Simplistic NJFET RIAA

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Salas

Salas

diyAudio Chief Moderator
Joined 2002
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RCruz said:
Just replaced the output wires inside the riaa from branded silver to mogami coax.

Noticeable lower noise due to the screening !!!:djinn:

Much better overall equilibrium, loosing some high freq frontalness I noticed after replacing the zeners on the shunts.

Now I have a real work of art :):violin::Olympic:

Ricardo

PS
When I touch the FT-3 or the cccp silver micas, I can hear big hum... should I connect those to earth ?
Click to expand...

Remember I insist on coax? Even in DCB1 threads I tell them, they won't listen. You may earth the caps although if not near to a transformer (like in 2 box builds) they will not receive some hum. Not to the star if you do, shortest individual wires to chassis nearby.
 
Salas

Salas

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Joined 2002
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Just came from a bar, its early.:D No heatsink data from me because I bolt the Mosfets on the metal box floor using silicone pads for insulation. If you run the shunt with R1=15R then the current will be around 150mA. Floor will do, 2 inch PCB individual sinks will do. Look in TP Placid thread to see some.
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
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I prefer to keep a 150mA CCS for the phono, because it runs the Mosfets better. The heat is very manageable at this level. If you like you can get each one down to 100mA. But it will subjectively get a bit thiner tone. Have done all those experiments. But its your ears and your components and system and it may be synergistic even. Try some different R1 when ready.
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
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P.S. If I remember well you are going to make one for MM? If so, use a 100k trimmer instead of Rload, and no Cx for start. Listen to circa 75k and circa 100k too. Then add 33pF,50pf,100pF, turn your trimmer a lot with those too.

You will be surprised of what your MM can do when tuned in. Of course if you have an HFN/RR test disc and FFT on some laptop, it will be very easy to home in into a couple of decent curves and then listen. Faster and more secure. After you feel content, you substitute a normal resistor and a quality cap. Polysterene or Silver Mica.
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
psgr said:
Salas,

what should be the value of R1 for 100ma?
Click to expand...

With most green leds around 22R. But depends on various Vgs and Vf tolerances at some current and voltage levels. In the end you measure its Vdrop acroos R1 and you divide by it so to derive the actual buid's current. Seen to be in the ballpark I gave you, in the big majority of builds that my friends tried.
 
P

psgr

Member
Joined 2008
Salas,

I worked in a greek restaurand and night club during my school days.
I'm familiar with the history of bouzouki(tsouras and baglamas) and the rebetiko music, as it was discribed to me by the musicians. I do have some greek music on CDs.

Is Hiotis and Zabetas still available on vinyl ?
 
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