Does anyone care about audio quality anymore? I do. In this video I show how horrible Class D is. I know this has nothing to do with CB or Ham radio, I was just bored yesterday and made a couple of audio related videos.
I understand your point but I think your assessment of “junk” is too simplistic. The square ware is the worst case scenario. You are right to look at this. A square wave is an infinite number of harmonics. This amp could produce enough harmonics of the low frequency to approximate a square wave. However there is no need for this amp to be able to produce harmonics in the 40kHz and 80 KHz range. So the result is the square wave didn’t look even close. But this is an audio amp. You would not be listening to square waves at 10 and 20 kHz so it doesn’t really matter that it can’t faithfully reproduce those. It does very well at audio frequencies producing sinusoidal waves. That’s what it is for.
Junk may be simplistic, but I believe it is accurate. Also, I am going to have to disagree with many of the points you mention in your comment. First, in my opinion the square wave is not the worst case, but more likely a square wave combined with other waves. Example: once a square wave has the output holding a high DC voltage, then you introduce another signal, what will happen? Second, you say (as many say) "a square wave is an infinite number of harmonics". It is not, you can theoretically "electrically" combine infinite harmonics to create an electrical square wave, but then you do not have the harmonics anymore. Try using an infinite number of speakers to reproduce an infinite number of harmonics and see what that sounds like. Third, you comment that "This amp could produce enough harmonics of the low frequency to approximate a square wave".... NO it cannot, you even say "the result is the square wave didn’t look even close" those are your words, and in the video you can clearly see that that it cannot reproduce square waves, even at 2k. Forth, you say "But this is an audio amp. You would not be listening to square waves at 10 and 20kHz so it doesn’t really matter that it can’t faithfully reproduce those." YES, It DOES matter, and YES people do listen to square waves at 10 and 20khz.... there are literally millions of songs with square waves of all frequencies out there. There have been synthesizers out there for many many years that create square, triangle, sawtooth, and many more of those types of waves and they are used in music at all frequencies. Fifth, you say "It does very well at audio frequencies producing sinusoidal waves. That’s what it is for." That statement is wrong, maybe that is all junk D class amps can do, but audio amplifiers are not just for sine waves. Music is absolutely not just sine waves. Audio amplifiers are suppose to reproduce the wave that you put in, not just sine waves, and as I mentioned in point number 4, there are millions of songs out there that use square, triangle, saw tooth, etc.... waves. Synthesizers have been around for many years and there is a ton of music out there with all of those waves from even below 20hz and above 20k. Finally, I would like to mention, all that junk in the signal you see when this amp is trying to produce a square wave.... that junk is going to be heard thru your speakers, junk that is not there in the recordings of your music. My opinion.... Class D is JUNK as I stated before... and for anyone who is going to mention that speakers cannot produce a square wave, yes, that is true, but I want the signal that is going to my speaker system to be as true as possible. Every little bit of distortion in an audio signal, from the limits of a microphone, mixers, amps, recording media, etc... it all adds up in a negative way, but I have rarely seen any device in an audio chain that adds as much distortion as a class D amp period. I would rather listen to the worst AB amp over a D any day. Cheers
Looks like just a coil.. that's being used....not an actual speaker nor even the permanent magnets anywhere in the field...so no BEMF... & the coil under observation is placed on the amp??? that's an aluminium chassis..so whatever the mag.field of the coil.. it's going to interact with 5he components inside. this is a poor way of doing a setup.
You are absolutely correct, and I am sure if I redid this test with some real speakers and the fact that the unlimited random bemf that would be created by all the different type of speakers and crossovers and enclosures..... well, this amp, and every other D amp would most likely reproduce each and every type of wave and signal perfectly. My test is flawed. ROFLMAO BTW, the reason I used that coil instead of a resistor or an actual speaker was so the amp would have a fighting chance of producing a decent wave 'without' the chance of random bemf while still letting it see some inductance. If you have ever seen the widely varying amount of impedance in a speaker in motion or the widely varying amount of back emf created by a single speaker in motion, then combine that with the widely varying differences in those parameters among all the millions of different speakers, crossovers, enclosures, etc, etc, etc, there is no way to expect the output filters of a class D amp to, well.... hopefully you get the idea. And since you brought up bemf, you should see what the difference in the ohm load on a D amp does to the signal at different loads and frequencies, it is disgusting. Then compare those results to an AB amps output signal at varying loads and frequencies. It is not even a close race. Also, one last note. Look at the video I made just minutes before this video you are complaining about, it is here: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-aMFEkzF5jPM.html it's where I test a 40 year old Sanyo AB amp with the voice coil also on top of the aluminum cover.
@@analoghardwaretops3976 maybe, but I have tested many class D over the years, and they are all horrible. I just happen to have this and a few others laying around still, left behind by the original purchasers that had me install AB in their place. How about this? I have some FOCAL class D amps also. Everyone loves FOCAL, maybe I will video them soon.
