Class D at low volume levels - Page 2 - 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 10th February 2010, 05:11 PM   #11
diyAudio Member
 
Join Date: Apr 2006
Location: Reykjavík
Haven't noticed any lack of low-volume quality with my 41Hz amps, except when I'm using uncased amps and cheap supplies and noise starts to be a factor ...
  Reply With Quote
Old 11th February 2010, 12:22 PM   #12
81bas is offline 81bas  Germany
diyAudio Member
 
Join Date: Jan 2006
Location: Kiel
Quote:
Originally Posted by Workhorse View Post
ERRRRRRRR........................

From which angle T 2020-amp becomes digital and from where these 24 bits DSP came in jumping for resolution

http://www.kafka.elektroda.eu/pdf/tripath/TA2020.pdf

T-amp uses spread spectrum analog modulation, no DSP with 24 bits
Anyway, they DO have some hi freq internal clock, making their modulation NON-contiguous or discrete, with limited resolution. Please, do not mix it with triangle wave, which is also some kind of clock, but is NOT an discrete modulation.

Last edited by 81bas; 11th February 2010 at 12:34 PM.
  Reply With Quote
Old 11th February 2010, 12:29 PM   #13
81bas is offline 81bas  Germany
diyAudio Member
 
Join Date: Jan 2006
Location: Kiel
Quote:
Originally Posted by wwenze View Post
Doesn't the loudness of the input signal (which is determined by the volume pot and not the amp) affect only the duty cycle in a class-D amp? Where does bits come in?
Tripath's amps work in complete other way. Typical square output from T-amp:
Quote:

___| |___| |_| |_| |___| |___| |_| |_| |____
This is very similar to the delta-sigma modulator output, but it is NOT an delta-sigma modulator...

Last edited by 81bas; 11th February 2010 at 12:32 PM.
  Reply With Quote
Old 11th February 2010, 01:23 PM   #14
wwenze is offline wwenze  Singapore
diyAudio Member
 
Join Date: Mar 2008
Quote:
___| |___| |_| |_| |___| |___| |_| |_| |____
I'm not sure if I understood you correctly, how is this different from other class-D amps?
  Reply With Quote
Old 11th February 2010, 01:48 PM   #15
diyAudio Member
 
Ouroboros's Avatar
 
Join Date: Dec 2003
Location: Nottingham UK
It looks as if the high time period is constant, which would effectively be pulse density modulation.

I must say that I thought the tripath amps were another self-oscillating design, with a more complex than usual feedback modulator. If they really were PDM, then a bridged version would need to use 3-level modulation. Are you really sure this is the case?
  Reply With Quote
Old 11th February 2010, 01:58 PM   #16
81bas is offline 81bas  Germany
diyAudio Member
 
Join Date: Jan 2006
Location: Kiel
Quote:
Originally Posted by wwenze View Post
I'm not sure if I understood you correctly, how is this different from other class-D amps?
To make it clear, this 'pattern' is shown for the moment, when the input voltage is constant. In usual class D amp, when the input voltage is constant, the duty cycle is constant also.
  Reply With Quote
Old 11th February 2010, 01:59 PM   #17
81bas is offline 81bas  Germany
diyAudio Member
 
Join Date: Jan 2006
Location: Kiel
Quote:
Originally Posted by Ouroboros View Post
It looks as if the high time period is constant, which would effectively be pulse density modulation.

I must say that I thought the tripath amps were another self-oscillating design, with a more complex than usual feedback modulator. If they really were PDM, then a bridged version would need to use 3-level modulation. Are you really sure this is the case?
Tripath amps are defenitely NOT the self oscillating amps...
  Reply With Quote
Old 11th February 2010, 02:28 PM   #18
diyAudio Member
 
Workhorse's Avatar
 
Join Date: Dec 2004
Quote:
Originally Posted by 81bas View Post
To make it clear, this 'pattern' is shown for the moment, when the input voltage is constant. In usual class D amp, when the input voltage is constant, the duty cycle is constant also.

Little knowledge is dangerous thing.

If the duty cycle with no signal condition is not uniform (means 50-50%) in tripath amps, then you will get considerable DC OFFSET AFTER INDUCTOR at output...............




  Reply With Quote
Old 11th February 2010, 02:37 PM   #19
81bas is offline 81bas  Germany
diyAudio Member
 
Join Date: Jan 2006
Location: Kiel
Quote:
Originally Posted by Workhorse View Post
Little knowledge is dangerous thing.

If the duty cycle with no signal condition is not uniform (means 50-50%) in tripath amps, then you will get considerable DC OFFSET AFTER INDUCTOR at output...............



Can you please read the messages carefully, before posting the answers in red color? I have said about the CONSTANT input voltage, not about absence of the input signal

And the following square wave will NOT produce any DC after lowpass filter, although it does NOT have 50% duty cycle:

____-_____------_------_____-_____-----_-----_____-_____-----_-----_____-_____-----_-----

Last edited by 81bas; 11th February 2010 at 02:49 PM.
  Reply With Quote
Old 11th February 2010, 03:01 PM   #20
sendler is offline sendler  United States
diyAudio Member
 
Join Date: Aug 2004
Location: ny
Default Tripath sounds excellent

Quote:
Originally Posted by Ouroboros View Post
It looks as if the high time period is constant, which would effectively be pulse density modulation.

I must say that I thought the tripath amps were another self-oscillating design, with a more complex than usual feedback modulator. If they really were PDM, then a bridged version would need to use 3-level modulation. Are you really sure this is the case?
Quote:
Originally Posted by 81bas View Post
Tripath amps are defenitely NOT the self oscillating amps...
Whatever topology the Tripath driver chip uses, it is sonic genius. At louder listening levels, the modified Sure 2X100 amp with a MeanWell switch mode supply is by far the best sounding amp I have ever had home. Transparency, dynamics, and speed like no other. For $100.00!!! Too bad they went out of business. Luckily, there still seems to be good availability of chips.
See the link for a comparison to a newer TI driver amp.
Class D Audio, Who are these guys?
__________________
Scott
  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
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
Tuneful bass at low levels alspe Full Range 28 1st October 2008 01:30 PM


New To Site? Need Help?

All times are GMT. The time now is 06:33 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