Simplistic NJFET RIAA

[RCruz]

Hi Salas

I am about to order the obbligato output caps.

The difference in size and cost for 4.7u to 6.8u is not uge.. should I try the bigger ones ? (Can I expect even more bass ?)

Ricardo

[nicoch58]

Optivol

is a simple shunt LED/LDR optocouplers, the series resistor are 27k (at fist I put a Dale but tantalum is a must ) that work well in jfet riaa (you can remove the resistor on out caps) change if the amp need...

the pot control the light on led ,ie you can put where you want !and ldr near the out

need 24vdc or so ,for 17€ shipping incluse you can only win !! a lot better then alps blu

problem,now is out of stock but contact Greg ,is fine men ,for preorder


alternative the ligthspeed on Diyaudio that are full ldr but parts and match are problem (you can order two matched optivol)

decent pot start with TKD at 61$

alternative 41-step Attenuator but $$$ link

[nicoch58]

from Zen mod, ldr+JC buffer kit .....are you sure that need buffer?

Poor Serbian Man Lightspeed packages

[RCruz]

Thank you nicoch... I will email Greg.

What about the 6.8u output caps ? Can I expect any gains ?

Ricardo

[nicoch58]

no

the amp gain/speakers db/room and if you like blast

Rload do a bit ,

[RCruz]

You mean 6.8u is not suitable as an output cap ?

[nicoch58]

Originally posted by salas


Means a John Curl buffer. But your RIAA is already buffered so it will not lose from its own gain. And a further buffer after the pot will not add gain either. It may interface the pot nicer, but that is all. The main thing is if you get enough drive for your habits to the main amps, speaker, room, system.

[Salas]

Originally posted by RCruz
You mean 6.8u is not suitable as an output cap ?

4.7uF is more than enough even down to 10k loading. Bigger means more aluminum foil for no reason.

[RCruz]

Thank you again.

I believe I will try to feed the Riaa directly into the power amp using a pot only and see what gain do I have.

It might clean up things a lot.

PS:
I like the optocoupler option, so I will mail Greg about them.

Ricardo

Thank you Salas... 4.7u it will be.

[nicoch58]

with 27k can be 1mf if I remember well ,I have used 2,2//0,47....

with optivol if you lower to much the rserie (now my is 18k) you lost a bit the 0 volume out.....(no signal)