Pre/Power Amplifiers

To misquote Sly & The Family Stone just a little, Swedish hi-fi company Engström – it only makes tube amplifiers – is a family affair. Founded by engineer Lars Engström and his industrial designer nephew Timo as recently as 2008, the company is based in Lund, just northeast of Malmö, and has its R&D HQ some 600km away in Nacka, south of Uppsala on the Baltic Sea coast. The division of labour in the company sees Lars Engström as chief engineer, having given up work in fields as diverse as navigation, microcomputing and railway signalling systems in 2001 to concentrate on amplifier development, while his nephew is responsible for the look of the products, and the company operations.

On Board At CES
Well, that's almost the story. Part of the company family, if not blood-Engströms, are board members Ihab Toma, who first encountered the brand at the 2010 CES in Las Vegas, and later went from client to joining the business, and Chakib Sbiti who, the company says, 'enjoys his AC/DC on Engström-driven sound systems'.

The Engström product range is a family, too. This includes the Arne integrated amp, the Monica preamp, and Engström's inaugural power amp, the Lars – named after the founder. And the £136,950 ERIC Encore monoblock power amps we have here? The original ERIC model, of which this is an upgraded version – more of which later – took its name from the celebrated Swedish choral conductor and teacher, Eric Ericson (1918-2013).

It's fair to say no other amplifier we've encountered looks quite like the ERIC Encore, with its huge custom-made 'ski-slope' glass cover over the valve complement channelling air up past the two massive power triodes, and thus out through the vent at the 'high end'. And neither has any amp we've tested seemed so extreme, at least on paper. You see, while this may not be the most expensive power amp we've tested, that honour taken by the £250k D'Agostino Relentless Monoblocks [HFN Mar '20], it's almost certainly the priciest per watt (W).

You see, while the Relentless monos deliver 1600W/8ohm, or £156 per stereo watt, the ERIC Encores are rated at 70W apiece, so each stereo watt is costing some £1950! So they'd better be very good watts indeed for these amps to make any kind of sense. Fortunately for Engström, while the numbers may not seem to add up on paper, the sound is something entirely different. But before that, we should explore under the hood with PM…

Under Glass
The 65kg weight of the ERIC Encore is largely divided between the custom German-sourced glass, the machined alloy plates that form the chassis and last, but certainly not least, the host of coupling and PSU transformers that fill its interior, writes Editor PM. The first version of the ERIC – as still seen on Engström's website – used an 845 power triode sourced from KR Audio (called the T100) but the Encore version uses a new tube from Germany's ELROG. This is an exquisitely hand-prepared tube and clearly built to last (scroll to the bottom of http://vinylsavor.blogspot.com/search/label/ELROG for pictures and videos). Nevertheless this was not a straight '845-swap' but necessitated a fairly significant reworking of the entire output stage.

But let's start at the input. Here there's a switch to select between RCA and XLR sockets, both routed through a Lundorf transformer, and a third position labelled 'DIR' that connects directly to the EC8010 frame-grid triodes. These are configured as a long-tailed differential pair that's capacitor coupled, using 'audiophile' foil and Teflon SCR caps from France, to the driver stage. The latter comprises a pair of 6L6GC beam-power pentodes, wired as triodes here, in a balanced configuration that's transformer-coupled to the main power amp stage.

Glorious Glow
Here's where we find the brightly-glowing ELROG ER845 power tubes, one push-pull pair per side connected to the outside world via a custom-wound transformer. These heavyweight lumps of iron and copper include two secondary windings that are connected in parallel to achieve 4ohm or in series for a notional 16ohm tap. A different output transformer is selected if the ERIC Encore is ordered in its 8ohm guise.

More transformers service the various power supplies. The largest, also with custom windings, is centre-stage in the 1kV (1000V) HT supply for the ER845s. In practice there are actually two mains transformers connected in series, with four 6CH3 tubes forming the bridge rectifier and filtered via two chokes and three 1500V polypropylene capacitors. The other power supply is a 400V line for the driver stage with its own mains transformer, GZ34 rectifier, choke filter and polypropylene capacitor. There's also a choke-filtered DC filament supply for the input gain stage, regulated down from the 400V PSU – as close to 'solid-state' as you'll find in the ERIC Encore!