X250 - My next project. - 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 13th February 2013, 07:47 AM   #1
diyAudio Member
 
Join Date: May 2011
Location: Ho Chi Minh city
Default X250 - My next project.

I like symmetrical topology, and today, i try to build this front-end, for my next project.

I's based symmetry topo, like Symasym, Mongrel CX, Gold Mouth ...
LTP used BC550C matched pairs. It's very good small signal transistor. Of course, you can use JFET (as 2SK170, 2SK30 or dual matched in one package like LSK389B/C, 2N3958, 2N5564 to better). I suggested 2mA - 3mA for BJT and >4mA LTP Iq for JFET ver.

Vas is simply. First, the Vas's current mirror used 2-Q mirror, but i have some problems with unbalance Ic of Vas. I read Rod Elliott page Current Sources, Sinks and Mirrors in Audio and I try with the Wilson improved current mirror 4-Q. He wrote it's extremely balance currents, improve dynamics, banwidth, distortions...
Wow, two Ic of Vas very balance. I set 12mA for Vas (6mA each). If you want, you can change R17 (10K/3W) by one PNP Medium power trans (2SA1381E is a good choise) - Active load of Vas differential.

In prototype circuit, i used EF2 like PB120/PB250N of Mongel II with 2 pairs Sanken power trans 2SC2922/2SA1216, drivers are 2SC2344/2SA1011 (Toshiba 2SC5171/2SA1930 are better, but i can't buy).
For last, i'll build EF3 output stage, to improve dynamic. And use ON-Semi audio power trans, like MJL4281AG/MJL4302AG...

For power supply, this project named by ''X250'' - it's means 250W per 8 ohms, 500W per 4 ohms and maybe 1KW @ 2R if i become rich man, keke (OMG, i don't want my money go away by this project , in my country, ON-semi power trans arevery expensive, about 10$/each.) The rails about 75 - 80VDC to make it. In this prototype, i used +/-55DC.

Anyone can comments about this? Thanks!!!
Attached Images
File Type: gif NguyenLabs-X250-Front_end-pwr-sch__Wilson_improved_current_mirror__BJT_ver..gif (45.3 KB, 284 views)
File Type: jpg DSC00718__Edited.jpg (137.5 KB, 283 views)
File Type: jpg DSC00721__Edited.jpg (120.6 KB, 268 views)

Last edited by Walkalone; 13th February 2013 at 07:52 AM.
  Reply With Quote
Old 13th February 2013, 08:31 AM   #2
diyAudio Member
 
Join Date: May 2011
Location: Ho Chi Minh city
I'm attact schema of JFET version. It's improve high frequency, lighting sound, soundstage larger, little more bass... I used equivalent devices is 2SK170 matched.

But, i have two questions:
Is current mirror needs for load of LTP (like Honey Badger schema) and about the lateral MOSFET like ECX10N20/ECX10P20 replace BJT on output stage.
Which are better? For sounding and anothers ...NguyenLabs-X250-Front_end-pwr-sch__Wilson_improved_current_mirror.gif
  Reply With Quote
Old 5th March 2013, 01:03 PM   #3
diyAudio Member
 
Join Date: May 2011
Location: Ho Chi Minh city
Today, i plan to build triple emitter EF3 for output stage. I'll use 8 pairs per channel. Supply rails around +/-75V. Power transistors are MJL3281AG/MJL1302AG. Drivers are MJE15034/MJE15035, 2SC3503E/2SA1381E in pre-drivers.
Can anyone suggest me quiescent current of pre-drivers, drivers and power transistors output to get best result. Vas set at 6.5mA.

At 75VDC rail, the driver transistors (MJE15034/MJE15035 or MJE15032/MJE15033) can drive 8 pairs power transistors? On datasheet, it's ok. But i wonder which good. Used a power transistor, like MJL/MJW/NJW, a driver is ok. But Cob too high.
Mark Levinson No.33H, used 2 parallel transistors MJE15030/MJE15031 in driver, to drive 10 pairs 2SC3281/2SA1302. Why they do not use a power trans as driver?
  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
X250.5 question aljordan Pass Labs 3 29th May 2008 08:25 PM
Has anyone ever modified a X250.5? mert Pass Labs 64 19th March 2008 06:23 PM
X250.5 rdietzel Pass Labs 3 6th March 2008 09:39 PM
Bridged X250 kilowattski Pass Labs 3 14th March 2005 10:29 PM
X250 review Duck-Twacy Pass Labs 1 6th April 2003 08:26 PM


New To Site? Need Help?

All times are GMT. The time now is 12:23 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