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When do you need an AMP?

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If you step into the HiFi audio rabbit whole, you will get two obvious terms. DAC and Amp. In our last article, we have discussed the necessity of a DAC.…
When do you need an AMP?

If you step into the HiFi audio rabbit whole, you will get two obvious terms. DAC and Amp. In our last article, we have discussed the necessity of a DAC. Then it arises, When do you need an amp? Well getting a straight answer is tough. Most of the audiophiles will tell you Amp helps to get better audio. 

Theoretically, your need for an amp depends on a few circumstances. In most cases, you might not need one. Let’s discuss the questions answer point by point until you have a better understanding. So…

When do you need an amp?

Amp refers to the Amplifier. It mostly boosts the analog signal from your source. However

You will feel the necessity of amps in the following cases. 

  1. Either your smartphone/laptop/pc cant power your headphones. 
  2. You are craving for more loudness but the output power is maximum, 

Nonetheless, Bluetooth audio gears have a built-in amplifier. So, You don’t have to worry about their power.

For wired audio gears, you should consider a few things. If you get reasonable volume out of your source for a 70-80% gain, you are ready to go. AMP won’t be a necessity for you. Mainly, An amplifier’s job is to boost the output signal of your source. You can crank it up to your preferred position. If you are happy with what you’ve got, keep enjoying it. 

On the other hand, if your volume doesn’t make you happy, you are facing the truth. You need an amplifier to push your audio gear. 

Every audio gear has specific power requirements to create sound. Having a power-hungry headphone isn’t a problem. A little increase in analog signal strength is sufficient. 

Firstly, get the specs of your headphones right. You need to take care of two things from the spec sheet. 

  1. Impedance
  2. Sensitivity

Impedance & Sensitivity

It is the ability of audio gears to resist current. Impedance is a very technical term. It would be hard to clear without equations and scientific terms.
On the other hand, sensitivity expresses what will be the volume with 1 milliwatt power. Let’s figure out the required power for your headphones to get a gentle listening volume.

This is the first step to understand “when do you need an Amp”

A story of electricity (Amp basic)

To push your headphones properly, your source should have the ability to do so. Though some factors can hinder your pleasure, you can work to solve them. Some easy points will be like the resistance to electricity, a bit more power requirement, etc.

Electric pathways are a lot like a water supply line. “Current,” can be considered as the rate of water flows through the pipes. Similarly “voltage,” will be “water pressure,”. Therefore, “impedance,” will refer to how shallow the pipes are. This shallowness constricts the water flow to a certain amount. This is just an analogy. It’s not a serious implementation. 

For headphones, we need to push a certain amount of “water” to work properly. Now you can replace water with current. Headphones need the right amount of power to gain up. 

An amplifier boosts the analog signal and pushes towards headphones. Thus your headphones get enough juice to sing proper.

Let’s do a math

We need to know what decibel (dB) is? dB is a unit of how powerful a sound (or signal) is. Its scale is logarithmic, So every time you increase the dB by 10, you’re increasing the total power 10 times over. Therefore, An 80dB signal is ten times more powerful than a 70dB signal. Moreover, it’s 100 times as powerful as a 60dB signal. The concept of  Loudness is more or less objective. Nonetheless, we know that we get 2x loudness with a change in 10dB. 50dB is twice as loud as 40dB. Therefore four times is as loud as 30dB. 

Now you can think about what the ideal dB for your listening is. Usually, 85dB is simply loud. But not so loud as to give you noise-induced hearing loss that quickly.

Now let’s break down the sensitivity stuff. It’s the loudness per milliWatt. To fix the baseline it’s easy to undermine how much power we need. Ohm’s law and our knowledge about decibels are enough to fix the “number” to achieve a certain volume level.

Let’s make it simple. For a 10 dB increase, we need ten times the power. So if you decrease 10 dB, you need to cut the power to 1/10th. Now talk about the voltage. 

Voltage(Vrms)=√[Power in Watts*Impedance]. Use the numbers from your spec sheet to get the proper result.

Note: As we’re dealing with milliWatts, divide any number in front of mW by 1000 first.

let’s talk about the real-life scenario

These are theoretical examples. So your mileage can vary a bit. Suppose A Headphone named “Dragon” comes with an impedance of 300Ω and a sensitivity of 85dB/mW. It requires 1mW at 0.55Vrms to reach a gentle listening volume of 85dB. If you want a satisfying listening session with “dragon”, you should push 10mW at 1.73Vrms to reach 95dB. That’s a lot of power. Your smartphone can’t provide it at all. In this scenario, you are in need of an amp. 

Alternatively, We have got a Headphone named “Berry”. It is made to use with smartphones. So its impedance is 32Ω and a sensitivity of 105dB/mW. “Berry” only requires 0.01mW at 0.02Vrms to reach 85dB. You can use any audio source to make it sing. It is easy to drive. So the necessity of amps is absent here.

Do cables matter?

Did you ask yourself “what about cables? Usually smaller cables, wouldn’t that make a difference. However, the majority of cables available to us are more than enough. They are sufficient and will support our needs. Headphones typically have much lower power requirements than speakers do. So changing cable will make minimum to zero difference in terms of headphones. On the other hand, the speaker shows a lot of changes in sound with a different cable. Nonetheless, experimenting with headphone cable is entertaining. It’s safe to say you don’t usually need to upgrade your headphone cable. If you want to do, its not the end of the world. So, do it, carry your research, and experiment with different stuff.

The Ending (When do you need an amp?)

A few headphones require a lot of juice to sing properly. When you step into the world of audio, you will find a ton of headphones with these characteristics. Most of the audiophile-grade headphones will get the benefit if you add a quality amp to it. The manufacturers are designing their products this way. A dedicated amp will push your headphones to sound effortless. Most of all you will get a clear and quality sound signal from an amp. 

However, you don’t need to spend a fortune to get a quality amp for your needs. You can get a standalone amp stacked with your DAC. A portable DAC amp can be handy for portable use. Some portable DAC amps with Bluetooth features like Shanling UP4, FiiO BTR5, Topping nx4 are available within an $80-150 range. Nowadays a lot of manufacturers make efficient headphones to use with smartphones, portable music players, and iPods. So, you need to think clearly about your need for an amp. If you are satisfied with the current setup, enjoy it. If you have a budget and plan to get a better amp, get one.

I hope I will guide you through the different types of Amp you can get according to your need. And you can read about What is DAC in my last article. 

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