Simplistic NJFET RIAA

[RCruz]

Right to the first question.

If you feel sound could be clearer, you can bypass the EL caps for sure... this will change treble presentation.... but it is a trial and error situation.

 

[AndrewT]

HEXFRED diodes for rectifier, then you placed 1 Ohm 10W resistor, and then Mundotrf 10,000µF /

this is effectively an RC PSU.
the 1r0 of added resistance changes little r to Big R.
This reduces the first charge current and spreads out the re-charge current over a greater proportion of the mains waveform, resulting in lower current peaks for the re-charge current.

 

[AndrewT]

Right to the first question.

If you feel sound could be clearer, you can bypass the EL caps for sure... this will change treble presentation.... but it is a trial and error situation.

If your supply is feeding "good DC" to your amplifier then adding more capacitance at the far end of the cable should not affect the sound coming from the amplifier.

If the amplifier needs a very good DC supply at it's power pins, then sort the DC supply AT THE POWER PINS, not at the far end of cables.

 

[RCruz]

Hi Andrew

I agree with you.... placing aditional caps Inside the riaa case near the amp does little to the sound but adding some extra carefully chosen caps on the psu case, near the smoothing caps can produce really strong effects.

I started with 15r, then 6r8, then 4r7 and settled with 1r before the smoothing caps. The higher value résistors seem to lower noise floor but somehow "muffles" the sound picture that loses impact and size.

 

[merlin el mago]

Ricardo could you try to add between the psu & the RIAA 1R + 3uF to filter RF above 53.000Hz inside the phono box if separate.

 

[RCruz]

I will try that Merlin

 

[merlin el mago]

Could be also 3R + 1uF, the cap must be the best quality possible.

 

[merlin el mago]

Salas wich values can I use for RX1,2,3,4 (as you know now I use Denon DL-103R)?

 

[Salas]

100 150 200 400 R

 

[merlin el mago]

Thank you.

 

[merlin el mago]

I have:

Shinkoh
100R
150R
200R
220R
330R
500R

Caddock MK132
100R
332R

PRP
220R
390R

Takman carbon
220R

What about if I will use all Shinkoh and PRP 390R?

 

[Salas]

Good choices.

 

[merlin el mago]

Wich is the best for 400R: PRP 390R or is too much Shinkoh 500R?

 

[Salas]

Shinkoh if you want consistency with the previous settings. 400-500R is almost same tone as load value. Can take well 103 plain version at 500R too.

 

[merlin el mago]

OK thanks.

 

[merlin el mago]

Time to start the psu.

 

[RCruz]

Nice build

 

[AndrewT]

Hi Andrew

I agree with you.... placing aditional caps Inside the riaa case near the amp does little to the sound but adding some extra carefully chosen caps on the psu case, near the smoothing caps can produce really strong effects............

I am alleging the opposite.

But if you have dirty DC and bring that dirty DC to the inside of the sensitive amplifier without filtering at the entry to the screening chassis then expect interference to affect your internal circuits.
Sometimes that interference will be audible.

But trying to filter the interference too early leaves the cables still able to pick up interference. And then to inject that interference to sensitive circuits once the cable enters the screening chassis.

You have two different jobs when the circuits are susceptible to interference.
Make the DC good. Adding an RC at the PSU end is good, provided the final C is adequate to maintain a stable non varying DC.
Add an RF filter to EVERY cable that enters/leaves the screening chassis/case.

And for good measure if the susceptible circuits have a changing current then good decoupling at the circuit is required.

None of this has anything to do with

If you feel sound could be clearer, you can bypass the EL caps for sure... this will change treble presentation...

 

[merlin el mago]

Nice build

Thanks Ricardo

 

[merlin el mago]

Salas max. Vin for FSP reg is 45VDC?