2sk135 2sj50

[Patrick]

that sound about right, thanks for that info,

the input GND to output GND is 10.5 ohms.

[Tube_Dude]

Input signal is the right one and common the left one. Is the screen on the input cable connected to the left one? (if it isn't that is weird)

No... the amp is a mono amp (for a monobloc pair)...so the input is right!

If the amp was Stereo it will need two speakers outputs also...

To Patrick:
Input is correct
Connect power supply + to the board +
" " " - " " " -
" the + of the loudpeaker to the output side of the inductor
" " power supply ground to the ground connection near the output inductor
And connect the - of the loudspeaker to the power supply ground...or to the point that connect the power supply ground to the board!!(this depend of the implementation of the circuit!!)

But please...short connections!!

After enjoy the music!!!

Cheers

[megajocke]

Originally posted by Tube_Dude


No... the amp is a mono amp (for a monobloc pair)...so the input is right!

If the amp was Stereo it will need two speakers outputs also...

<snip>

I meant that the right hole is input signal, and the left one is input ground. Not something with left and right inputs

[Tube_Dude]

Hi Megajocke!!

Sorry!!!...i haven't understand you right!!

Is because we both aren't talking our native languages...

Cheers

[Patrick]

thanks for the reply's.

i knew that this was a monoblock. the real problem that i was trying to solve was which out of all those wires was +ve power, -ve power, GND and audio output.

i have now solved this problem thanks to pinkmouse.

just one question, what setting should i have the POT (one in the center of the bord) set at (ie what volts).

other than that this amp makes quite a good sub amp.

thanks for all you input.

[pinkmouse]

The pot is probably for adjusting the bias current- to do that you will need advice from someone who knows the mosfets. I don't, sorry.

But if it works well, and doesn't run too hot, you can probably leave it for a while.

[Tube_Dude]

Originally posted by pinkmouse
The pot is probably for adjusting the bias current- to do that you will need advice from someone who knows the mosfets.

Yes the pot is probably for adjusting the bias current or for adjusting the of set voltage...only the schematic can tell ..but i bet that is for bias adjustment...!

The typical bias currents for 2SK135/2SJ50 are 100mA per device...

[megajocke]

Does anyone know anything more about these transistors? They seem to be similar to 2SK135/2SJ50. I can't find any datasheets.

2SK227: 160V, 7A, 100W
2SJ83: 160V, 7A, 100W

[universum]

Hi Akersa,

The replacements of the 2SK135 and the 2SJ50 are
the 2SK1058 and the 2SJ162.
They are nearly the same(from specs)but not so in service so look for the good bias...Prefer the old TO-3 ones(for sound and shielding),altough the flat-ones better mount:-))
The picture that Patrick shows is one of the cresendo from elektor...they had a miniversion (about half the size of the cresendo)
They recommended a current of 100 mA(measured by the 5 resistors of 1 ohm at their sources..)i would settle for 800mA,if you have a big enough cooling!!
They run very hot,but still work,after more then 20 years of service..idle still the same as then..nothing changed..yet...

Happy listening!

[Bernhard]

Originally posted by peranders
The K135/J50 are rather special, they have constant gm over a certain current! This is good for linearity but bad for output impedance.

Hi,

what is gm ? And in which area of current ?


Bernhard