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 7th May 2013, 07:33 PM   #321
diyAudio Member
 
Lazy Cat's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by Tyimo View Post
O.K. No problem, but now you should answer!
Ca. what is the value for ca. 400-600mA? The original has ca. 160mA bias.
Hi Tyimo

Well if you're using 2SJ162 and 2SK1058 pair, between both gates there should be something around 2,5 V to 3,5 V to get 400-600 mA drain bias current. For that purpose you can experiment a little and learn a lot by doing so.

First you can try resistive only bias spreader, like 1 k trimmer and 1,5 k resistor in series.

Secondly five 1N4148 diodes plus 500 Ohm trimmer in series.

Thirdly 2,4 V zener diode alone or with 500 Ohm trimmer in series.

You could even try Vbe multiplier with NPN BJT and at last but not the least TLVH431 shunt regulator.

Each of this versions would also need a shunt 1 uF capacitor from gate to gate.

The most stable bias would, without any doubt, provide you 431 shunt regulator, but in any case 400-600 mA should be set only with proper heatsink in mind.
__________________
First One VSSA
  Reply With Quote
Old 7th May 2013, 07:36 PM   #322
diyAudio Member
 
Lazy Cat's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by cats squirrel View Post
I'm building two stereo amplifiers to feed a pair of floor standing Usher 604 'speakers, in a biamplification setup.
WOW would like to see pic and comments
__________________
First One VSSA
  Reply With Quote
Old 7th May 2013, 07:46 PM   #323
diyAudio Member
 
Lazy Cat's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by PMI View Post
Any Q., please ask.
First, congratulations, very clean and professional built, size of PCB enables you to experiment with exotic parts too.

And the Q: What is your intention to produce so many channels? What kind of speakers will be connected to?
__________________
First One VSSA
  Reply With Quote
Old 7th May 2013, 08:44 PM   #324
PMI is offline PMI  United States
diyAudio Member
 
Join Date: Feb 2013
Location: Milwaukee, Wisconsin
Quote:
Originally Posted by Lazy Cat View Post
First, congratulations, very clean and professional built, size of PCB enables you to experiment with exotic parts too.

And the Q: What is your intention to produce so many channels? What kind of speakers will be connected to?
Thanks, hoping to do just that

Modified (and old) Boston Acoustics speakers, Slightly newer B&W 602 (03?), very old set of restored/modified JBL speakers... nothing too exotic. I may have to trade one of my cars in for a better set one of these days...

From experience, I learned to build more than one of anything before I am completely happy with it, and it is very hard to compare if you no longer have the previous version to listen to. If all works out well, I am hoping to use both sets, and perhaps build one set into a multi-channel configuration.

Two sets are going to friends who who are helping with other parts of the project. One person who has been reading this thread has asked for a set... couple spares, for when I make a mistake, or for anyone else who is interested... so, not that many, really.

I attached an example of what the test chassis may look like, machined, but not "finished" in this pic (heat sinks from Heatsink USA, 10"x4" w. 1" fins on 0.33 base, 0.65C/W).
Attached Images
File Type: jpg P3_Chassis.jpg (139.5 KB, 365 views)
  Reply With Quote
Old 8th May 2013, 05:42 AM   #325
Tyimo is offline Tyimo  Hungary
diyAudio Member
 
Join Date: Nov 2002
Location: Hungary
Quote:
Well if you're using 2SJ162 and 2SK1058 pair, between both gates there should be something around 2,5 V to 3,5 V to get 400-600 mA drain bias current. For that purpose you can experiment a little and learn a lot by doing so.

First you can try resistive only bias spreader, like 1 k trimmer and 1,5 k resistor in series.
Thanks LC. So It's mean that with a simple 1K trimmer it will be still under 400mA?

Greets:
Tyimo
  Reply With Quote
Old 8th May 2013, 06:55 AM   #326
diyAudio Member
 
Lazy Cat's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by Tyimo View Post
Thanks LC. So It's mean that with a simple 1K trimmer it will be still under 400mA?

Greets:
Tyimo
It depends how high is VAS bias current.

If VAS bias is set to 15 mA you would need to set the trimmer to 234 Ohm to get 3,5 Vgg, so at that point output bias would be 600 mA. Yes 1 k trimmer would do OK.
__________________
First One VSSA
  Reply With Quote
Old 8th May 2013, 07:05 AM   #327
vgeorge is online now vgeorge  Greece
diyAudio Member
 
vgeorge's Avatar
 
Join Date: Mar 2004
Location: poros island
Payment sent by bank transfer.

Thanks for everything!

George
__________________
"Without deviations from the norm, progress is not possible" - Frank Zappa
  Reply With Quote
Old 8th May 2013, 07:13 AM   #328
diyAudio Member
 
Lazy Cat's Avatar
 
Join Date: Sep 2007
Quote:
Originally Posted by vgeorge View Post
Payment sent by bank transfer.

Thanks for everything!

George
Hi George

You mean for VSSA? Thanks.

Shaan will be "happy"
__________________
First One VSSA
  Reply With Quote
Old 8th May 2013, 07:53 AM   #329
vgeorge is online now vgeorge  Greece
diyAudio Member
 
vgeorge's Avatar
 
Join Date: Mar 2004
Location: poros island
mmm, yes posted in wrong thread by accident! Sorry.
__________________
"Without deviations from the norm, progress is not possible" - Frank Zappa
  Reply With Quote
Old 8th May 2013, 08:04 AM   #330
shaan is offline shaan  India
diyAudio Member
 
shaan's Avatar
 
Join Date: Mar 2009
Location: Near the Ganges
Haha. Don't worry. People learn by mistakes, you are forgiven.

This is not a group buy thread and never will be. Can't make me more happy!
  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



New To Site? Need Help?

All times are GMT. The time now is 05:02 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