What level of maturity has class D reached in the commercial industry??

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It’s been a few years now that class - D audio has been commercially available in the wild, it’s of course had its criticism from many critics like its predecessors classification A and AB, it of course remains unbeaten in efficiency and size.

I'm curious to know the level of maturity the standard has adopted, are we seeing a wave of audio units using this technology or are companies still using AB in medium to high end products and shying away from this tech as a result of the complexity and myth it surrounds around EMI.
 

Tekko

Banned
2005-01-01 3:33 pm
Early class d was quite sad, but the new stuff like UcD and NCore are now rivaling the best class A and class AB amplifiers out there.

Even my crusty mono UcD prototype impressed a friend of mine that is an audiophile owning expensive high end equipment, and that on some crusty old "white van scam" speakers.
Hypex got it right, proving that UcD was the way to go.
 
It is clearly coming.
The CD in the 80s was a new technology, with many short comings - but good enough for the mass of listeners.
Ease of handling was the key for success, not the sound quality.

Despite my personal opinion that most classD implementations of the year 2013 are not deserving the name HiFi - also such average implementations are already good enough to win a growing amount of people.
Size and power density is sexy for the customers.
Already at medium power levels (level decreasing further) the material costs are significantly below class AB, which is sexy for the manufacturers.
Energy efficiency is another selling point.
Only R&D costs are still high, partially also because of EMI.
But that's just an initial barrier, which already has been taken by multiple companies. Efforts for derivates will decrease with experience.
It is a winning technology and also sound quality will improve further so that many companies will be able to satisfy also demanding High End customers.
I would also expect a slow shift from analogue modulators to digital solutions for modulator and feedback.
 

KatieandDad

Member
2011-11-17 3:49 pm
UK
From my experiments and what I read about Class D, there are still some serious shortcomings with the ability of Class D amps to drive complex loads. A good Class D amp with the correctly tailored load will sound superb but therein lies the problem. Class A and Class A/B are more forgiving and will drive less than perfect loads almost with impunity.
 
Class A and Class A/B are more forgiving and will drive less than perfect loads almost with impunity.

I cant say I have had any problems driving any sort of load.
The only time class d goes wrong is if the speaker is totally disconnected and the irs2092 goes to +17VDC.

I haver driven from 18 inch subs up to tweeters and it sounds great.

However I agree class AB are more forgiving than class d but from a design point of view. Most people can design a class AB amp and build it up with few problems. Class D layout is vitally important, you cant hang output transistors on 6 inches of wires and expect it to work. Decoupling and component layout is critical. Also getting the output filter right is vital to a good sound.

It took me 3 pcb revisions to get a class D amp working. But I learned a lot from the experience about class d and its cousin SMPS.
 
From my experiments and what I read about Class D, there are still some serious shortcomings with the ability of Class D amps to drive complex loads.

No so much an amplifier problem at all though. It's a speaker design and application problem. Complex loads almost only happens with passively filtered speakers. With class D there's little reason to passively filter speakers at all as active filters and more amp channels, each suited for the specific driver in question, or even digital filters if the signal is inherently digital which it most often is.

The only "problem" is that it inherently incurs a paradigm shift towards active speakers with amplifiers optimized for the exact speakers used, and very likely also built-in compensation algorithms which inherent sounds suspect to "audio old timers".
 
From my experiments and what I read about Class D, there are still some serious shortcomings with the ability of Class D amps to drive complex loads. A good Class D amp with the correctly tailored load will sound superb but therein lies the problem. Class A and Class A/B are more forgiving and will drive less than perfect loads almost with impunity.

Tell me your desired bunch of different complex RLC loads and we can go for measurements on my open design here in the forum .
You will see that load variations are handled with a smile.

The often mentioned strong dependency on the load is true in designs, which are 5-10 years behind state of the art.
...but of course still popular in the market - one of the reasons, why I say most of the implementations today are do not really serve High Fidelity.
 
In another posting, I read that Linkwitz is finally considering DSP crossovers as worthy. And this is from a very old school EE (?) At least I consider hand-building analog active x-overs hard core, and way above my pay grade.

On the other hand, there are odd balls like me that enjoy the best of (already built!) high tech -- in my case, a Behringer class D, and active eq, and the crossover free ancient Bose 901s (ca. 1970s).
 
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