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

Instruments and Amps Everything that makes music, Especially including instrument amps.

Power Amplifier [150Euros]
Power Amplifier [150Euros]
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 26th August 2019, 03:57 AM   #11
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: Maine USA
The value of the fundamental of a square wave is not 1.0 but 1.27. That does not cover the discrepancy, but reminds up that wave-smacking is not a simple thing.
  Reply With Quote
Old 26th August 2019, 04:16 AM   #12
Gnobuddy is offline Gnobuddy  Canada
diyAudio Member
 
Join Date: Mar 2016
Quote:
Originally Posted by PRR View Post
And that link contains the sentence "A pure square wave with infinite harmonics has THDF of 48.3%,[1][13][14]..."

The first of those references is available online, and proved to be readable, at least initially; I was able to follow the calculation of THD for a square wave, and it is {square root of ( ((pi^2)/8) - 1 )}, which works out to 48.3%.

So you are correct, and my estimate is badly wrong.

I think I found the mistake I was making: I calculated THD for a square wave and sine wave of the same peak value, visualizing an amp gradually driven from clean into clipping.

But if you take the Fourier series of a square wave, the amplitude of the fundamental is not the same as the amplitude of the square wave...it's bigger! (And so, THD is lower.)

This leads to something I didn't expect at all: if you feed an amplifier a sinewave, and gradually turn up the amplitude till clipping starts, and then push it further into clipping, the amplitude of that fundamental-frequency sinewave continues to increase!


-Gnobuddy
  Reply With Quote
Old 26th August 2019, 04:17 AM   #13
Gnobuddy is offline Gnobuddy  Canada
diyAudio Member
 
Join Date: Mar 2016
Quote:
Originally Posted by PRR View Post
The value of the fundamental of a square wave is not 1.0 but 1.27. That does not cover the discrepancy, but reminds up that wave-smacking is not a simple thing.
You posted that while I was composing my last post...I think we both found the error I was making at about the same time.


-Gnobuddy
  Reply With Quote
Old 26th August 2019, 04:04 PM   #14
PRR is offline PRR  United States
diyAudio Member
 
PRR's Avatar
 
Join Date: Jun 2003
Location: Maine USA
Quote:
Originally Posted by Gnobuddy View Post
And that link contains the sentence "... THDF of 48.3%..."
I didn't *read* my own citation! Thanks for spotting that.

> fundamental-frequency sinewave continues to increase!

Intuitively: if you tune your ear to just the 1kHz, and crank past clipping, the 1kHz *does* increase. Yes, that's not normal hearing: the harmonics cloud perception, and we are used to just hearing "louder" without reference to the fundamental. I would not trust my ears either way (blind or knowing). Band-filter meter would tell; so could a tuned pipe (snip of garden-hose) on an SPL meter.

me> reminds up that wave-smacking

Sorry, "...reminds us that wave-smacking..."
  Reply With Quote
Old 17th September 2019, 09:29 PM   #15
forart.eu is offline forart.eu  Italy
diyAudio Member
 
Join Date: Apr 2009
Location: Marche
Quote:
Originally Posted by Entas View Post
Hello,

Checking some Power Amps, the one that I like the t.amp E-400 Thomann Lithuania. Can I find better one than this? Is this thing actually have 190Wrms @ 4ohm?
What about Behringher A800 (2 x 400W @ 4ohms) which is a fanless Class-D reference studio amplifier available between 170-180 ?
  Reply With Quote

Reply


Power Amplifier [150Euros]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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Amplifier kit HOOD JLH 1969 Class A Power amp kit 2 channel amplifier 10W+10W hifisuran Solid State 2 21st July 2019 06:57 AM
Snail Power CA18 Professional Power Amplifier,Blown Fuse & Power Transistors shorted Peter Qiu Solid State 1 10th December 2016 12:01 PM
An amplifier to take to University - A small low power integrated amplifier monty78pig Solid State 33 31st August 2012 06:00 AM
Amplifier 3000 Wats Rms Power + Smps Higcht Power Bestiality MARAVILLASAUDIO Class D 1 5th November 2004 04:06 PM


New To Site? Need Help?

All times are GMT. The time now is 07:16 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki