Elliott Sound - "The Project 3A" - Page 3 - 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 26th April 2003, 11:37 AM   #21
Rudy is offline Rudy  Belgium
diyAudio Member
 
Join Date: Feb 2003
Location: Belgium
might i suggest a little different circuit for the biascurrent, becous in this situation you will not have any quasy current, or you have to many quasi current, couse of the high current gane in the output circuit it wil be very unstable and inpossible to know what it will do.

Greetz Rudy
  Reply With Quote
Old 26th April 2003, 06:29 PM   #22
Account Disabled
 
Join Date: Jul 2002
which part - that i need to change ?? - show me..... u mean medium -transistor stronger?

i will us in that amp for PA.... i have a transformer 48~0~48 2000VA for 2 che' .... and i us in 4 fan - 12V
  Reply With Quote
Old 26th April 2003, 07:01 PM   #23
Account Disabled
 
Join Date: Jul 2002
sajti - if i change all the MJE340-350 to MJE15030/1
in the circuit it will change something????
  Reply With Quote
Old 26th April 2003, 10:00 PM   #24
Rudy is offline Rudy  Belgium
diyAudio Member
 
Join Date: Feb 2003
Location: Belgium
no not the transistors, they are fine, you need to replace the 2 diodes D2, D3 with a little circuit, and make sure when you power the thing on that the middle connection of the potentiometer is conncted to the topside ( in the drawing ofcourse ) so that the transistor ( who must be connected to the same heatsink as the power transistors ) reduces the idle current to zero. Then slowly turn the potmeter around until you find yourself a descent bias value.

Good luck with your amp btw

Greetz Rudy
Attached Images
File Type: jpg bias.jpg (4.5 KB, 765 views)
  Reply With Quote
Old 27th April 2003, 12:44 PM   #25
Account Disabled
 
Join Date: Jul 2002
i dont understand..... i can edit my pic of the P68 amp.... and make the change there...?!
  Reply With Quote
Old 27th April 2003, 01:02 PM   #26
diyAudio Member
 
Join Date: Aug 2002
Location: Farmington, CT
Send a message via AIM to Mattyo5
DJ, just take out those 2 dioids, D2 and D3 and replace them w/ that circuit that was posted. I don't see any other changes you'd need to make...just trying to clarify what the other guy said.

-Matthew K. Olson
  Reply With Quote
Old 27th April 2003, 01:24 PM   #27
Account Disabled
 
Join Date: Jul 2002
i understanding now.....

but... if i will us in 70V +/- i need to replace the dioids...?
and if i us in 55V +/- i dont need to change nothing....?
  Reply With Quote
Old 27th April 2003, 01:55 PM   #28
Rudy is offline Rudy  Belgium
diyAudio Member
 
Join Date: Feb 2003
Location: Belgium
50 ..75V rail doesn't matter ( for this), its the output stage that is changed and thats why you better use that.

I myself advise that you go for a rail voltage below 60V, 75V is a lot for this amp...

Greetz Rudy
  Reply With Quote
Old 27th April 2003, 02:21 PM   #29
sajti is offline sajti  Hungary
diyAudio Member
 
Join Date: Apr 2003
Location: Vác, Hungary
DJ,

I have no good news for You MJE15030/031, are not very good instead of MJE340/350. With lower current the MJEs have lower B. They are ideal driver devices, but not ideal as VAS stage.
Try to get some MJE340/350. They are cheap, and common everywhere. (I live in Hungary, and I have 100 of them...)

Sajti
  Reply With Quote
Old 27th April 2003, 02:24 PM   #30
sajti is offline sajti  Hungary
diyAudio Member
 
Join Date: Apr 2003
Location: Vác, Hungary
With 48-0-48 tranformer You will get some +/-65V for Your amplifier. It's OK.
Just replace the two diodes, with the mentioned bias regulator. (Important! Put the bias regulator transistor to the heatsink of the output devices! BD139, os MJE340 OK for this stage. ) Withg this circuit You can safely adjust the bias current, and there will be no thermal runaway.

Sajti
  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
"Proac 2.5 clone" or "Elsinore project" Joel Wesseling Multi-Way 10 26th May 2011 05:51 AM
What makes an amplifier "bright", "warm", or "neutral"? JohnS Solid State 51 13th December 2009 06:42 PM
How to get rid of "CKK" Sound on "turn off" riotubes Parts 0 25th November 2006 03:50 PM
Can anyone suggest the "best" 300B SE sound quality schematic for a beginner like me? calico88 Tubes / Valves 42 18th July 2006 02:33 PM
Thiele-Small R_ms (mechanical losses) vs. "precise" sound? capslock Multi-Way 7 16th September 2002 09:32 AM


New To Site? Need Help?

All times are GMT. The time now is 03:44 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