Simplistic NJFET RIAA

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RCruz said:
When you have time, please comment on the drawing... I must be sure there are now flaws this time.

I think that you got all JFETS facing the wrong way.
 

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diyAudio Chief Moderator
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I meant to have one point still, but different take off alternatives just in case. Regarding R20 I thought it may help you if there is less voltage across Q5 regarding the noises you get. Since nobody else ever got the noises, I don't know more. Its a proposed experiment. You will tell if it helps the noises you get during warm up or if it changes the sound. The current remains the same.
 
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I believe noises come from bad solder joints... my pcb is now a real mess.... that is why I want to rebuild everything.

If nobody else reported any issues, maybe I should stick to your original design.

Another pertinent question:

I am now using 2K21 RC55Y Welwin 0,1% metal film for cart loading and really think this is the perfect value.

I would like to try Shinkoh in there but do not know if I need to change the value.

I would really apreciate your comment.

Ricardo
 
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Normally Shinkoh gives the most grain free and organic rendering there. But not heavy at the same time. I would keep the value. Only thing is that with Shinkoh you can normally go higher in value before you get some ''pinch'' as with other resistors.
 
Hi everybody,

just an update to my latest mods.
First I replaced the inductors with normal EI core 10H 200ma - as per Salas suggestion - and put first the 2200uF capacitor in my CLC filter.
There was some better refining of the sound, but nothing spectacular.
After that, I replaced the 47nF PIO in the RIAA with an Obligato premium, bypassed by a silver mica, in order to get 46,9nF.
This was a big improve of the sound!
Also not to forget, I moved the bypass capacitors closer to the positive leg.
Next, I am waiting for some 16nF russian silver mica, as well as some 47nF silver mica, in order to replace and compare.

Thanks everybody!
PS. Salas, tube project is going well!
 
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vgeorge said:

After that, I replaced the 47nF PIO in the RIAA with an Obligato premium, bypassed by a silver mica, in order to get 46,9nF.
This was a big improve of the sound!
Hi vgeorge

This is exactly what i was waiting for. I am now very confident to replace the 47n PIO by a 47n obbligato.
What value is the obbligato ? (Why did you need to bypass ?)

Ricardo
 
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Just email me before you put the 12B4 together, so to tell you a few things about different options to try (Anode constant current, electronic choke, resistor) bcs some systems lend themselves better to one or the other, considering gain, speakers SPL, main amp's sensitivity etc.
 
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Of course I remember! 1979. Catchy clean tempo.

Back in those days The Police did make great post Punk White Reggae. I would like to listen to Stewart Copeland again on a brand new vinyl copy of the 1979 Reggatta de Blanc, on a 100dB sens dipole midbass system with Constant Directivity horn mids and highs, and 5 subwoofers scattered in Geddes way.;)
 

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