how much power? - 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 18th February 2006, 02:04 PM   #1
diyAudio Member
 
Join Date: Sep 2005
Default mosfet or bipolar or darlington

Hellow!!

Which tranzistors are better for output stage of amp?

I noticed that someone are using mosfets,others are using darlington and again others use bipolar tranzistors?

Could anyone tell me which type is better and why?



Thanks!!!!
  Reply With Quote
Old 18th February 2006, 02:04 PM   #2
diyAudio Member
 
Join Date: Sep 2005
Default how much power?

i would like to do an amp which has around 600rms at 2 ohm with supply around +/-56V!

Is it posible to get around 800 rms with this amp using a 4 ohm load(need to push up supply voltage to...................how mutch)?

amp has 2x6 darlington tranzistors!

i think this could be done but will the amp heat up too much?

in my oppinion the amp would heat up more when using 2hm load witth supply +/-56V(more current) than using a 4 ohm load at 800rms



Give some answer!!!!!
  Reply With Quote
Old 18th February 2006, 02:10 PM   #3
diyAudio Moderator
 
pinkmouse's Avatar
 
Join Date: Apr 2002
Location: Chatham, England
Hi Smokingmachine. I have merged your two threads together as they clearly refer to the same project.

Have you had any experience in building amplifiers before?
__________________
Rick: Oh Cliff / Sometimes it must be difficult not to feel as if / You really are a cliff / when fascists keep trying to push you over it! / Are they the lemmings / Or are you, Cliff? / Or are you Cliff?
  Reply With Quote
Old 18th February 2006, 02:10 PM   #4
diyAudio Member
 
Join Date: Nov 2004
Location: sk
Send a message via AIM to ocool_15 Send a message via Yahoo to ocool_15
P=V^2/R
56.6VDC is needed for each rail at the load but you still have to account for losses in the amp.
  Reply With Quote
Old 18th February 2006, 02:12 PM   #5
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
Bipolars are the easiest to use and the more linear. MOSFETs may allow to get the same power output from less devices when properly employed, though.
  Reply With Quote
Old 18th February 2006, 08:18 PM   #6
diyAudio Member
 
myhrrhleine's Avatar
 
Join Date: Jan 2006
Location: Avalon Island
There is no 'better'
Each has good and bad points to them.
That's why different people use different devices.
It just depends on design philosophies and design skills.
__________________
Just because you can't hear it doesn't mean no one can.
  Reply With Quote
Old 18th February 2006, 10:42 PM   #7
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
Ocool there is something wrong with your calculator. 56.6^2/2=1600Wpk =800W into 2 ohm, more than he wants.

49^2/2=1200Wpk =600W into 2ohm.

Taking losses into account then +-55Vdc when loaded may be a target to aim for. 2 times 40Vac to 42Vac 1kVA.

I would go for MJ21193/4. Neither darlingtons nor Lfets can match at 2 ohm loading.

I'm told that Vfets might be able to compete and probably cheaper if you go quasi Nchannel.
__________________
regards Andrew T.
  Reply With Quote
Old 18th February 2006, 11:19 PM   #8
diyAudio Member
 
Join Date: May 2005
Location: Pretoria, South Africa
Smokingmachine,

As said this is indeed a difficult question with no simple unique answer.

But certain topologies are better than others. In an analysis by Prof. Otala a long time ago, a double emitter follower was rated 10 times better than quasi-complementary, and full complimentary topology (the best) 20 times better. The use of "better" is of course very unspecific; it refers to relative distortion but also to other characteristics. The details are somewhat long to post here, and it also depends on the type of semiconductor, etc. as others suggested. (These tests were for transistors but would broadly be valid also for MOSFETs).

This as a very general indication. It would appear that MOSFETs may have the edge over transistors, but I have no experience of them. When I last heard there was a very large spread in characteristics, which could make matching difficult. I wonder if this has improved.

Regards.
  Reply With Quote
Old 19th February 2006, 02:01 AM   #9
diyAudio Member
 
Join Date: Sep 2005
well the amp i am trying to do has mj11015(6x) and mj11016(6x)!!this are bipolars!!!

i wonder if this amp will do if I raise voltage to +/-80 or 85 volts and than it could deliver around 800 --- 900 rms at 4 ohm load or the amp will be heating too much(i will use a vent)

i think if amp could deliver 600 rms at 2 ohm load then the amp could deliver around 800 rms at 4ohm load(with proper supply)and still won`t be heating as much as if the amp would run at 2 ohm load with supply around +/- 56 V per rail!!!!
As I calculated the amp with +/-56V at 2 ohm load woult took much ampers than with +/-80........85 V(4 ohm load)!!

Am i right or no?


Ant thanks for all your answers!!!!!
  Reply With Quote
Old 19th February 2006, 02:14 AM   #10
diyAudio Member
 
Workhorse's Avatar
 
Join Date: Dec 2004
Quote:
Originally posted by AndrewT
I'm told that Vfets might be able to compete and probably cheaper if you go quasi Nchannel.
Hello Andrew,

Yeah Sure,

Quasi-N-channel VFETs always wins the race in 2-ohms loading.....

cheers,
K a n w a r
  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
40A 250V Schottky Power Diodes- Has anyone use in Power Amp to replace Diode Bridge? dtm1962 Solid State 10 15th September 2011 07:38 PM
LTspice tool for power amp power supply component evaluation andy_c Software Tools 2 23rd August 2009 05:10 PM
Power transformers versus amplifier output power..what is your option? destroyer X Solid State 38 9th May 2009 05:23 PM
Amplifier 3000 Wats Rms Power + Smps Higcht Power Bestiality MARAVILLASAUDIO Class D 1 5th November 2004 04:06 PM
power output calculations, rated power and required power output metebalci Tubes / Valves 7 22nd February 2004 05:49 PM


New To Site? Need Help?

All times are GMT. The time now is 12:15 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