AFAIK Class D measurements are not easily compared to linear amplifiers because class D performance almost always is measured with a higher order 20kHz LP filter (at least 7th order) to get rid of residual carrier noise.
When I measure THD+N on the AP on a linear amplifier I use 80kHz bandwidth, for FFTs I normally go for a minimum of 44kHz bandwidth.
So unless the stuff you want to compare is measured the same way – measurements are mostly used to convince B2B customers to buy something.
\\\Jens
When I measure THD+N on the AP on a linear amplifier I use 80kHz bandwidth, for FFTs I normally go for a minimum of 44kHz bandwidth.
So unless the stuff you want to compare is measured the same way – measurements are mostly used to convince B2B customers to buy something.
\\\Jens
I see that we share the same type of soldering iron.
😎[/QUOTE
I Want to Have the same s-iron ,
It's nice to see the Soundtech next to the Ap in BHK's lab. The former was Rich May's favorite---he did not take to something that required a computer.
My father finally acquired a Soundtech after he realized that a variable gain amplifier used for gain presets associated with a given demoed loudspeaker had to be specified at something "respectable". The old Heath analyzer just wouldn't cut it. And when he saw the dismal performance of the ancient VCA chip he'd been using, I was tasked to produce something better. I got a royalty check from that equal-dB-step circuit, which included a four-bit ADC made from an LM339, for some years thereafter.
My father finally acquired a Soundtech after he realized that a variable gain amplifier used for gain presets associated with a given demoed loudspeaker had to be specified at something "respectable". The old Heath analyzer just wouldn't cut it. And when he saw the dismal performance of the ancient VCA chip he'd been using, I was tasked to produce something better. I got a royalty check from that equal-dB-step circuit, which included a four-bit ADC made from an LM339, for some years thereafter.
Yes that happens a lot. Whenever you see a THD vs F graph that does NOT rise above a few kHz, chances are that the AP's 22kHz filter is on.
For the nCore I think the switching feq is at 300kHz or something.
Jan
Yes at idle.. it drops at higher power, so it could interfere with measurements done with 80kHz BW.
It's just one of those things that make it near impossible to compare.
\\\Jens
SACD also shows rapid noise shaping rise above 20 kHz - Sony dialed back the original 100 kHz low pass recommendation to 50 kHz - reportedly after the rising noise content caused some high end amps to self destruct
the filter should exceed 5th order to get ahead of the noise shaping used
but we are reliably told it is a superior format, way better, "more analog sounding" than RedBook CD
the filter should exceed 5th order to get ahead of the noise shaping used
but we are reliably told it is a superior format, way better, "more analog sounding" than RedBook CD
Well Guy`s
If one day I by that NC1200 and kick that unit at full power ~ 0,5KW inside of audio band , I think it will be nice to know how much Long Wave RF Watts I send to my loudspeaker in the same time from same NC unit ?
Anyone ?
If one day I by that NC1200 and kick that unit at full power ~ 0,5KW inside of audio band , I think it will be nice to know how much Long Wave RF Watts I send to my loudspeaker in the same time from same NC unit ?
Anyone ?
Uh, if you had been following along, not if distortion induces a coloration.
I doubt any such study exists.
Are you saying that brightness in SS amps does not exist? If you think that, you would be wrong....
The amp in question does not seem to qualify. Based on what I can see from the pdf, it appears that this amplifier may have audible distortion on several fronts. Curiously, there are several peaks in distortion above 5K (see: 2. Large Signal Tests). The human ear is the result of millions of years of evolution; in this case the distortion peaks occur in the same range as birdsong, which is a range to which the ear is particularly sensitive (in order to survive, our ancestors were very aware of birdsong, as bird calls are the early warning system should a predator be in the area). So it seems quite likely that this amplifier will exhibit some brightness on account of these distortion peaks, which are at a level much higher than in many amplifiers which also exhibit audible brightness despite having lower distortion.
You can see that there is a double whammy which is why test equipment does not seem to tell us the whole story. First, our ears use higher ordered harmonics to gauge sound pressure (meaning that they are very sensitive to higher ordered harmonics) and second, the area of brightness is that of birdsong frequencies, a range of frequencies that to which our ears are naturally quite sensitive as well.
Ralph, if I may be so bold, wold it be possible to have some comparable graphs of your stuff up for comparison? All in the interest of fairness and apples-2-apples and such? I looked at your website but aside from some creative ad copy, not much tangible data.
Jan
Jan
I`m afraid that answer will be probably cost me 70K-EU , way to much for me and for a one such simple question .🙂
I suspect that this is due to the AUX-0025 and/or AES17 filters that are applied in this sort for measurement for class D amps.
It renders THD vs. Freq invalid at frequencies above 5kHz invalid (IMHO)
\\\Jens
I call BS.
Birdsong & Urban Noise 2-5KHz except in urban areas where man made noise drives it up. Only one example but at least an example rather than hand waving
Birds have enhanced hearing sensitivity 1-5KHz like us, but birdsong goes from middle C all the way up to >20KHz. Now I have not read much on the current theories behind the evolution of our hearing but find it very hard to believe that we evolved sensitivity in that region just to hear birds.
Actually I remember a series recently called 'your inner fish' where they looked at various developments in evolution and there they did put forward that mammalian hearing evolved with high frequency sensitivity to hear small prey moving, which does at least make sense, and I can find references for.
That's true. We have had some distortion tests done by magazines over the years, unfortunately most of them have had troubles doing the test properly as the amplifiers have a floating output; neither side should be tied to ground else the drive becomes asymmetrical (resulting in a pronounced 2nd harmonic). As a result the magazine tests don't reflect the amplifier running correctly (a lot also depends on load impedance and the tubes in the amp at the time). In tests that we have done it seems the 3rd is the predominant harmonic component, just as you would expect from a fully differential circuit.
Not sure how that fairness part works in... But FWIW while the amps easily go to 100KHz they don't have a reputation for brightness. That's easy enough to Google.
(the sheer size and weight of those €70k things would suggest Mr Rowland was doing a number again, wouldn't be the first time. Class AB, just no heavy transformers)
I saw the Inner Fish series too. Once you know how important bird calls are in the environment you will also know that the small prey moving theory is wrong.
Bill, we have lived in communities with houses for so long that most people don't really realize how important birdsong is. Try to think about what it was like when there were still saber tooth tigers in the world. We didn't live in houses back then and relied heavily on our senses for defense. You are living proof that these senses worked. They still do.
Any hunter can tell you that it is birds and squirrels that are the most likely to give away your position to deer that you are hunting. This should not come as any surprise. The fact is that birds (and to a lessor extent, insects) are responsive to the environment and will give out an alarm call (insects will usually just shut up), which is picked up by other birds and spreads through the landscape. You don't have to be anywhere near the predator to know that it is about.