Question about Crescendo? - 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 21st May 2002, 11:31 AM   #1
Eccu is offline Eccu  Finland
diyAudio Member
 
Eccu's Avatar
 
Join Date: Jan 2002
Location: Finland/Oulu
Question Question about Crescendo?

I'm building (Elektor) Cresceno Millenium Edition amplifier and I have still one question.
Can I replace MJE340 and MJE350 with BD139 and BD140 or with something else?

Thanks!
__________________
right way boy... u sold farm and bougth booze
  Reply With Quote
Old 21st May 2002, 11:40 AM   #2
swede is offline swede  Switzerland
diyAudio Member
 
swede's Avatar
 
Join Date: Sep 2001
Location: Geneva, Switzerland
I believe OnSemi/Motorola MJE15030 and MJE15031 are good replacements. You might have to recalculate a resistor or two, don't remember exactly why/which.

If you're going to bias them a lot, you need to put heatsinks on them.

//magnus
  Reply With Quote
Old 21st May 2002, 11:45 AM   #3
diyAudio Member
 
Mr. Triatic's Avatar
 
Join Date: Feb 2002
Location: SWE EU
Wink BD139/140

Hi!
i use those transistors and they deliver acceptable results, but preferrably use MJE340 and MJE350 or MJE15030 and MJE15031.
i guess that BD139/140 is what you have in your scrap-box, so try them first and if you are not pleased, just replace them... just make sure all four transistors is the same brand/make and from the same batch of production.
-good luck!
__________________
www.joddla.net/audio/
  Reply With Quote
Old 21st May 2002, 12:00 PM   #4
Eccu is offline Eccu  Finland
diyAudio Member
 
Eccu's Avatar
 
Join Date: Jan 2002
Location: Finland/Oulu
Quote:
Originally posted by swede
I believe OnSemi/Motorola MJE15030 and MJE15031 are good replacements. You might have to recalculate a resistor or two, don't remember exactly why/which.

If you're going to bias them a lot, you need to put heatsinks on them.

//magnus
Thanks. Very quick reply.....

I ask this because local distributor don't have same manufacturer MJE340 and MJE350 transistors. ( MJE340 was manufactured by Motorola. MJE350 don´t have any other letters or identifiers besides MJE350.)
I have two MJE340 and MJE350. One of each per channel or so.
I have measured those transistors with multimeter and result is that both MJE340 hFE was about 42 and first MJE350 hFE was 50 and second MJE350 hFE was 64.

Is there still more important measuring "technology" exist?
Some WWW sites?




I hope You understand my english.
__________________
right way boy... u sold farm and bougth booze
  Reply With Quote
Old 21st May 2002, 02:06 PM   #5
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
BD139, BD140 is OK as long as the voltage across them don't exceeds 60-70 volts. They are rated 80 V (or was it 100V?).

You can also use BF469/470 or BF471/472 video transistors 250 and 300 Volts.

I have used BF471/472 (with very good results) in my Crescendo-like amp named QRO. See my homepage.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Tube Buffered Gainclone in work |Thread ||
  Reply With Quote
Old 22nd May 2002, 07:32 AM   #6
Eccu is offline Eccu  Finland
diyAudio Member
 
Eccu's Avatar
 
Join Date: Jan 2002
Location: Finland/Oulu
Thanks!

but damn... local distributor don't have those BF469-BF472 transistors.
There was only these BFxxx transistors:
BF 177, BF 180, BF 199, BF 200, BF 254, BF 259, BF 494, BF 858, BF 8712, BF 324, BF 509, BF 872, BF 914 & BF 968.

What I have to do now?

Can I use those MJE's even those MJE350's have so much bigger hFE

or anyhow does it make any problems?


I ask this because I don't wan't pay any postages.

If there is not any solutions for this, then I must order those transistors by mail...
__________________
right way boy... u sold farm and bougth booze
  Reply With Quote
Old 22nd May 2002, 08:14 AM   #7
swede is offline swede  Switzerland
diyAudio Member
 
swede's Avatar
 
Join Date: Sep 2001
Location: Geneva, Switzerland
Eccu: I tried to send you an e-mail, but you have disabled that feature. I think I can help you out. Drop me a mail on kmg@skip.informatik.gu.se

//magnus
  Reply With Quote
Old 22nd May 2002, 08:58 AM   #8
Electrons are yellow and more is better!
diyAudio Member
 
peranders's Avatar
 
Join Date: Apr 2002
Location: Göteborg, Sweden
Blog Entries: 4
ecco, you can buy the BF-types from Sweden and http://www.elfa.se

Higher gain is ALWAYS positive, never a drawback in amps if the design is good.

But beware of that other parameters may be not as good. Capacitancies will increase in some types and the gain will also change with current. BF471/472 are a little special in this respect.
__________________
/Per-Anders (my first name) or P-A as my friends call me
Tube Buffered Gainclone in work |Thread ||
  Reply With Quote
Old 22nd May 2002, 09:01 AM   #9
diyAudio Member
 
Join Date: May 2001
Location: Bangalore, India
Eccu,

You have listed BF871 (I guess incorrectly shown as BF8712) and BF872; go ahead and use these in place of BF471 and BF472. Yes the original circuit uses MJE340 and MJE350s and the sonic properties of these are supposedly superior to the BFs as pointed out in a related post in this site. I have built the Mini-Crescendo and Crescendo using BF 469, 470, 471 and 472s but was not too happy with the transparency and speed. The post I am referring to said that the MJEs corrected this aspect.

Perform a search!
__________________
Sam
  Reply With Quote
Old 22nd May 2002, 09:12 AM   #10
diyAudio Member
 
wuffwaff's Avatar
 
Join Date: Aug 2001
Location: Ingolstadt Germany
Hi Eccu,

don´t use BF469/470 transistors in a crescendo! BD139/140 do sound a lot better and MJE340/350 give a small improvement over the latter.
Since these parts are not expensive and there´s little work involved you can try out for yourself.
I was amazed how much difference the step from BF to BD made.

(even Elektuur admits in their article on the milenium that the BF couldn´t deliver the current needed to drive the output stage.)

william
  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
Crescendo ME (component) question.. Dxvideo Solid State 16 29th November 2007 06:36 PM
Help for the Crescendo ME!! FeFe Solid State 11 14th June 2005 01:56 PM
Another crescendo ME question kro5998 Solid State 8 5th May 2005 09:44 PM
Hey Helix... I have one question about Crescendo? Eccu Solid State 29 22nd July 2002 05:18 AM


New To Site? Need Help?

All times are GMT. The time now is 05:08 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