Transimpedance has too much gain?

I’m running an AT33PTG/II through an Andover Spinstage. Overall it sounds amazing but there definitely an emphasis on the 1khz region that makes some records hard to listen to. Its louder than the 20/20 and I have been swapping out parts to find the cause.

could the phonostage be adding too much gain?


@pinwa they sound more alike then different but the Spinstsge is more lively. I like it a lot otherwise I’d just send it back. What it does right it does beautifully. What it does “wrong” keeps me up at night.

I bought the ipower SMPS but also tried a LPS. They did relax the sound but not how I wanted.

i bought it as I was curious about current injected phonos. I was pondering the Lino C but now not sure what to do.

the few dozen jazz LP’s I have sound great, as do the handful of classical. But rock music where lots of guitar and vocal fall into that 1khz to 2khz zone sound annoying. The Cult’s Love album. Ian’s vocal is right in that pocket as is lead guitar. It’s annoying.


I had a look at the AT's specs, imp 10 ohms, output 0.3 mv. You definitely do not have a gain problem. That impedance is at the upper limit for a transimpedance stage. As impedance goes up gain drops. I assume other sources do not have this problem? Have you tried other cartridges? Make sure cartridge set up is right (miss tracking). You might also have a look at cartridges with lower coil impedance, ideally you want < 2 ohms. The Spinstage has uniformly great reviews, perhaps you got a defective one? 

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.

@mijostyn @lewm  unfortunately I DK t have another cart to test.  The album I specifically mentioned I’ve owned in cassette, cd, Lp in several versions/masterings. It’s always been a good sounding album. It still is a good sounding album other than this issue. I have been trying to see what interaction is causing this.

i have a few things I’ll try tonight when I get home. 

after that, not sure what to do.

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.