What is a Digital Amplifier receiver (1 Viewer)

I'm having a difficult time understanding the difference between a traditional receiver (such as my Yamaha RXV 1200) and one that has digital amplification (such as the Panasonics). I can't find any article that describes the differences in a way that makes sense.

Thanks in advance.

The suposed advantage is that the signal stayes digital through the amplifier section. And that the ampifiers are supposed to be more efficent than standard analog amplifiers, if I am not mistaken. Companies like H/K and Sony ES are marketing digital recievers that are said to sound as good as more exspensive higher end models. Nick's explanation is very good and I hope the link he provided helps. I heard the Sony STR-DA9000ES digital reciever at the CES show in Vegas last year. Needless to say I was not impress as it had a slightly harsh cold sound to it, lacking warm and detail. These digital amplifiers have been compaired to high end brands, but imho. While they may be the future they need more refinement and can not touch a really nice analog high end amplifier. I personally would not own a digital amplifier or reciever with a digital amp section. Heck I would rather keep my Yamaha 995 over a new Sony ES digital reciever!

Would like to know does it mean that digital receivers wont do 2ch like traditional receivers can.

Sure the digital recs will do 2 channel. The digital amps have nothing to do with processing/decoding. I think you're confusing the amps with the fact that digital source inputs are frequently used for multi-channel sources (Dolby Digital, DTS, etc.). Many CD players have digital outputs, and they are only two-channel.

I always thought that when you went into 2ch stereo mode it was analog.I guess you learn something everyday.

As I understood it, they are digital PATH amplifiers. There is no such thing as digital amplifier. How could there be?

There is such thing and here is how. Analog amp sends smooth AC current to the speakers. Digital amp sends discrete pulses of current. As long as the sample rate is high enough, the discrete pulsatile nature of the signal is inaudible.

That's still analog signal, isn't it? How would you amplify digital signal? Shift by n bits?

Check out ICEpower amps...really, really cool!

Class D amplifiers are not digital amplifiers. They are PWM switching amplifiers. They function in a similar way to the switching power supplies you find in modern computers. The faster power transistors available today made it possible to apply the same ideas to amplifiers capable of covering the full audio range.

The first step in a Class D amplifier is generating a series of pulses through Pulse Width Modulation. The resulting waveform from the PWM process is the analogue audio on an analogue carrier. The series of pulses are amplified and then the carrier is filtered out with a low pass filter. The resulting output is amplified analogue audio, NOT a series of pulses.

There are different ways to handle the PWM process, including controlling it with the digital audio you wish to amplify. This doesn't make the amplifier a digital amplifier though. The process is a form of digital to analogue conversion and it's still an analogue waveform that's getting amplified in the end. It's just pushing the digital to analogue conversion to the very end.

For the sake of simplicity and nomenclature, lets call PWM amplifiers digital, the same way we call PCM audio digital, when effectively PCM is only a storage/transport medium and not really audio, at least not until it comes out of your speakers.

not only is there such a thing as digital amplifiers - but there are a few different ways of doing it by different companies. Check out
http://www.tripath.com
http://www.ti.com (Equibit)
http://www.bang-olufsen.com (ICEPower) http://www.d2audio.com
http://www.flying-mole.co.jp/ and a couple of other companies I can't remember the addresses to.

That's just it, PWM in this case is the process of placing the analogue audio onto a carrier. The analogue audio is still there, it hasn't been converted into anything else. It's just riding on a higher frequency carrier. Place it through a low pass filter and you have your original analogue audio signal.

PCM is a way to carry a numerical representation of the original analogue audio. That numerical representation needs to be turned back into real voltages before our speakers can play it back and our minds can interpret it as music.

Yes real digital amplifiers do exist, I have quite a few devices that can function as such. I usually call them calculators though.

IIRC The TI Equibit converts PCM to PWM - don;t ask me how they do it, tho

As I mentioned it is indeed possible to use a PCM bitstream to control the PWM. The process is a digital (PCM) to analogue (PWM) conversion. It still doesn't make it a digital amplifier though, rather an analogue amplifier with a built in DAC.

Keeping the signal in the digital domain until the last moment isn't inherently better though. Going directly from PCM to PWM requires a more complicated design and seems to have an inherent flaw in that it impedes the use of feedback. A switching power transistor is also going to make a lot of noise, so now the final digital to analogue conversion takes place in the middle of the lion's den.

The aim of these switching amplifiers should be on it's efficiency. Smaller, lighter and less expensive (as a whole unit) while supplying the same output. The potential is there but so far too much effort has been placed into marketing these amplifiers as some sort of holy grail of signal purity wich they are not.

The Sound of Change: From analog to digital audio amplifiers (From eet.com)

Is this the same technology used in the Line 6 guitar amps? I think they've been out since around 1997, maybe earlier.

As for myself I dont feel that digital amps in most casses can compete with analog amps. At least not when we are talking about very good quality analog amps. This will most likely change as the digital amps are improved. I personally would not purchase and current recievers with digital amps inside. Last year at CES I heard the Sony ES flagship that had digital amps and while it shound decent. I was not really impressed enough with it to place one in my own home theater system that currently has a Yamaha RX-V995 in it. Which I am looking to upgrade to ether a Denon AVR-4806 reciever or a pre pro. Just depends on my income at the time and what I can afford to invest.