Simplistic NJFET RIAA

see attachment

Thanks for the info. Why 300mA? We need a version as first shunt regulator / pre regulator which handles all the current like before.

Next use 3 shunt regs for each stage and share it for left & right channel. The shunts should be as near as possible to the amplifier.

They are supposed to be looking on separated load nodes. Or at least that is what I thought was the idea. I would prefer to give chance to a dedicated first stage low Z active noise filter on the rail than all this complexity and dissipation non the less.

Correct and I agree.

I am ready for beta testing.... please let me know if I can mod over my previous build :)

Ricardo,

you know what I mean? Here again:


  1. use a preregulator in the power supply chassis
  2. use 3 regs in the amplifier chassis
  3. share the 1st reg for the 1st amplifier stages (connect the B+ from the left and right channel)
  4. same with the other regs for the 2nd & 3rd stage
If you like we can correspond by e-Mail for further questions.


A happy new year to all forum members here :)
 
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Hi João

I experimented using the same shunt for both right and left channels and also one shunt per channel.

The latter produces much more separation and detail.

Using two independent psu´s, further increases this effect.

Why not use 4 shunts instead of 3 .... feed both 1st stages individually and 2nd stages individually.

Why the need to feed the buffer individually ?
 
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Just finished implementing the Lundahl SUT on one 48dB Riaa and the results are quite good.

No hum and the sound does not get too fat even with a 0.8mv cart... hope it works allright with the target (A special 0.15mV cart).

Strangely, I notice that the SUT amplifies the signal but also amplifies the noise floor, so the usual hiss I hear at full volume (without input signal) is also amplified.
 
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Hi João
I experimented using the same shunt for both right and left channels and also one shunt per channel.
The latter produces much more separation and detail.

Ok that describes my experience as well. But the version I described makes you dance and enjoy more listening to the music. It makes better inner dynamics and rythm. Try it out.

BTW, we don't have true different mono signals as L+R channel. Mastering means to use pan pots (panorama pots) to place the groups or instruments. Think about this point.

Mono power supplies male sence in mono power amps to get smaller power supplies.


Why not use 4 shunts instead of 3 .... feed both 1st stages individually and 2nd stages individually.

Good point, but I'd recommend the opposite and feeding the output stages individually!


Why the need to feed the buffer individually ?

Make it stable and inependet for load problems, here cables to the line stage. And if you're using a passive pre, in form of a TVC, then you can drive it easily.

Um feliz ano novo. Amor, saude e dinheiro!