Luxman L58A / 2SK163-2SJ44? - Page 2 - 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 30th July 2010, 02:40 PM   #11
diyAudio Member
 
Join Date: May 2008
Default Replacement

Quote:
Originally Posted by EUVL View Post
I checked with Williges.
They don't have any in stock.

Patrick
Delay!

Seems that you know a lot about fet's - which I don't. I have worked with some valve amplifiers, and my old and long gone mosfet amplifier turns up constantly in my memory. - Same sound filosofy as valve amps.

Find the circuit attached.

I have listened a lot to my L58A from Luxman and like the sound very much, but irritated because of the lack of power - uses AR3a speakers.

Would like to built with 2SJ50/2SK135 ( have 8 pairs) and use the Luxman driver circuit. Which input devises could be used as replacement in L58A and used in a similar mosfet amplifier like the one attached?

Kim
Attached Images
File Type: jpg Mitronic 2a.JPG (270.0 KB, 353 views)
  Reply With Quote
Old 8th August 2010, 02:51 PM   #12
diyAudio Member
 
Join Date: May 2008
Quote:
Originally Posted by KJ2005 View Post
Luxman for the input differential stage has used 2SK163 and 2SJ44 from NEC.

It is possible to buy the 2SK163 in Europe but impossible to find the complementary 2SJ44.

Does anyone know if there is a substitute pair of fet's available with the approx. same spec's?


Any help would be appreciated.
Does anyone know something about the fet's mentioned by Cricklewood, UK:

"Could try any 40V TO92 PFET such as 2N5462, 2SJ103 etc ??"

could the complementary 2SK246 be used together with 2SJ103 as substitute for 2SK163/2SJ44??? -or can someone recommend a better pair?

Rgds.
  Reply With Quote
Old 8th August 2010, 03:27 PM   #13
diyAudio Member
 
StevenOH's Avatar
 
Join Date: Jun 2004
2SJ103-K246 can not serve as a replacement for J44-K163, because of too low transconductance. These J44 do not have direct equivalents.
The only suitable and available replacement will be LSJ74-LSK170 (when available)
and 2SJ109-2SK389, LSJ109-LSK389 for matched pairs. These parts will have higher capacitances.
2SJ74-2SK170 will have even higher transcondactance, than LSKs.
__________________
The truth is out there. Who can handle the truth?
  Reply With Quote
Old 8th August 2010, 04:01 PM   #14
wahab is offline wahab  Algeria
diyAudio Member
 
Join Date: Nov 2009
Location: algeria/france
Very nice amp, wether it s the power stage or preamp..
Awsome RIAA preamp..
As pointed by Jacco, 2 or even 3 power devices pairs
would had made it a reference...
  Reply With Quote
Old 8th August 2010, 04:32 PM   #15
diyAudio Member
 
Join Date: May 2008
Quote:
Originally Posted by StevenOH View Post
2SJ103-K246 can not serve as a replacement for J44-K163, because of too low transconductance. These J44 do not have direct equivalents.
The only suitable and available replacement will be LSJ74-LSK170 (when available)
and 2SJ109-2SK389, LSJ109-LSK389 for matched pairs. These parts will have higher capacitances.
2SJ74-2SK170 will have even higher transcondactance, than LSKs.
Thanks - I shall not try and ask you to explain the effect of too low transconductance , while I may not have enough background to understand the mechanism.
After I have heard a symmetrical mosfetamp with a differential fet inputstage (the L58A) I would like to built one. What is your opinion of the 2SJ74/2SK170 as inputfets? The old asymmetrical 100W poweramp attached erlier was quite well sounding without servo. The L58A schematic shows a servo, and as far as I can remember the sound from L58A is a little more detailed.

Do you recommend fet input? - and servo? - and symmetrical/ asymmetrical design?

Rgds.
  Reply With Quote
Old 8th August 2010, 04:39 PM   #16
diyAudio Member
 
Join Date: May 2008
Quote:
Originally Posted by wahab View Post
Very nice amp, wether it s the power stage or preamp..
Awsome RIAA preamp..
As pointed by Jacco, 2 or even 3 power devices pairs
would had made it a reference...
Yes - I have had my L100 and the L309 running for several hours and the L100 has more power but not "the gently touch" like L58A. The L309 can't compete with L58A.

How can we reproduce the powerstage from L58A with 2 or 3 pair of powerfets?

rgds
  Reply With Quote
Old 8th August 2010, 08:24 PM   #17
diyAudio Member
 
Join Date: Feb 2005
Location: Gelderland
i have a question about the luxman schematic;
first off, in a bunch of old components i found a bzx75c 2v8, which is so old it is in a Ge-diode like black glass case, and which i wanted to use as ccs reference perhaps, and i tried to measure if it works ok, with the diode test of my dmm, the voltage drop both ways is out of range of it (so i figured perhaps broken), but, with a very large resistor, fed by the hv of my amp as test, the breakdown the "forward" way is 2v3 (fraction of mA current btw), and the reverse "zener" breakdown voltage is 150V lol (note it is not changed by the test). i wondered, can it be that it is 4 forward junctions in series, kin like the references in the luxmann schematic?
  Reply With Quote
Old 9th August 2010, 07:37 AM   #18
diyAudio Member
 
Join Date: May 2008
Quote:
Originally Posted by jechentau View Post
i have a question about the luxman schematic;
first off, in a bunch of old components i found a bzx75c 2v8, which is so old it is in a Ge-diode like black glass case, and which i wanted to use as ccs reference perhaps, and i tried to measure if it works ok, with the diode test of my dmm, the voltage drop both ways is out of range of it (so i figured perhaps broken), but, with a very large resistor, fed by the hv of my amp as test, the breakdown the "forward" way is 2v3 (fraction of mA current btw), and the reverse "zener" breakdown voltage is 150V lol (note it is not changed by the test). i wondered, can it be that it is 4 forward junctions in series, kin like the references in the luxmann schematic?
Hi - I think you "lost" me! where did you find the bzx75c 2v8 zener?

We go for a short vacation and I shall return friday or saturday.

Do you own a L58A? - I hobe so.

rgds.
  Reply With Quote
Old 9th August 2010, 11:21 AM   #19
diyAudio Member
 
Join Date: Feb 2005
Location: Gelderland
no, i do not have such amp (so offtopic perhaps), however as i peered over the schematic i noticed those double series diodes as reference for the vartious ccs'es (or so it appears to me) and i already wondered of this 2v8 zener i have (unrelated to such amp) is just 4x0,7V forward junctions in series (say 4x 1n4148 in a black thinlead ge-diode glass casing) however i am sure it is a silicon device, because it is a "B" device (silicon).
what is the voltage of the reference diodes in the luxman amp btw?
  Reply With Quote
Old 9th August 2010, 11:34 AM   #20
wahab is offline wahab  Algeria
diyAudio Member
 
Join Date: Nov 2009
Location: algeria/france
The L58 has some drawbacks...
first, the power amp stage has a very high gain
of about 120..I suppose that it allow for preamp
circuits to work with low gain and reduce distorsion
of these first stages, but then, the power stage
lose some available feedback to reduce THD..

Second, the power mosfets drivers work at low current,
typically about 3 mA , wich is not enough...

Third, it seems that the cascoded differential stage work
with a relatively high current , so the bjt cascodes have
to dissipate something like 250mW each, wich is too much
for the 2SA872/2SC1775 ....

All in all, it s a pity, since the general design ideas are
fairly good but the practical implementation is not up
to these ambitions...
  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
Luxman Lv-105 Valerio Solid State 81 29th July 2013 01:54 PM
Luxman L-85v lefortd Solid State 0 11th March 2008 09:40 AM
Simple 2SK163 amp... Skorpio Solid State 0 8th April 2007 08:44 AM
Luxman L-100 ozaudio Solid State 18 30th October 2006 01:39 PM
FS: Luxman LV-105 Ron_Phelps Swap Meet 1 16th April 2006 11:35 AM


New To Site? Need Help?

All times are GMT. The time now is 03:29 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