What is the quiescent current of Hitachi 2SK1058 and 2sj162? - 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 1st April 2004, 03:13 PM   #1
guymrob is offline guymrob  Singapore
diyAudio Member
 
Join Date: Mar 2004
Location: Singapore
Default What is the quiescent current of Hitachi 2SK1058 and 2sj162?

Hi everyone,

I have finished contructing a 50W amplifier based on the Hitachi 2SK1058 and 2SK162 L-MOSFET. I need to adjust the quiescent current. What is the optimium setting that results in low distortion as well as reasonable power dissipation. Thanks for your feedback.
  Reply With Quote
Old 1st April 2004, 05:57 PM   #2
diyAudio Member
 
slowhands's Avatar
 
Join Date: Feb 2004
Location: Silicon Valley
The simple answer is just set it for 100ma per device.

The bias current is not critical, between 100ma and 200ma per deivice will work OK for class AB operation. Lower runs cooler, which I prefer. Borbely recommends about 150ma for Hitachi lateral MOSFETs, while Pass recommends about 100 ma for IR vertical MOSFETs

The optimal way to set this might be the slick method detailed in the Nelson Pass article on the Citation MF12, where you set it based on minimizing crossover distortion using only a scope, oscillator and power resistor.
http://www.passdiy.com/pdf/citation.pdf

Even though that MF12 implementation used vertical MOSFETs, and you are using laterals, the procedure is identical. The bias voltage will of course be quite different, perhaps 1 volt versus about 7-8 volts for the vertical MOSFETs. Both result in the same bias current and minimal distortion.
  Reply With Quote
Old 1st April 2004, 06:34 PM   #3
diyAudio Member
 
Join Date: May 2003
Location: Colorado
Here's a little more information:

1) 100 mA per device is a good starting point. Below that and you be in the area of a positive tempco, which isn't ideal.

2) There won't really be an optimum value that will minimize crossover distortion. There is an optimum bias for bipolars (besides full-on class-A), but not FETs.

3) Performance (sonic and measured) with FETs will basically increase without limit as the bias is increased. Unfortunately, so does the heat.

I would start at 100 mA, and go up from there. If you can rest your hand on the heatsink for a few seconds before it becomes uncomfortably hot, that is around 125 F. I wouldn't go much hotter than that or else you will risk danger of burns and also shortened component life.
  Reply With Quote
Old 1st April 2004, 08:15 PM   #4
diyAudio Member
 
Idefixes's Avatar
 
Join Date: Dec 2003
Location: Mulhouse - Alsace
Send a message via ICQ to Idefixes
According with slowhands and guymrob 100Ma in AB class is hr good way. In 5Ch Zenquito (SK1058/SJ162 push-pull) the front center CH and the rear Ch have 220mA/push-pull. The 2 front Ch have 1.12A/push-pull to have A Class up to 20W

Click the image to open in full size.

Click the image to open in full size.

Marc
  Reply With Quote
Old 3rd April 2004, 01:17 AM   #5
diyAudio Member
 
Nick Walker's Avatar
 
Join Date: Mar 2004
Location: Singapore
However in one of Slone's books he does explicityly say that he thinks the optimal bias current for these devices is 40mA. There is no explanation given though.
  Reply With Quote
Old 3rd April 2004, 02:15 AM   #6
diyAudio Member
 
Join Date: May 2003
Location: Colorado
Here's one explanation -- some people like the sound of high-order harmonic distortion. Or to be a little gentler about it, they consider a warm amplifier to be more of a problem than high-order harmonic distortion.
  Reply With Quote
Old 3rd April 2004, 02:35 AM   #7
sam9 is offline sam9  United States
diyAudio Member
 
sam9's Avatar
 
Join Date: Jun 2002
Location: Left Coast
"However in one of Slone's books he does explicityly say that he thinks the optimal bias current for these devices is 40mA. There is no explanation given though."

He changed his figures between books. In the earlier one he wrote 50mA between the source and output rail per device. Is the 100mA figure quoted here for each device or is it for each pair?

In a later book he uses the figure of 40mA to multiply by the sum of both of the source resistors to get a voltage figure, voltages being a little more convenient to measure.

Having built only bipolar amps so far, but contemplating a MOSFET effort entually, I'm curious to know if this is just a question of how the figure is stated or if there is actually a 2:1 difference in recomended bias measurement.
  Reply With Quote
Old 3rd April 2004, 03:06 AM   #8
diyAudio Member
 
Join Date: May 2003
Location: Colorado
Quote:
Originally posted by sam9
Is the 100mA figure quoted here for each device or is it for each pair?
The 100 mA figure suggested by slowhand (and by myself as a minimum) is per device. Spend some time with the data sheets and you will see that this is the nominal zero tempco point.
  Reply With Quote
Old 3rd April 2004, 05:37 PM   #9
PMA is offline PMA  Europe
diyAudio Member
 
PMA's Avatar
 
Join Date: Apr 2002
Location: Prague
In case that you want to prevent the effect of Gm decrease (higher order harmonics as said) then bias them at least at 100mA, I would say 200 mA.
  Reply With Quote
Old 3rd April 2004, 07:51 PM   #10
diyAudio Member
 
Ultima Thule's Avatar
 
Join Date: Jan 2004
Location: Koskenkorva Land
PMA,

I'm not sure I understand the rellationship between Gm and high order harmonics, could you (or anybody else) elaborate on this?

Thanks,

Michael
__________________
"If transistors are blueberries and FETs are strawberries, then tubes must be.. pears"
Michael 29th January 2010
  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
2SJ162-E and 2SK1058-E 1965GTO Vendor's Bazaar 5 7th August 2012 06:05 PM
Anyone know where to get 2SJ162/2SK1058 fossil2k Solid State 8 17th March 2008 12:07 PM
2sk1058/2sj162 Fs sandyhooker Swap Meet 3 12th March 2008 04:50 PM
Cheap Source for 2SK1058 / 2SJ162 Hitachi L-Mosfets Killjoy99 Parts 6 4th February 2005 10:50 AM


New To Site? Need Help?

All times are GMT. The time now is 06:42 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