Simplistic NJFET RIAA

[ide2003]

R5=220K terminal resistor, not 200R trimmer. You have to use 550, it sets the voltage lower also. Plus, its not going to play long on batteries. 14mA bias.

that what I'm afraid of , making another supply is unavoidable. back to the bench then. btw, R1 180R replaced by trim 200R, R5 220k under the board,

thanks
TeguhPS

 

[Salas]

Yep, but give it a check as it is now on batteries to see if you have any other issues, trim your gain, its a good opportunity now its assembled as it is.

 

[ide2003]

yes after I'll give me and my MM cart 1-2 days chance ha ha, before I messing up the setup for MC ..will let you know how it sound, thanks again Salas

 

[RCruz]

Yes new longer listening session & your very good tweak/advice getting off the resistor & capacitor is a very huge upgrade, remember me near the same subjective than getting off the cap in the 1st stage but the cap in the 1st stage was still worse. Output caps Mundorf Silver Gold in oil are very very transparents so I can hear very easy the differences to god or bad.

Hi Merlin

I do not have caps on the first and second stages and that is surelly the way it sounds better... Any cap there leaves a heavy signature.

I guess it would be even better to try no cap on the buffer... but in that case, in order to avoid the buffer starving the previous stages, it would be better to use another shunt only for this.

PS:

Are you using a balanced riaa ?

 

[merlin el mago]

Hi Merlin

I do not have caps on the first and second stages and that is surelly the way it sounds better... Any cap there leaves a heavy signature.

I guess it would be even better to try no cap on the buffer... but in that case, in order to avoid the buffer starving the previous stages, it would be better to use another shunt only for this.

PS:

Are you using a balanced riaa ?

Lytics caps are evils for good sound.

That's will be a solution but it's a little expensive one shunt reg + psu caps & tx only for the buffer.

I'm using SE RIAA post 2795 page 280

 

[merlin el mago]

Wich gain have now the schematic I'm using without C10 4700uF, R9 100R (jumper) & C5 470uF?

 

[merlin el mago]

Now I can hear clearly differences of +-0,1gr in Tracking Force

 

[AndrewT]

Hi,
I can understand why you have disabled R9 & C5 when using a quiet and well regulated supply for V1.

I cannot understand why you need to disable/remove C10. Could you explain?

What have you done with

 

[Salas]

He did not need in the end the gain he initially asked for might be a plausible scenario?

 

[Salas]

Wich gain have now the schematic I'm using without C10 4700uF, R9 100R (jumper) & C5 470uF?

I don't have it in my files anymore as I have replied you previously but it should be around 57-59dB now give or take the real Yfs of your JFETS if measured as a whole with precise input signal. Towards 59 more likely.

 

[merlin el mago]

He did not need in the end the gain he initially asked for might be a plausible scenario?

My Denon DL103R real output 0,29mV instead 0,25mV

 

[merlin el mago]

Hi,
I can understand why you have disabled R9 & C5 when using a quiet and well regulated supply for V1.

I cannot understand why you need to disable/remove C10. Could you explain?

What have you done with

Because I hear better.

Because don't need more gain.

 

[merlin el mago]

I don't have it in my files anymore as I have replied you previously but it should be around 57-59dB now give or take the real Yfs of your JFETS if measured as a whole with precise input signal. Towards 59 more likely.

What's Yfs? Idss is 10.5mA

 

[vgeorge]

How did you mesure it? I mean the output of your cart?

 

[merlin el mago]

My Denon DL103R has a paper with it's own specs

 

[Salas]

What's Yfs? Idss is 10.5mA

Transconductance. I.e. intrinsic gain potential.

 

[merlin el mago]

Transconductance. I.e. intrinsic gain potential.

Thanks for letting me know, I don't know.

 

[Salas]

There is a chart that shows its relationship trend to ID (if ID=IDSS when Rs=0 amounts to the same) in most Toshiba low noise JFETs data sheets. We have referred before here, but I remind for K170.

 

[RCruz]

Hi,
I can understand why you have disabled R9 & C5 when using a quiet and well regulated supply for V1.

I cannot understand why you need to disable/remove C10. Could you explain?

Hi Andrew

I built a 57dB machine and used C10 (4700u) to get it to 61dB but I clearly heard a diffused/boxed sound probably coming from the EL cap signature.

IMO the first stage jfet source is determinant to the overall low noise and definition. I did not like the cap there.

I remenber Merlin did not like the sound with the cap there also.

 

[RCruz]

There is a chart that shows its relationship trend to ID (if ID=IDSS when Rs=0 amounts to the same) in most Toshiba low noise JFETs data sheets. We have referred before here, but I remind for K170.

Hi Salas

From that chart we might deduce a higher Idss jfet has higher transcondutance.

A higher transcondutance means more Volt/current amplification potential right ?

If so, why not use only high Idss jfets instead of the average 8.5mA you calculated ?