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.

Ultra Low Cost Amp Design
Ultra Low Cost Amp Design
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 25th November 2003, 05:05 PM   #1
Lars Clausen is offline Lars Clausen  Denmark
diyAudio Member
 
Join Date: Oct 2003
Location: The Lab
Default Ultra Low Cost Amp Design

This thread is continued from 'What is the Gainclone Exactly?'

Ultra Low Cost Amplifier design, here is my first proposal...

Power is 50W in 8 Ohms, 100W in 4 Ohms, 5 - 100.000 Hz.

It is a fairly conventional amplification stage, followed by a industrial MOSFET output (extremely rugged). It can be tweaked and scaled to larger output power with ease....

The values around T5 may have to be experimented with a little.
It should build for less than 10$ including a PCB. (Which i will not be making or selling .. anyone else can do that if they want).

I encourage anyone with ideas for ultra low cost amplifiers to post them here, and let's discuss some solutions.

You can see an enhanced image here: www.lcaudio.dk/ulcamp1.gif

All the best from Lars Clausen
Attached Images
File Type: gif ulcamp1s.gif (17.9 KB, 4096 views)
  Reply With Quote
Old 25th November 2003, 05:42 PM   #2
jam is offline jam  United States
diyAudio Member
 
jam's Avatar
 
Join Date: May 2001
Location: Auburn, CA, USA
Lars,

Great idea to buffer the gain stage from the differential, but I think it would better to lower the value of the buffer resistor and attach it to ground, also use a current diode to bias the current sources. Just some thoughts.

regards,
Jam
  Reply With Quote
Old 25th November 2003, 05:49 PM   #3
chris ma is offline chris ma  Canada
diyAudio Member
 
chris ma's Avatar
 
Join Date: Sep 2001
Location: Pickering, Canada
Default no no

I do not think this can be done! A cheap pcb cost 8x5 more than $9cdn plus tax before etching...and where do you get a free power supply? etching chemicals are expensive too... I wish diy is really that cheap...

Best Regards,
Chris
  Reply With Quote
Old 25th November 2003, 05:53 PM   #4
Fred Dieckmann is offline Fred Dieckmann  United States
diyAudio Retiree
 
Join Date: Oct 2002
Location: Spain or the pueblo of Los Angeles
Default Say it isn't so......

Now you are doing free consulting.
  Reply With Quote
Old 25th November 2003, 05:53 PM   #5
peranders is offline peranders  Sweden
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Ultra Low Cost Amp Design
Interestng, some questions though: Why have you so high-ohmish feedback?

Why do you choose to have so little gain in the input stage? Isn't it a little bit better to have lower emitter resistance values?

Isn't it smarter to have a mosfet like BS170 for bias? I know that bias circuitry can be tricky but this was just a thought. With a BJT you can get too much mV/degC. I see that you have a zener also so maybe this is enough.

T8 is connected very unusual, never seen before but looks smart from distortion point of view.

How necessary are R1 and R2 in a single pair configuration?

Otherwise looks like a AKSA or Holton deluxe.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Group buy: DCT03 DC trap for big toroidal transformers. Sign up for interest HERE. 73 pcb's in order. 73 paid.
  Reply With Quote
Old 25th November 2003, 05:57 PM   #6
Lars Clausen is offline Lars Clausen  Denmark
diyAudio Member
 
Join Date: Oct 2003
Location: The Lab
jam: Thanks for your suggestions, i will try to find a current diode at a low price.

chris: The 10$ is of course only for the amplifier circuit, not the power supply and transformer or enclosure. I think this amp can be assembled on a PCB sized 2 by 3 inches. A photo board here would cost a couple of $ (4 by 6 inches) in an electronics shop.
  Reply With Quote
Old 25th November 2003, 06:02 PM   #7
Peter Daniel is offline Peter Daniel  Canada
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Ultra Low Cost Amp Design Send a message via AIM to Peter Daniel
The Aleph X group buy indicates that lowest you could go with large qty order is $4-5 per board. It is still equal to the price of a chip. And when you use 5 additional parts to complete the circuit, I don't see any justification in choosing discreet route for better performance.

Aleph amp can be regarded as a well implemented and simplified discreet design, actually a benchmark, however I can't say it is superior to a well implemented chip amp. Ask the guys who listened to sexy gear on a table
__________________
To order kits contact me through forum mail.
  Reply With Quote
Old 25th November 2003, 06:04 PM   #8
Lars Clausen is offline Lars Clausen  Denmark
diyAudio Member
 
Join Date: Oct 2003
Location: The Lab
Peranders: The high ohmish feedback is to partly balance the high input impedance 100k, and that one is intended to keep down the value of the 100nF cap in series with the input.
So it is still cheap to get a good quality cap.

High emitter values in the input stage is to keep open loop gain low ( = good sound ).

BIAS circuit, you are right, this stage may require a little fine adjustment, maybe some changes can also improve the design.

R1 and R2 may be unnessescary, depending on how good a thermal coupling you can make. I included them just to be extra sure it will work every time.
  Reply With Quote
Old 25th November 2003, 06:05 PM   #9
jam is offline jam  United States
diyAudio Member
 
jam's Avatar
 
Join Date: May 2001
Location: Auburn, CA, USA
Fred,

Sorry, a moment of weakness. I am truly ashamed of myself.............
Attached Images
File Type: jpg tlo0011l.jpg (23.7 KB, 3454 views)
  Reply With Quote
Old 25th November 2003, 06:08 PM   #10
Fred Dieckmann is offline Fred Dieckmann  United States
diyAudio Retiree
 
Join Date: Oct 2002
Location: Spain or the pueblo of Los Angeles
Default NO IT DOESN'T

"Otherwise looks like a AKSA"

I have an ASKA 55 in my amp collection and it is quite different. It is also an excellent sounding amp which is the result of much more than just the basic topology. I doubt you ever seen the schematic since Hugh keeps tries very hard to keep it of the hands of "entrepreneurs" and I haven't seen something similar on your website. Of course I know you would never copy a design into which so much effort was expended in getting it to something far beyond the ordinary.
  Reply With Quote

Reply


Ultra Low Cost Amp DesignHide 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


New To Site? Need Help?

All times are GMT. The time now is 08:36 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