Class D Design Issues

Ex-Moderator
Joined 2005
Re: Re: Tripath Chips

mhouston said:
I thought the Tripath was Class T?

Class "T" is marketing mumbo jumbo. There is no such class. Amplifiers that utilize Tripath chips are class d.

There are tons of ICs one can use to build a class d amp. Search the websites of well known manufacturers - TI, ADI, ST Micro, National Semi, etc. If you want to dig deeper, search this forum for a while. There are some older threads that get pretty technical regarding design.
 
mhouston said:
Can you build your own class D from scratch? Any schematics.

Tripath make class-D amps on chips. You can get development boards from them. Companies like 41Hz.com sell kits for Tripath-based amps.

Quite a few of the big semiconductor companies -- at least TI, Cirrus Logic, Analog Devices, and National -- have class D products. Some are amp-on-a chip, others are controllers that expect external transistors to do the heavy work. Freescale (Motorola's embedded CPU business spun off into a separate company) have a controller that does six channels.
 
you can make chip based amps from scratch easily. discrete amps are much more difficult. there were some made in the 70's. they were only mildly successful. the earliest ones had very low switching frequencies of about 40-50khz. board layout is one of the biggest challenges in discrete designs.
 
Re: Class D amps - chips/modules

mhouston said:
Is there a single Class D chip or module I can purchase, commercially, to make a complete amp from?

If so, from a musical point of view, what is the best chip or module?


You can try this website. www.amplifier.co.uk

Have heared that this amp was put up against some Krell monoblocks driving Wilson Watts and it blew the Krells away.
 
Disabled Account
Joined 2008
His so called analysis lacks any, and so his assertions amount to drivel. I'd be interested in seeing the sources he's parroting from.

Much of what he claims can be just as true or false for any class of amplifier, but every straw counts towards his pseudo objective subjectivism, where the later reads ignorance.

There is a sliver of truth to a lot of what he says as well, but he's removed it from any meaningful context where it may have applied, and compiled them all into a giant fallacious cesspool.

What fool takes such measures in condemning the whole of a topology based on the shortcommings of a few ill chosen examples and willfully ignores the few who've excelled proving it can be done right, again no less true than any other class.

If he applied that same brush to everything he'd still be sitting around a campfire debating to himself which log and stick combination sounds the most natural, and no question he'd find an audience to lap it up.

"Briefly summarising the test findings, the designers of 'switching amplifiers', ‘Class D’, seem to be perfectly happy to ignore several decades of conventional audio engineering wisdom.
These wisdoms have helped shapemany
great sounding linear analogue products."

Cue up the violin on your DAC, and don't quit your da..... ooh..hm. Actually, he did himself a disservice writing it like that because it takes away from the few good points he did have that may have otherwise been worth discussing more seriously.
 
Hi Berns

Thank you for your thoughts. I have been seriously thinking of putting together an amp based on the Hypex units. I am not wedded to any particular technology I just want excellent sound at a reasonable price.

This article was posted on another froum - the thread of which concerned Hypex units - and was cited as a possible reason to forget class d and stick with valves.

I can understand those who have found a particular technology be it valves, class d, class a etc. putting forward arguments as to why their chosen class of amp suits them and from listening to these arguments one can often form an idea of the strengths and weakness of one way of doing things over another. However to condemn a developing technology so totally seems a bit strong and one has to wonder about his motivation.

However, many do criticise class d for a lack of 'soul' and emotion. They seem beguiled by the quietness and the huge sound stage and such like but the attributes most important to me are timing, delicacy and musicality, things which I have heard class d criticised for.

Anthony
 
whitepeak said:
Hi Berns

Thank you for your thoughts. I have been seriously thinking of putting together an amp based on the Hypex units. I am not wedded to any particular technology I just want excellent sound at a reasonable price.

This article was posted on another froum - the thread of which concerned Hypex units - and was cited as a possible reason to forget class d and stick with valves.

I can understand those who have found a particular technology be it valves, class d, class a etc. putting forward arguments as to why their chosen class of amp suits them and from listening to these arguments one can often form an idea of the strengths and weakness of one way of doing things over another. However to condemn a developing technology so totally seems a bit strong and one has to wonder about his motivation.

However, many do criticise class d for a lack of 'soul' and emotion. They seem beguiled by the quietness and the huge sound stage and such like but the attributes most important to me are timing, delicacy and musicality, things which I have heard class d criticised for.

Anthony


Hello Anthony,

Since you are contemplating a Class D amplifier I can assure you that if done properly it will give you everything you need from an amp.

Should you be in Cheshire in the near future you are very welcome to come and listen to my Ecotec class D amplifiers. It will give you an insight as to whether this technology is for you.

John
 
Disabled Account
Joined 2008
Hi,

I found the market fodder where you got that link.

“All propaganda has to be popular and has to accommodate itself to the comprehension of the least intelligent of those whom it seeks to reach.” - Hitler

Pointing out failings that:

-Aren't near exclusive to the class
-Aren't all encompassing of the class
-Neglect the conditions when they may or may not apply
-Mislead by smoke and mirror substantiation of the entirety with a single lazy spooky graph that's void of test conditions but likely was hard clipping

Is just popular propaganda that speaks only to the least informed.

Questionable motivation? A reviewer that's also a "chartered engineer"and "technical advisor" as stated on his website, has a rare synergistically prosperous mix of professions. Where's the question, he's printing his own money.

I've commented somewhat on the Ecotec already:

http://www.diyaudio.com/forums/showthread.php?postid=1689584#post1689584

It's firmly amongst the examples of it done so wholly wrong that it embodies vast portions of that cesspool of an article if not the entirety and more. Sadly, it's by no means alone in camp, just another specimen of marketing in place of engineering to cover the lack of fundamental understanding. Sugar coat the resulting symtpoms of a lack of real engineering design by calling them subjective preferences, instant popular propaganda pudding pop. Best served cold with a heaping pile of professional review and a side of shill.

Examples like that are carriers for the potential to set the reputation of an emerging technology back 30 years undeservingly. However the best of the technology from thirty years ago was already more advanced than the worst of today. Just look at any of the recent $20k 135lb class d offerings that have repatended it.

You were on a good path already.
 
classdphile said:
Hi,

I found the market fodder where you got that link.

“All propaganda has to be popular and has to accommodate itself to the comprehension of the least intelligent of those whom it seeks to reach.” - Hitler

Pointing out failings that:

-Aren't near exclusive to the class
-Aren't all encompassing of the class
-Neglect the conditions when they may or may not apply
-Mislead by smoke and mirror substantiation of the entirety with a single lazy spooky graph that's void of test conditions but likely was hard clipping

Is just popular propaganda that speaks only to the least informed.

Questionable motivation? A reviewer that's also a "chartered engineer"and "technical advisor" as stated on his website, has a rare synergistically prosperous mix of professions. Where's the question, he's printing his own money.

I've commented somewhat on the Ecotec already:

http://www.diyaudio.com/forums/showthread.php?postid=1689584#post1689584

It's firmly amongst the examples of it done so wholly wrong that it embodies vast portions of that cesspool of an article if not the entirety and more. Sadly, it's by no means alone in camp, just another specimen of marketing in place of engineering to cover the lack of fundamental understanding. Sugar coat the resulting symtpoms of a lack of real engineering design by calling them subjective preferences, instant popular propaganda pudding pop. Best served cold with a heaping pile of professional review and a side of shill.

Examples like that are carriers for the potential to set the reputation of an emerging technology back 30 years undeservingly. However the best of the technology from thirty years ago was already more advanced than the worst of today. Just look at any of the recent $20k 135lb class d offerings that have repatended it.

You were on a good path already.

So Berns, You are exceptionally good at telling everyone what is rubbish (according to the Berns Theory of Guesswork) so why not enlighten us as to what is to be admired for design and performance.

Some of the best class A/B amplifiers did not meet with the eletist theorists measurements. I cannot argue specifications or theory, I am not qualified to do so, but at least I have listened to these amps and judge them against other well regarded kit, which is more than I can say for you. I know you will come back with the same old argument but at least I "know" you only "think you know"

John
 
jaydeecee said:



Hello Anthony,

Since you are contemplating a Class D amplifier I can assure you that if done properly it will give you everything you need from an amp.

Should you be in Cheshire in the near future you are very welcome to come and listen to my Ecotec class D amplifiers. It will give you an insight as to whether this technology is for you.

John

Hi John

Thank you for your kind invitation. If you were more local I would be around like a shot but if I can persuade my wife that she would enjoy a day out in Chester when the weather improves then I may take you up on that.

It is interesting that you also use valve amps - something I have also contemplated. Would you say your Ecotec amps are 'valve like'?
Some advertisers of course promote their class d products by declaring their valve like qualities. Which is probably why I became interested in the first place - valves without the hassle.

Anthony
 
whitepeak said:


Hi John

Thank you for your kind invitation. If you were more local I would be around like a shot but if I can persuade my wife that she would enjoy a day out in Chester when the weather improves then I may take you up on that.

It is interesting that you also use valve amps - something I have also contemplated. Would you say your Ecotec amps are 'valve like'?
Some advertisers of course promote their class d products by declaring their valve like qualities. Which is probably why I became interested in the first place - valves without the hassle.

Anthony

Hi Anthony,

You would be most welcome.

Yes, I have always used a valve pre-amp even when I had solid state power amps. The Ecotecs are niether valve like nor transister, they kind of sit somewhere in between but I would say leaning more towards valve than solid state. They are totally non fatigueing and in many ways I prefer them to my valve SET amps as they do the mid range so well (and that is where the valves excel) and also they are superb with the low frequencies where valves will start to struggle.

I am now actually using the Ecotecs with a passive pre-amp as my valve pre has quite a lot of gain so I dug out my home made pre from the loft and I have to say I am thoroughly enjoyng it.

Just give me the heads-up if you want to come over any time.

John
 
classdphile said:
Hi,

I found the market fodder where you got that link.

“All propaganda has to be popular and has to accommodate itself to the comprehension of the least intelligent of those whom it seeks to reach.” - Hitler

Pointing out failings that:

-Aren't near exclusive to the class
-Aren't all encompassing of the class
-Neglect the conditions when they may or may not apply
-Mislead by smoke and mirror substantiation of the entirety with a single lazy spooky graph that's void of test conditions but likely was hard clipping

Is just popular propaganda that speaks only to the least informed.

Questionable motivation? A reviewer that's also a "chartered engineer"and "technical advisor" as stated on his website, has a rare synergistically prosperous mix of professions. Where's the question, he's printing his own money.

I've commented somewhat on the Ecotec already:

http://www.diyaudio.com/forums/showthread.php?postid=1689584#post1689584

It's firmly amongst the examples of it done so wholly wrong that it embodies vast portions of that cesspool of an article if not the entirety and more. Sadly, it's by no means alone in camp, just another specimen of marketing in place of engineering to cover the lack of fundamental understanding. Sugar coat the resulting symtpoms of a lack of real engineering design by calling them subjective preferences, instant popular propaganda pudding pop. Best served cold with a heaping pile of professional review and a side of shill.

Examples like that are carriers for the potential to set the reputation of an emerging technology back 30 years undeservingly. However the best of the technology from thirty years ago was already more advanced than the worst of today. Just look at any of the recent $20k 135lb class d offerings that have repatended it.

You were on a good path already.


Hi Berns

You certainly have a way with words!

Actually I found that link on another web forum which is mainly devoted to valves. So I haven't seen the marketing fodder you speak of.

I do take your points though.

The best amplifier is a wire with gain.
This is the theoretical ideal but not achieved in practice so isn't it just a matter of how close one amplifier gets compared to another and whether one prefers one type of distortion over another?
Many valve amps measure very badly - especially SET amps I believe - but they still have a devoted following.
Personally, I prefer rosy tinted and euphonic to hard, shrill and fatiguing although I'm sure some amps manage all these.

Anyway your comments are much appreciated and I am viewing class d favourably once again.

Anthony
 
Disabled Account
Joined 2008
Hi,

A tube forum is perhaps not the best source for class d information. I kept seeing calls for "what's the wd take on class d", hence the fodder. I did however notice some had tried it, of them were those that liked Hypex and others that didn't like Tripath, see the measurements and you'll know why.

There's no shortage of examples of loyal followings, but there are of instances where they've ever proven beneficial. If the question is how close one gets to the ideal wire with gain, it can't also be a matter of the type of distortion one prefers, it's something of an oxymoron.

Striving for the most euphony possible places a short ceiling on the achievable experience. It's possible to have something that's not deplorably euphonic or analytically cold and harsh, but true enough to the recording to allow the music within it through enjoyably. It's just hardest to achieve as it requires the least flaws.

Euphony in itself isn't the base of the argument though, and it shouldn't be. It's that euphony and noise of every worst sort is inherent to a bad class d amplifier. It's not bad because it's euphonic, but the other way around.

John can talk though, his immovable faith in his product only seems weakened by his continual recruitment efforts. He admits to know nothing of them technically, he's not had it much more than a month, he's never heard another, but he "knows", somehow his intentially flawed-as-possible design can speak for the capabilities of a technology.