Simplistic NJFET RIAA

[kropo]

Is it possible to use two shunt regulators with one transformer? that left and right has own shunt?

Or is there any effect at all between use one or two shunt? And if I use two shunt, do I have to use two transformer?

 

[kropo]

I'm now trying to find all of those components and have couple of questions.

On the riaa components, is there any differences using components (C2, C3, C4..) between 50Vdc or 400Vdc Voltage Duration?

Which is better Ceramic capacitor or Polyester capacitor?

Thanks for anwers !

 

[merlin el mago]

If caps are with the same dielectric & conductor if possible try with more voltage, subjectively are better.

About ceramic or polyester if is for RIAA try better silver mica, for interstage try something better is in the signal way minimum film polypropylene or better teflon & metallized or better foil.

 

[merlin el mago]

Is it possible to use two shunt regulators with one transformer? that left and right has own shunt?

Or is there any effect at all between use one or two shunt? And if I use two shunt, do I have to use two transformer?

I suppose depends power Tx, but if you have 2 shunts better use 2 Tx.

 

[merlin el mago]

That is 2nd stage. You got it OK. If you want to play with gain you vary R2 slightly. That one drops more on R1 and ups gain or vice versa. Because the signal level is slight there, THD remains about the same. I don't recommend playing with 2nd stage for gain because it influences the total gain less drastically but changes THD by moving the bias point of the Q5 buffer. You may try optimize the distortion profile to your ears there, 10-11V Q2D-GND is where it measures best in general. Whatever you may like, stays matched between channels on second stage. First stage is much more suitable to balance out any total gain differences between channels. Takes output measurement capability when steady under mV signal is present on input somehow.

If increase value R2 less gain & decreasing value more gain?

 

[Salas]

Yes.

 

[merlin el mago]

Thank you

 

[psgr]

Merlin,
Thanks for your input.

One more thing, has anyone tried rhodium plated rca connectors like:
4 CARDAS GRFA Thick Female Jack RCA Connector rhodium - eBay (item 140369996600 end time May-24-10 22:35:42 PDT)
Do they make any difference?

Pete

 

[RCruz]

Hi Pete

I guess this connectors will make difference if you are already using duelund caps in the output and also 1k€ interconnects.

 

[merlin el mago]

Merlin,
Thanks for your input.

One more thing, has anyone tried rhodium plated rca connectors like:
4 CARDAS GRFA Thick Female Jack RCA Connector rhodium - eBay (item 140369996600 end time May-24-10 22:35:42 PDT)
Do they make any difference?

Pete

Yes I tried rhodium plated but not Cardas, they don't make any sonic improvement difference vs other decent connector.

 

[merlin el mago]

Hi Pete

I guess this connectors will make difference if you are already using duelund caps in the output and also 1k€ interconnects.

I believe more in the cap than in the interconnects

 

[RCruz]

You might be surprised with the Nordost

 

[merlin el mago]

I tried Nordost & I don't surprised

 

[cjcc67]

Hi Salas great work here.
I have zero experience with design. If i wanted to just use the Low MC as a head IE no RIAA, is this possible to use in series with my existing mm phono stage. The cartridge output is 0.4 mV

 

[Salas]

No. It will output 30dB gain before Riaa, and grossly overload your MM input.

Make this one I attach instead, you can check it out using just a 9V battery.
Has 10x gain with a 2SK170BL. The input resistor can be your MC cartridge manufacturer's recommended load value instead of the indicative 150R.

 

[merlin el mago]

New simplistic pre pre phono without riaa x10gain

Congratulations Salas for the new Simplistic Pre Pre Phono without RIAA gain x10

 

[Salas]

Just a basic proper gain stage so someone can use his MC cart on his MM phono in its most simple. There are sophisticated circuits with better noise. This one is handy to make fast and will do the job rather decently, thats all.

 

[massimo]

Jfet MC Head amp

A similar project, complete with "series" PS, published years ago on these pages by English member Kwei Yang Wang.

See also thread http://www.diyaudio.com/forums/anal...-addicts-phono-preamplifier-2006-edition.html

 

[Salas]

The gate stoppers add noise directly, and are not needed in practice IMO. Must be 2SK170BL too? Because I see same bias scheme.

 

[massimo]

Yes, k170 or any similar NJfet such as K147 or K370 (the older and the newer)