simple shematique needed - 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 7th January 2006, 07:49 PM   #1
bosse is offline bosse  Canada
diyAudio Member
 
Join Date: Nov 2004
Location: quebec
Default simple shematique needed

hi
i have a pair of output (2sd424 2sb554 ) driver(tip31 tip32) anyone have a good sonding shematic for this transistors. iam lookin for an amp in 40 50 watts range.
thank
  Reply With Quote
Old 11th April 2006, 03:34 AM   #2
drago is offline drago  Hong Kong
diyAudio Member
 
Join Date: Apr 2006
Location: Asia
Default 2SC424/2SB554 amp schematic

Here is a schematic from the Toshiba Data Book. It delivers 35 to 80W across 8 ohm depending on the supply voltage +/-31 to 45V. For the input differential pair I used the 2SA979 which is a dual pnp made by Mitsubishi. I built this some years ago and it still works fine.
Attached Images
File Type: png toshiba amp.png (27.7 KB, 400 views)
  Reply With Quote
Old 11th April 2006, 01:39 PM   #3
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
the input resistor to ground is shown as 1k. this gives a bass roll off RC = 1mSec. F-3=159Hz.
This resistor should be about 22k to 100k.

Similarly the NFB RC=6.6Hz. This should be set about half to one octave below the input filter.

The output devices could be changed to 2sa1943/c5200 for upto +-50Vdc on the supply rails. At this higher voltage one pair would only be suitable for an easy 8ohm load, but @ +-40V would drive any 8ohm speaker to about 60W.
__________________
regards Andrew T.
  Reply With Quote
Old 11th April 2006, 05:51 PM   #4
drago is offline drago  Hong Kong
diyAudio Member
 
Join Date: Apr 2006
Location: Asia
Default Corection of Toshiba power-amp

Thanks, AndrewT
You are right, the input resistor should be 51K and the input cap is 4.7uF. Here is the amended circuit with higher resolution.
From the data book there are another two circuits for 120W output. One is BJT and the other FET.(output devices)
Attached Images
File Type: png toshiba power amp_1.png (78.1 KB, 307 views)
  Reply With Quote
Old 11th April 2006, 06:45 PM   #5
drago is offline drago  Hong Kong
diyAudio Member
 
Join Date: Apr 2006
Location: Asia
Default for +/-50V supply

Hi, AndrewT
I think one pair of transistors working at +/-50V may not survive the high demanding passages of some music especially classical. Because the speakers impedeance can be anything from 3 to 10 ohms at different frequencies. It may not be a safe and reliable amp when using one pair of output transistors. I stuck to two pairs at least.
  Reply With Quote
Old 12th April 2006, 08:47 AM   #6
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi Drago,
here's what I said.
Quote:
one pair would only be suitable for an easy 8ohm load
That was my polite way of saying that the schematic would not work reliably with 1pair of 150W output transistors.

Then I went on to say that reducing the Vrail to +-40Volts would give a reliable 8ohm capable amplifier using the same single pair of 150W devices.

Your schematic did not show 2pair.
__________________
regards Andrew T.
  Reply With Quote
Old 12th April 2006, 08:56 AM   #7
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi Drago,
I see your later schematic shows input RC=240mS & NFB RC=24mS.

This ratio of 10:1 should be 1:1.4 or upto 1:2 for mimimum interaction between the pass signals and feedback.

The input RC will be affected by preceeding equipment and may go down to less than 50mS depending on the source components, but this is still higher than the 24mS of the NFB.

I recommend you alter the NFB to about 100mS to 200mS and then set the input to a smaller value by selecting an appropriate blocking capacitor.

Remember to connect the input end of the blocking cap to ground using a high value resistor, about 470k to 2M2 is suitable. This can be mounted on the input RCA rather than alter the PCB.
__________________
regards Andrew T.
  Reply With Quote
Old 12th April 2006, 09:02 AM   #8
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
Default Re: Corection of Toshiba power-amp

Quote:
Originally posted by drago
Thanks, AndrewT
You are right, the input resistor should be 51K
If you take 15k like the feedback resistor you will reduce the effects of input bias current offset.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Tube Buffered Gainclone in work |Thread || Diamond buffer |Thread for the group buy | Wiki
  Reply With Quote
Old 12th April 2006, 09:33 AM   #9
AndrewT is offline AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
Hi,
or raise the 15k & 510r to match the 51k. (51k & 1800r with 100uF gives gain =x29.3 +29.3db and RC=180mS)

This gets closer to the NFB RC that is required.

What disadvantages (including noise) are there to raising the feedback loop impedances in a power amp?
__________________
regards Andrew T.
  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
Simple EL84 PP design needed Giaime Tubes / Valves 42 1st July 2011 03:11 AM
Simple se parts, all needed? newtube Tubes / Valves 5 14th April 2009 09:26 PM
Simple pre-amp schematic needed imperfectcircle Solid State 12 23rd February 2007 01:49 AM
simple loudspeaker protection needed Flavio88 Multi-Way 0 11th January 2007 11:34 PM
super simple tube amp needed... nerd of nerds Tubes / Valves 2 17th September 2005 12:04 AM


New To Site? Need Help?

All times are GMT. The time now is 10:12 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