class d with atch - diyAudio
Go Back   Home > Forums > Amplifiers > Class D

Class D Switching Power Amplifiers and Power D/A conversion

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 18th March 2005, 02:18 PM   #1
diyAudio Member
 
Join Date: Mar 2005
Location: somerset
Red face class d with atch

Iím building a class D amplifier using the LM4651 and LM4652 chip set I intend to provide two full range and a subwoofer/ low pass channel. Power will be provided by three separate toroidal transformers to avoid crosstalk and something like 30 and 18 odd thousand uF on the board which I hope will stabilise it without regs. Any comments on this are welcome.
Iíve simulated a filter system which seems to work quite well which hopefully I can post here somewhere, but how does this affect the input resistance the main amplifier is required to see or match with the values of R1, R2 (not their ratio) and RLP, CLP should they be removed with such an active filter?
Is this a good way to take a low pass from a stereo signal?
Anyway has anybody please got any ideas on how to implement a volume control?

Cheers from spud
Attached Files
File Type: zip pre amps.zip (23.1 KB, 118 views)
  Reply With Quote
Old 11th April 2005, 09:23 PM   #2
jmateus is offline jmateus  United States
diyAudio Member
 
jmateus's Avatar
 
Join Date: Mar 2003
Location: US, New Jersey
Just curious, what did you do for PCB?
Or, on the other hand are you using perf board?
__________________
JLH 2005, Cyrus and so on...
  Reply With Quote
Old 13th April 2005, 07:43 PM   #3
diyAudio Member
 
Join Date: Apr 2005
Location: In the Wild, Wild West
If you are using an active filter then check out the full range schematic in the LM4651/52 datasheet. The Gerbers for it are also on the National site. On this board is a pre-amp with a gain of 10V/V and a 2nd order active low pass filter. The low pass filter is set up around 22kHz, I think. I think this might answer most of your questions.

As for your other circuits have you ever seen the AN-31 App. Note from National? Lots of Op. Amp circuits in there. If you want to sum the left and right signals you could probably use the summing circuit then low pass filter them. The order of filtering and summing probably doesn't matter.
  Reply With Quote
Old 14th April 2005, 09:07 AM   #4
rfasic is offline rfasic  France
diyAudio Member
 
Join Date: Jan 2005
Location: PARIS
Spudspud,

I got rather good results with the stereo digital volume control chip from Crystal (Cirrus Logic) CS3310.

The only extra thing you need is a little Ķc (pic, 8051 etc) with
very little code inside (16 bits data on SPI bus) to control the
output level.

Some high end audio amps are using this chip too.

Regards
  Reply With Quote
Old 19th April 2005, 06:01 PM   #5
diyAudio Member
 
Join Date: Mar 2005
Location: somerset
hi folks, not been here for a while, but the project is coming along fine, I've finished the power supply, we etched the boards at college as national sems data sheet shown and Ive been drilling the 273 holes per board at home for the last couple of days, I'm getting more proficient . I'm online to order some parts so best crack on, see ya later. Cheers for filter info.
  Reply With Quote
Old 19th April 2005, 06:05 PM   #6
diyAudio Member
 
Join Date: Mar 2005
Location: somerset
To Rfasic was that with this amp (been to your city a few times)
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
1500W RMS Class D PCB - which Class D Driver Chip is it ? mosfetsound Class D 11 1st April 2011 11:17 AM
Can a Class AB PP amp be said to be operating in Class A at low signal levels? ray_moth Tubes / Valves 19 23rd January 2009 07:52 PM
How about a round-up of Class A kit power amps, or collectable vintage class A? Brisso57 Solid State 4 14th February 2007 10:30 AM
JHL Class A ,Higher power circuit, 40W Class A nicolas888 Solid State 8 13th April 2006 04:27 PM


New To Site? Need Help?

All times are GMT. The time now is 01:50 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2