Op-amp ( BB OPA-134PA) based Phono preamplifiers. Fairly conventional, two stage, one with RIAA, one linear stage. With on-board power supply rectification and regulation.
PCB from eBay, IMHO very well made, nice layout and ground plane. Material as it should be, all low tolerance polypropylene caps on RIAA, Sanyo elcos..MBR diodes..etc.
You need only something like 2x15V AC transformer with this board.
Boards are new, only assembled and tested. I used some of these boards in past and IMHO they perform very well, electric and sound wise. Currently set for MM /47K/200pF.
--- Gain resistors for booth op-amp stages aren’t soldered, but inserted on soldered spring-loaded sockets. That is a practice I use a long time for Phonos..so you can trim a gain and load without removing the board and soldering. The same goes for loading resistors.
---These are fully DC coupled preamps. No capacitors on a signal path, so you can expect some DC offset at output, from my measurement around 2 to 8mV. If that is a problem, I suggest wiring output over some adequate capacitor.
Two boards available, price 30 USD board + shipping.
Regards
PCB from eBay, IMHO very well made, nice layout and ground plane. Material as it should be, all low tolerance polypropylene caps on RIAA, Sanyo elcos..MBR diodes..etc.
You need only something like 2x15V AC transformer with this board.
Boards are new, only assembled and tested. I used some of these boards in past and IMHO they perform very well, electric and sound wise. Currently set for MM /47K/200pF.
--- Gain resistors for booth op-amp stages aren’t soldered, but inserted on soldered spring-loaded sockets. That is a practice I use a long time for Phonos..so you can trim a gain and load without removing the board and soldering. The same goes for loading resistors.
---These are fully DC coupled preamps. No capacitors on a signal path, so you can expect some DC offset at output, from my measurement around 2 to 8mV. If that is a problem, I suggest wiring output over some adequate capacitor.
Two boards available, price 30 USD board + shipping.
Regards
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