3 Phono Stages (Aqvox, Holfi & SAC)

[Κώστας Φ.]

Holfi Viltalus €335; SAC gamma €649; Aqvox Phono 2 Ci MKII €949


Holfi Vitalus:

Holfi's Danish Vitalus has served me respectably for quite a while. It's a classic black box: one input, one output, mice piano in-between. With all eight DIPs to off, the MM input is active (47kOhm/200pF). DIP 1+2 selects MC and various combinations of the remaining switches dial in one of eight different input impedances from 13 to 5,000 ohms.


There's no subsonic filter and an external power supply avoids radiation inside the main enclosure. Germany presently has no Holfi importer but the Vitalus can be procured through SWS-Audio for example.


SAC gamma:

SAC's gamma received a face lift which is apparent belly up. Those little switches are new, enabling subsonic filtering and an MM/MC gain lift of up to 76dB. As does the Holfi, there's an external power supply whose 14VA rails (instead of 10VA) are scaled up.


"What about impedance and capacitance DIPs?" Nyet. For adjustments, refer to the parallel RCAs on the back. Each gamma is supplied with an order form for plugs that fix
desired impedance and capacitance. The customer simply provides either the values or the model names of the components to be used. SAC then supplies the custom fittings free of charge. Extra plugs cost 10 euros but Herr Axel Schäfer, chief of this Essen firm, contends that no adjustments sound best. Stock input impedance is 1k/47K for MC/MM respectively, with a frontal knob selecting between moving magnet and moving coil.


No further features. Or rather, one: Owners of older gammas are eligible for a 449 euro complete makeover which replaces all electronics. Incidentally, this upgrade program stretches across SAC's entire lineup. Rightfully proud, Herr Schäfer mentioned a 21-year old unit he recently received for overhaul modernization. That's a loyal fan club.


Aqvox Phono 2Ci MKII:

By comparison to the above, the Aqvox nearly conjures up a pilot's controls bay. Sorta. For sure, connectivity has advanced: two i/o ports each, balanced/XLR and single-ended/RCA. Gain, input Z and capacitance switches regulate the non-symmetrical input exclusively. Selectable impedance values are 100ohm, 1 and 47K. Internally switchable picofarad capacitance for MM is 47, 100, 220 or 470pf.

Around back, MM gain can be raised by 6dB, up to 20dB for MC. Incidentally, MM can only be had from the RCAs, MCs can take either input, with the maker clearly favoring balanced to benefit from "technological advances". How so?


Though merely three years on the market, Aqvox phono stages have nearly garnered classic status already, likely at least in part because of designer Carlos Candeias, perhaps supported by the pro aura which surrounds both machine and company Aqvox whose three-deep offering covers consumers and professionals alike. Occasionally, amateurs get hip to the fact that mastering engineers do use the good stuff, never mind don't always pay through the nose. Aqvox entered the market with the 2Ci for a mere 600 euros, which since has sadly been adjusted for inflation. The successor in MkII guise does weigh in with a serious power supply which, unlike with the other loaners, remains inside the main chassis where the Aqvox has more room to spare - on a separate board to be sure.

The current 950 euros charged (the upgrade from MkI to II is 300 euros) remain quite competitive for a fully balanced machine. Which naturally begs the question - is balanced really required? Aqvox responds with four bullets:

1. Symmetry
Because cartridges are inherently balanced, this advantage should be - um, taken advantage of. For one, it means reduced signal transfer distortion, sensible with the miniature voltages involved. Then there's the +6dB gain advantage since balanced amplification doesn't reference to 0 but anti phase.

2. Current gain
According to Aqvox, MC carts pass on "decent current" but "negligible voltage". There's little current change between high- and low-output MCs unlike voltage. Hence current gain becomes choice, which for MC picks up two advantages: the pickup is electrically damped (analogous to damping factor) which helps MC's bothersome HF resonance without undermining dynamics. Secondly, impedance matching for MCs become redundant as long as those (and only those) are run purely symmetrical. Plug 'n' play is the term, putting an end to audiophile night sweats and panic over "damn, perhaps another 20 ohm". Rather, our audiophile will grumblingly pull the comforter over his ears because you stole one of his toys...

3. RIAA plus Neumann
While the RIAA EQ curve is the official standard, plus Neumann is the unwritten law. Mister Neumann at the time limited
HF boost to protect the cutter heads of his cutting lathe. Having become the facto standard, this should be likewise employed on the re-EQ end, less attenuation above 10kHz than pure RIAA would have it. A rational argument.

4. LEF
This pertains to the Candeias gain modules also seen with C.E.C. To combat transistor nonlinearities and concomitant nonlinear gain, Load Effect Free circuitry (a form of floating cascade circuit) avoids running the voltage and current load lines through the output transistors. This is claimed to linearize gain without global feedback while cleaning up the sound. Further details on this can be found here. All Aqvox components (i.e. also the D/A converter and microphone preamp) rely on LEF. The Phono 2Ci sports four Candeias ICs, one per channel and gain block. Any reason for the disco lighting above though?

What else? Three buttons and two rotary knobs. MM/MC selection is on the back panel as is ground lift to avoid hum. The subsonic filter is upfront as are the dual mono gain trim pots. "When dimensionality and soundstaging lock in, you've got the perfect gain value" assures Aqvox's Herr Lübke, differentiating the importance of this setting from your preamp's or integrated's master volume which controls ultimate playback levels.

Needless to say, symmetrical circuitry requires symmetrical cabling. That's standard with most tone arms (Rega excepted - refer to the Aqvox home page for conversion). Should your interconnects terminate in RCA -- standard -- 25 euros add an RCA-to-XLR adapter. That's what I used to equalize things for comparative purposes. It also avoided readjusting VTA endlessly. My phono cable exits directly beneath the tonearm to require dismounting to change cables. True balanced operation with its attendant noise reduction is audible in practice, however. Backgrounds get blacker, hum drops and I'm not really missing the Russian radio news announcer during album swaps.




Conclusion

"The rather affordable Holfi Vitalus offers a lot of bang for the euro. Its key virtue is evenness, tonally -- nothing excessive anywhere -- and dimensionally where it stages broadly and with good depth. Image resolution could be better but clearly avoids the blurs. That more is possible across the board is self-evident given the price to make the only valid criticism a desire for greater dynamic contrasts.


Seemingly the SAC gamma's calling card, when one switches horses midstream of a rocking uptempo number from the Holfi to it, "Wow!" is the only apt response. To be more specific, this entails:

• Formidable bass with growl, rebound and dryness. Somebody really nailed these qualities on the head. Bravo.
• Dynamic high-contrast rendition with timing in its pocket.
• Extremely precise localization of instruments, voices and sounds to organize the stage for great transparency.
• The latter makes for good depth layering, albeit predominantly focused in the middle.
• A criticism is curtailed stage width. This does not equate to unduly dense or crowded – to the contrary, the SAC gamma separates very sharply - but a bit more space would be nice.

The Aqvox Phono 2Ci MkII meanwhile offers:

• Great stage width and depth with accurate localizations but no undue chiseling.
• The treble is in its own class: clear, beyond criticism, soft without indecision, perfectly balanced.
• Ditto for the mids: Vocal balance is spot on, neither too close nor too far, very very accurate without spittle hitting the microphone - unless it really did. Highly nuanced.
• Only the bass wants for the occasional dose of pepper not for quality -- grip, articulation and timing are spot on -- but simply raw quantity.
• Already the most detailed, nuanced and graduated, it's also microdynamically the most accurate of the three. The Aqvox is highly informative, weaving a dense net of apparently secondary sonic trivia yet exactly this -- plus brilliant staging -- adds up to the credible 'live effect' I appreciate. Macrodynamics are good but the SAC is better still.
• For the money, fit and trim are first rate, the latter probably due to the pro roots - unpretentious and solid, with balanced and single-ended i/o ports, ground lift, variable gain in front, around back and dual mono. Add four selectable capacitance values, only three for input impedance (because MC should use XLRs).
• On the latter point, if you own more MCs than inputs, the Aqvox 'auto-matching' feature is key (the RCA input, to my ears, is indeed a few degrees more subdued).

In a perfect world, the Aqvox would be fitted with a bass boost button. I wouldn't use it a lot but occasionally. If it were called gamma rather than bass boost, I'd simply grin mischievously."


Full Review: 6moons.com