Class A for home use - 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 13th December 2004, 12:33 AM   #1
anli is offline anli  Russian Federation
diyAudio Member
 
Join Date: Oct 2004
Default Class A for home use

Hi,

I see, the question is too common, nevertheless I'll try :-)

Please, suggest a _musically_checked_ schematics for power amplifier:

- with approximately 20-30W power peak (8 Ohm load),
- balanced (bridge) symmetric topology is preferable,
- MOSFETs in output stage are preferable,
- without capacitors and transformers in signal path,
- global NFB absence is preferable.

Andrew
  Reply With Quote
Old 13th December 2004, 01:22 AM   #2
diyAudio Member
 
kilowattski's Avatar
 
Join Date: Aug 2003
Location: Long Island, New York
Try the Pass Labs Forum. Maybe an Aleph or a Zen amp.
__________________
-----------------------------------------------
Kilowattski
  Reply With Quote
Old 13th December 2004, 01:56 AM   #3
anli is offline anli  Russian Federation
diyAudio Member
 
Join Date: Oct 2004
As you can see, I have mentioned "balanced symmetrical" topology,
as one of the aim is to make an amplifier more power-effective.

Such topology is not "Nelson's path", I think :-)
  Reply With Quote
Old 13th December 2004, 07:34 AM   #4
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
could the front end of a Leach meet part of your requirement?
regards Andrew T.
  Reply With Quote
Old 13th December 2004, 07:51 AM   #5
diyAudio Member
 
kilowattski's Avatar
 
Join Date: Aug 2003
Location: Long Island, New York
Are you not looking for a class A amplifier? Efficiency and class A are not usually used in the same breath. The Aleph X is the closest I can think of.
__________________
-----------------------------------------------
Kilowattski
  Reply With Quote
Old 13th December 2004, 08:52 AM   #6
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Clearly you are not interested in single ended topologies because of the low efficiency.
Meaning you want a push-pull output stage.

Secondly, you have no preference for a balanced design or amplifiers in bridged mode, as long as it has a balanced entrance.

That means practically any low power Mosfet push-pull design will do with the following constraints :
- A symmetrical circuit.
- DC coupled.
- No global feedback.

The latter is arguemental, for the last 20 years audio designers are talking local feedback.

As that still leaves a number of possible amplifier designs you may need to make a couple of choices more :
- a fully discrete circuit ?
- without a DC servo ?
- Easy to build ?
- Maximum cost ?

For example:

If you do not object to opamps in a circuit and a opamp DC servo,
with a couple of IRF630/IRF9630, a 5534 opamp and a OP07 for the servo it is possible to build a reliable amplifier fast,
the circuit components are probably less than $10 per channel.
There are a number of circuits like that around with proven results.

!!!! Just an example, of course there are way better components, i just mentioned a couple of cheap components !!!!

Other designs may call for selecting the components, or the need for a scope to measure and tweak the circuit.
For simple designs downloading a small scopefile for the pc soundcard from your fellow russian at edu.ru and a simple tonegenerator will do.

Important questions may also be :
- What is in front of the power amplifier ?
- What kind of speakers does it need to power ?
__________________
The buck stops Here
  Reply With Quote
Old 13th December 2004, 11:13 AM   #7
anli is offline anli  Russian Federation
diyAudio Member
 
Join Date: Oct 2004
Quote:
Originally posted by kilowattski
Are you not looking for a class A amplifier? Efficiency and class A are not usually used in the same breath. The Aleph X is the closest I can think of.
Saying "symmetrical balanced" I mean push-pull balanced topology, wich has
much more efficiency rather SE or something like SuperSymmetric has.
  Reply With Quote
Old 13th December 2004, 11:34 AM   #8
anli is offline anli  Russian Federation
diyAudio Member
 
Join Date: Oct 2004
Jacco,

I'll try to clarify:

- as I have said, I mean push-pull balanced topology with balanced input (I have
some ideas about discrete balanced line drive, but they are rather young :-),
- I'd prefer global NFB absence, but 5-6db feedback (to set output shifting and
output dumping factor) is not rejected at all,
- fully discrete,
- without DC servo; I'm not afraid of 100-150mV shifting :-) between balanced
output,
- two PS are possible, for example stabilized +/-50V for all except for output stage
with single 30-40V PS,
- hard to build :-),
- cost... OK, I can say "not too expensive". At any case an amplifier sinks,
box and transformers will have the main cost, I think,
- I have a scope, a signal generator, a software to see FFT ans so on on PC,
- speakers have standard design.

Probably you can see, my English isn't perfect. Please, explain me these words
meaning: "front of the power amplifier".

br,
Andrew
  Reply With Quote
Old 13th December 2004, 12:59 PM   #9
PMA is offline PMA  Europe
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
I was thinking about similar circuit you are speaking about, but did not find time enough to realize - maybe later.
  Reply With Quote
Old 13th December 2004, 01:03 PM   #10
diyAudio Member
 
jacco vermeulen's Avatar
 
Join Date: Oct 2004
Location: At the sea front, Rotterdam or Curaçao
Send a message via Yahoo to jacco vermeulen
Hi, Andrew.

With "in front" i mean what pre you intend to use with the power amplifier.

I think you should take a look at Mr Erno Borbely site.
He did a modular balanced symmetrical Class A Mosfet power amplifier in the '90s.

One of the versions is DC-coupled.
In Class A it does 50 watts, if you'd like it less lower the bias or the voltage.
__________________
The buck stops Here
  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
Custom Home Theater Project in New Home, Opinions appreciated. thadman Multi-Way 5 20th November 2008 12:40 AM
Alpine PDX class D for home audio use? keith89 Class D 2 17th January 2008 07:32 PM
higher power class T for outdoor home theatre draizinbrew Class D 2 24th October 2006 07:58 PM
Home home or pop pop noise from sub ricky fong Multi-Way 0 26th February 2003 01:15 AM
Class-A/Pass with home theatre Gabster Pass Labs 13 21st September 2002 08:19 AM


New To Site? Need Help?

All times are GMT. The time now is 12:00 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