Simplistic NJFET RIAA

[Salas]

Originally posted by ikoflexer
I've finished the prototype last night.

Pictures? Wanna know what parts you used so I can help you with tuning.

[Thomo]

Originally posted by RCruz
My first atempt on the schunt pcb.

It is the pdf image in negative

Hope the circuit is ok.... I had to hand paint everything over the lazer transfer because it was full of flaws.... I added some gotic artwork !

Ricardo

Excellent work Ricardo.

I can only apologise for the massive delay with your board, I really am very sorry. I just sent you an email.

Last night, for the first time in months I managed to have a play with my Phono stage. I fitted a discrete, low-noise reg and rearranged the psu to shorten and neaten the wires up.

It now really does sound great, I'm really impressed Salas! For the coupling cap I'm using a 0.1uF Mundorf Supreme, and I'll swap that for a 47nF Russian PIO when I get chance to compare.

I also fitted extra Rubycon ZA's accross the one's already fitted. Doubling each one's capacitance to 440uF. This seems to have given better dynamics. Are larger uF caps much more beneficial?

Cheers, Lee.

[RCruz]

Hi Lee

Just read your e-mail. I am glad you did the board for me as well as source the dificult caps.

Regards

Ricardo

PS: Tonight I will put the shunt PCB on the etchant...

[nicoch58]

HI Cruz

I see that you mod a lot your meridian ......

by the way he have metal shield around phono ,a simple psu design and one opa-amp ,buffer?

I thinks the Salas phono-shunt are super design ,DIY are always better you want connect in the meridian ?

you can thinks a pot like otptivol and connect direct to amp

best

[nicoch58]

HI Salas

what you thinks about a JC buffer for how need ?

[Salas]

Originally posted by Thomo
I also fitted extra Rubycon ZA's accross the one's already fitted. Doubling each one's capacitance to 440uF. This seems to have given better dynamics. Are larger uF caps much more beneficial?

Cheers, Lee.

With the Shunt, not that beneficial. With other PSUs yes, the bigger (up to 1000uF), the lower in frequency they will decouple the power source impedance and the more energy they will store. Depends on their quality for optimum. I would say that about 470uF Nichicon KG can be nice, or 1000uF BG NX.

[Salas]

Originally posted by nicoch46
HI Salas

what you thinks about a JC buffer for how need ?

Very good buffer. The less the 1K input resistor can be with your input cabling (its there to protect from possible oscillations) the more open it will sound. Maybe you can do well with 220R if carbon and attached directly to the JFET pin.

[ikoflexer]

Originally posted by salas


Pictures? Wanna know what parts you used so I can help you with tuning.

Sadly, I was very busy with work and other stuff at home, but I'll post pics soon.

I have no boutique parts, unfortunately. All the parts I used were regular stuff. The electrolythic caps I measured for low ESR. The resistors are generic metal oxide. The .1u interstage cap is polypropylene.

You mentioned the 150p input capacitor. I only made room on the board for it, but never used it. I will try an input resistor smaller than 47k, it may make a difference.

I listened to the phono again last night, after I fitted a pair of newly matched sk170s. The same impression, great bass and highs, but the mids are sort of lifeless. It is especially evident when playing some classical music and a couple of violins play together.

[ikoflexer]

Originally posted by RCruz
My first atempt on the schunt pcb.

It is the pdf image in negative

Hope the circuit is ok.... I had to hand paint everything over the lazer transfer because it was full of flaws.... I added some gotic artwork !

Ricardo

Nice board Ricardo! Well done. Once you find the proper paper for the transfer, you will not see many flaws at all. It is also important to press decidedly with the iron edge (or tip) in one place repeatedly, Also, when printing it, the printer has to be set to the darkest setting (done in properties in software, advanced option). They also sell special transfer paper in electronics parts stores, but it's a bit pricey.
When I have to retouch, I use black nail polish (donated somewhat reluctantly by my wife ).

[ikoflexer]

Guys, what's the recommendation for high quality resistors, and does anyone have a good source for them? salas, you mentioned at least kiwames; is it worth getting better than kiwames?

Did I mention I'm cheap?
Thanks!