can anyone identify this RIAA Phono

[glennjarrett]

Hi
I purchased this pcb off ebay with no info
after studying the tracks i have managed to get it working and it sounds very good
i am using a MM cart
the pcb has a switch on it which is shown in the schematic sketch i have drawn
with the switch open the sound is clear
when closed sounds dull and no top end
am i right in saying the closed switch setting is MC ??
mistake in pic the feedback is connected before the 4.7uf output cap

20201126_134152 by glenn jarrett, on Flickr
20201126_134106 by glenn jarrett, on Flickr

 

[glennjarrett]

mistake in pic the feedback is connected before the 4.7uf output cap

 

[PRR]

There are other errors. See attached.

Yes, the switch puts 100 Ohms (||10nFd) across the cartridge which sure will roll-off the treble on nearly any moving-magnet needle.

 

[U230421]

PRR is a drawingmaster!


Is IC2 really inverting the signal this way?
And a bleeder is missing after the output capacitor - connect a 10kΩ to gnd there to avoid popping.
Anyone with the datasheet of this SSM2134? Curious because of direct connection to +input.

 

[PRR]

Redraw for clarity:

 

[U230421]

So it is an inverter circuit. Provide or link.

 

[dreamth]

some variation of JLH shunt preamp http://www.hembrow.eu/personal/johnlinsleyhoodphono.html