Filterless Class D

gpapag · 31st October 2005, 03:44 PM

Hi all
I would like to ask if anyone has connected a Class D amp without a LP output filter to speakers as this Texas Instrument .pdf suggests www.eie.fceia.unr.edu.ar/ftp/Comunicaciones/reducing%20and%20eliminating%20class%20D%20output% 20filter.pdf

Regards
George

matjans · 31st October 2005, 04:00 PM

a friend of mine (pitch254 i think his nick is) has, a tas50xx based class d digital amp.

Tweeters managed perfectly, no probs there. Only thing was that it gave so much hf junk on the speaker lines & the internal wiring that it had trouble locking on the spdif signal when turning up te volume. even at normal listening volumes it would sometimes lose the signal.

That, and the tv & radio were completely useless when the amp was playing music

gpapag · 31st October 2005, 04:07 PM

matjans
the article deals (theoretically) with this problem. Some measures have to be taken during construction.
What i am interested in is the sound of the filterless versus the filtered (same) class D. Any experience?
The supplied URL does not work. Use this insteadhttp://focus.ti.com/lit/an/sloa023/sloa023.pdf

Regards
George

matjans · 31st October 2005, 04:12 PM

ah, sorry, no experience with that. I've never heard it WITH a filter

gpapag · 31st October 2005, 04:59 PM

Does this mean it was already agreed that it sounded better filterless?

gpapag · 31st October 2005, 05:04 PM

I just realised that i opened this thread in "Chip Amps" area instead of the more appropriate "Class D" area. If the moderator wishes to transfer it there , please do so.
Regards
George

pinkmouse · 31st October 2005, 05:24 PM

Moved, and your link fixed as well!

gpapag · 31st October 2005, 05:45 PM

A double thanks Al.
Talking about links, here is another from Maxim dealing with (manageable) calculations for LC output filters. http://pdfserv.maxim-ic.com/en/an/AN624.pdf
Regards
George

rjb · 31st October 2005, 07:53 PM

Filterless Class D radiates frequencies via the speaker leads well into radio bands used by others, and you may have a man in a peaked cap knocking on your door:

PWMan · 1st November 2005, 07:06 AM

I've been measure a 2W stereo filterless class-D chip in the EMI anechonic chamber, a pair of speaker cable is only 30cm, the EMI radiation result is really bad even in the quiescence and supply voltage is only 5V, don't even think about rated power output.

Filterless type class-d is only suite for "no speaker cable outside" applications , You needs to install all componenents in a shielded case, such like a laytop PC or mobilephone.

31st October 2005, 03:44 PM	#1
gpapag diyAudio Member Join Date: Nov 2002 Location: Athens-Greece	Filterless Class D Hi all I would like to ask if anyone has connected a Class D amp without a LP output filter to speakers as this Texas Instrument .pdf suggests www.eie.fceia.unr.edu.ar/ftp/Comunicaciones/reducing%20and%20eliminating%20class%20D%20output% 20filter.pdf Regards George

31st October 2005, 04:00 PM	#2
matjans diyAudio Member Join Date: Aug 2003 Location: Utrecht, NL	a friend of mine (pitch254 i think his nick is) has, a tas50xx based class d digital amp. Tweeters managed perfectly, no probs there. Only thing was that it gave so much hf junk on the speaker lines & the internal wiring that it had trouble locking on the spdif signal when turning up te volume. even at normal listening volumes it would sometimes lose the signal. That, and the tv & radio were completely useless when the amp was playing music __________________ Si fractum non sit, noli id reficere!

31st October 2005, 04:12 PM	#4
matjans diyAudio Member Join Date: Aug 2003 Location: Utrecht, NL	ah, sorry, no experience with that. I've never heard it WITH a filter __________________ Si fractum non sit, noli id reficere!

31st October 2005, 05:24 PM	#7
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Moved, and your link fixed as well! __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

31st October 2005, 07:53 PM	#9
rjb diyAudio Member Join Date: Jun 2004 Location: Piha	Warning Filterless Class D radiates frequencies via the speaker leads well into radio bands used by others, and you may have a man in a peaked cap knocking on your door:


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31st October 2005, 04:07 PM	#3
gpapag diyAudio Member Join Date: Nov 2002 Location: Athens-Greece	matjans the article deals (theoretically) with this problem. Some measures have to be taken during construction. What i am interested in is the sound of the filterless versus the filtered (same) class D. Any experience? The supplied URL does not work. Use this insteadhttp://focus.ti.com/lit/an/sloa023/sloa023.pdf Regards George

31st October 2005, 04:59 PM	#5
gpapag diyAudio Member Join Date: Nov 2002 Location: Athens-Greece	Does this mean it was already agreed that it sounded better filterless?

31st October 2005, 05:04 PM	#6
gpapag diyAudio Member Join Date: Nov 2002 Location: Athens-Greece	I just realised that i opened this thread in "Chip Amps" area instead of the more appropriate "Class D" area. If the moderator wishes to transfer it there , please do so. Regards George

31st October 2005, 05:45 PM	#8
gpapag diyAudio Member Join Date: Nov 2002 Location: Athens-Greece	A double thanks Al. Talking about links, here is another from Maxim dealing with (manageable) calculations for LC output filters. http://pdfserv.maxim-ic.com/en/an/AN624.pdf Regards George

1st November 2005, 07:06 AM	#10
PWMan diyAudio Member Join Date: Mar 2005 Location: Taiwan	I've been measure a 2W stereo filterless class-D chip in the EMI anechonic chamber, a pair of speaker cable is only 30cm, the EMI radiation result is really bad even in the quiescence and supply voltage is only 5V, don't even think about rated power output. Filterless type class-d is only suite for "no speaker cable outside" applications , You needs to install all componenents in a shielded case, such like a laytop PC or mobilephone.

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