This morning on the morning show they said electric cars are not going to take off for another 15 years. Where are we at with class D right now? Everyone keeps saying that the future is class D but where is that in the future?
They’ve been saying that since the 1910s- but about 1912 Ford and Edison had an electric that could cruise at 60mph and had a 100 mile range, using Edison’s nickel iron batteries, which had a service life of about 25 years. Imagine what things would look like if Edison’s labratory hadn’t been burnt to the ground 2 weeks after Ford and he made that announcement! See ’Internal Combustion’ by Edwin Black.
Class D is very attractive because of energy, just like electric cars. The difference is that we can have Class D although IMO it still has a way to go.
@georgehifithis then allows the low order switching noise output filter to do it’s job completely without leaving any effects and any left over switching noise artifacts within the audio band.
I think you don’t understand how the filter works, based on this statement. The Technics filter does not filter out all the residual, which is what the leftover switching artifact is called. The residual is always a very clean sine wave; the real question is what amplitude does it have? The filter really has nothing to do with ’left over switching noise artifacts’!! What can happen in a class D is the switching noise can radiate into other parts of the circuit where it can be rectified and amplified. Again, the filter has nothing to do with this- the noise problem is dealt with through good layout and compact (surface mount) design.
@minorlIn car audio it was really the only way to go to get the power output needed. you can’t do it from 12 VDC.
Just a correction: My Denon car stereo amp that I had in my Bronco (RIP) made 150 watts per channel and was an AB amplifier. It employed an inverter to boost the DC voltage. Inverters were used back in the old days when car radios had tubes in them, although they were a different technology, using something called a ’vibrator’ which was essentially a high speed relay that reversed the DC to the power transformer about 50 times per second.
@kosst_amojanIt’s also nice not having a massive pile of filters trying to turn garbage into a signal again.
This statement is problematic. If you listen to digital, something similar is happening there (and of course its an objection that analog guys often raise). And the Berning amplifiers employ a filter at their output too- and those amps are class A or AB despite a switching component that has to be filtered- and it gets very good reviews!
The filter on a class D is usually quite simple; there is not a ’massive pile’. If you raise the switching frequency sufficiently, the inductance of the speaker itself can be sufficient to attenuate the residual. The filter is there mostly to prevent the speaker cable from acting as an antenna for the switching frequency. Because the filter is usually set somewhere well below the switching frequency, the residual is a simple low distortion sine wave which won’t cause interference to higher frequency (radio) services.
