The matter is now moot, but...isn't that Class H? Also, looking at distortion spectra, I wouldn't expect any class H design to match the best class Ds, but I'm not a guru. I'm thinking about QSC's and Crown's PA amps as well as the usual suspects. Just curious, thanks.anatech said:
Correct on both counts.
DcibeL, very assertive of you. Would have been nice had "The Saint" made the comment here himself, but it probably got ugly the last time he posted it. He's had an eye on the thread though.
Like I said, all anyone had to do was look, it's all there. Little bit of reasoning works too. This whole "but the price.... wow, he can have my money", good luck with that.
Member
Joined 2003
I must apologize for quoting Anthony's email above, he did not mean for me to copy and paste his email to me. I have reported my own post requesting that the quoted email be removed.
The information that I would like to relay to the DIY Community from Anthony Holton is:
Anthony Holton designed the amps that Class-D Design sells. However, the Class-D company makes false claims about efficiency and power of these amps.
The NX200 is claiming 400 Watts from a single pair of dual die lateral MOSFETS, however they simply cannot produce that kind of power. Similar claims are made of other modules sold by Class-D Design.
The amps sold at Aussie Amplifiers are completely different and any reviews and testimonials on the Aussie Amps website cannot be used to support the claims of Class-D Designs products.
The information that I would like to relay to the DIY Community from Anthony Holton is:
Anthony Holton designed the amps that Class-D Design sells. However, the Class-D company makes false claims about efficiency and power of these amps.
The NX200 is claiming 400 Watts from a single pair of dual die lateral MOSFETS, however they simply cannot produce that kind of power. Similar claims are made of other modules sold by Class-D Design.
The amps sold at Aussie Amplifiers are completely different and any reviews and testimonials on the Aussie Amps website cannot be used to support the claims of Class-D Designs products.
very nice find cirrus!
I can't believe how small these amps are
what ps are you using? do you use +/-70v ?
I can't believe how small these amps are
what ps are you using? do you use +/-70v ?
Hi Sam Lord,
An oversimplification would be a class D amplifier for each supply rail to a normal class AB amplifier. The normal amplifier blocks the evils from the modulated power supply rails, the tracking power supplies maintain a more even C-E voltage across the transistors. The Lightstar idled with approx 13 VDC supply rails that could easily run up to the full 125 VDC levels. Using PWM and filters greatly reduces to feed through as the supplies change value.
-Chris
I really try to ignore most of the higher class names. Many are simply splitting hairs.
There are so many ways to build something that exceptions to the rule are more than possible. Depends on how good a job was done designing and construction of the amp.
Think more along the lines of Carver amplifier designs. The Lightstar was a natural progression of the design ideas that Carver Corp. were following. They went from switchable supply tiers to PWM power supply rails. The results were much increased efficiency and much lower heat production.
An oversimplification would be a class D amplifier for each supply rail to a normal class AB amplifier. The normal amplifier blocks the evils from the modulated power supply rails, the tracking power supplies maintain a more even C-E voltage across the transistors. The Lightstar idled with approx 13 VDC supply rails that could easily run up to the full 125 VDC levels. Using PWM and filters greatly reduces to feed through as the supplies change value.
-Chris
Hi cirrus18,
I have no bias, but I plan to fix that!
Honestly, I have zero bias towards one or another class D amplifier. I don't care for any of them yet. We do like to check reports like yours for the simple reason that a sales tactic like this has been done before, and we are seeing an increase of this type of report.
Please don't take offense, we just need to find out some background. You have provided that. Thank you.
When quoting from another source in a situation like yours, you should provide a link or location so that interested members can read the entire report or article. If you don't, expect that you will be asked to provide that information. Then we do have members who are careful and suspicious. People have been burned before with the earlier class D type amplifiers. Remember that it's an emerging technology. Things are getting better all the time.
-Chris
I have no bias, but I plan to fix that!
Honestly, I have zero bias towards one or another class D amplifier. I don't care for any of them yet. We do like to check reports like yours for the simple reason that a sales tactic like this has been done before, and we are seeing an increase of this type of report.
Please don't take offense, we just need to find out some background. You have provided that. Thank you.
When quoting from another source in a situation like yours, you should provide a link or location so that interested members can read the entire report or article. If you don't, expect that you will be asked to provide that information. Then we do have members who are careful and suspicious. People have been burned before with the earlier class D type amplifiers. Remember that it's an emerging technology. Things are getting better all the time.
Because I didn't see that post for one. For two, I didn't accuse you of anything. I just wanted to know if any relationship existed. The answer from you was simple, and accepted. Besides, I already gave you the framework for my query when I asked.
I completely agree with you on that. If others before you had not used the "comparison report" as a sales tool, your reception would have been different. You have been a victim of the actions from other manufacturers before you even joined. A new member extolling the virtues of an unknown amplifier does appear suspicious due to the history of "advertposting". I just made that word up. You get the idea though.
-Chris
Agreed on your first point, there are many class names whose primary distinction is commercial. I do think the differences are pretty dramatic spanning from A to D, just given the amount of mass and dissipation needed for a good result and reasonable power output.anatech said:
Thank you for the clear analogy. I have the concept that Class D can be done with fewer major feedback circuits. I would think that the Carver still had the usual AB crossover distortion to correct, *but* I haven't looked at the circuit, I will. It is fine idea to *efficiently* regulate the rails.anatech said:
Thanks again Chris for the history and a great forum!
Thanks Chris, your comments are duly noted. Here is a link to the thread I quoted from- http://www.avforums.com/forums/8294433-post21.html
I phoned up Class D. today to see if I could get some more information from them and spoke to a gentleman there.
He said they started off making Class D amps, hence their name, and still do, he admitted it was a bit confusing and that they might start trading under one of their other companies names.
They stopped making their class D. amplifiers because they found that they got better results using their own designed and manufactured Lateral Mosfets.
He also informed me that they were in the process of updating their website, as they realised there wasn't adequate information on it.
They're going to update it with a much fuller information together with details of two SMPS power supplies they are bringing out. They have a few of them already if anybody is interested. The smaller one I think he said was 400 Watts at £60.
So Chris, why don't you you try out a couple of these amplifiers and give us a report. A report coming from you would carry a lot of weight Two amplifiers would cost less than $100 and I'm sure you could put them on eBay and get most of your money back if you didn't like them.
I phoned up Class D. today to see if I could get some more information from them and spoke to a gentleman there.
He said they started off making Class D amps, hence their name, and still do, he admitted it was a bit confusing and that they might start trading under one of their other companies names.
They stopped making their class D. amplifiers because they found that they got better results using their own designed and manufactured Lateral Mosfets.
He also informed me that they were in the process of updating their website, as they realised there wasn't adequate information on it.
They're going to update it with a much fuller information together with details of two SMPS power supplies they are bringing out. They have a few of them already if anybody is interested. The smaller one I think he said was 400 Watts at £60.
anatech said:
So Chris, why don't you you try out a couple of these amplifiers and give us a report. A report coming from you would carry a lot of weight Two amplifiers would cost less than $100 and I'm sure you could put them on eBay and get most of your money back if you didn't like them.
Of course they recognize it's confusing, that was the intention of it. It's usually a problem when a company operates under multiple names too.
Now they expect to change names and all the lies will be forgotten? Will the new company be responsible for delivering as promissed to the contest winners?
Will the new company's amps still be as efficient as class d, at 30%?
Nobody's opinion carries enough weight to strip truth from reality. After all this you still feel comfortable telling us of their new upcomming products and business plans???
Now they expect to change names and all the lies will be forgotten? Will the new company be responsible for delivering as promissed to the contest winners?
Will the new company's amps still be as efficient as class d, at 30%?
Nobody's opinion carries enough weight to strip truth from reality. After all this you still feel comfortable telling us of their new upcomming products and business plans???
Hi Sam Lord,
From what I've read, applying feedback to a class D design might be more complicated than a class AB amp. However, I believe that each system can be just as complicated as the other. It's just that your considerations might be different.
-Chris
Well, that's actually not true at all. You need to provide feedback for each system. Always remember that feedback is not bad. It's just that there are many non-linear amplifiers that "fixed" their problems by applying feedback. You need to have a low distortion design before you apply feedback if you are planning on really good performance.
From what I've read, applying feedback to a class D design might be more complicated than a class AB amp. However, I believe that each system can be just as complicated as the other. It's just that your considerations might be different.
-Chris
Hi cirrus18,
More information is always good. It allows people to make more informed decisions. External verification of any ratings is a tool that most audio companies use to keep their claims believable.
Hi classdphile,
I didn't apply for samples for the simple reason that I am not well versed in class D amplifiers. I have no comparisons to draw from, only really good A and AB amplifiers. I currently believe that class D type amplifiers are still in the embryonic stage. Much improvement will probably still come. Probably unfair to compare these directly to more mature technologies. But hey, I could be easily mistaken on this too!
-Chris
Mostly because, like most of us here, my funds are extremely limited. I do have the facilities to examine amplifiers closely, but time is more the issue as well.
I would simply report exactly what I found. Not unlike the other members here with the required equipment. I think anyone who tested and published what they found would carry the same weight as anything I could say. That's the beauty of electronics. It's a science that uses repeatable experiments and test methods.
Nope, no way. The most I'll get involved would be samples to test and return once done. That way I have zero invested and no reason to colour the findings. Can you imagine trying to sell a product I found that didn't measure up?? If they were that good, I might then purchase them. Either way, a performance report must be conducted in a way where the tester has no financial interest in the outcome.
More information is always good. It allows people to make more informed decisions. External verification of any ratings is a tool that most audio companies use to keep their claims believable.
Hi classdphile,
I think we should withhold opinions until more is known for sure. For instance, the samples have had no reporting as yet. Waiting for at least that info would be wise.
I didn't apply for samples for the simple reason that I am not well versed in class D amplifiers. I have no comparisons to draw from, only really good A and AB amplifiers. I currently believe that class D type amplifiers are still in the embryonic stage. Much improvement will probably still come. Probably unfair to compare these directly to more mature technologies. But hey, I could be easily mistaken on this too!
-Chris
Hi Chris,
There's plenty of information regarding this company to form an opinion. They've proven themselves through their completely deceptive marketing and flat out lies.
I don't feel the need to wait on subjective opinions from hand picked winners that won't change their continued deception. I'd also put forth, it's extremely poor taste to hold such a contest, one intended as nothing more than a public relations damage control campaign, and not promptly deliver the prize. That speaks louder than any user opinion ever could.
It's been two months since the end of the contest. This is not a group buy waiting on a small hobbyist's best efforts, but a manufacturer-supplier that's not delivering on promisses. I don't afford them the same courtesy in the name of free goods.
Philisophies and religions aside:
Thank you for demonstrating the danger of their lies. These are not class d amplifiers.
There's plenty of information regarding this company to form an opinion. They've proven themselves through their completely deceptive marketing and flat out lies.
I don't feel the need to wait on subjective opinions from hand picked winners that won't change their continued deception. I'd also put forth, it's extremely poor taste to hold such a contest, one intended as nothing more than a public relations damage control campaign, and not promptly deliver the prize. That speaks louder than any user opinion ever could.
It's been two months since the end of the contest. This is not a group buy waiting on a small hobbyist's best efforts, but a manufacturer-supplier that's not delivering on promisses. I don't afford them the same courtesy in the name of free goods.
Philisophies and religions aside:
Thank you for demonstrating the danger of their lies. These are not class d amplifiers.
Basic Carver 'downconvertor' design.
http://home.comcast.net/~jhidley/SubTwoi_Amplifier.pdf
Full-range amplifier uses all-pass delay on input to class AB amplifier, sub amp doesn't have it.
http://home.comcast.net/~jhidley/SubTwoi_Amplifier.pdf
Full-range amplifier uses all-pass delay on input to class AB amplifier, sub amp doesn't have it.
Hi djk,
Yes, that is a very basic version. It is very good to examine and show the principle.
While this linked amplifier does show the principle behind the Lightstar and Sunfire amplifiers, this one is very stripped down. Therefore, do not try and judge the Lightstar and Sunfire amplifiers from this example.
This amp as shown has the ability to sound okay I think, but the main virtue would be it's very low heat output. It should also be very reliable unless the down converters are not as robust as the output stage under these operating conditions.
Any idea on these as far as reliability and sound quality goes? I am very curious as I really enjoyed the series one Lightstar I had for a while. Not the very best amp, but one of the best Carver produced as far as I'm concerned. Capable of delivering awesome power as long as the AC service is up to the task.
-Chris
Yes, that is a very basic version. It is very good to examine and show the principle.
While this linked amplifier does show the principle behind the Lightstar and Sunfire amplifiers, this one is very stripped down. Therefore, do not try and judge the Lightstar and Sunfire amplifiers from this example.
This amp as shown has the ability to sound okay I think, but the main virtue would be it's very low heat output. It should also be very reliable unless the down converters are not as robust as the output stage under these operating conditions.
Any idea on these as far as reliability and sound quality goes? I am very curious as I really enjoyed the series one Lightstar I had for a while. Not the very best amp, but one of the best Carver produced as far as I'm concerned. Capable of delivering awesome power as long as the AC service is up to the task.
-Chris
Hi Berns,
In the end, the wording of the offer did confuse the issue and probably cost them a lot of interest. That's what I mean by reporting on facts as I understand them. Yes, it did provide proof for your comments.
-Chris
My opinion is simply that I do not have any first hand information about these people, therefore I would reserve comment until I do. So for now, let us just state facts please. That really ought to be enough said given what you have said about them. In no way am I defending anyone. The people involved ought to have an opportunity to respond to questions rather than duck a volley of rocks. That would not buy anyone additional information.
From what I had read and remember, this is the information I was given, and the reason I didn't wish to participate. Had I known they were not a class D amplifier, I might have registered to be able to test a pair.
In the end, the wording of the offer did confuse the issue and probably cost them a lot of interest. That's what I mean by reporting on facts as I understand them. Yes, it did provide proof for your comments.
-Chris
photos
Dear Oldgeezer
May we see photos of your amplifier with NX200, expecially of power supply?
Thank you
ecodoppler
Dear Oldgeezer
May we see photos of your amplifier with NX200, expecially of power supply?
Thank you
ecodoppler
Hi Chris,
It would be nice if you'd afford class d that same courtesy. Your comments regarding it in this thread have consistently demonstrated non factual bias with no experience. If you fall prey as you have to their deception what makes you think a greater number of people than you who don't share your same bias, but rather have an interest in cutting edge technology that's getting a lot of press also wouldn't be easily fooled? Which one would you say represents the bigger market?
The mention of class h to excuse away a wild lie, and that calling it by its proper class h name if so amounts to splitting hairs, not so factual either. After all in this case it's the split hair that divides fact from fiction. The facts were readily available to anyone who took the effort to look them up, so there's no reason to fuel the deception even inadvertently. I'm not saying and don't believe that was your intention, but perhaps it was the effect.
Given the intent of the thread I hope it wasn't ever your intention to use it as a proving ground for personal non factual bias.
Believe me I would much rather stick to the facts, even if I should be the only one at a gun fight with a knife.
I'll end my last post by stating that nothing is preventing them from taking two minutes to post an update for their contest winners, even though after two months they're owed a lot more than an update. The people involved ought to be less deceptive and not make offers they're unwilling to fulfill. I hope you and the forum masters will not support their doing business here until they've come good on their offer for the users, and maybe after two months it is time it got looked into. Nobody appreciates being strung along indefinitely, not even for free.
It would be nice if you'd afford class d that same courtesy. Your comments regarding it in this thread have consistently demonstrated non factual bias with no experience. If you fall prey as you have to their deception what makes you think a greater number of people than you who don't share your same bias, but rather have an interest in cutting edge technology that's getting a lot of press also wouldn't be easily fooled? Which one would you say represents the bigger market?
The mention of class h to excuse away a wild lie, and that calling it by its proper class h name if so amounts to splitting hairs, not so factual either. After all in this case it's the split hair that divides fact from fiction. The facts were readily available to anyone who took the effort to look them up, so there's no reason to fuel the deception even inadvertently. I'm not saying and don't believe that was your intention, but perhaps it was the effect.
Given the intent of the thread I hope it wasn't ever your intention to use it as a proving ground for personal non factual bias.
Believe me I would much rather stick to the facts, even if I should be the only one at a gun fight with a knife.
I'll end my last post by stating that nothing is preventing them from taking two minutes to post an update for their contest winners, even though after two months they're owed a lot more than an update. The people involved ought to be less deceptive and not make offers they're unwilling to fulfill. I hope you and the forum masters will not support their doing business here until they've come good on their offer for the users, and maybe after two months it is time it got looked into. Nobody appreciates being strung along indefinitely, not even for free.
Being interested in the low cost factor, I tried to do some looking around. There is a lot history to these modules right here in diyaudio going back to around 2006.
Hi Berns,
So, if a class D amplifier has been the best that you have listened to, then that's okay. However, not once have I labeled a class D amplifier as junk. All I have stated is that the technology is young and that I do expect further improvements. Am I mistaken here?
Cutting edge technology does not mean "good" or "better" than existing technology. All it means is that the technology is both different and evolving (in other words, not mature).
What I will say is that there are a few main classes of audio output stages. Then there is a a class of how power is supplied to the output stages. Each may have drawbacks that can manifest themselves in the output signal, but the main idea of each is similar. Yes, you can then simplify everything, but since the focus is in the amplification of a signal, really only the idea that power can be controlled and varied to the output stage is important. In class D, the analog output stage is eliminated and the power delivery section connects directly to the load (speaker) through some method of pulses of power. So, tell me where that statement is in error. Yes, I know it is simplified, but I do not want to get dragged into a discussion of each method. It is the idea that is important.
It would appear to me that your problem is the fact that we might disagree on some points. You can not make it out to be more involved than that, 'cause it isn't. If you have some specific points that you disagree with, why not detail them instead of accusing me of everything you can think of?
-Chris
I have only stated what I know about this technology. I am not biased against it at all. Any commercial examples I have heard fall short in sound quality from what I am accustomed to. I own several examples of tube and solid state equipment, and have been able to examine many more that I do not own.
So, if a class D amplifier has been the best that you have listened to, then that's okay. However, not once have I labeled a class D amplifier as junk. All I have stated is that the technology is young and that I do expect further improvements. Am I mistaken here?
Hardly. I've just been accustomed to better sound quality. I do have a good technical understanding how a class D amplifier operates. Just because I'm not that interested further only means that the technology does not interest me. Nothing more.
Is having an interest in "cutting edge technology" mean that we exclude all other developments in audio? Or, does it mean that it's okay to use customers as beta testers without full disclosure?
Cutting edge technology does not mean "good" or "better" than existing technology. All it means is that the technology is both different and evolving (in other words, not mature).
Who cares here? This place is all about discussing audio technology, not sales. You are talking about popularity, and that has more to do with advertising than reality. This is why the world is full of plastic throw away stuff.
No one is excusing anything. I fail to see where you are going with that comment. It is inflammatory though.
What I will say is that there are a few main classes of audio output stages. Then there is a a class of how power is supplied to the output stages. Each may have drawbacks that can manifest themselves in the output signal, but the main idea of each is similar. Yes, you can then simplify everything, but since the focus is in the amplification of a signal, really only the idea that power can be controlled and varied to the output stage is important. In class D, the analog output stage is eliminated and the power delivery section connects directly to the load (speaker) through some method of pulses of power. So, tell me where that statement is in error. Yes, I know it is simplified, but I do not want to get dragged into a discussion of each method. It is the idea that is important.
Never is. I will state facts that are known to me though. To the best of my knowledge, I only really commented after I saw one company being attacked - by you. Even then, I only stated that I didn't know about their product or intentions. If you have a bone to pick with these people, why not contact them directly?
Depends entirely upon the range of your attacker and whether the field is clear or not. 🙂
Okay, just for interests sake, are you one of those people how have apparently not received the demo product? Otherwise, you could be seen as poking your nose into other people's business.
I don't have first hand, personal knowledge of any of this. Guess why?
And this would be the reason why. None of us on the moderating team or site management are involved in any of these offers. We are not involved in group buys, personal trades or other offers. We do try to prevent obvious attempts at fraud from occurring. That is about it.
It would appear to me that your problem is the fact that we might disagree on some points. You can not make it out to be more involved than that, 'cause it isn't. If you have some specific points that you disagree with, why not detail them instead of accusing me of everything you can think of?
-Chris
cirrus18 said:
Unless you like to watch TV or listen to radio at insanely loud levels you are probably using less than 1W of output power... At this low output power even a class AB amp will not produce that much heat (but will have terrible efficency).
anatech said:
It's pretty obvious there's nothing fancy like rail switching or tracking going on in this amp module by looking at the PCB:
http://www.classd.ltd.uk/images/D/CDNX200.jpg
If it was of some kind of high efficency type linear amplifier it would either need downconverters (no coils on board so it isn't) or multiple power supply voltage connections for low and high rails. It doesn't have that either.
Might still be a nice class AB amp though, but I seriously doubt it will be able to push out 200W into 4 ohms continously. Maybe possible on peaks on a good day with a cold heatsink...
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