Quality of LP filters for PWM - for audio performance
Posted:
Tue Oct 05, 2004 6:31 pmby John K5PRO
Maybe its been posted here before. Jim Tonnes (formerly of Collins Broadcast) has some useful software and analysis of low pass filters used in PWM audio amplifiers for broadcast/amateur modulators.
http://mywebpages.comcast.net/tonne/app ... wmham.html
His main website has software and other tips. Its at:
http://mywebpages.comcast.net/tonne/index.html
Posted:
Wed Oct 06, 2004 8:28 amby frank carcia
John,
Very Good find. Notice the corner of the first filter section is a lot lower than the second. Also the first inductor is larger than the second. fc
Posted:
Fri Oct 08, 2004 7:29 amby ke1gf
John,
There are lots of good points in this page that you posted.
I'm wondering if Blaine could make the page sticky, understanding jim's stuff would be a great help to the PWM beginner.
I downloaded Elsie a few weeks ago, it doesn't seem to want to run on my WinXP,SP2 machine but runs OKFINE on the WIN98 box, haven't tried it yet under WINE.
Speaking of WINE, SWCADIII runs good under it.
-Bill
Yes, good paper.
Posted:
Thu Nov 25, 2004 5:12 pmby N9NEO
I just had an interesting email volley with Jim T. He is putting some rigs together to get back on the bands. Hope he stops by here. He would be a good contributor.
Below are links to more of his app notes and also some cool software.
73
Bob
http://mywebpages.comcast.net/tonne/appnotes.html
http://tonnesoftware.com/
Re: Quality of LP filters for PWM - for audio performance
Posted:
Wed Apr 16, 2014 5:19 pmby Brian K1LI
I found Jim's note at the end of his paper, re: scaling the filter's input and output impedances, to be somewhat cryptic. A freeware program called AADE Filter Design allows the designer to explicitly set the filter's input and output terminating impedances. I validated my design by porting it to LTSpice and to Elsie.
See
http://www.aade.com/filter.htm