That isn't my point - my point is that Class D is thought to be very efficient, but it ain't at low volume which you often are in HiFi. There is switching losses - don't forget.
Let us see your loudspeaker - it could be interesting...
Do me a favour and google "Boominator"
That's of course not my home speakers, there I use an FE206E based BLH.
Same amp, yes, and with a solar cell backed up battery supply (yes, it works all year round even in Denmark). No sub or EQ used.
You suggest anyone to connect resistor in very wrong way. Connecting resistor in series with loudspeaker makes it less control and wrong damping. The resistor should connected in parallel with loudspeaker in current driving, or use active damper (negative feedback).
You don't know anything about loudspeaker driving technique and designing classD are easier than the others because it doesn't care how the loudspeaker move will be.
Hi guys, take a look here, another SMALA:
http://www.diyaudio.com/forums/soli...-hybrid-linear-switching-power-amplifier.html
http://www.diyaudio.com/forums/soli...-hybrid-linear-switching-power-amplifier.html
Um.. Just found this. It says that classD efficiency are fakes and they going to combine all classD+G+H.
Exploding the Efficiency Myth of Class D Amplifiers | ECN: Electronic Component News
pdf:
http://www.newelectronics.co.uk/articles/22076/p21-22.pdf
I don't know which one is true here, but the most efficient I ever achieve is using forward converter, not soft switching but it really reach high efficiency in all the way, nothing gets warmed also no warming inductor at 100W output into 8ohm, the only problem is its reversing plus minus polarity. The key is discharge all the inductor current always to zero for each cycle.
Exploding the Efficiency Myth of Class D Amplifiers | ECN: Electronic Component News
pdf:
http://www.newelectronics.co.uk/articles/22076/p21-22.pdf
I don't know which one is true here, but the most efficient I ever achieve is using forward converter, not soft switching but it really reach high efficiency in all the way, nothing gets warmed also no warming inductor at 100W output into 8ohm, the only problem is its reversing plus minus polarity. The key is discharge all the inductor current always to zero for each cycle.
If you know anything about electronics you really don't need to read further than this sentence to file it under fairy wings and karma improved input caps.
Can we agree that Class D hasn't high efficiency at low levels? Should be possible.
Interestingly is that Class D is pretty good at high level, but at clip level they very often sound terrible because of poor power supplies again because of the designers thought of high efficiency ! Their ultimate purpose is often in PA and here you often see IcePower modules that doesn't perform that convincing. One of the many companies that use IcePower is RCF for their Line-Array systems, but you will discover that fans are employed to cool the amps! Recently I were at a demo of a RCF TTL55 with subs and it was quite okay at levels between -60dB and -10dB full level, BUT above -10dB it was scary bad
And when measuring Class D it's allow to filter the output with low-pass filters - this isn't allow for the other Classes !
Can we agree that Class D hasn't high efficiency at low levels? Should be possible.
Depends on what we compare it with. If we exclude the power supply from the equation then all classes of amps scale exactly the same compared to output plus the needed bias and quiescent current of the circuit.
And when measuring Class D it's allow to filter the output with low-pass filters - this isn't allow for the other Classes !
That's not exactly true, you can make filterless class D amps but output filters are most often used because it's a PWM or PDM amp. All classes of PWM or PDM amps usually has output filters to prevent the switching frequency from reaching the speakers.
There's nothing to stop you from using low-pass filters on the output of a PCM amp, it's just not necessitated by the design.
My point is that the claim of high efficiency isn't viable for Class D because it's for audio signals that often are low compared to sin full level.
And I am not talking about output filters on the amplifier it self - it's filters inserted between the amplifier output (after the PWM amplifier own output filter) and the measurement system!
Don't get me wrong I like Class D for the right purpose and engineered right!
I have used Lab.Gruppen LAB2000, LAB2000C, LAB2002, LAB4000, fP6400 and fP+10000Q for nearly two decades - all with tracking Class D technology ! And at the same time their Class B for compression drivers, because of the better sound quality.
@ luka - year maybe clip is dumb, but this is reality in PA anyway. And I have seen this too in HiFi related equipment because of very low sensitive passive loudspeakers and to get a realistic reproduction of the music signal.
Tell us about your speakers. please!
And I am not talking about output filters on the amplifier it self - it's filters inserted between the amplifier output (after the PWM amplifier own output filter) and the measurement system!
Don't get me wrong I like Class D for the right purpose and engineered right!
I have used Lab.Gruppen LAB2000, LAB2000C, LAB2002, LAB4000, fP6400 and fP+10000Q for nearly two decades - all with tracking Class D technology ! And at the same time their Class B for compression drivers, because of the better sound quality.
@ luka - year maybe clip is dumb, but this is reality in PA anyway. And I have seen this too in HiFi related equipment because of very low sensitive passive loudspeakers and to get a realistic reproduction of the music signal.
Tell us about your speakers. please!
The reason why a filter is allowed for class-d maesurement is because the carrier residual simply increases THD measurement without actually having higher THD present. This is happening with both - old fashioned THD meters and DSP-based ones. The first ones simply measure the total amplitude of what is going on above the first harmonic and therefore include the carrier to some degree and the latter ones may have problems due to being sampling devices.
Speakers don't have these problems so it is valid to measure with a low pass in place IMO.
Regards
Charles
Speakers don't have these problems so it is valid to measure with a low pass in place IMO.
Regards
Charles
Hi,
If you smear some oil on the surface of your speaker system (external of box), the voice spectrum changes completely. So, it is true that I can not hear over the 18K (single sound), but the harmonic component, that of course. is the harmonic component that defines the sound, which is why it is difficult to play well on a digital amp.
Regards
Roberto P.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.