Power Supply Resevoir Size - Page 151 - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

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 October 2012, 01:38 PM   #1501
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
No.
Either the amplifier is clipping, or the amplifier is not clipping.

You are drawing a conclusion that is false.
__________________
regards Andrew T.
  Reply With Quote
Old 18th October 2012, 01:42 PM   #1502
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
For the amplifier not to clip the average music signal must be well below clipping, not just below. This is because of the large peak/mean ratio for real music and the slightly smaller ratio for well-recorded music.
  Reply With Quote
Old 18th October 2012, 01:45 PM   #1503
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
I don't care what the music might do, the statement is
"the amp is not clipping the signal"

The conclusion that the amp
"must have some method to prevent clipping."
is not a valid.
__________________
regards Andrew T.
  Reply With Quote
Old 18th October 2012, 05:22 PM   #1504
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
That would depend on how clipping is avoided. Running near clipping for most of the time I take to mean that the average level is near clipping, as for most of the time music is near its average level. Maybe that is not what he meant, but that is what he said. If he meant to say that the music is at a much lower level, nowhere near clipping, then this tells us nothing about the PSU because it is not having to deliver very much current and there will be very little droop.
  Reply With Quote
Old 18th October 2012, 05:44 PM   #1505
diyAudio Member
 
Nico Ras's Avatar
 
Join Date: Nov 2005
Location: East Coast of South Africa
Quote:
Originally Posted by AndrewT View Post
I don't care what the music might do, the statement is
"the amp is not clipping the signal"
Precisely!

The amp power supply may be modulated pretty severely but that does not necessarily imply that amp is driven into clipping.

Also music and pure sine waves would behave quite differently and that is what Frank is referring to. If it is a sine wave, the the powers supply modulation would be in sync with the signal and may affect the way it sounds but it would not be horrible.

However, if it is a complex signal the power supply will be modulated most by the highest power signal which would "mix" with all other signals and besides smearing due to inter-modulation artifacts these artifacts could also contain dissonance which is most fatiguing because it is sounds our brains do not like.

Exactly what this thread is trying to address.
__________________
Kindest regards
Nico

Last edited by Nico Ras; 18th October 2012 at 05:48 PM.
  Reply With Quote
Old 18th October 2012, 10:08 PM   #1506
fas42 is online now fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 11
Quote:
Originally Posted by DF96 View Post
That would depend on how clipping is avoided. Running near clipping for most of the time I take to mean that the average level is near clipping, as for most of the time music is near its average level. Maybe that is not what he meant, but that is what he said. If he meant to say that the music is at a much lower level, nowhere near clipping, then this tells us nothing about the PSU because it is not having to deliver very much current and there will be very little droop.
There has been a misunderstanding of what I meant, I most certainly am not talking about average levels of the signal being near clipping, rather whether the peak level ever clips. I'm very much aware that music has dynamics , so when I say close to clipping I am referring to the piece of music as a whole; in the same way that a recording engineer will master a non-compressed CD so that the maximum level ever reached, at probably one point in the whole disk, is perhaps zero, one or two bits from the absolute maximum - the term used is to normalise the levels.

I have got my chip amps to overload, but this was thermal overload, the sound starts to chatter as the protection cuts in and out; interestingly, this is never on pop but rather operatic -- the soprano hits a big note and sustains it, a very pure, high level tone over a decent period was enough to start overcooking the chips ...

As regards drooping, it is, or was, endemic to amplifiers. Back when I was really into trying to understand what caused sound quality problems I made a point of experimenting with every system in a dealer's showroom that I came across, and they all displayed this characteristic. Irrespective of how massive the metalwork was, there would be a certain volume where the sound would start to collapse, not clip, which I interpreted as the power supply being overtaxed ...

Frank

Last edited by fas42; 18th October 2012 at 10:19 PM.
  Reply With Quote
Old 18th October 2012, 11:57 PM   #1507
diyAudio Member
 
Kindhornman's Avatar
 
Join Date: Aug 2012
Location: Los Angeles, California
It would seem to me that what we need here is an absolute definition of clipping in this instance. I can understand when a power supply reaches the point where the sag in the rails is enough to change, or cut a waveform that the amplifier is trying to produce. A square wave that has rounded corners or a sine wave that has the tops cut off would make me think of clipping. On the other hand you could have a power supply so over-sized that you will never get into that condition but the amplifier is driven so hard it is out of the SOA and also is clipping in that the waveforms are distorted by thermal conditions. So who is going to define the actual term clipping as we are trying to use in this instance? I have always assumed that if you never reach the point where the loudest or sustained peaks do not become changed in any way that you are under the clipping level of the system. You have enough headroom to stay out of that condition.
  Reply With Quote
Old 19th October 2012, 12:40 AM   #1508
fas42 is online now fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 11
Perhaps as good as any -- from the Rane dictionary: http://www.rane.com/par-c.html:

Quote:
clipping Term used to describe the result of an amplifier running into power supply limitation. The maximum output voltage that any amplifier can produce is limited by its power supply. Attempting to output a voltage (or current) level that exceeds the power supply results in a flattoping effect on the signal, making it look cut off or "clipped." A clipped waveform exhibits extreme harmonic distortion, dominated by large amplitude odd-ordered harmonics making it sound harsh or dissonant. Hard clipping is the term used to describe extreme clipping of a signal, producing highly visible flattoped waveforms as viewed on an oscilloscope; soft clipping refers to moderate clipping that results in waveforms having softly-rounded edges, as opposed to the sharp edges of hard clipping.
I am talking otherwise of the power supply voltage rails being sufficiently modulated by the current demands to interfere with the correct functioning of the amplifier circuitry: the PSRR not being good enough, or the regulation or smoothing being insufficient, causing the SQ to deteriorate ...

Frank
  Reply With Quote
Old 19th October 2012, 01:55 AM   #1509
diyAudio Member
 
Kindhornman's Avatar
 
Join Date: Aug 2012
Location: Los Angeles, California
Thank you Frank for the definition. It appears that I had the correct idea about the term. Now I have a separate question. On an amplifier with a clipping light what exactly is the light indicating when it is triggered? I know it is called a clipping light but where in the circuit is the clipping indicator located and what is it actually measuring?
  Reply With Quote
Old 19th October 2012, 03:12 AM   #1510
fas42 is online now fas42  Australia
diyAudio Member
 
fas42's Avatar
 
Join Date: Jun 2012
Location: NSW, Australia
Blog Entries: 11
At least one take on an indicator, by that ever prolific chap, Rod Elliot, is here: Power Amp Clipping Indicator. It doesn't cover how it's often implemented in commercial units, but explains precisely how such a circuit should work ...

Frank
  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
Valve power supply - How to size transformer? SanderW Power Supplies 25 4th January 2013 04:12 PM
How do you calculate choke size in a power supply? Original Burnedfingers Tubes / Valves 25 5th January 2012 12:23 AM
power supply bypass cap size BigE Power Supplies 11 5th July 2011 02:59 PM
Power Supply Case Size diymixer Power Supplies 1 10th October 2010 05:47 AM
What size power supply should I get for repair work? spooney Car Audio 3 6th December 2007 11:50 PM


New To Site? Need Help?

All times are GMT. The time now is 11:07 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