How to choose the power amplifier? Constant voltage amplifier vs constant resistance amplifier, don't buy it wrong again.

In the construction of sound system, power amplifier is the core power source, and choosing the right type of power amplifier directly determines the stability, sound quality performance and use cost of the system. Many people will fall into the tangle of "constant voltage amplifier vs constant resistance amplifier" when purchasing, and even the equipment will not work normally and the sound quality will be greatly reduced due to the wrong selection. Today, from the core principles, applicable scenarios, advantages and disadvantages, etc., we will help you completely distinguish the differences between the two, accurately select the amplifier that meets the needs, and avoid buying minefields.
First, the core principle: the essential difference lies in the "output mode"
To choose the right amplifier, we must first understand the core difference between them-different output methods, which also determines their adaptation scenarios and use logic.
1. Constant voltage power amplifier: output with "voltage" as the core.
The output terminal of constant voltage power amplifier will keep a fixed voltage value (70V, 100V, 120V, etc.), and adjust the output current to adapt to different loads when working. Simply put, its output voltage is stable, and the current will be automatically adjusted according to the number of connected speakers and impedance, just like "a power supply with fixed voltage, which distributes current as needed".
In order to realize constant voltage output, this kind of power amplifier is usually equipped with an output transformer, which can stabilize the voltage through the transformation of the transformer and realize impedance matching at the same time, which is also the key for the constant voltage power amplifier to drive multiple speakers.
2. Constant resistance power amplifier: with "impedance matching" as the core.
There is no fixed voltage requirement at the output end of the constant resistance power amplifier, and the core is to accurately match the impedance of the speaker (common impedances are 4Ω, 8Ω, etc.). Its output power will change with the change of load impedance, and the smaller the impedance, the greater the output power; The greater the impedance, the smaller the output power, just like "two sides need to be' opposite' to work efficiently".
Generally, there is no output transformer in this kind of power amplifier, so the structure is simpler, the output signal is more direct, and more attention is paid to the restoration degree of sound quality.
Second, the applicable scene: choose as needed to avoid stepping on the pit.
The adaptability of the two scenarios is very different, and the wrong selection not only wastes costs, but also may lead to equipment damage. The following is a comparison of specific scenarios:
1. Constant voltage power amplifier: suitable for "large-scale, multi-speaker and long-distance" scenes.
The core advantage of constant voltage power amplifier is "long-distance transmission and multi-speaker parallel connection", which does not need complicated impedance calculation and is convenient for wiring. The specific adaptation scenarios are as follows:
-Public broadcasting scenes: campuses, shopping malls, parks, stations, airports, etc., which need to cover a large area, and the number of speakers is large and scattered, and the voltage loss is small during long-distance transmission, which can ensure the uniform volume in each area.
-Background music scene: hotel lobby, restaurant, office corridor, workshop, etc., which requires less sound quality, but needs stable and even sound coverage, and is convenient for expanding the number of speakers later.
-Emergency broadcast scene: fire broadcast, emergency notice, etc., which requires stable transmission and high reliability, and can ensure normal signal transmission even if the line is long.
2. Constant resistance power amplifier: suitable for "small range, high sound quality, short distance" scene.
The core advantages of constant resistance power amplifier are "good sound quality restoration and strong dynamic response", which can accurately restore audio details and is suitable for scenes with sound quality requirements and few speakers:
-Professional audio scenes: stage performances, KTV, conference rooms, home theaters, etc., which require clear voices, full low frequencies, high requirements for sound quality details, and few speakers, close to the power amplifier.
-High-end audio scenes: recording studio monitoring, HIFI sound system, etc., pursuing low distortion and high resolution. The direct output of fixed-resistance power amplifier can better restore the original texture of audio signals.
-Small event scenes: small press conferences, salons, family gatherings, etc. The number of speakers is limited, so it is necessary to flexibly adjust the power to ensure the sound quality.

Third, the key points of purchasing: avoid misunderstandings and accurately select models.

1. Clear usage scenarios and give priority to matching core requirements.
First, determine the core requirements of the usage scene: if it is a large-scale, multi-speaker, long-distance public broadcast/background music, give priority to the piezoelectric amplifier; If it is a small-range, high-quality and close-range professional audio/home theater, the resistive amplifier is preferred. Don't blindly pursue "high power", just adapt the power to the scene to avoid wasting costs.
2. Pay attention to impedance matching to avoid equipment damage.
Constant-resistance power amplifier must strictly match the impedance of the speaker, and the common 4Ω and 8Ω speakers should correspond to the output impedance of the power amplifier to avoid the overload of the power amplifier and the damage of the speaker due to impedance mismatch; Although the constant voltage power amplifier does not need accurate impedance matching, it should also be noted that the total power of the speaker does not exceed the rated power of the power amplifier to prevent overload operation.
3. Pay attention to the transmission distance and choose the adaptive line.
Constant voltage power amplifier is suitable for long-distance transmission. When the line length exceeds 50 meters, constant voltage power amplifier is preferred, and it is recommended to use special audio line to reduce signal loss. Fixed-resistance power amplifier is suitable for short-distance transmission, and the line length is recommended to be controlled within 30 meters. Too long will lead to sound quality degradation and power loss.
4. Combine the budget and give consideration to the cost performance.
The overall cost of constant voltage power amplifier is low, which is suitable for large-scale scenes with limited budget; Fixed-resistance power amplifier pays attention to sound quality, and its cost is relatively high, so it is suitable for scenes with sound quality requirements and sufficient budget. You don't need to blindly pursue high-end models when purchasing. You can choose products with high cost performance according to your own needs and budget to avoid excessive consumption.
5. Add pit avoidance tips
① Don't mix power amplifier types: Constant-voltage power amplifier connected with constant-resistance speaker and constant-resistance power amplifier connected with constant-voltage speaker will lead to sound quality damage or even equipment damage, so be sure to match the corresponding speaker type when selecting the type; ② Pay attention to the rated power of the power amplifier: whether it is constant voltage or constant resistance power amplifier, the total power of the speaker should be controlled at 70%-80% of the rated power of the power amplifier, and the service life of the equipment can be prolonged by reserving margin; ③ Reject "Three No Products": Look for the products of regular manufacturers when purchasing, check the product qualification and after-sales guarantee, and avoid buying inferior power amplifiers to affect the experience.

Summary: There is no best amplifier, only the most suitable amplifier.
There is no absolute advantage or disadvantage between constant voltage power amplifier and constant resistance power amplifier. The core lies in whether to adapt to the use scene. Constant voltage power amplifier is superior to "wide coverage, simple wiring and high stability" and is the first choice for public broadcasting and background music; Fixed-resistance power amplifier is superior to "good sound quality and accurate reproduction" and is the core of professional audio and high-quality scenes.