Class B w/o crossover distortion (1975) - Page 7 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 4th February 2010, 12:55 AM   #61
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by Eva View Post
Warning: Performing speaker THD measurements may result in permanent changes in your point of view about amplifier THD
Not necessary. It may cause a curiosity, why hearing ignores distortions caused by mechanical things, but don't forgive distortions caused by electronics. That will lead to Tube forum for answers why.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 4th February 2010, 01:07 AM   #62
AKSA is offline AKSA  Australia
diyAudio Member
 
Join Date: Sep 2001
Location: Melbourne, Australia
Wahab,

You are right. Q1/Q2 are indeed a diff pair, though a series connection. Voltage feedback is the mode of operation, and pnp driver current is indeed limited by the RC boostrap load resistors. And the current variation through the RC is the weak point of this design.

In truth, it is a power buffer, not an amplifier, and presented here as a curiosity, just another way of doing a power output stage.

Rod's article is good, it is consistent with most of my past designs. The road to a commercial amplifier is (and should be) littered with many different theoretical amplifiers, whose pros and cons must be carefully assessed. I am more than happy to throw up some of these ideas, but if you (and others) prefer I'm happy to remain silent.

Please remember that I make no claim to excellent design here, I am merely presenting an idea.

Hugh
__________________
Aspen Amplifiers P/L (Australia)
www.aksaonline.com
  Reply With Quote
Old 4th February 2010, 02:18 AM   #63
Eva is offline Eva  Spain
diyAudio Member
 
Eva's Avatar
 
Join Date: Oct 2003
Location: Near the sea
Send a message via MSN to Eva
Music is currently being recorded by feding the output of a microphone to an ADC and then to the input of a digital data storage device.

The data used to analyze the THD from a loudspeaker or an amplifier is obtained exactly in the same way.

Waveforms are just information, and that's what we hear. Speaker THD and amplifier THD must be the same thing.
__________________
I use to feel like the small child in The Emperor's New Clothes tale
  Reply With Quote
Old 4th February 2010, 03:34 AM   #64
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally Posted by Eva View Post
Speaker THD and amplifier THD must be the same thing.
For computer?
Sure.
For brain?
No.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 4th February 2010, 08:23 AM   #65
AKSA is offline AKSA  Australia
diyAudio Member
 
Join Date: Sep 2001
Location: Melbourne, Australia
Now now you two, just agree to disagree........
__________________
Aspen Amplifiers P/L (Australia)
www.aksaonline.com
  Reply With Quote
Old 4th February 2010, 09:15 AM   #66
hahfran is offline hahfran  Germany
diyAudio Member
 
Join Date: Dec 2007
Quote:
Originally Posted by Eva View Post
Music is currently being recorded by feding the output of a microphone to an ADC and then to the input of a digital data storage device.

The data used to analyze the THD from a loudspeaker or an amplifier is obtained exactly in the same way.

Waveforms are just information, and that's what we hear. Speaker THD and amplifier THD must be the same thing.
No. A well known example is the strike sound of a church bell. When the tongue hits the bell we hear this particular strike sound but objectively it does not exist. As a matter of fact we hear a lot that objectively does not exist and we don't hear a lot details in sound fields which objectively exist.
Your assumption that human audition is in any way linear ( i.e. a linear system) such that it linearly maps an objective sound field onto a subjective impression is entirely wrong. So briefly all that matters is how it sounds and that is not a matter of thd if thd is around some %.
  Reply With Quote
Old 4th February 2010, 11:00 AM   #67
wahab is offline wahab  Algeria
diyAudio Member
 
Join Date: Nov 2009
Location: algeria/france
Quote:
Originally Posted by AKSA View Post
Wahab,

You are right. Q1/Q2 are indeed a diff pair, though a series connection. Voltage feedback is the mode of operation, and pnp driver current is indeed limited by the RC boostrap load resistors. And the current variation through the RC is the weak point of this design.

In truth, it is a power buffer, not an amplifier, and presented here as a curiosity, just another way of doing a power output stage.

Rod's article is good, it is consistent with most of my past designs. The road to a commercial amplifier is (and should be) littered with many different theoretical amplifiers, whose pros and cons must be carefully assessed. I am more than happy to throw up some of these ideas, but if you (and others) prefer I'm happy to remain silent.

Please remember that I make no claim to excellent design here, I am merely presenting an idea.

Hugh
no pun intended, hugh...
just wanted to highlight the fact that numerous topologies
where tested during the 70 s, and that few working ones did
emerge from the then inventive times...
there s 4 schematics mainly, with the three last being evolutions from
the first one..
first, a simple vas + output stage..
second, the same with an added input stage,giving
the cfb i quoted..
three, the latter with yet another device to make a differential
at the input, this is the lin that was and still the most used...
four is symetrisation of this differential, to go to a symetrical
differential...
almost all circuits are variations of these four ones, and it happens
that nothing better has been found since despite the claims
of numerous designers...



regards,

wahab
  Reply With Quote
Old 4th February 2010, 08:45 PM   #68
AKSA is offline AKSA  Australia
diyAudio Member
 
Join Date: Sep 2001
Location: Melbourne, Australia
Wahab,

The fact this is a road well trod, and one so universally below par (how many commercial amps sound good?), is strong reason to continue the quest.......

I hope you are not discouraged by the conventional, which is all around us. It should be motivation to do better, to come up with something completely different. Certainly that is what drives me, despite having no more than second year undergraduate math.

Hugh
__________________
Aspen Amplifiers P/L (Australia)
www.aksaonline.com
  Reply With Quote
Old 5th February 2010, 09:45 PM   #69
hahfran is offline hahfran  Germany
diyAudio Member
 
Join Date: Dec 2007
I found another even older design idea that is intended to avoid switching and crossover distortion. However I am unfamliar with PSpice the free version. I need a bunch of transistor models and a method to load these, if found, in the model library.
  Reply With Quote
Old 5th February 2010, 11:04 PM   #70
AKSA is offline AKSA  Australia
diyAudio Member
 
Join Date: Sep 2001
Location: Melbourne, Australia
Hahfran,

Simulations won't tell you how the amp will sound, but are useful development tools. I suggest LTSpice, which is quite good and has readily available models, some on this forum. You can insert them into the model library using a text editor like Notepad; PSpice models work just fine.

Would you be happy to share your latest find?

Hugh
__________________
Aspen Amplifiers P/L (Australia)
www.aksaonline.com
  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
low crossover-distortion class AB output stage topologies capslock Solid State 72 10th May 2013 07:48 PM
Exactly titles of old transistor data books from NEC, SONY and Fujitsu (1975 - 1985) tiefbassuebertr Solid State 5 12th December 2011 05:31 PM
Crossover distortion - be gone! Circlotron Solid State 4 24th August 2009 12:09 PM
Crossover distortion lumanauw Solid State 100 14th January 2005 12:58 AM
Crossover Distortion? Killjoy99 Multi-Way 8 30th March 2004 05:10 AM


New To Site? Need Help?

All times are GMT. The time now is 06:55 AM.


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