Phono Preamplifiers

It's always welcome when individuals or companies offer up their future plans. If not, we'd never have known that Sean Connery was to abandon James Bond after 1971's Diamonds Are Forever, that Ferrari would not be launching an SUV and that Norwegian hi-fi manufacturer Hegel had no intention of ever making a phono stage. Of course, Connery did return to his role of suave super-spy in 1983's Never Say Never Again, Ferrari's Purosangue SUV is due later this year, and here I am writing about Hegel's £1350 V10 phono stage.

I cannot speak for Connery or Ferrari, but I can tell you that Hegel's about-turn was due to a combination of factors. Firstly, several projects were in full swing at the company's Oslo HQ, but all were digital in nature so the 'analogue guys' were a little light on work and looking for a project. Secondly, there's that small matter of the vinyl revival putting more than a little pep back into the LP-spinning market.

Taking A Dip
The V10 has its roots in a simple phono amplifier company founder Bent Holter designed for his own use some 15 years ago. This has now evolved into a well-specified unit able to cater for both MM and MC cartridges and which offers unbalanced inputs plus unbalanced RCA and balanced XLR outputs.

Power is provided by an external PSU, slightly bulkier than the average 'wall wart' and custom-designed for the V10 to sport two separate 18V feeds. This includes a Y-shaped lead with dual plugs that connect into a pair of recessed sockets located in a void underneath the chassis of the V10 itself. This void also acts as a physical barrier between the PSU regulation inside the front of the amplifier and the audio/RIAA circuitry, which is located to the rear.

Setting-up the V10 to best match the gain and loading requirements of your pick-up is achieved via two rows of DIP switches. Yes, these are fiddly things at the best of times, but the approach is not uncommon in phono preamps and it's an efficient – read least costly – route to offering a comprehensive range of options. In this instance Hegel is using ten DIP switches per channel.

Of these, the first two toggle a subsonic filter that operates below 20Hz, while the third and fourth bring added boosts of +5, +10 or +12dB to the standard MM and MC gains. The latter are specified as +34dB and +54dB, respectively, through the unbalanced outputs, while the balanced outputs increase this to +40dB and +60dB.

The fifth, sixth and seventh switches select load capacitances of 100, 147, 200, 220, 247, 320, 420 or 467pF for the MM input, while the eighth and ninth select a 100 or 300ohm input impedance for the MC section. Finally, the last switch toggles between the MM and MC phono inputs.

Switch Trials
These settings are supplemented by internal controls and links that can add a further +6dB gain to both MM and MC sections and extend the MC loading options from 50 to 500ohm. Hegel says these adjustments are best left to a dealer, however.

While the flexibility is certainly commendable, the configuration of these DIP switches, and the MM/MC inputs, is not without its foibles. For example, while there are separate MM and MC inputs, and switches to select them, the MC headamp connects directly into the MM section so it's not possible to have connections made to both sockets simultaneously.

Then there's the complexity of the DIP switch permutations – illustrated by Hegel's screen printing on the underside of the box. Puzzlingly, a pair of switches rather than a single one is employed to select the subsonic filter – this leaves two permutations (both DIP switches in the 'On' or 'Off' positions) that are disallowed and clearly labelled 'Do Not Use'. I refrained from finding out what would happen if I selected either non-state, but surely it would be simpler if just one switch were fitted, where 'on is on' and 'off is off'?