Simplistic NJFET RIAA

diyAudio Chief Moderator
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A long time indeed Nick. Meanwhile I enjoyed your riaa amp for nine years, how is that? :)
I tried several grounding variations, now it's making an extra popping sound of circa 5Hz, haha. I'll have look at daylight again.

I use RF coax for input and some low capacitance coax from an old tape deck out. Maybe it's the shielding, with the Denon it was fine.

Are there PCB's for this build?

Best regards, Jaap

That's great, the test of time they say.

You know something, test the NTM4 step up best wiring and shielding on the oscilloscope first by touching it and by using the mobile phone near it. The phono cartridge is inherently a current balanced source being a transducer but how is the arm grounding wired regarding the cart's output pins is another thing. Maybe the cart's return pin is tied to the arm and TT chassis then goes out through shield wire? To have noise rejecting transmission there has to be balanced impedance. So to use the primary balanced it also takes microphone wire style from end to end. If the cart end has one side already grounded then the trafo's input corresponding end must be too.

Double mono PCB for folded simplistic version only is available from time to time on Tea's GBs (better input stage in folded cascode with Toshiba K369BL, MC or MM configurable + integrated shunt regs).
 
Hello,
after many years of Paradise RIAA now I'm building my Folded Simplicistic RIAA with the original PCb's.
The idea was to power the circuit with the Paradise Preregualtor.
Without load the output voltage is about 81V and when I power your boards, go down to 60,8V (CLRC).
One channel works perfect (The second I connected, with the preregulator off and caps empty), the other was connected for a mistake with the preregulator ON and D2x, D3x , D4x and Q2x go to the paradise of the semiconductors.
So I think that the output voltage of the preregualtor is a bit too high, can you have any suggestion for a more safe operations?
Grazie
Guglielmo
 
diyAudio Chief Moderator
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You are welcome and enjoy the Folded. Post a photo even if easy. I know firsthand that those two phonos are different beasts with their own animal grace.

(I was participating in the Paradise team's thread back when it was brewed and I took part in its first transistors GB and first PCB GB. So I had made one. But I used less mF for the input stage's emitters decoupling to roll off earlier, I changed the servo time constant also, and I tweaked the RIAA curve to less smiley shaped. Although its shunt reg section was a variation on the SSLV topology theme for the parallel voltage part, its CV+CC somewhat complex series current source BJTs never settled well for stability on me until I replaced that section completely with a simple CCS. A peculiar to fit modification in an existing layout, so it took some creative short wiring additions).
 
Here some picture of my low cost build, I use the Paradise pre-regulator .
Grazie
Guglielmo
 

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diyAudio Chief Moderator
Joined 2002
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Here some picture of my low cost build, I use the Paradise pre-regulator .
Grazie
Guglielmo
Nice orderly build. Well thought out minimal distance GND "T". What is the perfoboard in the middle for? Maybe variable loading with LDR? Using a handmade interstage wax capacitor also? After some more use the whole thing will open just a bit further due to the electrolytics shaping up.
 
Compact and sweet. Congrats.

How do you like it after enough months? Something else you meanwhile changed in the system? Or still MM as it was set for a Nagaoka?

Thank´s Salas!

I like it very much! Was little afraid about hiss or hum when put the contruction in boxes but no worries here:) Dead quiet even with my ears close to membranes. No other changes yet but curious about 2 or 3 steps up in Nagaoka series
 
Here is some info for people who would like to try further V-ripple suppression on Raw DC part of our FSP.. Salas introduced it awhile ago and I tested it last weekend. FSP shunt regulator is not sensitive to high capacitance input, so no issue to use such device when you multiply C by BJT’s gain.
Please see results attached.
Vin – 25VDC with about 300mV ripple
Load – 90-100 mA
For such load, I see V drop is equal to 1.4V.
Yellow trace is input and Blue one is output from Cap Multiplier.
Sorry for high frequency noise. I used regular x10 probe with regular pigtail GND connector with crock. Unfortunately, it was impossible to use tiny-sprig GND connector with my perfboard.

I’m looking for volunteer to create Grabber files for Capacitor Multiplier PCB manufacture. Would be nice to get two multipliers on one board with possibility to connect them as double “mono” (+/0; +/0) or bipolar (+/0/-), As I say, would be nice have flexibility to reverse Caps and use BD 139 instead of BD140 in negative side.
I used DirtyPCB twice in the past and got no issues. 5x5 is like $14 for 10 PCBs and 10X10 is $24. All double sided and 1.6mm thick boards with moderate Cu thickness. If you know US based relatively cheap one facility, then please let me know.
Promise to send two free beards to Graber files designer.
 

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diyAudio Chief Moderator
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Nice cheap and handy switching PSU modules for general use those. But very noisy indeed. This multiplier did a great ripple eating job at 70kHz as I see in your scope's picture. The second order type has usefully controlled output impedance in the HF too. It skyrockets in high frequencies for those with just a resistor and a cap.