phono/preamp analog front end

Actually problem w phono section and getting it repaired. Just weighing options

Here's something to keep in mind.


Loading of low output moving coil cartridges is not for the cartridge- its for the preamp, but only if the preamp has problems with RFI. Cartridges generate RFI because they have inductance, which is in parallel with the capacitance of the tone arm cable. The resulting peak can be 30dB.


If the phono section has poor overload margins, this can also result in ticks and pops generated by the phono section rather than the LP surface!


If the designer has sorted this out then you will get less ticks and pops and it will sound right without the need for loading. Loading causes the cartridge to do more work, and so stiffens the cantilever, making it less able to trace higher frequencies, or affecting its mechanical resonance in the tonearm. This can result in the cartridge mistracking.

So its worthwhile inquiring about these issues; if you are told that the preamp has a loading switch, its a pretty good bet the designer hasn't thought this stuff through!

@atmasphere  Just so I understand, you're saying that all phono preamps that have a loading switch inherently haven't effectively dealt with RFI issues in their design?  

Just so I understand, you're saying that all phono preamps that have a loading switch inherently haven't effectively dealt with RFI issues in their design?  

Generally, yes, more to the point they've not sorted out how that peak affects the phono section. The loading resistor detunes that peak and so gets rid of the RFI and so the phono section sounds better (usually less bright). But the tradeoff is now the cartridge cantilever is stiffer so not performing as designed.


The thing is, if you talk to digital guys, they complain about ticks and pops. It turns out that many ticks and pops are generated by the phono section if it has poor RFI immunity and poor overload margins. This BTW is an epidemic in phono preamp design; I would think that anyone interested in LP playback would perk up their ears on this one!