Class d sub

hacknet · 7th December 2002, 09:06 AM

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?

Rarkov · 7th December 2002, 09:33 AM

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

Luke · 7th December 2002, 10:01 AM

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

phase_accurate · 7th December 2002, 10:14 AM

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.

hacknet · 7th December 2002, 12:49 PM

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

joensd · 7th December 2002, 03:10 PM

The LM4651 can drive mosfets up to 170W.
National semiconductor recommends to use it with the LM4652 (integrated power mosfets).
It´s all in one datasheet.(LM4651)

Jens

hacknet · 8th December 2002, 03:07 AM

is it not possible to build a class d sub with normal components?

how come all come in chip form?

djk · 8th December 2002, 09:32 AM

"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.

phase_accurate · 8th December 2002, 10:35 AM

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

djk · 8th December 2002, 02:02 PM

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

7th December 2002, 09:06 AM	#1
hacknet diyAudio Member Join Date: Nov 2002 Location: sg	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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7th December 2002, 09:33 AM	#2
Rarkov diyAudio Member Join Date: Aug 2002 Location: North East, UK	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

7th December 2002, 10:01 AM	#3
Luke diyAudio Member Join Date: Sep 2001 Location: Wellington NZ	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

7th December 2002, 10:14 AM	#4
phase_accurate diyAudio Member Join Date: May 2002 Location: Switzerland	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.

7th December 2002, 12:49 PM	#5
hacknet diyAudio Member Join Date: Nov 2002 Location: sg	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

7th December 2002, 03:10 PM	#6
joensd diyAudio Member Join Date: Dec 2001 Location: Germany	The LM4651 can drive mosfets up to 170W. National semiconductor recommends to use it with the LM4652 (integrated power mosfets). It´s all in one datasheet.(LM4651) Jens

8th December 2002, 03:07 AM	#7
hacknet diyAudio Member Join Date: Nov 2002 Location: sg	is it not possible to build a class d sub with normal components? how come all come in chip form?

8th December 2002, 09:32 AM	#8
djk diyAudio Member Join Date: Feb 2001 Location: USA	"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.

8th December 2002, 02:02 PM	#10
djk diyAudio Member Join Date: Feb 2001 Location: USA	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