Simplistic NJFET RIAA

[buzzforb]

You the man. Trimming up b+ brings collector voltage up.

 

[Salas]

Try to find a half point TP2 to TP1 when its steady. 4.4Vish in your case I would suppose. 2nd stage should come up too. Your Jfets are stronger than you think most possibly. Don't wind up the SSLV too fast lest you get any magic smoke incident.

 

[RCruz]

It,s alive

 

[etoiledusoir]

I have a bunch of matched 2sk170 at 6-6.5 ma, can I use them for the schematic version for 4mv output cart with 4,0 ma iddss without major modification ?

 

[Salas]

I will have to reply that later when I will get the opportunity to check the sims.

 

[buzzforb]

What is max b+ i can deal with without messing up anything. Does the b+ affect the Riaa?

 

[Salas]

for the schematic version for 4mv output cart with 4,0 ma iddss without major modification ?

What do you mean 4mV cart with 4mA idss? Is your nick French for night star btw?

 

[Salas]

What is max b+ i can deal with without messing up anything. Does the b+ affect the Riaa?

In your case its just setting it up correctly. You may end up with 60dB gain, no negatives. Position the TP2 trimmer few turns below half value first. Max B+ you may regard the one that is going to give you 11V at second stage's drain to GND.

 

[RCruz]

What is max b+ i can deal with without messing up anything. Does the b+ affect the Riaa?

Maybe you could decrease R13 (1k5) instead of increasing Voltage.

 

[buzzforb]

If decreasing 1k5 is iption that is fine. I think perhaps i should lower jfet gain stage Rs, as with B+ at 39V, it is only 6.6V. Clearly the high idss fet there is causing geater Vdrop and lower idss through stage.

 

[etoiledusoir]

Yes it is night star. In the 19th century people were refering to the same star with two dirrefent names. Etoile du soir and etoile du matin (morining star).

I'm refering to the shematic in the wiki:
Salas Simplistic NJFET Riaa Schematics - diyAudio

Sorry for the ambiguity. Maybe i'll be more clear if I describe what I really want to do.
I'm using for now the shure m97 cartdrige and I have a bunch of 2sk170 matched at 6-6.5 ma that I want to use.

 

[Salas]

Maybe you could decrease R13 (1k5) instead of increasing Voltage.

Not preferable. Its increasing it actually. Will lose gain, needs Rs mod, and he still needs more drainV in his second stage, it was low for good swing.

 

[Salas]

Yes it is night star. In the 19th century people were refering to the same star with two dirrefent names. Etoile du soir and etoile du matin (morining star).

I'm refering to the shematic in the wiki:
Salas Simplistic NJFET Riaa Schematics - diyAudio

Sorry for the ambiguity. Maybe i'll be more clear if I describe what I really want to do.
I'm using for now the shure m97 cartdrige and I have a bunch of 2sk170 matched at 6-6.5 ma that I want to use.

Briefed clearly. Will reply in time and in detail.

 

[buzzforb]

Salas,
can i not bring up the second stage drain voltage by lower rs? They did not have 43R in Smd, so i have a 33R and 10R in series.

 

[RCruz]

Its increasing it actually. QUOTE]

What do you mean Salas ?

 

[buzzforb]

Lowering 1k5 would lower voltage and gain. Would need more degeneration ann less idss to ,aintain same gain level, correct

 

[Salas]

Yes.

 

[Salas]

Its increasing it actually. QUOTE]

What do you mean Salas ?

Its preferable to increase than to decrease much there for various reasons.

 

[RCruz]

I am not understanding... lowering 1k5 can lower gain, but voltage at collector should rise

 

[Salas]

Buzz, have you got any 6.8R for Rs?