A Transimpedance Head Amp Is A Current Affair

easy step up when used with an appropriate MC cartridge

Jazzed by the positive review here of Ortofon's X40 moving coil cartridge, a friend asked what he should do for a step up solution. He liked his excellent sounding Graham Slee MM phono preamp and wanted to keep using it. There's nothing worse in an analog audio chain than a bad step up transformer and known good ones don't come cheap.

You can take a chance on a step up transformer you find on Ebay (and admittedly I saw a few good known used ones), but why risk it? Hagerman Audio Labs sent me a Piccolo Zero a while back that I've not had a chance to audition so now is the time.

Current mode (zero impedance) step up circuits are not new though it's only over the past decade of so that they've become popular, in great part due to the many low internal impedance MC phono cartridges now being manufactured.

Back in 2018 I sat with the late Roger Modjeski at a San Francisco Audio Foundation event talking about transimpedance phono preamps and he took out a pen and a napkin and drew one for me he'd designed as I recall it, decades earlier.

Low internal impedance (generally 15 ohms or preferably lower and as low as possible) is an essential cartridge characteristic for it to effectively work with a transimpedance circuit.

Achieving low internal impedance requires fewer coil turns. Fewer coil turns produces lower voltage output that's not a problem for transimpedance circuits but is when used with a voltage based phono preamp, which is most of them. Stronger magnets and better magnet infrastructure over the decades has produced cartridges with reasonable output (.2mV-.25mV) and low internal impedance.

Hagerman Labs' $269 Piccolo Zero is a versatile, active step up solution powered by a small 24V "Wallwart" that features 4 gain levels adjustable via very small internally mounted DIP switches. The actual gain produced is determined by the internal impedance (resistance) plus tonearm wire divided by the cartridge's voltage output. The gain (µV/µA) is expressed in ohms.

If math isn't your strong suit, the instructions' back page gives you an approximate gain value for a given cartridge replacing a given conventional step up transformer expressed as a transformer ratio, though some of the numbers in the grid are not achievable (not that it matters).

It's not difficult to experiment with the four options available via the DIP switch settings: 220 (both switches off), 110 (switch 1 on), 69 (switch 2 on) and 53 (1+2 on) to find the one that produces the ideal gain for your set-up.

I auditioned the Piccolo Zero with the Ortofon X40 (6Ω internal impedance, .5mV output), the Lyra Atlas Lambda SL (.25mV output, 1.52Ω internal impedance) and and MuTech RM-HAYATE (.45mV, 1.75Ω internal impedance). No, the MuTech spec isn't a typo. Its unique ring magnet construction produces low internal impedance and relatively high output.

Granted I ran the Piccolo Zero into a MM input on the CH Precision P10 ($76,000) (45dB gain setting), and that's not a likely real world combo, but if there were issues with the Piccolo I'd for sure hear them through the P10! Also used Analysis+ Silver Apex interconnect ($1301) so that's probably another not real world combo but....

Of course the MuTech/Piccolo combo was powerful, quiet, dynamically robust and timbrally neutral, plus detail resolution was outstanding. As good as the P10's transimpedance input? No. The P10 produced a more subtle and supple textural presentation among other qualities the Piccolo Zero lacked, but it's a ridiculous comparison. Also ridiculous though, is how good the Piccolo Zero sounds (or doesn't sound)—how out of the way it gets, how essentially timbrally neutral it is and how its deficiencies are mostly of omission.

If you hear "liquid magic" in transformers and I admit I do with the good ones, the PIccolo Zero's lack of personality may not be for you, but not having to worry about loading is enticing!

The Piccolo Zero worked well with all of these cartridges, though even at the highest gain setting for some reason the Atlas Lambda SL produced both the best sound (not surprising) especially transparency and 3 dimensionality, but not quite sufficient output with the darTZeel NHB-18S preamp at 00dB. I'd say don't use the Piccolo Zero with a .25mV or lower moving coil cart

That's hardly a problem since I doubt anyone plans on using a $14,295 cartridge with a $269 Piccolo Zero! However, if you're considering moving to a reasonably high low output MC (.4mV and higher), and you're in MM world, it's very easy to recommend the Hagerman Piccolo Zero and I do!