[Dogmatrix]

It seems to me there wouldn't be much advantage in converting from PCM to PWM then converting PWM to analog when a simple DAC can do that in a single step.

Are "digital" class D amps common, or did I get dragged into a discussion about curate's eggs that don't really exist in the real world again?

They are common in sound bars , subs , portable speakers and active monitors among others , due to their efficiency

 

[Dogmatrix]

I am thinking wireless headphones , iems likely use class D amps but checking the big players in the market none of them mention any amp at all so if they are class D they don't seem proud of it

 

[bigshot]

That sounds like a car stereo.

 

[Dogmatrix]

On further investigation the active monitor and sound bar people are happy to talk about multiple class D amplifiers often one for each driver

From Adam T8V blurb

"The U-ART tweeter’s 4:1 velocity transfer ratio, in combination with the new Class D amplifiers’ high dynamic range, yield respective max. peak SPL of 118 dB per pair. The tweeter, which extends up to 25 kHz, works as a team with the HPS Waveguide."

 

[jagwap]

Sound quality-wise no, but class D amps have some advantages such as excellent benefit factor (low energy comsumption + amps run cooler) and that you can't really overdrive a class D amp.

Seems like they are becoming more common. Battery powered portable devices are obviously candidates to use class D amps.

Let's clarify something: Class D amps are not often digital. I'm not saying you don't know that, but it is an easy assumption from some of teh thing people are saying.

You really can overdrive Class D amps. They often clip poorly so is a reason why people do not like them for some purposes, like guitar amps where overdrive is important. Of course there are ways around this, but it has been a hindrance to then doing badly in uncontrolled tests.

Maybe you mean you cannot overdrive a digital amp with a signal that peaks at 0dBFS? That would be potentially true.

 

[jagwap]

On further investigation the active monitor and sound bar people are happy to talk about multiple class D amplifiers often one for each driver

From Adam T8V blurb

"The U-ART tweeter’s 4:1 velocity transfer ratio, in combination with the new Class D amplifiers’ high dynamic range, yield respective max. peak SPL of 118 dB per pair. The tweeter, which extends up to 25 kHz, works as a team with the HPS Waveguide."

Class D has come a long way in the last 10 years. But they are not necessarily digital.

 

[bigshot]

Class D digital amps don't appear to be used much for what we talk about here. It seems to be yet another esoteric digression.

 

[Dogmatrix]

Class D has come a long way in the last 10 years. But they are not necessarily digital.

Yes I did lose the point a little . For the record all the devices I looked at with class D amps still had dac chips so nothing unusual about class D in those terms

 

[Dogmatrix]

To quote a modern philosopher: "sounds good, doesn’t work".

That should have been the end of this whole digital amplifier thing , looking back it was a technical misunderstanding
Stemming I think from this line in Wiki
"The modulator clock can synchronize with an incoming digital audio signal, thus removing the necessity to convert the signal to analog."
Later in Wiki it also says somewhat confusingly
"The term "class D" is sometimes misunderstood as meaning a "digital" amplifier."
At least we proved that true

 

[KeithPhantom]

For me, the biggest difference in equipment comes from DSP and transducer frequency response curves. I don’t care about DACs, amplifiers, cables, audio formats, etc. as long they are in compliance of some minimum operating performance, and this minimum level of performance exceeds what any transducer can ever hope to achieve. DSP helps a lot in terms of linearity with transducers and being as close as possible to your desired frequency response curve.

 

[Dogmatrix]

This from the good chaps at Ti

https://www.ti.com/lit/an/sloa319/s...ttps%3A%2F%2Fwww.ti.com%2Fproduct%2FTPA3116D2

It appears the "Digital amp" is simply an integrated dac/amp solution

 

[gregorio]

PWM doesn't need decoding? Huh? Of course it does! It is a series of pulses of differing widths, not the analog signal we want to feed into speakers.

Maybe my understanding is incorrect. Aren’t those “pulses of differing widths” our actual output signal, albeit filtered?

G

 

[71 dB]

Maybe my understanding is incorrect. Aren’t those “pulses of differing widths” our actual output signal, albeit filtered?

G

Audio PWM amps need filters. If PWM is used to drive say a motor, filtering is not needed (the inertia of the motor acts as a low pass filter).

 

[gregorio]

Audio PWM amps need filters.

So the signal is not decoded/converted, it’s the same signal just LP filtered?

G

 

[71 dB]

So the signal is not decoded/converted, it’s the same signal just LP filtered?

G

PWM and PDM signals are "decoded/converted" using just a low pass filter. Sometimes a low pass filter isn't even needed if the load has certain properties. In audio it is about how well you want the PWM signal filtered to call the result high fidelity sound?