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?

gochurchgo

Thanks @mijostyn  it’s definitely in the 1k - 2k region. The Sutherland 20/20 doesn’t have this forwardness and after going through everything I can only think maybe the gain is off or a cart mismatch.

 

 

The Andover Spinstage is about 71 dB of gain if I am remembering correctly and that is more than most MC Phono Preamps.  But I don't hear any tonal emphasis on mine.  It just sounds much much better than it should for the price.  But you might find a benefit from using a linear power supply rather than the wall wart they supply.  I felt it sounded a bit smoother and perhaps less dynamic with a linear power supply and I'm guessing you would find that more pleasing.  Of course even a cheap linear power supply will set you back about half the cost of the Spinstage.

But how do you think it compares to the Sutherland 20/20 in general?  It is nearly a 10x difference in price.  

@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.

@gochurchgo 

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.