Simplistic NJFET RIAA

[RCruz]

Anyway, first channel is up and running.....

Now starting to populate 2nd board.... I did a much better job in the filter this time

 

[Salas]

Highly tuning to extract that last drop of orange juice...

 

[RCruz]

A real pleasure this is

 

[RCruz]

While waiting for a suitable case I have the board working on my bench and I am profiting to do some measurements.

Everything looks perfect but when I try to measure Q6 gate, every time the probe touches Q4 - R10 node, the voltage starts to drop.... Why does it behave like that ?

The board is not connected to anything so there is no load on the output .... The input is also unloaded but I left R1 = 1Meg ..... Every time I short the input, the leds on Q3 base flicker.... why should this happen ?

 

[Salas]

Difficult to just guess the interactions. Attach scope probes to associated nodes, so to can watch what happens.

 

[Siberia]

No affiliation. I know some members on this thread like this arm:

SME IV Tonearm | eBay

 

[bucurb]

Changes...

Hello,

It's difficult to follow every day changes in such a very long thread. And it seems that there are changes both in Regulators and RIAA.
Where are the actual schematics, please?
Thank you!

 

[vgeorge]

Have a look at the links at the first post.

 

[cygnus x1]

Can I replace two 2SK170BL for one 2SK369BL (Q1 and Q2)? The reason I ask is I have a medium output MC (.7mv) and according to the instructions, I sould use only one 369 and resistor (remove Q2/R3). I realize the 170 will need to in the same IDSS ma range (10 to 15) as the 369. Wouldn't two 170 be quieter than one 369?

 

[Salas]

They wouldn't be quieter. They would be the same nVrtHz as one K369. Still the K369 has better 1/F region behavior due to lower GR noise, so I recommend one K369 vs 2xK170 in this application.

 

[RCruz]

Very true.

I built it with one, two and three k170 and it sounds much better with only one k369

 

[orelli]

Anyone use the 369 in the DCB1 buffer? Have a sense in that " stupid circuit"?

 

[RCruz]

Anyone use the 369 in the DCB1 buffer? Have a sense in that " stupid circuit"?

Cool question (besides the "stupid" quote)

 

[orelli]

"stupid circuit" are Nick's words, maybe John Curl disagree. Jokes apart, I think it sounds more dinamic,cause the more transconductance ( 40 mS).

 

[Salas]

No problem using it apart from the higher input capacitance so better make do with 10K pots.

*Don't remember the quote but I should have used stupid in the sense of stupidly simple.

 

[stajo]

I like stupid circuits

 

[orelli]

*Don't remember the quote but I should have used stupid in the sense of stupidly simple.

yes

 

[RCruz]

I think it sounds more dinamic,cause the more transconductance ( 40 mS).

No problem using it apart from the higher input capacitance so better make do with 10K pots.

Maybe we could use those also in the output buffer of the folded.... More dynamics you say.... I like the idea

 

[Salas]

They are more useful in very low input signal duty but if having spares its alright. Got to keep about same voltage headroom across the output stage buffer as was with the K170s. If higher idss, as usual with most 369BL, the R in the rail's last RC must become smaller. Also, by using the oscope, make sure it does not react on output interconnects due to the higher Yfs.

 

[RCruz]

Good news these are.... talking about flexibility ... Simplistic Flexibilistic