Luxman L58A / 2SK163-2SJ44?

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I have just bought a very nice Luxman L58A still working - But , the circuit for the amplifier part showed, that 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?

Have just bought the output fet's - the original were 134/49 but the 2Sk135/2SJ50 bought takes 160V instead of the original 140V.

Any help would be appreciated.

Rgds.
Kim Hansen
Denmark
Europe

Please find some vintage Luxman amps at: www.tubeamp.hobbysider.dk and find the link to "Skysite"!
 
Luxman L58A schematic

I have just bought a very nice Luxman L58A still working - But , the circuit for the amplifier part showed, that Luxman for the input differential stage has used 2SK163 and 2SJ44 from NEC.

To "Fixingthings"

Luxman L58A
Hello

I'm looking for a repair manual schematic of a L58A amplifier. I've downloaded and payed for several pdf wich supposed to be the right schematic but it was for the 55a ampli, Do you have the correct one.

Thanks

Well - I have just received a scanned copy of the Luxman L58A schematic.

I was about to open a new thread to see whether someone has a better scan or pdf?

Some Luxman L100/L58A and valve stuff on:

http://leakstereo20.skysite.dk/

Rgds Kim

Ps. if this difficult to read post me.
 

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Nearest source is Williges electronics in Bremen, at some 200 sniper clicks from the southern Danish border.

Nice power amp stage, a parallel pair of the 1S devices in the output stage would have turned it a killer in the late '70s, early '80s.

Thanks Jacco - I shall try to find Williges Electronics.

Yes, I have been told that the L58A design is very good, and I agree, while the sound , at least to me, is very detailed and "musical".

When I bought the L58A , I thought that the powerstage included 4 output Hitachi fet's per channel. Unfortunately there are only one pair per channel, and the lack of sufficiant ampere-power is possible to hear by use of speakers with efficiency as low as 85-86 dB/1watt.

This is the reason why I tried to find a Luxman L100 ( four output transistors per channel and approx 110W). This amplifier is not with fet's in the output stage I think. I like the sound of the old Hitachi 2SJ50/2SK135 - well, I have just received the L100 and the old amplifier need a chance to demonstrate it's reputation.

You can find the "new" L100 on:

leakstereo20

Rgds
 
Nice power amp stage, a parallel pair of the 1S devices in the output stage would have turned it a killer in the late '70s, early '80s.

Anyone who has changed the Luxman L58A outputstage from one pair to 4 Hitachi's per channel? The internal space for the change is sufficient in L58A.

If so - anyone who has experience whether the powersupply is capable to deliver the extra ampere?
 
Jacco,

Have you bought any 2SJ44s from Williges or first hand experience with them ?
Are they original ?

According to this forum at least, they do sell non-original, third-party parts :

kleinere Endstufe, symm aufgebaut, Elektronik-Selbstbauprojekte - HIFI-FORUM

"hab doch noch zum glück einen kleinen laden um die ecke gefunden, der die dinger auf lager hatte! sind zwar keine "original"-Sanken, die hier scheinbar gefeiert werden, aber der kleine, feine unterschied war auch, das Williges für einen EIC nicht 8-13€ plus versand und 25 € mindestbestellung haben wollte, sondern 3,30€ plus märchen."

Williges-Online-Shop

(4 Euros for a 2SC1116.)


Patrick
 
Replacement

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
 

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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.
 
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.
 
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.
 
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
 
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?
 
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.
 
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?
 
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...
 
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