How to Increase Your Car’s Volume of Speakers without an Amplifier

Would you like to increase your car’s speaker volume yourself? Here are some pointers that might help jumpstart your quest for more sound.

Everyone tries to achieve car speaker volume in their own way. Basically, most try to connect as many speakers to one amplifier. Less often, though, some install a powerful 4 channel amplifier. Many are looking for speakers with high sensitivity.

Here are three aspects to start down your own road of increasing your car’s speaker volume.

A Little Math to Start

There is such a parameter – sound power level. This is the power characteristic of sound, which is directly related to the sound pressure. The connection is about the same as between electrical power and voltage. One can be easily calculated from the other. What determines the sound power? Naturally, from the number of speakers.

J = j * n


J – Resulting sound power

j – Sound power developed by a single speaker

n – The number of speakers.

What determines the sound power developed by one speaker – j? Naturally, it comes from the power dissipated on it (supplied from the amplifier). And it depends on the return of the speaker per unit supplied to it from the power amplifier.

j = j0 * P


P – Amplifier power

j0 – sound power developed by the speaker by unit applied to it by the power amplifier, the power analog of the usual parameter – sensitivity of the speaker.

Thus, we obtain a formula for the dependence of the recoil of the sound system on the number of speakers in it, on their sensitivity and the power supplied to each speaker:

J = j0 * P * n

What can be understood from this formula? Unfortunately, almost nothing.

Judging by it, though, everything is simple: add more speakers, and everything will be OK. The more you install, the better.

Amplifier also, the more powerful, the better.

But it’s not that simple.

The human perception of sound is not linear, but logarithmic. We notice a difference in volume if it differs significantly. Roughly speaking, we hear the volume of sound in decibels.

If we bring the last formula in logarithmic form, then by simple mathematical manipulations, which I will not cover here, we get the expression of the dependence of sound pressure:

SPLDB = E0 + 10lg(P) + 10lg(n)


E0 – the sensitivity of the speaker, specified in the characteristics

P – The power dissipated by the amplifier on each speaker

n – The number of speakers in the system.

Going to decibels, we get this formula, by which it’s possible to figure out a great deal.

The most important is the last term. It shows that the number of speakers should be doubled, then the volume gain will be good.

The Nitty Gritty

Let’s say you decide to install double mid-range speakers. Compared to one pair, you will get +10lg (2). Numerically it would be +3dB. It’s a lot, and it’s a noticeable difference.

If you install four pairs, then in relation to one pair, you will get +6dB. Each time, when you double the number of speakers, you get a gain of 3dB. **Note, in this case, on every speaker, the same capacity is dissipated, as with one pair. That is, the number of amplifier channels should also be doubled, which is certainly not rational.

Based on this, what number of speakers is optimal for a loud front. In my opinion—4 pairs.

It is feasible to install four pairs, but a further increase in the number of speakers I would consider not appropriate. For example, the installation of the fifth pair will give an increase of 0.95dB. Such a difference may not be noticed. After the 8th pair, the gain will be only 0.5dB. The ninth pair definitely no one will notice. And you will have to pay for the amplifier.

From this, we can conclude, that increasing the number of speakers as a method of getting high volume works well, but with a limitation. To get a noticeable difference, you need to double the number of speakers at the optimum level of 4 pairs. A further increase is not effective.

Importance of the Amplifier

A dual set of speakers gives the biggest effect. One amplifier can be used for it. Let’s say you have one pair of mid-range speakers on a 2-channel amplifier, and you want to get more volume. Buy another pair and connect the speakers in parallel with the existing ones: two per channel nets a gain of +3dB.

Modern amplifiers allow such a maneuver. The power arriving on each speaker will be the same as at one pair: minimum cost, maximum effect. And if the amplifier allows the load of 1 Ohm. Install four speakers on the channel, and you will be happy.

You can also increase the recoil by increasing the power of the amplifiers in the system. Here as well as with speakers, double the power, and gain +3dB.

The only deterrent is the price of the amplifier. It grows in the logarithmic progression of power. It is worth remembering that you need to feed amps, and power consumption increases in proportion to power.

This method is used very rarely because of the cost of the amplifier. Although it is the most effective.

The fact is that a good speaker has a very large power reserve. If you have funds for power supply and amplifiers, apply this method, and you will be satisfied. The loudest systems in the world are based primarily on the use of powerful amplifiers, rather than on a large number of speakers.

It should be noted that connecting a large number of speakers on one channel, combining serial and parallel connections, does not make sense. For example, connect four pcs. 4-Ohm speakers to one channel of the amplifier. Connect the speakers in series and parallel, so that the total load was not lower than 4 Ohms. Even though the number of speakers will be 4, the power dissipated on each of them will be four times less, and there will be no gain. Such a scheme should be used only if the power of the amplifier is a multiple of the power of the speakers.

Well, the very first term, the most important thing, really, is sensitivity. This parameter is specified on all speakers without exception. The only trouble is that modern manufacturers make up the sensitivity value, but not all.

You can increase the volume of the system if you replace or purchase speakers with higher sensitivity. And this method has advantages. The difference in sensitivity can be very large, by 6-10dB, while the issue of the price is not always significant.

Another priority—speakers with neodymium magnets. They have greater sensitivity. When it comes to midrange speakers, 6.5-inch often have a higher sensitivity than 8-inch or 5.25-inch.

In summary, if you build a loud front and are focused primarily on the result of the maximum volume, then, in my personal opinion, it is better to do it on 6.5-inch speakers with a neodymium magnet, using as powerful an amplifier as possible, working on as low-impedance load as possible (2-channel, 1 Ohm – ideally).

David Wardell has been a car enthusiast for years, and has an incredible knowledge of cars and how to work on them. The founder of the website, which covers tips on car repair and maintenance, reviews, and tests of new products of the automobile world.

Editor’s Note: The opinions expressed in this article are those of the author.

Photo attribution: Mark Doliner licensed under ShareAlike 2.0 Generic (CC BY-SA 2.0). 

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