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Class D Switching Power Amplifiers and Power D/A conversion

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Old 23rd December 2006, 06:36 PM   #1
felixx is offline felixx  Romania
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Default The best sound on the class D

I'm interested to know what is the best "sounding"...overall class D kit existing right now for diy zone comparing with class A -amps in transparency,details,dinamics and definition.

All comparing ..let say on 50W power.

No matter the price...the best sound kit available....
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Old 23rd December 2006, 10:11 PM   #2
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The problem is people differ in their opinion. Some prefer sound richer in 2nd harmonic.

Cheever in his Masters thesis experimentally correlated sound quality with harmonic distortions when each harmonic is weighed with its order to a power. Thus 7th or higher HD results in unpleasant sound, etc... However audio analyser mfgs don't subscribe to his approach, yet, even though it's pretty easy to add a simple math routine to their THD measurement. Google Cheever if you want to read his thesis.
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Old 23rd December 2006, 11:34 PM   #3
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You might want to hold off final judgement ... there are several very interesting Class-D amp projects underway here and at other DIY and commercial sites, many based on very new chips just now coming to market (TI, National and others): ...

My personal favorite thread starts about here: http://www.diyaudio.com/forums/showt...68#post1072668 ...

DIYAudio WiKi here: TAS5261EVB WIKI == http://www.diyaudio.com/wiki/index.p...ards+and+parts

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Old 24th December 2006, 10:28 PM   #4
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I've feeling, that any class D amp, if can provide enough accuracy, will sound very close to the UcD, but not like typical class A/AB, however which of this ones will play more truth, that's good question.
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Old 27th December 2006, 03:03 PM   #5
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What do you think about this:
http://www.cl3.fr/FR/FR_technologie.htm

Anyone hear these?.... don't need heatsink.
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Old 27th December 2006, 05:11 PM   #6
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From the link: http://www.cl3.fr/FR/FR_technologie.htm ... an Altavista.com Babelfish Translation / French to English:

" The performances of any amplifier in class D are limited by the quality of what one calls the stage of commutation. It is the heart of the amplifier with cutting. It is him which allows the transfer of energy of the food towards the enclosures.

" Rather than Žvertuer to correct the errors generated by a stage of commutation weakening, the team of search for CL3 devoted itself to the development of a cell of ideal commutation, intrinsically freed from the technical constraints most disturbing. The result is Gemincore technology: a solution of optimized energy transformation, exceeding the exigeances the audio amplifiers most powerful and the most effective converters DC/DC.

" Gemincore technology is protected by an international patent. "

Also, the data sheet has better pictures: http://www.cl3.fr/FR/GEMINCORE_ampli..._D_par_CL3.pdf

... and this:
" ImpŽdance dÕentrŽe : 56 K½
- ImpŽdance de sortie : < 50 m½
- SensibilitŽ dÕentrŽe ˆ 55 V : +1,23 Vp
- Filtre de sortie du 4me ordre
- DC offset en sortie maximal : ± 15 mV
- DC offset en sortie typique : ± 10 mV
"
...
" GEMINCORE a ŽtŽ prŽvu pour fonctionner avec une large plage de tensions d'alimentation
(de + 30 V ˆ + 55 V) afin de pouvoir dŽterminer la puissance maximum de sortie selon une
charge donnŽe. ... pour un amplificateur de 150 W RMS, une alimentation de 300 W RMS. "

Apparently the above implies: 150 Watts RMS from + 30 volt power supply and 300 Watts RMS from +55 volt power supply ... ! ??? ! ... must be "bridged" some how ... (Maximum +60 volts possible):

Pour V = 30 V, 8 ½ de charge, Puissance Max RMS = 49 W
Pour V = 40 V, 8 ½ de charge, Puissance Max RMS = 88 W
Pour V = 50 V, 8 ½ de charge, Puissance Max RMS = 138 W
Pour V = 55 V, 8 ½ de charge, Puissance Max RMS = 167 W


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Old 28th December 2006, 04:01 AM   #7
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Quote:
Originally posted by FastEddy

...
" GEMINCORE a ŽtŽ prŽvu pour fonctionner avec une large plage de tensions d'alimentation
(de + 30 V ˆ + 55 V) afin de pouvoir dŽterminer la puissance maximum de sortie selon une
charge donnŽe. ... pour un amplificateur de 150 W RMS, une alimentation de 300 W RMS. "

Apparently the above implies: 150 Watts RMS from + 30 volt power supply and 300 Watts RMS from +55 volt power supply ... ! ??? ! ... must be "bridged" some how ... (Maximum +60 volts possible):

Pour V = 30 V, 8 ½ de charge, Puissance Max RMS = 49 W
Pour V = 40 V, 8 ½ de charge, Puissance Max RMS = 88 W
Pour V = 50 V, 8 ½ de charge, Puissance Max RMS = 138 W
Pour V = 55 V, 8 ½ de charge, Puissance Max RMS = 167 W


I don't really read French, but if "alimentation" translates as 'feed' (tensions d'alimentation = feed voltage), then I think it means that for a 150 W RMS output amp one would use a power supply capable of 300 W RMS. That would agree with the last line, 55 V into 8 ohms = 167W RMS max.
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Old 28th December 2006, 04:41 AM   #8
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Any manufacturer can put together some verbose to try to impress. I looked at their plots. Quite good except they don't show THD as function of frequency. Why? I suspect they're only good for 1Khz and below. Otherwise they would have shown THD vs freq.
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Old 28th December 2006, 04:43 AM   #9
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"The performances of any amplifier in class D are limited by the quality of what one calls the stage of commutation." CL3

This is true when there's no or low level of feedback. Post filter feedback coupled with high loop gain can do wonders to THD.
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Old 28th December 2006, 06:33 PM   #10
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koolkid731: " ... I looked at their plots. Quite good except they don't show THD as function of frequency. Why? I suspect they're only good for 1Khz and below. Otherwise they would have shown THD vs freq. ..."

Excellent point! ... It's not what they say, but what they don't say ...

koolkid731: " ... Post filter feedback coupled with high loop gain can do wonders to THD. ..." ... or not! (Aside: I built a gopher chaser once that was a simple low power amp / op-amp with a notch filter in the feedback loop = it oscilated nicely in the 18k to 25k Htz. range and played heck with the sex life of the gophers in the garden = they left in a hurry.)
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