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Old 27th January 2004, 04:02 PM   #11
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1. You will still need OP amps for the generation of the triangular waveform and for the NFB.

2. Use of the LM319 per se does not mean that you will end up with a high-quality amp.

3. Compared to some modern op-amps (and some other comparators of course) also the LM319 is still quite sluggish !

Regards

Charles

P.S. One advantage of the LM319 is that it is dirt cheap !
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Old 27th January 2004, 04:11 PM   #12
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Default Op-Amps

I'm only talking about the stage where the audio is converted to PWM. The LM319 seems to be the device of choice with class-d designers. It is certainly better than using an op-amp. Besides, the speed is still quite fast enough. What is more important is having a low and stable offset voltage and a match between the comparitors for this spec.

The ICEPower modules use the 33078 and 33079 op-amps for the places where op-amps are needed and the LM339 for the shut down circuits.
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Old 28th January 2004, 02:44 PM   #13
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Extreme Warm ThanX to SIR, CHARLES

For his Phase_Accurated Comment!

BUT i recently viewed some high-end amps schematics in which they are using Sawtooth @ 300KHz instead of Triangular and they also claim that using Sawtooth improves linearity in Pulse Switching.

Whats ur Opinion,SIR.

Regards
Ampman
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Old 28th January 2004, 04:01 PM   #14
km is offline km
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hi.

>ICE1000A amplifier module, 1000W RMS and they sound great>

its a subwoofer amplifier , and it goes to 1 khz

i guess your definition of great sound is different from most of us, but nice marketing again

rgds karsten madsen - www.cadaudio.dk
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Old 29th January 2004, 03:37 AM   #15
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Quote:
Originally posted by km
hi.
i guess your definition of great sound is different from most of us, but nice marketing again

Welcome to the ARENA Mr.karsten madsen !

PLZ CLARIFY ur STATEMENT regarding my definition of great sound as well as on nice marketing .

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Ampman
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Old 29th January 2004, 06:55 AM   #16
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O.K.

Those convenient SMPS ICs (which I have never used, so I can't comment on them) use an integrated sawtooth generator.

If you want to generate the waveform by YOURSELF then it is much easier to generate a decent triangular than a sawtooth, as others already have mentioned before.

If the waveform and the comparator were ideal, both the sawtooth and the triangular would give a perfectly linear modulation though.
I assume that the claims about sawtooth being better are just marketing BS (as are many claims amongst switching amps).

There is one property of a sawtooth that is disturbing me (though I don't know how much it affects quality): The rectangular is not only modulated in pulse-width but also in phase.

Regards

Charles
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Old 29th January 2004, 10:20 AM   #17
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Default ICEPower

Quote:
Originally posted by dmfraser
Actually I'm talking ICEPower. I find the ICEPower are the best class D amplifiers available in terms of cost and sound quality. I am paying inder $100 (OEM 500 lot price) for the ICE1000A amplifier module, 1000W RMS and they sound great.
AES publications about ICEPower.
http://www.medicom.bang-olufsen.com/sw1062.asp
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Old 29th January 2004, 11:02 AM   #18
km is offline km
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hi.

amp_man i wasnt answering you.

>I find the ICEPower are the best class D amplifiers available in terms of cost and sound quality.>

what other types did you hear and compare to?

others dont seem to share your high thoughts about their sound quality either but im glad you can at least confirm that they are cheap (we had that discussion here some time ago in a discussion with av reality who claimed the opposite

rgds karsten madsen - www.cadaudio.dk
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Old 29th January 2004, 11:13 AM   #19
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So , Mr Madsen U think that ICEpower amps are far better than the amplifiers fabricated by u .

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Ampman
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Old 29th January 2004, 12:56 PM   #20
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Isn't Jeff Roland Design using the ICEpower modules now too? Roland is well known for his perfectionism. Hard to believe he would have chosen them if he weren't satisfied with them.

I heard from many people that attended the recent CES that heard them that they were quite excellent. I have also been told that these new Roland amps are almost impossible to get at the moment as the demand has greatly outstripped supply. Clearly more than a few people like them.

I'm curious Mr. Madsen, you seem to be quite critical of many current class d amps on the market. Are there any you do like?
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