In which Mark Wheeler listens to this phonostage, and Werner Ogiers shines some light on its technology ...
Product: Phono 2 Ci
Manufacturer: AQVOX - Germany
Reviewers: Mark Wheeler & Werner Ogiers
Reviewed: April, 2006
I have already wired my Hadcock GH242SE in balanced mode. It is balanced even when fitted with those truly horrible RCA connectors so contrarily loved by the domestic audio business. The Hadcock, thus wired, keeps the true earth separate from the signal return. Thus, playing with the Aqvox 2Ci is a doddle. At first I try it with my favoured rebuilt Decca fitted with a Len Gregory extended contact diamond. First impression is of a very lean sound, the White Stripes Digital is Evil sounding like the excesses of early CD. I worry that 2 days was inadequate burning-in with nothing more elaborate than a bit of wire to generate hum (I do not have an inverse RIAA filter to feed a RIAA input properly). Days of playing later I am realising that this is not the whole story.
Musical qualities of pace, pitch, rhythm & timing are all intact, indeed among the best I have heard from a moving magnet input. I am reminded of my modified Naim phonostage. The music bounces along and the traditional Naim forwardness is also present but there is much more to this. While I struggle to decide whether it is forward upper mid-range I am hearing, or a bass-light balance to exaggerate pace and speed, I begin to notice other qualities as I acclimatise to the balance.
The higher registers are spectacularly clear without ever becoming too much. Aqvox designer Carlos Candeias has chosen to adopt the Neumann variation on the usual RIAA equalisation. This has an extra pole, usually at 3.18uS to equalise for the 50kHz roll-off introduced by Neumann to reduce cutting head failure rates. This is well described by Allen Wright. The effect of this deviation from the playback standard is to extend the high frequency response of the cartridge-headamp system but also to reduce the out of band phase-shift, resulting in improved high-frequency timing. Even though the action is an octave beyond middle-aged steady-state audibility, the effect is similar to adding a supertweeter.
The Aqvox 2CI looks like a pro-sector product, sized very much like a 1U rack item, and their website lists a rackmount option. The XLR connectors reinforce that impression. Lifting the cover reveals a well constructed board populated with good quality parts and a modest power supply 40mm from the edge of the audio board. The gain blocks are (presumably) regulated by LEDs making this look as good as a valve pre-amp with the lid off. The sound opens up slightly with the lid off, as is a common experience with aluminium (but better than steel)casework. If I were selling this product to the domestic audiophile I'd fit a tinted perspex top to show off the innards.
The professional audio look inspired me to begin listening with balanced high-quality shielded multistrand cable output, which generally suits pro sources better than audiophile single strand. Substituting a single ended (shield connected at only the Aqvox end) phono-cable immediately improved the frequency balance. Typically the cable choice is dictated by the send-end.
Fortunately, while I had the Aqvox 2CI in my system, Bill Dyer arrived with his Digital Audio Systems Harefield active monitors. These have a more pro-sector balance and match the 2Ci perfectly, and will be reviewed on TNT-audio soon. This symbiosis in my listening room may seem fortuitous, but C G Jung might have suggested it is the synchronicity of the audio world collective unconscious at work. Bill Dyer is also on a mission to introduce accurate high-frequency phase to the domestic audio world, and this attribute of his speakers works wonders with the clear extended treble of the Aqvox 2Ci.
Sadly the various input impedance combinations available for the RCA inputs of the Aqvox 2Ci do not include the 30kohm that suits the Decca better than 47k. I try the Cartridge Man MusicMaker II but it too has the apparently lean balance, or forward upper-midrange I experienced with the Decca. This balance is mitigated by Bill Dyer's Harefields, but would not suit the majority of typical small modern domestic speakers. This is not a criticism of the Aqvox, more a comment on the lean balance of recent loudspeakers ever since the ultra-rich sounding Linn Sondek defined front-end expectations in the '80s.
Using my variable transformer as a passive volume control feeding the active DAS Harefields via 7m of balanced cable, the only single ended connection is the output of the Aqvox 2Ci to the transformer primary. Graham Nalty of Black rhodium was good enough to loan me 700€ worth of balanced Opera DCT interconnect fitted with high quality XLR plugs. I have no idea what the construction is but this combination takes another step closer to the music. The balanced output works better than single ended in my system, once the right wire type had been identified.
Rewiring my arm leads to XLR connectors I can now try the Aqvox 2CI trump card. The XLR input is a fully balanced current amplifier. Because it uses the cartridge current swings to modulate the gain stage its impedance should be irrelevant. I dig out one of my most awkward old cartridges to test this theory. This Linn Asak T-DC2100K (dc to 100k?!? dates from Ivor's finest hour of hype, bless 'im) is based around Supex innards and I recall I spent many hours in the 80s trying different input resistors and found 470 ohm worked best. The Aqvox RCA input can switch between 100 & 1k but nothing in between. What will the balance be like I wonder as I crimp the armlead terminals over the Linn's non-standard undersized four-in-a-row pins?
As good as the Naim 'S' boards designed for this cartridge is how the Aqvox sounds. Digging out the Nimbus Supercut of Little Feat's Feats don't fail me now that spun many times on my old Linn under this cartridge the sound is right there. The Asak was notorious for a spitty quality with the wrong moving-coil input; it could upset transformers and transistors alike. It doesn't upset the Aqvox, even when I hurl weird live recordings of Captain Beefheart's Magneticism. The final Asak test is Latin Quarter Modern Times, with its nasty sibilant vocal microphone EQ, and the Aqvox tames the Asak's wilder tendencies without masking any of the musical substance.
A more typical selection of old Ortofon, Audio Technica and something whose identity I've forgotten all give of their best into the Aqvox 2Ci. The balanced current sensing input obviously works for all my low output moving coils. I do not own any high output (above 2mV for 5cm/S) moving coil cartridges since my Sumiko Blue point Special broke, but I'm curious what might happen with a balanced output cartridge of moving iron persuasion. My Decca gets refitted to the Hadcock GH242SE, where it tends to reside most often. The Decca generator is unlike either conventional moving-magnet nor moving coil; it generates its output in lateral and vertical coils whose outputs are sum-&-difference wired to create left & right channel outputs. It is fully floating with respect to earth so is as 'balanced' as a moving-coil.
The Decca London does not give of its best into this input. It sounds slightly similar to the RCA input even though the configuration is completely different. The Decca is famous for its weirdness and so untypical that its mismatch is no criticism, but illustrates that no generator input (cartridge or microphone) can be truly universal, and for acoustic blues I'd choose the Decca feeding the Concordant Excelsior for scary delusions of realism.
Speaking of acoustic blues, the final curved ball thrown at the Aqvox 2Ci phonostage is the MusicMaker II into the XLR input. My hunch is that this shouldn't work. VTA just gets set cartridge top level with vinyl surface on thinnest 70s disc (dynaflex style) so tail-down on the Anadisc 200g Original Master Recording that next lands on the Michell Orbe SE platter: Muddy Waters' Folk Singer. The frequency balance is as one might expect from a moving magnet fed into a low Z input: deeply scooped midrange (the antithesis of the correct adjusted load RCA input) and muted highs...but despite this, the ambience retrieval is spectacular, suggesting good HF phase response despite the wrong resistance and capacitance to match the cartridge. The ambience is very well portrayed, surrounding a soundstage of average dimensions. Return to the low Z mc; the balanced input doesn't suit the mm MusicMaker.
This superb ambience is even present with mono recordings (as it should be) and the illusion of space was uncannily similar to the all-valve Concordant Excelsior. The accurate frequency response and phase performance are especially obvious with mono recordings; the central image remains accurate and in proportion, but the sense of space is present in the reverberation and flutter echoes.
The Aqvox 2Ci is a remarkable accurate phono amplifier, even more remarkable at a shade under 700€. The Dyer DAS Harefield active loudspeakers were a fortunate inclusion in my system while the Aqvox was performing head-amp duties. The Harefields allowed the Aqvox 2Ci strengths to blossom, where more typical modern domestic speakers might have masked the strengths while emphasising the lean balance. The Aqvox heavily regulated power-supply and modest power-supply capacitors keep the pace up with the quickest, but might contribute to the lean effect. The bass response sounds accurate but is qualitatively different from the familiar audiophile presentation, which can be offputting at first.
Musically, rhythms are flowing well and timing is impeccable right up to the limits of high-frequency audibility. Ambience is very well portrayed and full-bandwidth phase accuracy maintains soundstage proportions from low to high frequencies without inappropriate instrumental wanderings.
The Aqvox 2Ci doesn't pretend to the full gloss of high-end couture, and occupies a price point in the middle of the sector. It is much more accurate than many budget (sub 200€) products, and almost as transparent as more expensive products. This is a very accurate and versatile product and one I would recommend to anyone with a drawer-full of cartridges.
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© Copyright 2006 Mark Wheeler & Werner Ogiers - www.tnt-audio.com