Simplistic NJFET RIAA

[RCruz]

Originally posted by Thomo


I have just double-checked my layout against the schematic and everything seems in order. (I think the fets are the correct way round, lol).

Hi Lee

Wonderfull work.!

Can I use your layout for the schematic Salas designed for my benz ACE 0.8mv output ?

After some surprises related with my meridian 101 (I found it has opamps instead of DIS ), I am convinced I need to replace the preamp.... I will need your help to build a simple one including Salas RIAA.

This is becoming a feast.

Ricardo

[nicoch58]

Pass b1?

[Thomo]

I currently use a variation of Pedja Rogic's buffer, but have been meaning to have a go at the Pass B1 for a while.

I need to get a working phono before trying anything else though.

Cheers, Lee.

[Salas]

Originally posted by RCruz


Hi Lee

Wonderfull work.!

Can I use your layout for the schematic Salas designed for my benz ACE 0.8mv output ?

After some surprises related with my meridian 101 (I found it has opamps instead of DIS ), I am convinced I need to replace the preamp.... I will need your help to build a simple one including Salas RIAA.

This is becoming a feast.

Ricardo

Your 46dB schematic is already playing with a Benz Ace Clear medium output on a Pink Triangle with Origin Live DC motor (battery) mod. A friend of mine who lives on a Greek island made it and uses it there. He called several times to tell how his Benz plays 2 times better now. He has used very highly regarded commercial transistor or tube phono stages and step ups before. He will not retip his VDH cart now, because the Benz highs bettered it with this phono now he says, and he will save EUR 750!. So, I don't think that you will have any fidelity deficiencies with Benz Clear + Salas regarding your 101 competition. Since my friend reported that the gain I chose works very correctly with the Benz Clear, do you want me to calculate Lee's version for 46dB so you can make it on his PCB, only changing a few values and the B+ voltage?

[Salas]

Originally posted by Thomo
LOL. Oh yeah.

I was thinking of keeping the psu either on a separate board, or in a separate case.

I could add the regulator Salas posted, but I don't have the time to test if it works before implementing into the layout.

I have just double-checked my layout against the schematic and everything seems in order. (I think the fets are the correct way round, lol).

Regards, Lee.

Nice work Lee. Better keep PSU option separate, correct. Whatever wins for taste or availability, better not be carved in stone. The PSU will lend a lot of its character to such a circuit and we better be flexible here. Here is the 2SK170 pin designation for your final check.

[Salas]

Since Lee has taken the hassle and prepared a PCB, I think that a 52dB MC version based on the particular PCB schematic is in order. This one has gain centered for 0.5mV MC and can cater for the majority of normal MC carts. This one has all. Cascode, common source, buffer, local current sourced shunt PSU for cascode. Its an all rounder. Now both the MM and MC people have a common version and a common PCB. In such a way we make things more DIY ready.
Only thing still in question is if we have a really good shunt PSU design that adds a lot of performance to my RIAA, or an oscillating, noisy, blown mess... Cygnus X will soon tell!

[RCruz]

Originally posted by salas


Your 46dB schematic is already playing with a Benz Ace Clear medium output on a Pink Triangle with Origin Live DC motor (battery) mod. A friend of mine who lives on a Greek island made it and uses it there. He called several times to tell how his Benz plays 2 times better now. He has used very highly regarded commercial transistor or tube phono stages and step ups before. He will not retip his VDH cart now, because the Benz highs bettered it with this phono now he says, and he will save EUR 750!. So, I don't think that you will have any fidelity deficiencies with Benz Clear + Salas regarding your 101 competition. Since my friend reported that the gain I chose works very correctly with the Benz Clear, do you want me to calculate Lee's version for 46dB so you can make it on his PCB, only changing a few values and the B+ voltage?

Hi Salas

That would be "gold over blue".

Somehow I keep finding exceptional people in diyaudio always willing to help in the most difficult and critical areas.

By all means do post a Benz ACE Clear version !

I have recently found that the RIAA is indeed a critical point. I opened my 101 and found the discrete MM stage I have been listening to for 30 years now. Some time ago I purchased a MC module that I finally tried last weekend (This MC version is based on a opamp RIAA... the sound looses all the stereo imagery, instruments are projected forward and loose detail and attack).

I know this Benz has potential (wonderfull stylus). I have been listening to a VDH with a Naim MC pre + big Naim PSU and the timbre is quite identical. With a good RIAA it might outrun the VDH.

So I believe a jfet class A zero feedback passive RIAA might elevate things a lot. (I always loved the coherent sound of tubes but since I built this jfet output stage for the CDP, I believe these are like solid state valves)

Thank you for all the support and trouble.

Ricardo

[Thomo]

Just a thought, but I could easily build a Sulzer/Borbely type voltage reg into the layout of the board.

Would be nice to discover how good the Salas reg posted above is first though.

I will try and get a stereo board etched tomorrow and test.

Cheers, Lee.

[RCruz]

Wonderfull !

I am now reading about the B1, as I also need a buffered pre for the CDP.

[Salas]

Originally posted by RCruz

By all means do post a Benz ACE Clear version !
Ricardo

OK, here you are.