Will surely do it. See its really 16VAC off your wall, if more, use 35V cap for longevity. See to use good quality proper value load resistor for the cart (evaluate a couple, don't follow the manual's minimum blindly), and VERY good quality 0.47uF coupling output cap. Will be happy to know if it worked for you well enough.
P.S.
That is what the specific post 7809 cap multiplier filter in your circuit is supposed to do for cleaning its DCin (LT SPICE sim).
Attachments
I bought a set of 0.47uF ft-3 caps and some TX2575 resistors for Rload. Why is a 7809 used, most phono stages thrive on shunt supplies and being a MC-pre with it's tiny signals I thought a shunt is in the right place here. Guess I'm wrong here 
- so no output swing, therefore no shunt needed, no gain here to use a Salas 1.1 ?
Regards, Erik
- so no output swing, therefore no shunt needed, no gain here to use a Salas 1.1 ?
Regards, Erik
I bought a set of 0.47uF ft-3 caps and some TX2575 resistors for Rload. Why is a 7809 used, most phono stages thrive on shunt supplies and being a MC-pre with it's tiny signals I thought a shunt is in the right place here. Guess I'm wrong here
- so no output swing, therefore no shunt needed, no gain here to use a Salas 1.1 ?
Regards, Erik
You can try whatever instead of the 7809 but leave the multiplier noise filter that comes after the 7809 there. That one defines the PSU Zo also. See not to have serious heat sources near the input JFETs.
Hi Salas,
I have fired this up without success. I have measured some voltages on the circuit attachment. Fets are IDss 6.5mA What do you think? I have only fed signal from my cartridge as i dont have anything with such a low output. If the dc readings look ok i might make up a divider from the cd ouput as the next step.
cheers
Craig
I have fired this up without success. I have measured some voltages on the circuit attachment. Fets are IDss 6.5mA What do you think? I have only fed signal from my cartridge as i dont have anything with such a low output. If the dc readings look ok i might make up a divider from the cd ouput as the next step.
cheers
Craig
Attachments
Last edited:
Thanks Salas i'm embarrassed to have them in the wrong way.
After reversing I still can't get any sound through either of the amps though.
I used different fets this time matched at 8.5 mA IDss is this ok?.
This is a question on my skills with so few parts!!!
Does the 5.95v measured at the drains seem ok?
Measuring output resistance gave 224k input resistance was as per loading value.
Are the two fets in parallel to reduce the noise?
I made them on perf board so i will check the layout again.
Thanks for your assistance
After reversing I still can't get any sound through either of the amps though.
I used different fets this time matched at 8.5 mA IDss is this ok?.
This is a question on my skills with so few parts!!!
Does the 5.95v measured at the drains seem ok?
Measuring output resistance gave 224k input resistance was as per loading value.
Are the two fets in parallel to reduce the noise?
I made them on perf board so i will check the layout again.
Thanks for your assistance
Last edited:
The voltage drops look logical. Would expect more but they still drop. Yes, paralleling is for less noise. It has been tried out recently with success by a member in the simplistic phono thread also. Maybe you can cooperate a bit for debugging?
http://www.diyaudio.com/forums/analogue-source/129126-simplistic-njfet-riaa-635.html#post2584529
http://www.diyaudio.com/forums/analogue-source/129126-simplistic-njfet-riaa-635.html#post2584529
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.