HoweSound
Active Member
No discernible pops from my DIY Nilai stereo. My speakers are reasonably sensitive, say 90 dB. I have usually been turning on the Nilai last, but , not in a premeditated way. - now I'll do it consciously.
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Hypex Nilai500DIY Amplifier Review
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Robert-Hifi
Active Member
That seems to be the best practice. Turning on the Nilai last and turning it off first in the chain.
I think that minimizes the issue in the best possible way.
I have been getting this same very minor pop (very faint) when the Nilai amps are turned on and off, my speakers are 4ohm 87db.. I know you can adjust the CM and DM pots but haven't got around to doing it. I will contact Hypex again. My DC Offset was a little on the high side when I first turn on my amps after completion of my Nilai bild. Measured 74mVdc on one and 41mVdc on the other. Hypex told it shouldn't have been like that since the modules are automated adjusted. But they told me which ones for what issues to adjust. I got mine DC Offset down to near 0mVdc.
I have been really enjoying these little amps and they sound really nice but take a long time to break-in before sounding their best.
I have been really enjoying these little amps and they sound really nice but take a long time to break-in before sounding their best.
Verified how?
There's no such thing as 'break-in' of such a class D amp. The only thing time will do to those electronics is degrade them but if they aren't faulty to begin with, the time scale is years if not decades.
You probably just got used to it
One year and a few months of Nilai 500. Hours a day on good days. Never ever gets warm to the touch, even after playing Deep Purple recordings at > 100 dB peak, added one Arendal large sub to the two old REL. Mains Paradigm Studio 100 v.3. Source Weiss MAN-301 to DAC8 Stereo. No problems from the amp ever. No reason to upgrade.
OldManMatt
Active Member
When I'm rocking out for hours my Nilai is barely warm to the touch.
If I forget to shut it down and it sits idle overnight it's pretty warm/hot in the morning. Big difference in temperature.
If I forget to shut it down and it sits idle overnight it's pretty warm/hot in the morning. Big difference in temperature.
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OldManMatt
Active Member
Yep yep
D
Deleted member 58670
Guest
I've stacked two Nilai stereo amps on top of each other. They never get more than 10 degrees Celsius above room temperature.
Apologies for what may be a silly question - where the THD+N plot shows increasing distortion with frequency, this is purely the harmonics we're talking about, yes? So for example in the blue 10 kHz plot, the distortion products being shown are at 20 kHz, 30 kHz, 40 kHz etc.and therefore inaudible?
Exactly. And this is intentional by design: the feedback loop is strongest in the audible range and let loose where it is inaudible. We see that 5kHz and higher it starts to allow harmonics in, which are pretty much inaudible (loudness contour levels, etc).
FAQ #7.
Class D FAQ
This topic is dedicated to Frequently Asked Questions about class D amplifiers. If you have been directed here the reason is that it is easier to concentrate the frequent answers here instead of repeating them in several topics. Q1: Class D power ratings cannot be true. How can these small and...
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antcollinet
Grand Contributor
Yes.
Many thanks for the replies @Matias & @antcollinet.
It is in fact academic interest in the topology of Class D. Anything above 5 kHz is likely to be inaudible for the small amount of music signal above that threshold in the harmonic range of 2nd and 3rd. However, those who consider themselves purists might raise one or both eyebrows to it.
Hmm you might call this a purist perspective... but a 10Khz tone (5khz 2nd Harmonic) when reproduced by an imperfect device (a speaker) - can in turn generate 5khz frequency distortion (subharmonics)...
Although these tend to be lesser in magnitude as standard harmonics, I wonder how much impact these might have on the sound?
Subharmonics isn't discussed much, and in the case of an amp, like this, would be generated mechanically in the speaker driver most likely... and would therefore be highly speaker dependent.
The harmonics measure are very low - so presumably the subharmonics at the speaker would be even lower - but still.... (which might then make it a "purist" concern... and possibly below thresholds of audibility)
Although these tend to be lesser in magnitude as standard harmonics, I wonder how much impact these might have on the sound?
Subharmonics isn't discussed much, and in the case of an amp, like this, would be generated mechanically in the speaker driver most likely... and would therefore be highly speaker dependent.
The harmonics measure are very low - so presumably the subharmonics at the speaker would be even lower - but still.... (which might then make it a "purist" concern... and possibly below thresholds of audibility)
I hear you. If you look at the graph, the peak of the 15 kHz THD+N is at -78dB, which is 0.0125%. Speaker transducer distortion is orders of magnitude above this, so any harmonics/subharmonics would be masked by the drivers' own distortions.
Additionaly, odd order harmonic distortion audibility threshold is generally accepted to be ~0.1%, with even order distortion ~1%, so the levels are well below hearing thresholds.
My typical listening levels are ~75 - 80 dB(A), so the worst distortion products will be at give or take +/- 2 to 3 dB(A). The ambient noise level in my listening room is ~ 30 dB(A).
As a 54 year old my Hearing perception just about reaches 16 kHz.
These distortion levels just aren't going to be audible.
I wouldn't be concerned much with subharmonics, but maybe somewhat with intermodulation distortion. That nonlinearity will make two tones, e.g. 15 + 16 kHz intermodulate and generate a 1 kHz tone that might be audible.
On the other hand, most conventional class AB amps also have less loop gain and more distortion at 15 kHz than they have at 1 kHz
On the other hand, most conventional class AB amps also have less loop gain and more distortion at 15 kHz than they have at 1 kHz
Having measured the Nilais, I'm even less worried. Not a subharmonic in sight.
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