Thanx. Well, little bit strange point is -1db power, why not -3db as usual? Actually, and Bender can confirm it, i always told -real pro=Bruno 
IMO NCD1 THD&Noise measurement vs promises looks quite predictedly yet, Classd4sure was right..
http://www.newclassd.com/index.php?page=10
IMO NCD1 THD&Noise measurement vs promises looks quite predictedly yet, Classd4sure was right..http://www.newclassd.com/index.php?page=10
Re: Re: Re: ELEKTOR September article
Exactly! In view of modules perfomance/price rate (UcD120euro vs NCD286euro), hypex put on the market excellent product. Imho other words original UcD is quality standard for D class amp in midpower range, or entire range for home use amps.
IVX said:.. Bender can confirm it, i always told -real pro=Bruno
Exactly! In view of modules perfomance/price rate (UcD120euro vs NCD286euro), hypex put on the market excellent product. Imho other words original UcD is quality standard for D class amp in midpower range, or entire range for home use amps.
IVX said:Thanx. Well, little bit strange point is -1db power, why not -3db as usual? Actually, and Bender can confirm it, i always told -real pro=Bruno
http://www.newclassd.com/index.php?page=10
Hello Ivan
We double checked the modules when they returned from the test in Elektor, because the level of THD would be rejected in our quality control. So it looked strange that a module with this high THD (0.03%) would have gotten through.
Our control check showed that the 0.03% was correct on one of the modules, at 10 kHz, while at the rest of the audio band the THD was 0.005%. After a further examination, it turned out that the trimmers on the module had been tampered with, even if they are locked with laquer, and it takes quite a bit of violence to loosen them. The other module showed 0.002% THD throughout the audio band, and the trimmers were locked.
As we examined the test in Elektor more carefully, they measured the output power to ~100W with a 40V supply, even though it is stated in our datasheet that the nominal voltage is 60 - 63V DC. This might give the less observant reader the impression that our module is only delivering ~100W while our competition put out ~200W. When in fact the only difference on that point is the power supply voltage being wrong by the test team.
We don't know if these 'faults' are deliberate or just sloppyness on behalf of the journalist, however we find it of less importance how our product is rated in Elektor, while it is much more interesting how our customers rate the sound and quality of our modules. So we have no reasons to worry.
Best regards
Lars Clausen
Lars,
I find it a bit strange that you post here that they tampered around with your modules before testing them. Did you ask ELEKTOR before what happened? It may seem easy to blame others when the test did not work out as expected.
How do you justify the relativly high price of your modules?
Klaus
I find it a bit strange that you post here that they tampered around with your modules before testing them. Did you ask ELEKTOR before what happened? It may seem easy to blame others when the test did not work out as expected.
How do you justify the relativly high price of your modules?
Klaus
Klaus: Thank You for posting these questions.
You are right, maybe it does look a bit strange. I wanted to point out some discrepancies in the test, as a comment to the conclusions made by IVX earlier in this thread.
One flaw of the test is very obvious if you look at the data presented in Elektor. Our amplifier is only putting out around 100 W in the Elektor test, which is only half of what we promise in our datasheet. Some people who read the test might notice this underperformance, and think we oversell our product.
However if you study the test specs in Elektor carefully you will see they have tested our module at 40V and not the recommended 60-63V from our datasheet, building instruction etc. That is the obvious reason the module is only putting out half the promised power. Why did they do that?
I hope for your understanding that i will not wish to make any futher comment on this issue, partly because i have said my points, and also because i don't think that Elektor as a media really target our customers. Personally when i used to buy Elektor, it was because i wanted to see schematics, and new components. Not so much finished audio modules. But admittedly thats some years in the past now.
Why our amplifier is highly priced compared to many other Class D modules? Well our module cost just almost the same in components, as we can estimate other modules cost. So it's not so much about the material cost.
However on top of that we put about one technician hour into each module for THD adjustment, to cancel dead-time distortion. This has to be done at working temperature, and a THD curve is drawn for every module from 20 to 20.000 Hz. The module does not pass until the THD at all frequencies is below 0.004%. They are typically 0.002% though. (1W 8 Ohms). About 1 of every 5 modules don't pass at all, because they have too high capacitances in the Gates of the MOSFET, and so they can not fully meet the test limit.
Why don't we launch a low cost 'light' version on the market without this heavy adjustment? Well we did exactly that 8 months ago to see if there was a market for low cost options at half the price of the NCD1. But after 2 months we had received all but no interest from the market for this low cost module. However in the same period, we sold hundreds of full price - full adjusted modules. So we took it as a sign, that people are actually interested to pay a little more to get the best module.
I think a good explanation to this is that the 'mid price' market is already crowded with dozens of other brands, and the other main reason is, that even though the NCD modules might cost double what other modules cost, when the whole amplifier is finished with enclosure, transformer, plugs etc. the price difference is only maybe 20%. And i think most people are more than willing to pay 20% more for the amplifier if the sound is notably better.
You are right, maybe it does look a bit strange. I wanted to point out some discrepancies in the test, as a comment to the conclusions made by IVX earlier in this thread.
One flaw of the test is very obvious if you look at the data presented in Elektor. Our amplifier is only putting out around 100 W in the Elektor test, which is only half of what we promise in our datasheet. Some people who read the test might notice this underperformance, and think we oversell our product.
However if you study the test specs in Elektor carefully you will see they have tested our module at 40V and not the recommended 60-63V from our datasheet, building instruction etc. That is the obvious reason the module is only putting out half the promised power. Why did they do that?
I hope for your understanding that i will not wish to make any futher comment on this issue, partly because i have said my points, and also because i don't think that Elektor as a media really target our customers. Personally when i used to buy Elektor, it was because i wanted to see schematics, and new components. Not so much finished audio modules. But admittedly thats some years in the past now.
Why our amplifier is highly priced compared to many other Class D modules? Well our module cost just almost the same in components, as we can estimate other modules cost. So it's not so much about the material cost.
However on top of that we put about one technician hour into each module for THD adjustment, to cancel dead-time distortion. This has to be done at working temperature, and a THD curve is drawn for every module from 20 to 20.000 Hz. The module does not pass until the THD at all frequencies is below 0.004%. They are typically 0.002% though. (1W 8 Ohms). About 1 of every 5 modules don't pass at all, because they have too high capacitances in the Gates of the MOSFET, and so they can not fully meet the test limit.
Why don't we launch a low cost 'light' version on the market without this heavy adjustment? Well we did exactly that 8 months ago to see if there was a market for low cost options at half the price of the NCD1. But after 2 months we had received all but no interest from the market for this low cost module. However in the same period, we sold hundreds of full price - full adjusted modules. So we took it as a sign, that people are actually interested to pay a little more to get the best module.
I think a good explanation to this is that the 'mid price' market is already crowded with dozens of other brands, and the other main reason is, that even though the NCD modules might cost double what other modules cost, when the whole amplifier is finished with enclosure, transformer, plugs etc. the price difference is only maybe 20%. And i think most people are more than willing to pay 20% more for the amplifier if the sound is notably better.
A well done blind test with some "leading" Class D modules built to amps by the manufacturers would be more interesting to me than traditional measurements of distortion with static signals as in THD and IM distortion analysis. Traditional measurements may tell if an amp is sufficient well engineered, but not necessarily if it´s musically satisfying. Of course low distortion figures are a good thing and I don´t believe in euphoric distortion making reproduced music sound more "real".
Designing a blind test can be tricky, but it can be done in a clever way, and maybe a test called F/E here in Sweden (translated; Before/After) can be the tool to get reliable results. In short it is made so that the test signal, usually music, passes or doesn´t pass the object under test. Levels are adjusted so it´s attenuated before passing an amplifying device like a power amp thus no level differences occur that could be detected. The result can be treated with statistical methods to see if the test persons can determine a clear influence of a distorted or "coloured" signal that has passed through an amp.
Designing a blind test can be tricky, but it can be done in a clever way, and maybe a test called F/E here in Sweden (translated; Before/After) can be the tool to get reliable results. In short it is made so that the test signal, usually music, passes or doesn´t pass the object under test. Levels are adjusted so it´s attenuated before passing an amplifying device like a power amp thus no level differences occur that could be detected. The result can be treated with statistical methods to see if the test persons can determine a clear influence of a distorted or "coloured" signal that has passed through an amp.
Some words on THD:
According to SpectraLAB software, my THD perception threshold is somewhere between 1% and 5% for a 1Khz tone progressively clipped to get odd harmonics (listening at approx 80dB SPL). Adding other frequency components (or music) only makes THD perception harder.
Anybody owning a computer with sound card, a pair of speakers or headphones and some THD analysis software or equipment can do the same test and see the shocking results for themselves.
Arrange the sound card in loopback mode (or monitor the speaker output with a THD analyzer). Close your eyes, then increase the playback level until you feel that you no longer hear a pure tone (clipping), then open your eyes again and check the THD meter
We are really wasting a lot of effort trying to improve amplifier non-linearities that just can't be heard. Tweeters and woofers are the #1 THD generators. Next time get a precision microphone and insert your favourite loudspeaers in the measurement loop. Play loud tones and start crying when 5% appears in the THD meter
According to SpectraLAB software, my THD perception threshold is somewhere between 1% and 5% for a 1Khz tone progressively clipped to get odd harmonics (listening at approx 80dB SPL). Adding other frequency components (or music) only makes THD perception harder.
Anybody owning a computer with sound card, a pair of speakers or headphones and some THD analysis software or equipment can do the same test and see the shocking results for themselves.
Arrange the sound card in loopback mode (or monitor the speaker output with a THD analyzer). Close your eyes, then increase the playback level until you feel that you no longer hear a pure tone (clipping), then open your eyes again and check the THD meter
We are really wasting a lot of effort trying to improve amplifier non-linearities that just can't be heard. Tweeters and woofers are the #1 THD generators. Next time get a precision microphone and insert your favourite loudspeaers in the measurement loop. Play loud tones and start crying when 5% appears in the THD meter
I totally agree with Pierre and Eva.
Once a reasonable good level of THD is reached (say, below 0.1%), the rest is pure make-up. Not saying that is worthless to try to improve this figure, as a better number means a careful and well adjusted design, but I am only saying that trying to reach ultra-low numbers is a waste of time when other points are much more interesting in Class-D designs that have to be investigated.
To be sincere, I am saying this when we try to make our COLDAMP amplifiers as low THD as possible. By the way, we have also seen higher figures in the ELEKTOR article than what we get at our labs (below 0.02% at 1W/8ohm). They simply didn't have too much time to setup the measurement properly and even to hear the amplifiers. Perhaps it was the same story with NCD?
However, we are not worried about that, as we know that our customers value the sound of our products above all, and some of them clearly prefer them to other modules with lower THD even for very high quality and precision demanding applications such as recording studio monitors, etc.
Once a reasonable good level of THD is reached (say, below 0.1%), the rest is pure make-up. Not saying that is worthless to try to improve this figure, as a better number means a careful and well adjusted design, but I am only saying that trying to reach ultra-low numbers is a waste of time when other points are much more interesting in Class-D designs that have to be investigated.
To be sincere, I am saying this when we try to make our COLDAMP amplifiers as low THD as possible. By the way, we have also seen higher figures in the ELEKTOR article than what we get at our labs (below 0.02% at 1W/8ohm). They simply didn't have too much time to setup the measurement properly and even to hear the amplifiers. Perhaps it was the same story with NCD?
However, we are not worried about that, as we know that our customers value the sound of our products above all, and some of them clearly prefer them to other modules with lower THD even for very high quality and precision demanding applications such as recording studio monitors, etc.
Keep in mind that the pure percentage figure doesn't say much. The high THD figures of loudspeaker drivers are usually less disturbing than things like crossover distortion of AB amplifiers for instance.
It is therefore not a bad idea to keep the nonlinear distortion of any electronic part of the audio chain as low as reasonably possible.
Rregards
Charles
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