Hypex DIY Poweramp

[Chris H]

Any one here built a Hypex amp DIY project, or had a listen / evaluation? Any opinions? They are getting a very good rap from some audio people.
http://www.hypex.nl/

I'm thinking of buliding the UcD400

[rick]

looks interesting , the digital amp revolution started about tens years ago and everybody thought there where only good for bottom end stuff , nowadays there are heaps of audiophile amps that use this technology and there seem to be for full range stuff nowadays
give it a go ..? lets us know

[Chris H]

From what i read it is not a digital amp but a new design application. Not being that techo minded i don't understand it all but below is an explination of the design principal.

http://www.hardwareanalysis.com/content/article/1822/
Although Hypex is known for their subwoofer plate-amps they’ve recently endeavored to offer kits that allow you to construct your own full-range amplifier. What’s interesting about the kits that Hypex offers, however, is the fact that these are not your run-of-the-mill amplifier kits. They’re based on a whole new amplifier technology called ‘class-D’. Conventional kits regularly use amplifier technology dubbed ‘class-AB’, which has powered the majority of amplifiers over the past four decades and has basically reached a point where further improvements are unlikely.

Enter class-D, which sets a new standard. Although class-D is often referred to as being a ‘digital amplifier’ that’s not an accurate statement at all. There’s nothing digital about these amplifiers, so the ‘D’ in class-D has no relevance to the word digital. In essence the amplifier works much like an AM-radio. The amplifier oscillates at a given frequency, usually around 400KHz, which is called the carrier-frequency. The audio-signal is then mixed in with this carrier-frequency, so the carrier-frequency becomes amplitude modulated (AM) by the audio-signal, similar to AM-radio signals.

This mixed signal is then amplified and fed through an output filter. This output-filter, which is a classical 12dB/oct. low-pass L/C filter, will filter out the carrier-frequency; hence the net result available at the amplifier’s output will be the amplified audio-signal. Class-D offers a number of advantages over the established amplifier technologies such as class-AB. A distinct advantage of this technology is the fact that distortion is kept at a set level across all frequencies. Another advantage is the high efficiency (~90%) requiring less cooling, less stringent power-supply constraints and enabling smaller amplifiers to be built.

[rick]

class d
equals digital amplifier !
note : this is not pcm digital its "d class amplifier " digital
sure its new ( ten years ) but
nearly every sub amp in every car installation in the last 4 years is a d class amp

its a pretty safe bet that all amplifiers are heading this way

simliar to all power supplies heading towards being switchmode supplies which is a simlar type of technology

light cheap , does not chew up power and does not get too hot

still i say " build one and tell us how things work out" , there is nothing like getting your hands dirty to really understand how something works

[rob]

Rick and Chris are both halfway there.

Class D is not digital, nor is it AM modulation.

Digital implies that that the analogue audio input is converted to some form of code that represents the audio as a bunch of numbers. In a class D amp, the analogue audio is used to modulate the pulse width of a very high frequency rectangular waveform. The high effeciency of class D is achieved as the ouput power devices ( transistor or usually FETs ) are always either fully off or on and thus minimise the heat wasted when a transistor is partially turned on. ( as in class A or AB ).

The very high frequency pulse is passively filtered out with a low pass filter at the amp's output, leaving the amplified analogue input.

This technique has been used for ages in motor speed control as a very efficient way of controlling motor speed, now it is possible with audio power amps.

Does it sound any good?.....Who knows...hop to it Chris

Rob

[Chris H]

Sitting in a restaurant in Hobart at the moment. Soon to check out some of the classic timber boats at Constitution Dock. Will buy the kit and build one in the next few weeks and let you know what i think