Simplistic NJFET RIAA

[Salas]

Merlin, have you got any sketch for df_genious by the way?

 

[merlin el mago]

Do you want a photo? balanced or unbalanced?

 

[SGregory]

df_genious,
Thats the fun of it. One strip board won't work for another due the the parts selected. It is a really simple circuit so it doesn't take long.

 

[merlin el mago]

df_genious,
Thats the fun of it. One strip board won't work for another due the the parts selected. It is a really simple circuit so it doesn't take long.

df_genious, SGregoy has right, each one is specific for needed gain dependeing your cartridge & njfets stash that you have on hand thanks to Salas

 

[vgeorge]

Going well I see, but decouple those long incoming DC twisted pair wires right at the regs input connectors with some 0.1-1uF film cap each, also. I think its good practice. Or you are going to connect the M-Lytics for that?

I will connect the M-Lytics first and see if a film cap makes a difference later.
Ok, I connected everyting and initially both channels were working fine. But after a couple of minutes one channel the leds stoped working. Also DS voltage on Q1 stated to rise. Could you please help? Maybe problem with Q5?

 

[Salas]

90% its a Q5.

 

[RCruz]

Hi vgeorge

Would you please point us your schematic so we can follow this repair... what Q5 are you refering to ?

 

[Salas]

He is referring to the LEDs feeding CCS JFET.

 

[SGregory]

Upped the load resistor to 182R tonight. The presentation is getting back to right. Imaging is solid and tonality seems to be more balanced. Starting to notice some of the spookyness returning. Will try 220R in a day or so.

Starting to work on the v1.2R. Is the loop size as critical as the plain V1.2?

 

[Salas]

Loop size its easier on the R. Not to make it wide like Red Square Moscow though.

 

[vgeorge]

Changed a 170 and a led and everything is fine!
Playing music now, and I can only say it is fantastic!
Much more detail, resolution and naturaleness.
Measured DS voltages and this is what I got:

Q1 L=5.46 R=5.45
Q2 L=8,58 R=8,50
Q3 L=13,09 R=12,95

 

[Salas]

Give us Q4 collector and R7 too, Q3's IDSS too.

 

[vgeorge]

Q4 collector to ground L= 12,74 R=12,69
R7 L=8,68 R=8,62
Q3 DS L=13,80 R=14,10 IDSS L=14,99 R=14,87 (I readjusted B+ after warm up)

 

[Salas]

Looks fine. Is it tonally even also? Do you have a picture of the whole system it plays in?

 

[vgeorge]

All I can say is that the sound is very dynamic and sweet at the same time. I will listen for a few days and then tell you more.
Rest of the system now is VPI Aries1, Shelter 901, RB300 modified, DBC1 to F5 and my speakers GPA 288 with AH4525 horns, Fostex 925 tweeter and dual Eminence 1512 for bass. Estimated sensitivity around 104-105 db. It doesn' t do very low bass though. Also building now a #26 pre.
Thanks Salas for everything!

 

[Salas]

You are welcome. How is hiss and hum with 105dB(!) real deal speakers? Also what exact type of output coupling Mundorf you use?

 

[vgeorge]

For hiss, let me check later and tell you. So far nothing at listening levels.
Output cap is a 3.3 Mundorf silver oil.

 

[Salas]

I just wanted to know that the input equivalent noise is subjectively adequate for listening to records even with such speakers with this single input jfet design & V1.2R. That's all, thanks.

 

[merlin el mago]

All I can say is that the sound is very dynamic and sweet at the same time. I will listen for a few days and then tell you more.
Rest of the system now is VPI Aries1, Shelter 901, RB300 modified, DBC1 to F5 and my speakers GPA 288 with AH4525 horns, Fostex 925 tweeter and dual Eminence 1512 for bass. Estimated sensitivity around 104-105 db. It doesn' t do very low bass though. Also building now a #26 pre.
Thanks Salas for everything!

Congratulations, what about the Shelter 901: sounds good as all people said, I want to do also the #26 pre if you know where to get cheap & good tubes & Tx let me know, I will use the Salas HV shunt reg. for B+ & I will buy to Rod Coleman his famous CCS for filaments, what are your plans for #26 pre?

Salas sorry for OT

 

[massimo]

Looks like we gonna have some #26 linestage around here (or the the SSHV thread) in the near future
Going to order a couple of Rod's kit too!
What I have in mind is an LC design with Tango chokes.