2SK170 BL MC step up amp

[acidbrain]

20dB

 

[merlin el mago]

Same gain like the double SK170BL 7809 regulated?

 

[acidbrain]

Hi Felipe,

I used the same supplyvoltage as with the original setup, so I imagine the gain would be identical, but I haven't measured it.

 

[merlin el mago]

Hi Erik,

If I remember well Salas posted 20dBs but for a newbie like me the only reason to have same gain it's the double njfet Idss is 7mA & the single njfet is higher Idss but I'm not sure I only want to know Idss range for single njfet & if the gain it's the same because for me it's more easy one single njfet powered with alkaline 9V.

 

[merlin el mago]

Done, now I only need a box, RCA connectors & chassis GND to connect the TT.

 

[Salas]

Wich gain have this schematic MC pre-pre, wich Idss something 7,5-9mA?

That one is not this thread's pre-pre. Its a single fet 20dB to work off a 9V battery for low enough consumption due to one degenerated fet and easy PSU, but hissier than two fets with no source resistor.

 

[merlin el mago]

Thanks for the info Nick.

 

[Salas]

ANOTHER approach at the mc- pre. This time with a BiB shunt, the power an open sound it gave made me go back to the FT-3 teflon cap. I had some issues to tackle hum, put the mc-stages in metal boxes and installed some RC filters in front of the BiB.

Maybe it's premature when I say that this is my final setup of Salas his MC stage,
because you never know, but it's good !

Impressive work. Leaving out the local filtering took extra PSU and can measures to be more dynamic still noise free, but you did go heroic to have all. Nice.

 

[acidbrain]

Thank you for your kind words and yes I went totally ballistic.

Without filters the sound is even better, but the hum was way too much.

Erik.

 

[merlin el mago]

Done, now I only need a box, RCA connectors & chassis GND to connect the TT.

That one is not this thread's pre-pre. Its a single fet 20dB to work off a 9V battery for low enough consumption due to one degenerated fet and easy PSU, but hissier than two fets with no source resistor.

Anyway battery powered I don't hear any hiss and sounds very very good remind me Simplistic njfet mc RIAA, thanks again Salas. Next step I'll try with two 2SK170BL 7809 regulated to compare vs single 2SK170BL battery powered

 

[Salas]

What cart does it step up to what MM stage? If you will judge battery life long enough and you hear no hiss plus liking the sound, no need to make a pre pre collection.

 

[merlin el mago]

DL103R modified without body + modified big brother Puresound P10 MM 40dB (x 100).

I prefer single SK170BL battery powered vs Jim Hagerman Piccolo mc pre-pre, also I prefer single SK170BL battery powered vs Partridge 977 step up.

All test is for the future Valve Itch MM....

 

[merlin el mago]

What cart does it step up to what MM stage? If you will judge battery life long enough and you hear no hiss plus liking the sound, no need to make a pre pre collection.

How many current spends the single 2SK170BL per channel?

 

[Salas]

~3.5mA for when using circa 8mA IDSS in the circuit you posted.

 

[merlin el mago]

Thank you, how many time using one alkaline battery of 9V per channel?

 

[Salas]

Don't know, depends on battery quality. Say 30 hours to 75% of nominal voltage? Maybe. You will see by using it.

http://data.energizer.com/PDFs/522.pdf

 

[merlin el mago]

Thanks Nick.

 

[Benna]

Can I raise the amplification - say to 28dB?

How?

 

[Salas]

If you make R1 430R with 7815 chip reg and 20V raw DC input in post#2 circuit, you will get 28dB gain.

 

[Benna]

If you make R1 430R with 7815 chip reg and 20V raw DC input in post#2 circuit, you will get 28dB gain.

Thanks a lot Salas!

I wondered if the 2SK389 would be better - it certainly has lower noise...