I recently bought the $14 Pyle PP444 after some research. Turns out that this design uses thru-hole components so device replacement is possible.
https://www.vinylengine.com/turntable_forum/viewtopic.php?t=118661&start=12
After a quick listen a hum started getting louder and louder. The turn table was grounded to the chassis but I'm not sure if the chassis is grounded to earth very well.
Comment 1
The hum reported on the test of the Pyle PP444 is easy to solve. All you
need is to replace two capacitors on the power supply circuit.
Comment 2
The negative side of the power supply and the lower rail voltage of the
op-amp are tied to ground. So some biasing is needed on the input, and
the lower side of the input resistors (R8-R9, 47k) are connected to a
voltage divider (R5-R6) filtered by capacitors C5 and C8. Although the
ripple at C5 is attenuated by the presence of the cartridge, this
attenuation factor is of the same magnitude as the mid-band gain of the
phono preamp. But there is 16dB more gain at 60Hz, and 12dB more gain at
120Hz. This is where the hum is coming from in the Pyle PP444 test
report.
Compared to the VSPS
https://phonoclone.com/diy-pho5.html
