Power amplifier with low thermal distortion - 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 19th January 2013, 03:09 PM   #1
diyAudio Member
 
Join Date: Sep 2009
Location: Lithuania
Default Power amplifier with low thermal distortion

Hello,

I create and build this power amplifier.
Ideas for building were to check mr. Lavardin theory about thermal distortions.
I used low feedback, open loop gain about 50db. Traditional distortion is low till half power. Currents for first stage 1mA, for VAS 2,5 mA, for EF 4,6 / 12 / 200 mA.

Sound is clear, voices and instruments have clear separation.
For listening was used Klipsh RF-3 speakers, sensitivity 98db.

I am looking for ideas how to improve this amplifier.
Attached Files
File Type: pdf LowThermal.pdf (30.8 KB, 137 views)
  Reply With Quote
Old 19th January 2013, 04:53 PM   #2
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Can you give some info on how you took care of the thermal distortion?
Did you do any measurements or something to check it?

jan
__________________
If you don't change your beliefs, your life will be like this forever. Is that good news? - W. S. Maugham
Check out Linear Audio!
  Reply With Quote
Old 19th January 2013, 05:09 PM   #3
diyAudio Member
 
Join Date: Sep 2009
Location: Lithuania
I use method published there: Memory Distortion Philosophies

Dalius
  Reply With Quote
Old 19th January 2013, 05:15 PM   #4
diyAudio Member
 
Join Date: Sep 2009
Location: Lithuania
Main idea, ensure constant power for gain stages. I use cascode for gain stage and for current sources.

Dalius
  Reply With Quote
Old 19th January 2013, 06:28 PM   #5
Bigun is offline Bigun  Canada
diyAudio Member
 
Bigun's Avatar
 
Join Date: Jan 2009
Blog Entries: 2
I have looked at these claims before. In the experiments I saw posted on the web, simple topologies are compared with more complex topologies. The use of CFP and of Cascodes. The results seem to be positive - less distortion and clearer sound. The theory makes sense, but it is claimed that memory distortion is an serious issue and that it's removal makes a big difference to the sound.

BUT the issue I have is that the experiments posted on the web do not prove that 'memory distortion' is a real practical issue that affects sound quality.

The reason is that these more complex topologies are inherently superior in technical performance even if you ignore ALL aspects of memory distortion from the analysis. The CFP has very low distortion compared with a single device. A Cascode reduces the Early Effect and greatly reduces Miller capacitance. You can't separate out the huge performance improvements from these more complex topologies due to better linearity and higher OLG from their impact on so-called memory distortion.

These are all very good design approaches and make for good amplifiers. But I don't see any evidence that 'memory distortion' is an issue for sound quality, or that it has been vanquished as an issue with these improvements. But it sure does make for some fun marketing.

I would like to add that the website you linked is very nicely presented and some good quality work is presented there. I admire the effort taken to do the work and share it for us to see.
__________________
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.

Last edited by Bigun; 19th January 2013 at 06:32 PM.
  Reply With Quote
Old 19th January 2013, 06:58 PM   #6
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: Great City of Turnhout, Belgium
Blog Entries: 7
Quote:
Originally Posted by dmatiukas View Post
Main idea, ensure constant power for gain stages. I use cascode for gain stage and for current sources.

Dalius
But the greatest thermal cycling is in the power output devices. So that is where I would expect thermal distortion, not in the pre stages.

jan
__________________
If you don't change your beliefs, your life will be like this forever. Is that good news? - W. S. Maugham
Check out Linear Audio!
  Reply With Quote
Old 19th January 2013, 07:58 PM   #7
diyAudio Member
 
Join Date: Sep 2009
Location: Lithuania
I before modified NAD receiver differential input stage and VAS. Stages become cascode, with low stable ~0,7V Vce for gain transistors. Sound quality was improved. Stable and low Vce ensure low power dissipation changes for gain transistor. Main think is low power dissipation changes.
  Reply With Quote
Old 19th January 2013, 08:04 PM   #8
diyAudio Member
 
Join Date: Sep 2009
Location: Lithuania
Pre stages have small power changes, bet very great impact (Vout >1V), because gain. Output stage has voltage gain <1, and heat impact make output voltage change ~15mV.
  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
Midgard, a low distortion Lateral FET output Headphone Amplifier Neutrality Headphone Systems 8 14th December 2012 07:31 PM
FS: Krohn-Hite Ultra Low Distortion Power Amplifier, model UF-101 dripdig Swap Meet 3 2nd July 2012 05:23 AM
Fender Twin low power and distortion mario13 Instruments and Amps 7 26th June 2011 09:07 AM
From Power Compression towards Thermal Distortion / developing on a point of view mige0 Multi-Way 190 28th December 2008 07:28 PM


New To Site? Need Help?

All times are GMT. The time now is 04:05 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