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

Solid State Talk all about solid state amplification.

Whats this for?
Whats this for?
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 24th July 2006, 04:18 PM   #1
davidallancole is offline davidallancole  Canada
diyAudio Member
 
Join Date: Nov 2005
Default Whats this for?

What is R14 for in this picture. It is Doug Selfs Blameless Class B amp.
Attached Images
File Type: jpg doug self blameless class b amp.jpg (53.1 KB, 242 views)
  Reply With Quote
Old 24th July 2006, 04:24 PM   #2
richie00boy is offline richie00boy  United Kingdom
Did it Himself
diyAudio Member
 
richie00boy's Avatar
 
Join Date: Nov 2003
Location: Gloucestershire, England, UK
Whats this for?
It changes the slope of the thermal compensation mV/degC.
__________________
www.readresearch.co.uk my website for UK diy audio people - designs, PCBs, modules and more.
  Reply With Quote
Old 24th July 2006, 04:41 PM   #3
mikeks is offline mikeks  United Kingdom
Account Disabled
 
Join Date: Jun 2004
Location: Animal farm
See Hawksford here
  Reply With Quote
Old 24th July 2006, 04:42 PM   #4
davidallancole is offline davidallancole  Canada
diyAudio Member
 
Join Date: Nov 2005
I went and read the Hawksford paper on the circuit. My understanding from reading it is that this circuit will minimise the changes in the bias voltage based on changes in the current going through it. So it would then keep your bias voltage more stable for any changes temperature wise in your VAS stage.

So, richie00boy, your saying you can change your compensation slope as well? You could then change it from -2 mV/degC to -3 mV/degC or what ever you want to put it at by changing the R14 resistance?
  Reply With Quote
Old 24th July 2006, 05:13 PM   #5
mikeks is offline mikeks  United Kingdom
Account Disabled
 
Join Date: Jun 2004
Location: Animal farm
Quote:
Originally posted by davidallancole
..... this circuit will minimise the changes in the bias voltage based on changes in the current going through it.
Correct.
  Reply With Quote
Old 24th July 2006, 05:45 PM   #6
sreten is offline sreten  United Kingdom
R.I.P.
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

From what I remember from Selfs book :

it changes the slope of the Ivas vs Vb curve to a gently peaking
characteristic, with the right value you can set Vb to be in the middle
of this peak. Consequently Vq thus Iq becomes less dependent on
ambient temperature, variations in mains voltage and power supply
droop.

It does not change the thermal compensation mV/C in Selfs design.
Its purpose is to stabilise Vq, i.e. in Hawkfords paper R3opt is used.

Self shows elsewhere in his book how to manipulate mV/C of the bias.

/sreten.
  Reply With Quote

Reply


Whats this for?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
Whats should I do???? kino-schmid Solid State 6 1st March 2009 07:15 PM
whats this... tomtt Everything Else 18 17th May 2007 06:15 PM


New To Site? Need Help?

All times are GMT. The time now is 01:31 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki