Transimpedance has too much gain?

Atmasphere described this. Most current drive phono stages use an op amp input stage which provides a “virtual ground” the impedance between the inputs and the virtual ground can be zero. But there is also a true ground, and the impedance between hot and real ground cannot be zero. Many manufacturers admit to a finite input impedance in their fine print. Up front they like to say”zero”. None of this means they can’t sound good, but because there is some input impedance the sound seems to vary more unpredictably with cartridges having different internal resistances, albeit the lower the better .

pinwa, Any tonearm can be easily adapted to provide balanced output from the cartridge, because nearly all cartridges in common use are naturally a balanced source.  We use them in single-ended mode most often, but that is just because we ground one side of the output in order to use the RCA inputs on a typical single-ended phono stage. And of course, the turntable is an innocent bystander, when it comes to the signal output.  It's all about how the tonearm wires are terminated.

In the RIAA specification, frequencies from 20 to around 500Hz are boosted with a slope of about 6db/octave. At 500Hz to 2kHz, there is a plateau; those frequencies are not boosted. Then from 2kHz on up, the boost resumes at the same slope. If you are accurate in placing the peak, then maybe there is something askew with the RIAA (there may be no plateau for frequencies between 500Hz and 2kHz due to a faulty IC or whatever), but you have also to take into account that your other LPs sound good. That really suggests that either you are particularly sensitive to the instruments and the voice on those few LPs that bother you, or that they are otherwise the source of the problem. Others might also suggest you check all aspects of cartridge alignment. By the way, not many male vocalists (except castratos, maybe) can get up to 2kHz or even 1khz. So maybe your issue is lower down in frequency than you estimate.

To amplify on what I wrote above, Mijo is correct roughly speaking to say that as internal R goes up, gain using a current driven stage goes down, but this is because the voltage output divided by the internal R gives a rough approximation of current output of the cartridge. So as R goes up, if you hold voltage output constant, current output goes down. The other factor is the actual input impedance of the current driven stage. An ideal current driven stage would have zero input impedance. But that is not feasible; if input Z is zero then the signal will go to ground. That is the equivalent of a mute switch. So, all of these stages have some finite input impedance, and manufacturers are not good at revealing numbers. The actual input impedance of the stage will have a big effect on the efficiency with which the stage is actually driven by current. Typically, the impedance is between 1-2 ohms to as high as 10-20 ohms. If you mate an LOMC with an internal R of 2 ohms to a "current drive" stage with an input Z of 20 ohms, then you get voltage drive, depending upon the sensitivity of the input to voltage. This is why I hate the term "transimpedance", which implies that impedance doesn’t matter. It most certainly does make a big difference in the success or failure of these cartridge/phono stage matches.

Could it be that those LPs actually sound bad when accurately reproduced? Have you tried a different LOMC cartridge? I disagree with Mijostyn that the internal resistance of the cartridge must be 2 ohms or less; most current driven stages work fine up to around 10-12 ohms and many use them happily with even higher internal resistance cartridges. In any case that issue is probably not a cause of your problem. Maybe there is an issue with the RIAA correction filter in your unit, if indeed what you report is real. Try another cartridge and compare it using the Sutherland vs the Spinstage.