Dx Blame MKIII-Hx - Builder's thread - Page 165 - 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 4th January 2013, 03:11 PM   #1641
bonfis is offline bonfis  United States
diyAudio Member
 
Join Date: Jan 2010
Location: Land of 10,000 Lakes
Quote:
Originally Posted by destroyer X View Post
Several years ago i have used these transistors (2SD669A and 2SB649A).... a very high gain transistor but die like a bird....they die easy..fell down almost dead when sick...poor bird close eyes and fell down..when reach the floor it is already dead..... this transistor die so easy as a bird... i have lost all six 6 pairs i had...this seems, at least to me, they are not that reliable...or strong...or resistant.

regards,

Carlos
Thanks Carlos for sharing you experience with the 649,669. My MK III has somewhat lower rail voltages (55 v) so maybe the bird will be less stressed. I will keep a close eye on her.
Steve
__________________
"I tend to believe that the absence of evidence is evidence of absence" - Christopher Hitchens
  Reply With Quote
Old 4th January 2013, 03:33 PM   #1642
diyAudio Member
 
destroyer X's Avatar
 
Join Date: Feb 2004
Location: Recife - Brasil Northeast
Default You are welcome.

Carlos
  Reply With Quote
Old 4th January 2013, 05:40 PM   #1643
evette is offline evette  Canada
diyAudio Member
 
Join Date: Jun 2006
Send a message via Yahoo to evette
Mr. Carlos sir,, have you ever tried to use 2sc3245 transistors I have and got very good results. Regards Joe
  Reply With Quote
Old 4th January 2013, 07:21 PM   #1644
diyAudio Member
 
destroyer X's Avatar
 
Join Date: Feb 2004
Location: Recife - Brasil Northeast
Default No, i have not tried dear Joseph...but it looks it is no good

For this power amplifier.

The VAS main transistor, in stand by mode, will dissipate 1.8 Watts of power... without signal.

This one is 900 Miliwatts maximum...it will not survive to this amplifier...maybe will be good to the Dx Super A and lower voltage and lower current models.

2SA1285 is the complementary and the capacitance is less than 3 picofarads....good transistor..high speed and high voltage device (120 to 150 volts)

The gain can be too much...can go to 800.... this amplifier was not made to all this gain.... more than 250 may produce troubles.

regards,

Carlos
  Reply With Quote
Old 4th January 2013, 08:08 PM   #1645
evette is offline evette  Canada
diyAudio Member
 
Join Date: Jun 2006
Send a message via Yahoo to evette
It Works great in the st. Joe
  Reply With Quote
Old 4th January 2013, 08:56 PM   #1646
diyAudio Member
 
destroyer X's Avatar
 
Join Date: Feb 2004
Location: Recife - Brasil Northeast
Default Oh!....that's made me curious

Yes...i am feeling curious about that...will search this transistor in Brazilian electronic shops.... we still have this kind of things here.

regards,

Carlos
  Reply With Quote
Old 4th January 2013, 09:18 PM   #1647
evette is offline evette  Canada
diyAudio Member
 
Join Date: Jun 2006
Send a message via Yahoo to evette
I use 1 of my st. for headphone setup works great. Evette
  Reply With Quote
Old 4th January 2013, 10:57 PM   #1648
diyAudio Member
 
destroyer X's Avatar
 
Join Date: Feb 2004
Location: Recife - Brasil Northeast
Default Super A beat that one easy

Enjoy your amplifier....Blame ST is great too...but watch Juan post.

regards,

Carlos
  Reply With Quote
Old 10th January 2013, 03:20 AM   #1649
diyAudio Member
 
Join Date: May 2011
Location: Quebec
I received my 2SA968B and 2SC2238B for the drivers replacement and some 2SC1819 for VAS position.

The 2SC2238 seems to be genuine Toshibas, the 2SA968B are ISC copies, and the 2SC1819 seems genuine Matsushitas, but they're used.

The joy of grey market components...

I tried them on one of my boards, but one of these parts doesn't fit the bill as now I have some ringing on the positive side of the wave (like Bonfis depicted before increasing base-stoppers from 22 to 56r (I have 100r)...
The dent on the positive side at clipping is gone though...

... to be continued

Last edited by canonnica; 10th January 2013 at 03:32 AM.
  Reply With Quote
Old 12th January 2013, 01:26 AM   #1650
diyAudio Member
 
Join Date: May 2011
Location: Quebec
Default For the VAS gurus...

For the specific design of this HX amp with miller compensation, is it very important to have the lowest possible Cob for VAS transistor?

Let's say I have the choice between:
A) a transistor with a Cob of 5pF and a fT of 100Mhz
B) a transistor with a Cob of 16pF and a fT of 200Mhz
... and all the other specs being similar, what would be the best choice?

We can read all over this board that the lowest the Cob and the highest the fT, the better the results, but in this particular case, what spec shoud be preferred over the other?

Martin.
  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
Dx Blame ST - Builder's thread - post pictures, reviews and comments here please. destroyer X Solid State 1730 15th September 2014 11:01 PM
Dx Blame MKIII Supercharged will soon be released destroyer X Solid State 346 22nd April 2014 04:01 PM
group buy for DX Blame MKIII Hx PCBs ByronInPortland Group Buys 247 5th December 2012 01:05 AM
Group By: DX Blame MKIII Hx boards ByronInPortland Group Buys 9 19th July 2011 08:21 AM
Dx Blame MKII, an obvious evolution from the Dx Blame ES/ST destroyer X Solid State 4 25th September 2010 07:41 PM


New To Site? Need Help?

All times are GMT. The time now is 07:39 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