coldamp class D power amplifier audio modules

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BP4078 400W RMS / 4 Ohm full range, high-fidelity amplifier module

 

Coldamp implements class D technology in all of its amplifier modules

 Unlike conventional class AB designs, massively present in the market until now, class-D amplifiers are based on switching the output between only two states, both of them being theoretically non-dissipative.  A modulator circuit controls this switching basing on the information within the audio input. The actual technique used by coldamp amplifiers is called Pulse Width Modulation (PWM). After an (almost-lossless) low-pass filtering, the original amplified signal is recovered. All this process, in practical use, has an efficiency above 90%, as opposed to 30-40% reached in conventional amplifiers.

This increased efficiency has two fundamental consequences:

  • Lower cooling needs, allowing a drastic reduction of weight, size, cost, and lower temperature operation, that undoubtfully also improves reliability.
  • Power consumption is also reduced considerably when compared with traditional systems. As an example, in order to obtain 100W rms with class-AB technology, a power supply capable of deliver around 200W is needed, when only 110W are more than enough for a class-D amplifier.

Complexity of class-D designs is, however, higher, so a very careful design and component selection are mandatory in order to obtain high efficiency and excellent sound quality at the same time. These two factors have traditionally relegated this kind of amplifiers to band-limited systems or where distortion is not a primary concern (i.e. subwoofers or industrial applications).

However, thanks to a long experience and the use of premium quality components, Coldamp offers full-range amplifiers (7Hz to 30KHz, -3dB typ.) with a surprisingly high sound quality. But... what are the keys?

First, Coldamp implements some important improvements to the basic Class-D design, such as global feedback, that reduces distortion, improves output impedance and provides an almost load-independent frequency response (a common flaw in other Class-D designs). The result is a high-end sound, very appreciated by true audio professionals such as studio recorders, that demand the most precise and pure sound possible.

We have also been very careful with EMI. Coldamp amplifiers are designed with this in mind from the start, and our amplifiers feature one of the smaller switching residue, thanks to a special notch filter centered at the (fixed) switching frequency, providing excellent rejection but leaving audio band unaffected.

These characteristics, joined to the great flexibility and extensive documentation, have contributed to the great success of our BP4078 amplifiers, a consolidated member of our product familiy.

For best performance and in order to take advantage of the small size and weight that Class-D allows, we recommend to feed our amplifiers with one of our Switching Power Supplies.