All Hitachi Lateral Fet amplifier for DIY described by Paul Kemble

Hello

I open these thread for these all Hitachi Lateral & Jfet amplifier.
Here is the circuit & website.
A Paul Kemble web page - Hitachi Fet designs.
Now for these amplifier the mosfets are still available but the JFet must be replaced because they are no longer on the market.
We started a conversation about these amp on the Naim 140 clon from Ebay thread.
We think it is time to keep that threat to Naim clone and open a new for these.
AndrewT advised to dedicate these amp to Borbely...He was famous using fets in his own high-end amplifiers etc.
There is two amplifier circuit. You all welcome if you interested to comment, redesign etc these amplifier.
To the all Hitachi fet I have all the mosfets at hand just need the JFet.
I really would like to give a try (at least test these amp)but not without modifying the front end since those JFet are past now.

Greetings Gabor:)
 

Attachments

  • hitmosfet2.gif
    hitmosfet2.gif
    12.1 KB · Views: 5,877
Last edited:
Very similar circuit was in The Audio Amateur over 20 years ago by Erno. The MOSFETs in the middle are unobtanium, although you sometimes see them on EBay.

Hello
Those mosfets I have that would be no problem at least to me.
The J fet is the problem. I did tried to look up the mentioned circuit maybe Mr. Borbely did used Toshiba or some other type (still available JFet) but with out success.
I do like these circuit a lot (all do I would be more interested how it sound)
A great circuit not always equal with a great sound:D

I started to draw the layout but I stopped because I don't know what JFet I could use to replace those old Hitachi, or what kind of modification I need so I can use Toshiba JFet..
Greetings Gabor
 

Attachments

  • All fet Hitachi amplifier.bmp
    56.8 KB · Views: 1,140
Hello
Thanks, good to know those still available the 2SJ77/2SK124, in case someone else interested on the amp.:)
I have at home 8 pair right now, also I have a lot of different type power mosfet from Hitachi, Class D, EXICON..
The issue here the JFet, unfortunately those are not available and if I will get the still problem because those must be matched.
There are companies who sell obsolete (hard to find)devices but min order $500 or they sell them for horrible price.:rolleyes:

Greetings Gabor
 

Attachments

  • Picture 001.jpg
    Picture 001.jpg
    97.9 KB · Views: 4,262
  • Picture 002.jpg
    Picture 002.jpg
    97.6 KB · Views: 3,801
  • Picture 003.jpg
    Picture 003.jpg
    106 KB · Views: 3,667
Hello

I open these thread for these all Hitachi Lateral & Jfet amplifier.
The amplifier was designed by Paul Kemble (head of NAIM company)
Now for these amplifier the mosfets are still available but the JFet must be replaced because they are no longer on the market.
We started a conversation about these amp on the Naim 140 clon from Ebay thread.
We think it is time to keep that threat to Naim clone and open a new for these.
AndrewT advised to dedicate these amp to Borbely...He was famous using fets in his own high-end amplifiers etc.
Here is the website of Paul K.
A Paul Kemble web page - Hitachi Fet designs.
There is two amplifier circuit. You all welcome if you interested to comment, redesign etc these amplifier.
To the all Hitachi fet I have all the mosfets at hand just need the JFet.
I really would like to give a try (at least test these amp)but not without modifying the front end since those JFet are past now.

Greetings Gabor:)
Did Paul Kemble design the amp in the Hitachi databook?
http://sjostromaudio.com/pages/downloads/directly-to-downloads/Miscellaneous

EDIT: It seems to be fetched from the Hitachi app note.
 
Last edited:
Hello

I open these thread for these all Hitachi Lateral & Jfet amplifier.
The amplifier was designed by Paul Kemble (head of NAIM company)
Now for these amplifier the mosfets are still available but the JFet must be replaced because they are no longer on the market.
We started a conversation about these amp on the Naim 140 clon from Ebay thread.
We think it is time to keep that threat to Naim clone and open a new for these.
AndrewT advised to dedicate these amp to Borbely...He was famous using fets in his own high-end amplifiers etc.
Here is the website of Paul K.
A Paul Kemble web page - Hitachi Fet designs.
There is two amplifier circuit. You all welcome if you interested to comment, redesign etc these amplifier.
To the all Hitachi fet I have all the mosfets at hand just need the JFet.
I really would like to give a try (at least test these amp)but not without modifying the front end since those JFet are past now.

Greetings Gabor:)

In that amplifier diagram, I think the designer did not understand how a J-FET transistor work. So, the operation of a JFET is not the same as a MOSFET. There are notable differences.
 
You could use just a pair of
2SK215 for the input .......
No cascode needed .......

Hello
I don't think is a good idea to replace the JFet with fet specially on the input:confused:
Even sound wise it has a huge differences between the two, like day and night.
Is a reason many Aleph X builder replaced the mosfet input to JFet and got a big sound improvement
Let s keep the JFet on the input, we can use BJT for cascode.
There are some Toshiba JFet we could probably use here with some minimal modification.
That is the reason the circuit up in here on the forum.
I do think is a well designed circuit worth to give a try specially those who like the sound of the laterals
We all know many famous amplifier was designed around the Hitachi circuit just to mention some: Goldmumd, Grand mos etc

Greetings Gabor
 
Qua-Co is a reliable seller for 2SJ74 and 2SK170 matched pairs. He's supported the older Hafler DH- and XL- series amplifiers for many years.
HAFLER XL-280 OTHERS 2SK170 2SJ74 MATCH JFET SET OF 4 | eBay

Hello
I have those (or these) 2SK170BL&GR, 2SK246BL&GR grade and 2SK117 JFet! Can I replace the Hitachi how is the circuit? I think not..
Here I need some help, or idea. I think if we could fix up these circuit by using available devices there would be other guys who will build these amp..

Greetings
 
Hello
Hard to believe so little interest on these amp circuit :confused:
I did look at all those Hitachi devices (good sounding fets) I thought it will be more interest....
I feel bad to give up, now when Alex already designed a layout, also I spent a couple hours drawing my layout..
Now is it time to give up??
I don't think so, I will do some test since already has all the fets (I will try to use 2SK170BL for input).
What can I do these schematic not Goldmund (yet) or other brand with $$$$$ price tag ...:D

Greetngs
 
Just another Moderator
Joined 2003
Paid Member
I have a DIY 100W mosfet amp based on the bipolar input version in the Hitachi datasheet. It has served as my main amp for the last 25 Years :)

Just because you aren't getting a lot of interest (could be fet availability, but that shouldn'y be an issue for you) doesn't mean you should abandon your project!

Tony.