2SK170 BL MC step up amp

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#90
I'm willing to give a try at that MC step-up circuit. It seems easy to build and a much cheaper alternative to step up trafos.
I already have all the components needed, except the 2SK170s, of course. Now, the typical question : to find a reliable source for genuine Toshiba units.
On Ebay there're a number of vendors offering them. Some swear that theirs are genuine. Others even offer matched pairs or quads.
As a side note, I see that there's an available substitute : the LSK170 ( by Linear Systems) which performs as the original (or so they say).
http://www.micross.com/pdf/LSM_LSK170C_TO-92.pdf

Any opinion or experiences on the LSK170 or on buying 2SK170s ( Ebay or elsewhere) will be greatly appreciated. 🙂
 
#92
acidbrain said:
Looking at the official Simplistic NJFET RIAA thread I want to change the Mc pre-pre with JFET-BJT cascode stage & local shunt type voltage stabilizer to keep Miller capacitance low. Is that a good idea ?

http://www.diyaudio.com/forums/atta...ic-njfet-riaa-folded_simplistic_pcb_guide.pdf

Erik.
Click to expand...

With a low impedance MC cartridge as source the Miller won't annoy things. For MM it will. The FSP has a cascode (folded to ground type) but its configurable for all cartridge types not just a dedicated MC pre-pre
 
#95
Artur5 said:
I'm willing to give a try at that MC step-up circuit. It seems easy to build and a much cheaper alternative to step up trafos.
I already have all the components needed, except the 2SK170s, of course. Now, the typical question : to find a reliable source for genuine Toshiba units.
On Ebay there're a number of vendors offering them. Some swear that theirs are genuine. Others even offer matched pairs or quads.
As a side note, I see that there's an available substitute : the LSK170 ( by Linear Systems) which performs as the original (or so they say).
http://www.micross.com/pdf/LSM_LSK170C_TO-92.pdf

Any opinion or experiences on the LSK170 or on buying 2SK170s ( Ebay or elsewhere) will be greatly appreciated. 🙂
Click to expand...

LSK are good enough and there is the LSK389 monolithic matched pair in shiny metal can with golden legs they make also. Online for K170 used to be Spencer from Fet Audio and Alweit on eBay who had a good track record. For LSK the DIYA store.
 
#96
Moltes gràcies Merlin.. Thanks Salas and Walter. BTW I never thought of looking here at the diy audiostore.😀
A last question for Salas: I want to get a bit more of gain; say 23 db instead of 20. Is it enough to raise the value of R1 ( from 180 to 240-250 ?) or it's also necessary to increase the output of the regulator above 9V ? ( I'd use an adjustable LM1086 instead of a 7809 )
 
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#97
As a higher R1 will drop more voltage, increase the regulator output as much needed as to restore the provided voltage across the FETS at 1/2 compared to R1's top when measuring from drain pins to ground
 
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