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Old 7th December 2002, 09:06 AM   #1
hacknet is offline hacknet  Singapore
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Default Class d sub

im intending to build a class d sub since it is very efficient... i cudnt care less abt the quailty becuz is for blasting.....

i want about 200w...

can anyone shed so light? schematics?
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Old 7th December 2002, 09:33 AM   #2
Rarkov is offline Rarkov  England
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It is clear that you haven't searched the forums...It is a regularly discussed topic...

However, the likes of Tripath, Zetex, TI all do chips. The Zetex one is the ZXCD1000 (http://www.zetex.co.uk)

Strictly speaking, the Tripath in not Class D at all, it's called a class T. I believe the differences are that it has variable sample rate or something. It also uses predictive DSP algorithms etc etc. I challenge you to find a review of an amp using the Tripath that doesn't get a good write up. I know you're not interested in that...but there you go - a bonus. Find those at http://www.tripath.com.

Obviously TI is at http://www.ti.com...Do a search on their website.

Also Maxim may do a Class D driver...I know they do class D amplifiers for headphones but you may be able to get the PWM output...http://www.maxim-ic.com.


Like I said before, search the forums, there is loads. But for now, I hope that helps,
Gaz
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Old 7th December 2002, 10:01 AM   #3
Luke is offline Luke  New Zealand
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Heres an inexpensive 300 watt sub amp from Rod Elliott. Its not class D but you may want to consider it.

http://sound.westhost.com/project68.htm

He sells the PCB too.

happy hunting
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Old 7th December 2002, 10:14 AM   #4
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There is a German manufacturer selling class-d plate amps for subwoofers. I can't remember which one but I will try to find out. Maybe there are others as well.

Regards

Charles

BTW: Class-T is uses delta sigma modulation.
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Old 7th December 2002, 12:49 PM   #5
hacknet is offline hacknet  Singapore
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thx man...

but...

im looking for thoses that you can put together....

those that use mosfets wud be good....

IGBT is find...

my top piority is effiecentcy
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Old 7th December 2002, 03:10 PM   #6
joensd is offline joensd  Germany
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The LM4651 can drive mosfets up to 170W.
National semiconductor recommends to use it with the LM4652 (integrated power mosfets).
Its all in one datasheet.(LM4651)

Jens
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Old 8th December 2002, 03:07 AM   #7
hacknet is offline hacknet  Singapore
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is it not possible to build a class d sub with normal components?

how come all come in chip form?
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Old 8th December 2002, 09:32 AM   #8
djk is offline djk
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"is it not possible to build a class d sub with normal components?

how come all come in chip form?"

https://www.onsemi.com/pub/Collateral/AN1042-D.PDF

Linear Technology also has a design for a full bridge amplifier but it looks even more complex.

The voltage balance circuit may be eliminated from the Motorola (ON semiconductor) design if using a non-regulated supply. Use a 40-0-40V 300VA transformer for 200W/4R, 55-0-55V 300VA for 200W/8R, use IRF640/9640 for outputs.

If an input diode clipper (NAD 'soft clip') is used the duty cycle limit switches could be eliminated.
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Old 8th December 2002, 10:35 AM   #9
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djk wrote:

Quote:
If an input diode clipper (NAD 'soft clip') is used the duty cycle limit switches could be eliminated.
I like it if an amp can be driven as close to the rails as possible, so I used a different approach on a class-d amp 10 years ago, to overcome latchup during overdrive situations (although you might still use some circuitry to achieve a soft clipping characteristic):

The MOSFET drive-circuit is basically the same as with Motorola AN1042 (though the rest of the circuit is different), but I used a parallel DC-path using a transistor in common base circuit. This has to supply only miliamperes to work properly.

Regards

Charles
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Old 8th December 2002, 02:02 PM   #10
djk is offline djk
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I still like the NAD circuit:

http://www.gmweb.btinternet.co.uk/nad3020pwr.htm

You can get within a fraction of a dB of full power as the clipper follows the supply voltage as it varies. Very simple, inexpensive, low parts count circuit.

The LT1162 full bridge driver IC has built in duty cycle limiting, but is a little expensive at $9 in single lot quantity. See fig.6 p.13

http://rocky.digikey.com/WebLib/Line...,%20LT1162.pdf
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