Coldn't resist: feedback from 4th order lowpass !!

no you dont see many but there are some (we have a few....)

Hi Karsten

We know that already. But I think you still owe us some specs. You won't have to repeat that specs are not telling everything, we know that as well. ;)
But they are still interesting for techheads like us, specially when chances are small that anyone of us will ever get a chance to hear one of your amps.

Regards

Charles
 
hi.

charles have you visited our website recently?

we do have specs there and i dont know why you say "specially when chances are small that anyone of us will ever get a chance to hear one of your amps."

we do sell them just like we sell some from other manufacturers as well, so i would think you have a good chance to hear them and compare them to whatever you like or fancy ;)

k madsen - www.cadaudio.dk

ps. i still think that the topology in question with feedback after the output filter has advantages in terms of audio quality , this however isnt too easy to illustrate with specs, is it?
 
ps. i still think that the topology in question with feedback after the output filter has advantages in terms of audio quality

We don't have to argue about that since it is already common belive here !!!

I was indeed posting my above statement before I visited your site for the last time. It has indeed improved significantely, but there could still be some more specs published (which might also improve sales).

Regards

Charles
 
Hi Charles,

I guess it is high time to give the 4th order filter with post filter feedback a try, since my application has 270VDC mono rail voltage in Full-Bridge BD2 mode, the resulting ripple was quite high with 2nd order filter. I am going to try both Butterworth and Bessel curves.

regards,
Kanwar
 

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Hi Kanwar

That seams to be a "real workhorse" ! ;)

What is the switching frequency and what is the cutoff frequency of the originally intended 2nd order filter? If the problem aren't the the higher order switching residues but only the fundamental then maybe some notch filter could work as well.

Regards

Charles
 
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Hi Kanwar

That seams to be a "real workhorse" ! ;)

What is the switching frequency and what is the cutoff frequency of the originally intended 2nd order filter? If the problem aren't the the higher order switching residues but only the fundamental then maybe some notch filter could work as well.

Regards

Charles
Hi Charles,

FSW is 52kHz [BD2 will do a 104kHz ripple at output, not the usual 2X classic AD half bridges performing full bridge operation but switching pulses will follow signal polarity like in linear class-B in each half bridge. Will force the idle current with minimum pulse width to minimize x-over like distortion though] and I am designing the output filter for cutoff frequency around 5kHz. This is purely for large driver application [22-24"] in subwoofers with industrial IGBTs.

Regards,
Kanwar