Simplistic NJFET RIAA

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Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
JimT said:
Capacitors the short story
I cheated. I used some music with harmonica. In one test the harmonica did not have quite enough edge to it, one was a tiny bit harsh, the middle was just right.

Capacitors the long explanation.
To get C2Y correct I changed one capacitor on a side and then listened with headphones to compare the tone directly. The leads from the turntable were switched twice to make sure the improvement was due to the capacitor. The album was Chicago: The Blues Today. My intention was to focus on Junior Wells and the harmonica to get the sound of his voice and the harmonica just right. It worked fine. I planned to use the same method with the Obligato Gold and Mundorf Supreme capacitors, but the capacitors had their own plan. At the beginning of the first side Junior gives a short introduction to the song. There was a bit of a rumble before the intro started. I changed out the Orange Drop (C3) for the Obbligato Gold. I could now hear that the faint rumble was a quiet voice. The new capacitor had made low level signals clearer. After changing the other side and a relisten it was now obvious that it was Junior's voice and that it was probably a taped earlier version that Junior was listening to on a monitor. It was set to run for a short while before Junior started, I assume he used this a prompt. Next I changed one of my Solen's (C4) out for the Mundorf Supreme. I could now determine the words from the faint monitor. After changing the second one I actually could hear an even fainter version leading this now clear version. Clearly the producor had taped an earlier version and used it as a prompt for Junior. That version was used and the result taped and then used as the prompt for the final version. It was amazing that these low level sounds were clear and distinct. Normally I would find this kind of thing technicaly interesting but not care that much as it is really the music I am listening to. As it turned out this improvement in low level detail improved the music. The voices and instruments became more distinct and the music sounded even more realistic. I could easily close my eyes and imagine I was in a smoky bar listening to a live band, a common occurance in my misbehaved youth.

Thanks
Jim
Click to expand...

That's a good example on subjective tuning. Headphones are a trusty tool.
 
alexkosha

alexkosha

Member
Joined 2013
Hi Salas,

I added one more 4700uF to TB Raw DC PCB and with 15R my CRC has about 3mV ripple (130mV was with RC).
However, the noise level at max volume remains the same and also can hear some light clicks/crackles there. I suspect that my 4 LED set exceeds 7.75V (I use 2 red and 2 green). Can that be a course of regulator noise?

One more question.
I set C2+C2Y to 15.152/3nF (1->15uF + 2->100pF), but I think I still have too much bass and low highs. I'm going to add 47uF tomorrow and do use think such small cap can create a difference?
 
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Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
With 3mV ripple its a slim chance you got a problem through the rail. Or due to some little different local voltage. Nah. Seems like a system grounding or local shielding thing if its a minor issue at all. You got 20dB of tube pre gain don't forget maybe you ask the chain much for total absence of harmonic noise when you add another 52 from TT as source with the pot whacked up and head near speaker. But do try minimize.

Needing highs is lowering C2Y. Jim found 15.2nF correct on headphones too as recommended but that is not carved in stone for every system as a whole. Feel free to deduct down to zero C2Y if beneficial to your installation.
 
pellesmil

pellesmil

Member
Joined 2010
Raw PS in the making.

300VA 36v toroid from Poland running smooth like a V8

Mur 860 diodes, my favorite

CRC chain consenting of:

Mlytic 4 pole 6800uf 80v
Mills 15 ohm 5W
Mlytic 4 pole 6800uf 80v

470ohm load

Spot on 47.4Vdc output
1,56v across 15ohm
36vac @ 221vac mains

According to PSU designer the ripple is 860uV

mains voltage normally runs about 230 ish

A mains voltage raise to 230 gives 4% raise
I can live with that that

Per

Edit: crap writing
 

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Turbon

Turbon

Member
Joined 2011
pellesmil said:
Raw PS in the making.

300VA 36Vac toroid from Poland running smooth like a V8

Mur 860 diodes my favorite

CRC chain cinsiting of:

Mlytic 4 pole 680uf 80v
Mills 15 ohm 5W
Mlytic 4 pole 680uf 80v

470ohm load

Spot on 47.4Vdc output
1,56v across 15ohm
36vac @ 221vac mains

According to PSU designer the ripple is 860uV

mains voltage runs normaly about 230 ish

A mains voltage raise to 230 gives 4% raise
I can live with that that

Per
Click to expand...

:D What will you build pellesmil?

Regards
 
alexkosha

alexkosha

Member
Joined 2013
Salas said:
With 3mV ripple its a slim chance you got a problem through the rail. Or due to some little different local voltage. Nah. Seems like a system grounding or local shielding thing if its a minor issue at all. You got 20dB of tube pre gain don't forget maybe you ask the chain much for total absence of harmonic noise when you add another 52 from TT as source with the pot whacked up and head near speaker. But do try minimize.

Needing highs is lowering C2Y. Jim found 15.2nF correct on headphones too as recommended but that is not carved in stone for every system as a whole. Feel free to deduct down to zero C2Y if beneficial to your installation.
Click to expand...

You know, its a tiny noise at max volume and I do not hear anything at volume that I use to listen my record (which is still pretty loud per taste of my wife :)).
BTW, I removed insulation and connected TT GND lug to the chassis.
Still do not have my cover (it is in machine shop for extra vents drilling).

For C2Y cap, I mistaken and yes I need to lower values there. I'll go and remove all what I placed there and I'll start from empty, then 47pF and 100pF.

I'll report soon.
 
Salas

Salas

diyAudio Chief Moderator
Joined 2002
Paid Member
alexkosha said:
Hi Salas,

Can you please elaborate since I did not get what should I do with my GND.
So far, this what I have (please see attached picture) and my TT GND lug is attached to the chassis (not insulated).
Click to expand...

Its OK now that it refers to chassis. Make sure that the lid contacts the chassis electrically too I meant. Since you got some wooden frame also.
 
nezbleu

nezbleu

Member
Joined 2009
Erlend Sæterdal said:
Nezbleu have you compared KZ and FG ? FW is a booring sounding cap I think.
Click to expand...

No, I have not. I have never swapped PSU caps and listened for a difference. I have used Panasonics, United Chemi-Cons, and Nichicons, and they all seem fine to me. (I never hear much about UCC's, but another phono pre I built using them sounds great. I suspect that has more to do with the circuit and good PSRR than with the caps though.)
 
alexkosha

alexkosha

Member
Joined 2013
Salas said:
Its OK now that it refers to chassis. Make sure that the lid contacts the chassis electrically too I meant. Since you got some wooden frame also.
Click to expand...

Yes, I'll make sure it is connected electrically. It should be ready today....
Does it make sense to install 0.1uF and 10R resistor in parallel at the GND lug and to connect FSP GND to it? I saw such concept in Audio Note Phono. They also connected In GND to it.
 

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