100w amp ( no O/P transistors ) - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 10th February 2009, 07:47 PM   #1
diyAudio Member
Join Date: Nov 2008
Default 100w amp ( no O/P transistors )

I have been given a 100w amp board, It was thought that the O/P transistors were ALL 2n3055, ( but I'm not sure) , I was hoping someone will recognize the layout.
Do you think they are all 2n3055 or a couple of NPN's and a couple of PNP's


  Reply With Quote
Old 10th February 2009, 08:08 PM   #2
diyAudio Member
Join Date: May 2005
Location: Avesnes/Helpe

First this is not a class d design !!!!

Look at your module:

The two power transistors that have Emittors connected to -Vee are NPN type by deduction. (collector=case are connected to low value resistor 0,1 to 0,47 ohm maybe)

The two power transistors that are connected to +Vcc (Collector=case) are also NPN.

This is a quasi complementary design.

So All TO3's are NPN type.

2N3055 or better MJ1500X, MJ1502X (don't remember the last figure for NPN type !)

It's very similar to Bernard Corde Module (DAGONE POWER AMPLIFIER) in France.

Hope it Helps.

Could U send me Hi res pictures for information ?


Thanks !
  Reply With Quote
Old 10th February 2009, 08:32 PM   #3
diyAudio Member
Join Date: Nov 2008
Thanks for the quick reply
Sorry I didn't know where to post, ( Not Pass Labs, not solid state, not tube and not a chip amp ).

I will take clearer photo's tomorrow and send

Do you know where I could get some info on the circuit, ie min/max volt supply, current rating of transformer needed.

Thanks for your time
  Reply With Quote
Old 10th February 2009, 09:06 PM   #4
diyAudio Member
Stuart Easson's Avatar
Join Date: Oct 2002
Location: Santa Cruz, CA
Send a message via MSN to Stuart Easson Send a message via Yahoo to Stuart Easson
Default actually...

...this is definitely solid state.

2n3055 has a quite limited Vce, 60v, so that tells you the upper limit of rails, ie +/- 30v. With a stiff enough supply the amp will barely make 50w RMS into a 8ohm resistive load, but with a big enough supply can probably do nearly double into 4 ohms.

50w rms/8r, +/- 28v PK, +/-3.5A peak, 2.5A continuous
100w rms/4r, " , +/-7.0A peak, 5.0A continuous

Good replacements for 2n3055:

mj15003: good robust transistor, but like 2n3055 slooww. Probably only need 1 pair to more than equal 2 pair of 2n3055. Check soar at your supply voltage, or just use 2 pair.

mj21194: better linearity, still a very robust transistor and quicker, probably more expensive. Slight chance of instability.

Have fun

  Reply With Quote
Old 11th February 2009, 10:28 AM   #5
diyAudio Member
Join Date: May 2005
Location: Avesnes/Helpe
You're right,

+/- 30V DC for upper and lower rails are the limit for 2N3055.

If you decide to replace them with MJ15003 for example you could increase rails to +/- 70 V but taking care of the other stages max voltage ratings (Drivers BD239/240, Differential input amp...).
If you don't know how to, don't try to !!!

If you decide to change power transistors only: +/- 30 V is the limit.

so transformer with dual 22VAC secondary 300VA for stereo amp or 160VA for mono amp should do the job.

  Reply With Quote


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
Eti-480 100w Amp Help Please jacquesl Solid State 25 6th May 2017 08:05 PM
12v dc to dc 100w psu razordave123 Power Supplies 13 7th February 2006 04:29 PM
Evolve Amps 100W+100W Stuff 4 Sale WALTER BURKHARD Swap Meet 4 8th June 2005 10:57 AM
100W using STK nbcd Chip Amps 3 16th October 2004 05:51 PM
100W amp Vivek Solid State 13 23rd December 2001 07:57 PM

New To Site? Need Help?

All times are GMT. The time now is 09:43 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright 1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2