Simplistic NJFET RIAA

[Salas]

So i went today and got me the irf9610's.
Replaced the old ones and............. IT WORKS !!
Well i dont know if it actually works properly yet but at least it lights up.

Murphy gotcha one time only it seems.
Tell the guy over the bench where you got the older ones not to rub MOSFETS on the shop's cat before he hands them to the customer from now on.

 

[skouliki]

Very nice! There are not many things that can wrong there.
What voltage you have on R1X?

I have 1.6v across the resistor in both boards

 

[skouliki]

Murphy gotcha one time only it seems.
Tell the guy over the bench where you got the older ones not to rub MOSFETS on the shop's cat before he hands them to the customer from now on.

The old ones were bought from Fanos. I'll let him know!!
I got the last remaining 9610 of Katoumas today and the other one from Venieris. Price difference: Katoumas 1euro, Venieris 2.20 euro

 

[vgeorge]

I have 1.6v across the resistor in both boards

Looks good, go ahead and bias as per guide and let us know!

 

[Salas]

The old ones were bought from Fanos. I'll let him know!!
I got the last remaining 9610 of Katoumas today and the other one from Venieris. Price difference: Katoumas 1euro, Venieris 2.20 euro

Its I told you go to Katoumas bcs they used to be IR official importers. Maybe NOS genuine stock in older prices and you got their last Mohicans for now.

 

[skouliki]

After half an hour warming up voltages are not right. I have rail+ gnd 31.7v ,tp1-tp1 4.5v and rail+ gnd 30.8v, tp1-tp2 4.8v for the other board . This is with VR2x adjusted for max voltage

 

[Salas]

Your Q3x IDSS choice is weak for your R3x choice. You need a little more B+ range. About 1K more on R3x value should suffice.

 

[vgeorge]

Did you use 9.1K R3x? You may need to adjust R3x to get the correct voltage, What is the IDSS of your 2sk117?

 

[vgeorge]

Salas got me first!

 

[Turbon]

So i went today and got me the irf9610's.
Replaced the old ones and............. IT WORKS !!
Well i dont know if it actually works properly yet but at least it lights up.

Very good!

Regards

 

[skouliki]

With R3x=10kohms i get 33.1v , tp1 tp2=3.9v and 34.1v , tp1-tp2 3.5v.
Is that good enough?

 

[skouliki]

Very good!

Regards

Thanks!

 

[vgeorge]

Do you have it boxed or is it open air? I would prefer a little lower tp1 tp2 voltage, as it will rise after warm up.
If you have VR2 max then go a little higher on R3x.

 

[skouliki]

It is on open air. Next resistor value in my hands now is 15k dale rn55. You think i should use that? Is the wattage rating important in r3x?

 

[nezbleu]

Parts arrived!

Nice early surprise from Santa, my Mouser order arrived yesterday. That was fast!

 

[vgeorge]

It is on open air. Next resistor value in my hands now is 15k dale rn55. You think i should use that? Is the wattage rating important in r3x?

If it' s in open air, when you put in box, tp1 tp2 voltage will rise, up to 0.5V.
Wattage rating is not important, but it' s nice to have a quality resistor there.
Maybe you can parallel two resistors to get to 11k or 12k temporary?

 

[Salas]

It is on open air. Next resistor value in my hands now is 15k dale rn55. You think i should use that? Is the wattage rating important in r3x?

Do you have 4 so to parallel pairs for 7.5k per channel?

P.S. Forget it I just saw you are at 10K already. 15K will overshoot to the other direction.

 

[Salas]

Nice early surprise from Santa, my Mouser order arrived yesterday. That was fast!

 

[vgeorge]

Nice early surprise from Santa, my Mouser order arrived yesterday. That was fast!

Nice collection of parts! But I see you ordered a CT transformer. Why?

 

[Salas]

Nice collection of parts! But I see you ordered a CT transformer. Why?

36VCT. Its just another way to state 18-0-18V I guess.