One definitely positive attribute is their capability for driving almost any load with ease. There is still a slight shortfall (compared to good class A and AB) regarding the load dependancy of the frequency response but this has been improved greatly. There are many topologies around for achieving this, some even unpatented.
Another point of criticism might be the need for an output lowpass which keeps one from achieving really high cutoff frequencies. But this could be overcome by hybrid constructions, i.e. something like a fast A- or AB- amp supported by a switching current-dumper in parallel. Below you will find the simulation result of such a hypothetical topology when fed with the sum of a 1kHz sinusoidal and a 10 kHz rectangular. The main disadvantage is the increased complexity. The green track BTW is the residual current that has to be fed by the linear amp (into 6 Ohms).
Regards
Charles
Another point of criticism might be the need for an output lowpass which keeps one from achieving really high cutoff frequencies. But this could be overcome by hybrid constructions, i.e. something like a fast A- or AB- amp supported by a switching current-dumper in parallel. Below you will find the simulation result of such a hypothetical topology when fed with the sum of a 1kHz sinusoidal and a 10 kHz rectangular. The main disadvantage is the increased complexity. The green track BTW is the residual current that has to be fed by the linear amp (into 6 Ohms).
Regards
Charles
Attachments
Re: Take a look, opinion and see how he turn full of enthusiasm
destroyer X,
this is a class T amplifier. Truly digital.
Class D have nothing in common with digital and - in my opinion -with audiophile.
"Tripath Technology has developed a category of digital audio power amplifiers using a unique technology. Tripath amplifiers use a completely new proprietary method of Digital Power Processing™ that provides superior performance to conventional methods of amplification. For the first time, both high signal fidelity AND high power efficiency can be
achieved with the same technology. Tripath refers to this DPP™ based amplifier as a Class-T design. The underlying technology of Class-T does not use PWM and is not a pure analog approach (Classes -A and -AB). It combines the benefits of both with a completely
new approach."
destroyer X said:
destroyer X,
this is a class T amplifier. Truly digital.
Class D have nothing in common with digital and - in my opinion -with audiophile.
"Tripath Technology has developed a category of digital audio power amplifiers using a unique technology. Tripath amplifiers use a completely new proprietary method of Digital Power Processing™ that provides superior performance to conventional methods of amplification. For the first time, both high signal fidelity AND high power efficiency can be
achieved with the same technology. Tripath refers to this DPP™ based amplifier as a Class-T design. The underlying technology of Class-T does not use PWM and is not a pure analog approach (Classes -A and -AB). It combines the benefits of both with a completely
new approach."
I didn't expect that people from Eastern Europe were that gullible regarding American sales BS !!!!!
Ther ARE no digital amplifiers and there will NEVER BE ANY. Amplifiaction per se is an analog process, be it within a linear amplifier or within a switching amp.
The Tripath amps are either a self-oscillating hysteresis-controlled class-d or sigma-delta topology.
And they don't even take NFB at the output !!!!!!
I don't know where the rumour comes from that class-d per se was bad. A good PWM modulator is much more linear than a classical VAS without NFB. There are of course problems that have to be sorted out, but I think class-d is approaching a quality area only slightly below the better linear amps around. As already mentioned: The only disadvantage is the quite low upper cutoff frequency.
Regards
Charles
Ther ARE no digital amplifiers and there will NEVER BE ANY. Amplifiaction per se is an analog process, be it within a linear amplifier or within a switching amp.
The Tripath amps are either a self-oscillating hysteresis-controlled class-d or sigma-delta topology.
And they don't even take NFB at the output !!!!!!
I don't know where the rumour comes from that class-d per se was bad. A good PWM modulator is much more linear than a classical VAS without NFB. There are of course problems that have to be sorted out, but I think class-d is approaching a quality area only slightly below the better linear amps around. As already mentioned: The only disadvantage is the quite low upper cutoff frequency.
Regards
Charles
Tvicol, message received, thanks, and i understood what you mean.
Yes, i put them all inside same bag, as half digital because of digital pulses, the on and off and half analogic as main pre amplifiers is analogic and speaker also.
But as i used to say, and many times i said that in our solid state forum.
"When we feel deep love we can hear music in our brain, and music not playing.... the noises, the party or street noises are cancelled and you enter another perception dimension, when you see the moving lips in a slow motion form, her voice is music"
Well, many of you lived that strong passion experience, if not...sorry for you guys, it is something for whole life...when i hear her, or watch her, or listen her name....i go into a deep delirium again...and i do not use any time of drugs, even not coffee because dislike it....not alcohol too.
If we can "create music"...if we can cancell noises of the environment...it is clear to me that brain can make "the difference" related to sound sources.
We know that exist some amplifiers that turn us tired when hearing long time..... you have enormous pleasure to shut them off!.....this do not happens with my Philips class D, half discrete system...have a lot of chips to amplification and to triangle wave creation to comparator and many microprocessor functions related commands.
We, as many friends bougth the same model, can hear without turn tired..... i am thinking, that the "difference" can be something easy to be "reconstructed" by brain, to be "processed" by brain and things hard to be "reconstructed".... to be "repaired"...or adjusted by brain..... class D seem to be easy to brain, as we do not feel tired, distort less than A and AB, and the sound is more clear...but really, lost that "spatial positioning" that i could perceive in good AB amplifiers as JLH and AKSA as examples, many others can be good too.
This construct inside me more "acceptance" to the ones imagine us as Barbarians (very good that!)..but i feel good to see the resistance movement.
That kind of amplifier, the class D is very old... and people "erasing it" ouf of the reasonable sound map!...this circuit was arrested by pre- conceptions along more than 25 years...i have some 1987 design, almost the same as my Philips....and was not accepted by the community.... a lot of people even do not hear and start to send bombs and making noise against it...this is non sense...not hearing, and judging.
I think may be some psychologic problem related that.
" All my life i worked, assembled, i sold, i suggest, i made and i heard class AB and others classes, except D.
Now it is clear that class D can beat all i heard, all i done, all i sold, all i suggest...and can do it easy...even at maximum volume!
This technology are killing what i made, what i heard, what i done and what i suggest..... are killing myself as a result!
Accept that, is to recognize i heard crab all my life (cannot use the correct word to crab)...this way...i suggest crab, i constructed crab, i made crab and i sold crab.....i may be a crab too.
Not to be a crabm, i have to dennie...to resist...to oppose...to shut their mouthes...i will say that output filter is crab...i will say that have intermodulation intersinc sensational counter galactid modulation defects!
If i do not do that!.... i will be recognize to wide world that i am a crab...i may enter depression...so....cannot do this way.
Self defense mechanism will find defects even in the blue colour os the sky, if you pass all life seeing colors wrong, and realise the correct color is the one you see as green.....so...green is blue to you....and this is disgusting."
Well, i do not speak english, you can see because of my errors when typing things...not a native English language.... i am doing strong efforts to say to you what i think, and i fell happy when people say that could understood me, when agree and when disagree...the second, saying why!
regards,
Carlos
Yes, i put them all inside same bag, as half digital because of digital pulses, the on and off and half analogic as main pre amplifiers is analogic and speaker also.
But as i used to say, and many times i said that in our solid state forum.
"When we feel deep love we can hear music in our brain, and music not playing.... the noises, the party or street noises are cancelled and you enter another perception dimension, when you see the moving lips in a slow motion form, her voice is music"
Well, many of you lived that strong passion experience, if not...sorry for you guys, it is something for whole life...when i hear her, or watch her, or listen her name....i go into a deep delirium again...and i do not use any time of drugs, even not coffee because dislike it....not alcohol too.
If we can "create music"...if we can cancell noises of the environment...it is clear to me that brain can make "the difference" related to sound sources.
We know that exist some amplifiers that turn us tired when hearing long time..... you have enormous pleasure to shut them off!.....this do not happens with my Philips class D, half discrete system...have a lot of chips to amplification and to triangle wave creation to comparator and many microprocessor functions related commands.
We, as many friends bougth the same model, can hear without turn tired..... i am thinking, that the "difference" can be something easy to be "reconstructed" by brain, to be "processed" by brain and things hard to be "reconstructed".... to be "repaired"...or adjusted by brain..... class D seem to be easy to brain, as we do not feel tired, distort less than A and AB, and the sound is more clear...but really, lost that "spatial positioning" that i could perceive in good AB amplifiers as JLH and AKSA as examples, many others can be good too.
This construct inside me more "acceptance" to the ones imagine us as Barbarians (very good that!)..but i feel good to see the resistance movement.
That kind of amplifier, the class D is very old... and people "erasing it" ouf of the reasonable sound map!...this circuit was arrested by pre- conceptions along more than 25 years...i have some 1987 design, almost the same as my Philips....and was not accepted by the community.... a lot of people even do not hear and start to send bombs and making noise against it...this is non sense...not hearing, and judging.
I think may be some psychologic problem related that.
" All my life i worked, assembled, i sold, i suggest, i made and i heard class AB and others classes, except D.
Now it is clear that class D can beat all i heard, all i done, all i sold, all i suggest...and can do it easy...even at maximum volume!
This technology are killing what i made, what i heard, what i done and what i suggest..... are killing myself as a result!
Accept that, is to recognize i heard crab all my life (cannot use the correct word to crab)...this way...i suggest crab, i constructed crab, i made crab and i sold crab.....i may be a crab too.
Not to be a crabm, i have to dennie...to resist...to oppose...to shut their mouthes...i will say that output filter is crab...i will say that have intermodulation intersinc sensational counter galactid modulation defects!
If i do not do that!.... i will be recognize to wide world that i am a crab...i may enter depression...so....cannot do this way.
Self defense mechanism will find defects even in the blue colour os the sky, if you pass all life seeing colors wrong, and realise the correct color is the one you see as green.....so...green is blue to you....and this is disgusting."
Well, i do not speak english, you can see because of my errors when typing things...not a native English language.... i am doing strong efforts to say to you what i think, and i fell happy when people say that could understood me, when agree and when disagree...the second, saying why!
regards,
Carlos
phase_accurate said:Yes, indeed another advantage of many class-d topologies (that I almost forgot about) is the fact that one can define the open-loop BW almost freely.
Regards
Charles
From my understanding, you can say that ClassD has openloopbandwidth
flat up to it's carrierfrequency. Also you can say that a ClassD has
a max openloop - delay/phaseshift of 0.5uS (For 200khz carrier),
abolutely fixed. ClassD is not handicapped by feedbackcaps needed
for stabilizing.
This is nearly impossible for ClassAB, but i will try...
My fastest stable circuit reached down to 5us openloop.
It think that this is the reason why ClassD shows so dramatic
transientresponse, dynamics / details / soundstage.
In my own ClassD first steps, it's the deadtime that shows up
as the biggest problems with this technique.
Mike
IF you want to use NFB then you will for sure have to make a trade-off. You can't get flat open-loop FR up to the carrier frequency AND apply NFB at once. So you may most probably use a topology with a flat open loop gain up to 10 or 20 kHz (which alone beats many class-AB amps !!!). The loop itself is much easier to calculate than with an ordinary class AB. And if you still want more NFB then you can use a multiloop topology.
I remember how we listened to a classs-d amp we once developed (in 1991) that had THD as high as 0.44 % but an open-loop BW of 15 kHz and it did not sound harsh in any way - the contrary was true in fact . And this amp was not even intended as audio amp at all but as a lab power source.
Regards
Charles
IMHO, one of the beauties of UCD amps (I've not heard other classD amps) is that, being able to drive and make sound very good even non HiEnd speakers, and making good partnership with transformer based volume controls, one really can focus (money an effort) on the source!
Enjoy your music now...
Mauricio
Enjoy your music now...
Mauricio
Big Charlie...the amplifier
Scotish bag pipes are wonderful, they make music right to be
amplified by Class D, class T amplifiers, like the modules of 41Hz.com.
Is this a pretext to speak about these modules? I have to resist to
the impulse of speaking about these modules, they look gorgeous,
I'm about to finish one but I didn't as of yet.
May be later...
But Carlos, how about a military march from Germany?
Scotish bag pipes are wonderful, they make music right to be
amplified by Class D, class T amplifiers, like the modules of 41Hz.com.
Is this a pretext to speak about these modules? I have to resist to
the impulse of speaking about these modules, they look gorgeous,
I'm about to finish one but I didn't as of yet.
May be later...
But Carlos, how about a military march from Germany?
I was interested in some translations, but my German friend do not like to talk about
This subject..... i do not know his reason, but must exist a good reason to avoid.... some cloudy days to Germany i suppose.
But i visited Heindrich Grune in Petropolis, they buried a lot of old Nazi enormous phonograph discs.... i was there to recover that historic material..... and i made recordings.... and have a lot of conversations on it.....i do not understand 90 percent of the words.
Those voices, hard to understand, because of old recording quality, despite re-adjusted, are noise and unclear, but in my class D, the reproduction is more clear....the unit that can let me understand some words.
Where's the pictures?..... what about the popping, jumping SMDs?
You can put some rubber point when fixing it to solder, to avoid send them to "space"....hehe...they like to fly away, and no one can find them in our "damned trashed dirty laboratories!"
Carlos
This subject..... i do not know his reason, but must exist a good reason to avoid.... some cloudy days to Germany i suppose.
But i visited Heindrich Grune in Petropolis, they buried a lot of old Nazi enormous phonograph discs.... i was there to recover that historic material..... and i made recordings.... and have a lot of conversations on it.....i do not understand 90 percent of the words.
Those voices, hard to understand, because of old recording quality, despite re-adjusted, are noise and unclear, but in my class D, the reproduction is more clear....the unit that can let me understand some words.
Where's the pictures?..... what about the popping, jumping SMDs?
You can put some rubber point when fixing it to solder, to avoid send them to "space"....hehe...they like to fly away, and no one can find them in our "damned trashed dirty laboratories!"
Carlos
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