Simplistic NJFET RIAA

[vgeorge]

Experiment.
For start disconnect all ground wires.

 

[merlin el mago]

When no hear music was without all gdn ground wires connected to chassis.

 

[vgeorge]

No buzz and no music?
Check for ground continuity from input to output then.
Something is wrong there I suspect.

 

[merlin el mago]

Always right channel with/without gnd wires: no buzz no music

Left channel:
Without gnd wires: only buzz no music
With gnd wires: buzz & music

 

[Salas]

Try your step up again, still the same? No music? Reference your PSU 0 to chassis also.

P.S. Ask at batty's pre-pre only build thread too, there they had made several ones, maybe they can advise you on how they connected/grounded theirs.

 

[merlin el mago]

I referenced PSU 0 to chassis, left less buzz with music and right channel no buzz no music.

I tryed connecting Low MC pre-pre to EB lineamp without MM pre: sounds low as expected without buzz with music in both channels so as I suspected is the Rotel MM the issue of buzz in channel left & no buzz no music in channel right, I will open to inspect.

 

[Salas]

Maybe there is some button to press or something dip switch to set on the Rotel?

 

[merlin el mago]

I can't see nothing wrong

 

[merlin el mago]

Rotel MM left channel 1kHz sinu. probe x1 0.1V/cm

 

[merlin el mago]

Rotel MM right channel 1kHz sinu. probe x1 0.1V/cm

 

[Salas]

Its jumping. Is there DC on its MM input?

 

[merlin el mago]

My DMM can't measure but flashes the - with 0 Volts

 

[merlin el mago]

1kHz sinu. 0.2V/cm both channels same wave

 

[Salas]

I suggest you check your TT. MC pre pre, and SUT to another MM stage of friend's if possible, or make a typical stage from cheap op amp datasheet. Nothing makes sense till now, contradicting evidence, that can't make us useful opinion givers.

 

[merlin el mago]

DMM is jumping between 0.2mVdc & 0.3mVdc at tape output when I take the measurements with scope

 

[Salas]

Nothing serious.

 

[merlin el mago]

I forget that I have one cheap opamp MM battery powered, connected the Low MC pre-pre to MM and no buzz, both channels sounds music perfectly well congratulations & thanks Salas for suppot & to design this little jewel.

 

[Salas]

Send me the Rotel to personally blow it up, it drove us crazy.😀

 

[merlin el mago]

Yes it droves us crazy, I always suspected of it😡

I give a chance to the Rotel for integrated amp without phono MM input, I'm waiting to have a LS3/5A in the future if I have lucky but I suspect can't drive the loudspeaker due to it's high impedance but always can drive it with EB Millenimum 75W RMS Class A monoblocks.

 

[Salas]

OK, you blow it up then and you save the shipping cost.😀😀😀