Try stripping down to VSPS, sound great:
Project page:
RJM Audio - The Very Simple Phono Stage
My PCB:
Picasa ???? - johnsonlam - Share
thx for your advice will try to do like you
have you choose other than OP27
what type resistors and caps are good for RIAA
1. Using moving coil cartridge with VSPS.
2. Incorrect resistance values in R1-R5.
3. Zapped op amp.
)Good morning. Just built the stereo VSPS on a prototyping board using the 47b schematic and am having a bit of a problem. With the IN- connected to GND, I get no sound. If I disconnect it from GND, I get foggy, fuzzy sound. Distortion isn't the surprise. The surprise is that with GND connected, there's zero sound.
I've given the circuit a very quick once-over and wasn't able to find a problem. I've swapped the NE5532P for another (same) chip and still the same problem. I get a steady 12.48V at the power pins, although I haven't checked that with the GND connected. Yet.
Obviously I've screwed up a connection somewhere and will give it a very thorough check, but wanted to see if you might be able to point me in the right direction. I know it's not much to go on, especially without a photo, but thought I'd give it a shot.
Appreciate your time and any thoughts you might have.
I've given the circuit a very quick once-over and wasn't able to find a problem. I've swapped the NE5532P for another (same) chip and still the same problem. I get a steady 12.48V at the power pins, although I haven't checked that with the GND connected. Yet.
Obviously I've screwed up a connection somewhere and will give it a very thorough check, but wanted to see if you might be able to point me in the right direction. I know it's not much to go on, especially without a photo, but thought I'd give it a shot.
Appreciate your time and any thoughts you might have.
@topdog
IN- OUT- COM and GND must be all connected and at the same potential. Are you using a split supply? Just checking the obvious first. The problem with building it on prototyping board is you can get all kinds of connection errors, but from the language of your post I wonder if its something more basic like you haven't connected the power supply common to the circuit ground for example.
@Crabpeople
Looks nice, but the wiring is pretty messy. Try cleaning that up so the power wires are well away from the input wires.
Both of you might find the construction guide to be of some help.
IN- OUT- COM and GND must be all connected and at the same potential. Are you using a split supply? Just checking the obvious first. The problem with building it on prototyping board is you can get all kinds of connection errors, but from the language of your post I wonder if its something more basic like you haven't connected the power supply common to the circuit ground for example.
@Crabpeople
Looks nice, but the wiring is pretty messy. Try cleaning that up so the power wires are well away from the input wires.
Both of you might find the construction guide to be of some help.
Thanks for the quick reply. The power supply is from your construction guide. I think you've pointed toward the problem with your comment on the prototyping board. It's a connection error somewhere. Checked voltages more thoroughly and while there's a steady 12v at the op amp, the LM7912 is showing almost zero voltage and is heating up. There's a short somewhere I need to track down.
Hi Richard, what Cap do you use for C3?
my transformer -toroidal 100VA rating, i hope this is good enough.
How about the diodes?cause i am using bridge rectifiers as per parts guide.
My phonocable is VDH the first ultimnate-very nice so i am pretty content with it ATM.
Would a pre-regulating power be better?
Thanks.
my transformer -toroidal 100VA rating, i hope this is good enough.
How about the diodes?cause i am using bridge rectifiers as per parts guide.
My phonocable is VDH the first ultimnate-very nice so i am pretty content with it ATM.
Would a pre-regulating power be better?
Thanks.