カー オーディオ アンプのしくみ– 入力ステージ

現代のカーオーディオアンプがどのように機能するかの入力段を見てみましょう。入力ステージは、ラジオとのインターフェイスを担当し、ゲイン コントロール、クロスオーバー、バス ブースト、リモート レベル コントロール、ステレオ システムのサウンドと信頼性の高い機能を実現するためにインストーラが使用するシグナル サミングなどの機能を提供します。アンプのこの部分のコンポーネントの詳細に入る必要はありませんが、用途に適したソリューションを選択するには、機能の重要性を理解することが重要です。

RCA プリアンプとスピーカー レベル入力

アンプをラジオに接続できない場合、アンプは音声信号を増幅できません。市場に出回っているほぼすべてのアンプには RCA 入力ジャックがあり、設置者はアフターマーケットのラジオをすばやく簡単に接続できます。一部のアンプは、工場で取り付けられたオーディオ システムとの統合専用に設計されているため、「ほぼ」と言います。これらのアンプには、信号を受信するためのピグテール ハーネスに一連のワイヤが含まれている場合があります。

ほとんどの場合、スピーカー レベルの信号はプリアンプ信号と同じですが、通常は電圧が高く、(工場で取り付けられたラジオまたはアンプの) アンプ ステージを既に通過しているため、もう少し多くの電圧が含まれている可能性があります。

アンプがプリアンプまたはスピーカーレベルの信号を使用するかどうかにかかわらず、バランス差動入力と呼ばれる機能、またはそのバリエーションが必要です。それらの言葉。この単純な回路は、中心導体の信号 (またはノイズ) と RCA 相互接続のシールドを比較し、オペアンプ (2 つの信号を比較または結合して 1 つの出力にするように構成できる小さな集積回路) を使用して何かを除去します。両方の導体に共通です。ツイストペア相互接続を使用している場合、EMI または RFI ノイズは両方の導体に共通である必要があるため、この回路によって低減または除去されます。アンプを購入するとき、バランス型差動入力は、販売員に最初に尋ねるべきことの 1 つです。

信号処理機能

アンプの次の重要な機能は、感度またはゲイン コントロールです。 This adjustment allows your installer to configure the amp to produce maximum power for a specific voltage that matches the maximum undistorted output of your source unit, or your power requirements based on the design of your audio system. The gain control is something that should be set once using an oscilloscope and a real-time analyzer (RTA), then not touched again unless the design of the system changes.

Most modern amplifiers include some form of electronic crossover that limits the range of frequencies that pass from the inputs to the outputs. A high-pass crossover only allows frequencies higher than the crossover point to pass and would be used on midrange and high-frequency speakers. A low-pass crossover allows audio signals lower in frequency than the crossover point to pass through the amp. This type of crossover would be used for woofers and subwoofers. Depending on the design of your audio system and the features of your amplifier, your installer may choose to combine high- and low-pass crossovers to create what is known as a band-pass crossover. This crossover would be used on midrange or midbass drivers to cut out low- and high-frequency information.

Many amplifiers have a bass boost control. This control operates as a single-band equalizer that the technician installing your sound system can use to reinforce a narrow band of frequencies being sent to a subwoofer. In reality, adding a narrow-bandwidth boost to your audio signal, from a purist perspective, makes no sense. Most systems sound better with proper DSP equalization to deliver smooth and predictable response across the entire operating range from 20 Hz to the upper limit of your sub around 60 or 70 Hz. A peak at any particular point will sound unnatural.

Remote Level Controls

Most high-quality subwoofer amplifiers come with a remote level control or remote bass boost control that can be installed in the front of the vehicle. This control allows the driver to turn the bass up or down to suit the music he is listening to or his mood. When shopping for an amp, look for units that offer a level control as opposed to a bass boost. As we mentioned above, adding emphasis to a narrow band of frequencies doesn’t sound as natural as turning as adjusting the overall output of the subwoofer.

Amplifiers with Integrated DSP

A friend of ours was in charge of developing a series of high-end amplifiers for one of the well-known head-unit manufacturers. The goal was to include as much flexibility as possible in terms of crossovers and signal summing. The complexity of the amp grew to a point where it was becoming difficult to fit all the switches and adjustments on the side of the amp. To provide their clients with the features they wanted, the company decided to remove all the controls and implement a digital signal processor (DSP) to handle everything. Now, the installer could combine signals from multiple sources, set crossovers very accurately and equalize the signal to deliver a smooth and predictable response from the speakers. Sure, your technician will need to connect a computer to the amp, but the results will be fantastic!

Great Features and Great Design

As important as the features of the amplifier you choose are, the design and component layout of the input stage of a car audio amplifier can have a huge effect on the performance of the amp. Keeping these components away from noisy sections of the amp like the power supply and output stage can dramatically reduce the signal-to-noise ratio of the amp. For this reason, larger amplifiers often sound and perform better than their compact counterparts. As with any design, the electronics engineers and technicians who develop the circuits and lay out the components have to balance performance, features, cost and size.

Find the Latest Car Audio Amplifiers at Your Local Car Stereo Shop

When it’s time to shop for a new amplifier for your car, truck, motorcycle or boat, make some notes about why you need an amp and what you want it to do. Armed with that information, the product specialists at your local stereo shop can help you find a solution that will meet your requirements quickly and efficiently and ensure that your mobile audio system sounds magnificent.