Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Class D Switching Power Amplifiers and Power D/A conversion

My class D amp
My class D amp
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 5th July 2013, 03:35 PM   #401
exflaco is offline exflaco  Armenia
diyAudio Member
 
Join Date: Mar 2005
Location: Santa Fe
Syaelend schematics please, thanks
  Reply With Quote
Old 5th July 2013, 04:27 PM   #402
syaelend is offline syaelend
diyAudio Member
 
Join Date: Feb 2011
Quote:
Originally Posted by exflaco View Post
Syaelend schematics please, thanks
Hi Exflaco,

I'll prepare it first, and post it after finish, coz now I have no any schematic of it.
  Reply With Quote
Old 5th July 2013, 04:30 PM   #403
syaelend is offline syaelend
diyAudio Member
 
Join Date: Feb 2011
Quote:
Originally Posted by manojtm View Post
Hi Syaelend,

AUD600 Ver1.0,1.1,3.0 & 3.0.1 donot using PIC629(PIC microcontroller)

Regards
MANOJ
Dear Mr.Manoj
there's ic that mark PIC629, what ic is i?. Is it replace Timer IC 555?
Warm regards

Syaelend
  Reply With Quote
Old 6th July 2013, 03:24 PM   #404
manojtm is offline manojtm  India
diyAudio Member
 
manojtm's Avatar
 
Join Date: Aug 2008
Location: KERALA
Hi Tekko,

The heart of a Class-D amplifier(all type) filter is a L-C low-pass filter. The corner frequency of the filter is chosen so that the filter will have minimal effect on the desired output frequency range while attenuating the switching noise as much as possible.

The optimum value for the filter inductor is

L = RL/2pfC

where fC is the desired corner frequency of the filter and RL is the load (speaker) resistance. Note that the inductor value is dependent on both the desired corner frequency and the speaker impedance so the inductor value will changes if the speaker impedance changes.

Practical designs require the use of standard component values so small adjustments usually have to be made to the ideal inductor and capacitor values. Rather than calculating the inductor and capacitor values independently and then adjusting their values, it's better to calculate the inductor value, select the closest standard inductance value, and then calculate the required capacitance using the selected inductor.

C = 1/((2pfC)2 L)
The quality factor (Q) of a filter is the ratio of the center frequency to the filter bandwidth.

Q = RLv(C/2L)
A high Q produces an underdamped curve and a low Q produces an overdamped curve. The Q of the filter should be in the range 0.6 > Q > 0.8 to avoid underdamped or overdamped behavior. If you use the equations above the filter should have a Q of about 0.7, which provides good performance and allows for impedance variation in the speakers. Note that the Q of the filter will change if the speaker impedance is changed without adjusting the filter component values, which can result in an underdamped or overdamped response.


Not only is it important to choose the correct L-C filter values, it is also important to choose the correct types of components for the class-D amplifier in order to avoid losses and minimize harmonic distortion.

The DC current rating of filter inductors must be greater than or equal to the maximum current that it will see. The change in inductance versus load current should not be more than 10%. The core material can affect the amplifier's harmonic distortion and should have very low hysteresis losses.
  Reply With Quote
Old 6th July 2013, 04:28 PM   #405
doctordata is offline doctordata  Australia
diyAudio Member
 
doctordata's Avatar
 
Join Date: Apr 2010
Location: Brisbane
My class D amp
Quote:
Originally Posted by Tekko View Post
I switched between open circuit and 0.8 ohm load on my ucd class d in BTL mode yesterday and the switching freq dident even flinge, it stayed on ~360kHz and did not move.

The problem with pre filter feedback self osc as several have outlined is that if the amp is made for 4 ohms, then at 8 ohms the freq response will increase as a spike at higher frequencies, whilst it may not be audible to most its still unacceptable as it means the amp is unstable.

Likewise a amp made for 8 ohms will start rolling off at early as 5kHz with a 4 ohm load.

While on UcD (post filter fb selfosc) the frq response barely changes at all from 0.5 ohms(some car subwoofers) to unloaded, it never starts spiking/peaking at higher freq like pre filter fb does.
What's the big deal here. I have 8 ohm speakers for years now and will probably have them for another 20 years . My ( pre ) filter is designed for 8 ohms , so fine and flat response here, no roll off in the highs .If I ever buy new 4 ohm or whatever impedance speakers to replace my current ones with the same quality , I have to spend at least a couple of thousand dollars . Replacing my output filter with high quality inductors and caps to match the new speakers impedance will set me back at least 12 dollars per channel

Cheers ,

Rens
__________________
If you measure, you know; if you guess, you don't
  Reply With Quote
Old 7th July 2013, 06:32 AM   #406
akraj is offline akraj  Bangladesh
diyAudio Member
 
Join Date: Nov 2010
Quote:
Originally Posted by syaelend View Post
Hi Mr. Manoj,
On your AUD600 ver 3.0 you use PIC629, is it a micro controller ic? what does it used?
Regards

Syaelend

I modified the schema, it is used for protections such as DC, OVP, OCP etc.

Thanks
Raj
  Reply With Quote
Old 7th July 2013, 09:59 AM   #407
syaelend is offline syaelend
diyAudio Member
 
Join Date: Feb 2011
Quote:
Originally Posted by akraj View Post
I modified the schema, it is used for protections such as DC, OVP, OCP etc.

Thanks
Raj
Dear Raj,

Thanks for your explanation,
Could you please send your modified schematic to my email add. syaelend@gmail.com

Many thanks in advance.
  Reply With Quote
Old 8th July 2013, 05:07 PM   #408
wattaniya is offline wattaniya
diyAudio Member
 
Join Date: Oct 2009
pls anybody tell me is this core suitable for class d amps,
outer dm-2 inch
inner dm-1.25 inch
Attached Images
File Type: jpg T200_8.jpg (42.0 KB, 950 views)
  Reply With Quote
Old 9th July 2013, 07:15 AM   #409
manojtm is offline manojtm  India
diyAudio Member
 
manojtm's Avatar
 
Join Date: Aug 2008
Location: KERALA
Hi Nazirdigi,

I think it is suitable for class d amp (Al=18)

Regards
MANOJ
  Reply With Quote
Old 9th July 2013, 07:57 AM   #410
JLesterP is offline JLesterP  Philippines
diyAudio Member
 
Join Date: Sep 2010
Location: Quezon City
Yes, micrometals material 2(red), 6(yellow/clear) and 8(yellow/red) are good for class-D.
__________________
amplifier PCBs and modules
  Reply With Quote

Reply


My class D ampHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
TBJ's Class D - a discrete class D amp that anyone can build! (Work-In-Progress) tbj Class D 11 18th January 2017 08:49 PM
Leaving class A how to make this amp leave class A to AB when volume is increased? rhythmsandy Solid State 3 14th June 2016 02:16 AM
Contest: Linear Power Amp in a mint tin (class Aa, class AB, or class B) danielwritesbac Chip Amps 206 19th January 2013 09:52 PM
does class A amp feel more powerful with same ratings compared to class AB? rhythmsandy Solid State 7 10th December 2012 06:21 PM
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 08:52 PM


New To Site? Need Help?

All times are GMT. The time now is 10:08 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki