this to be the easiest method. However, it’s not recommended. Your chances of correctly tuning it are low.
So, you need a multimeter to help you find out the speaker impedance. You’ll need to multiply this with the amp’s wattage and get the square root of the product to get the output voltage, which is essential for the successful adjustment of your amp.
What Should LPF Be Set on Amp?
With only one amplifier receiving a signal from your head unit, play your favorite type of music at about 75% volume with the LPF filter on your amp set to its maximum position.
Adjust the frequency down until you no longer hear all of your subwoofers’ high frequencies.
How Do You Wire a Monoblock Amp to 2 Subs?
To wire a monoblock amp to 2 subs, here’s what you need to do:
- Wire the positive wire of one sub to the positive terminal on your amp.
- Next, wire the negative wire from that same sub to a separate section on your amp with an “INPUT” label.
- Repeat this for each speaker you have and connect them all separately to their input sections of your monoblock amp.
- Lastly, ensure they’re wired in parallel! That means if you take two identical wires (for example both +12V or both ground), then attach them at only ONE end of the connection.
To learn more, check out our guide on how to wire 2 subs to a monoblock amp.
What Hz is Best for Bass?
The Hz rerating is just the frequency rating in hertz. A 20-120 Hz rating is the best option for bass in most subwoofers.
The lower the Hz, the deeper the bass you may get. Some of the most effective subwoofers available have a Hz range of this sort.
If you’re buying a subwoofer with a specified Hz rating, make sure it’s below 80 Hz if the bass is essential to you.
What Does Subsonic Do on an Amp?
A subsonic is a component that helps to reduce the intensity of notes that come through at lower frequencies. It also decreases the amplitude of the low notes that you feel more than you hear.
Now you know when to use a digital multimeter or the manual method to tune your monoblock amp. It’s upon you to choose the most suitable one based on your circumstances. Of course, you can find a few others. However, these two are the most effective and easy ones that can help you achieve your goals without any issues.
Norvan Martin is the founder of BoomSpeaker.com. He is a professional Electronics Engineer and is passionate about home theater systems and AV electronics. BoomSpeaker was created as an online hub to share his knowledge and experiences as it relates to home theaters and home audio electronics.