A new British company adopts isobaric bass loading for its heavyweight floorstanding speaker
When John Durbridge and Ian Hanson met in 1993, both were studying electronics, and both chose to develop a hi-fi prototype as their degree project. John’s design was a two-way speaker, while Ian came up with a 100W power amplifier. Each then made a career in electronics but, with audio interests pushed into the background, John worked in industrial electronics while Ian then specialised in ultrasonics.
Of course, their interest in hi-fi had never died, and in 2005 they decided it was time to do something about it. The result was the first Hanbridge speaker, the 501.
If you see the 501 in a showroom, the first thing you’ll notice is the beautiful veneer, the confident yet traditional outline softened by the rounded front edges and a styling line marking the join between baffle and main carcase. On the other hand, if you are a delivery man or a reviewer, the first thing you’ll notice is the weight. Once I’d managed to get the speakers out of their boxes and standing upright, I was surprised to read in the instruction book that each one weighs only 36.7kg. It felt like more.
Well, a heavier speaker is usually a better speaker. In this case, the 1020mm-high cabinets are of 18mm MDF, 25mm for the front baffles, with asymmetrical bracing and large amounts of bitumen-based damping material applied inside. But some of the weight comes from the hidden extra bass driver. This operates on the isobaric principle, used famously by Linn (who spelt it with a ‘k’ of course), more recently by Wilson Benesch and Siltech. In the Hanbridge speaker, the isobaric combination of two 215mm drivers is bass-reflex loaded via a 70mm diameter flared port, which exits at the front.
These bass drivers, and the 174mm midrange, are magnesium/aluminium alloy-coned units from Hi-Vi. Completing the line-up is a 19mm SEAS Sonomex Crescendo soft-dome tweeter. SEAS also makes magnesium alloy coned units, but it was felt that the SEAS/Hi-Vi combination worked particularly well. Crossover points are 300Hz and 2.5kHz, with second-order filters, the network mounted on the inside of the bolted-in rear ‘hatch’.
The designers engineered a response dip centred on around 2.8kHz, taking the view that loudspeakers with a flat response can sound too bright and hard in normal rooms, due to the contribution of reflected sound.
With fairly low sensitivity, and the paralleled bass units bringing the impedance down, the speaker needs a capable amplifier. I used a Classé CAP-2100 integrated. The 501 also needs careful placement. As I found out when I initially just plonked them down and put on Kind Of Blue [CBS 480410 2], if too close to walls they will give far too much bass, making the music sluggish and obscuring any other qualities. But once I’d found the right spot – in my case 1m from the back wall – I settled down to listen with enjoyment.
Now, with the two speakers optimally placed, Paul Chambers’ bass had a substantial, tangible weight but the music flowed organically forward, free of that fatal tendency to drag the beat. Like the piano, the horns sounded mellow. It’s true that the 501 sounds less bright than other speakers, and the initial reaction can be to think that it is less detailed. On this CD, though, it just seemed as if the removal of a hard edge of presence, or brightness, allowed you to hear into the recording more easily.
Moving on to Eric Bibb’s Diamond Days [Telarc CD 83660], this time I almost laughed at the opening sound effect of a needle dropping on to a disc, because there was such a realistic ‘whoomph’ of a bass wave underneath the snap, crackle and pop of ‘surface’. But the music played well too, the bass underpinning the track with a kind of singing quality. The overall sound had an enveloping warmth, background vocals seeming to come forward and cosily surrounding the lead.
With Marta Gomez and Entre Cada Palabra [Chesky JD301] you are physically in a church, rather than being adjured to go to one. The bass and various percussion sounded heavy but well controlled, so you heard detail in these accompaniments which is often obscured. Rhythms came over well, and the vocals didn’t get completely swamped, although there were a few flood warnings. Yet at times I felt that the vocals could sound marginally veiled, and in terms of imaging, didn’t quite come into focus. Turning to Rickie Lee Jones [Warner 256 628] and the everlasting ‘Easy Money’, Red Callender’s string bass managed to sound full and deep yet still with a spring in its step. Rickie Lee sounded sweet and smooth, with a reasonable effect of placement, though the ambience around her voice was not very explicit.
At the end of all this, I have to say I had slightly mixed feelings. The free-breathing extended bass was a real joy on many recordings. Very often, the combination of this deep bass and a softened presence region succeeded in making the music sound warmer and more intimate. On other recordings, though, the balance could seem just too warm, and the bass excessive.
Although there was plenty of detail, and often a pleasant sensation of depth, the stereo image was not particularly wide, deep or precise, and however I positioned the speakers, I could not quite get the image precision I felt should be there.
Of course, this will be more important to some recordings and to some listeners than others, so you need to listen to the 501 for yourself. The speaker does have a very accessible, smooth, unforced and unfatiguing character. If you’ve searched in vain for such qualities elsewhere, try to hear the Hanbridge. It could be just what you’re looking for.
This is a handsome floorstander from a new UK company, and it sounds distinct from name-brand rivals. Its extended bass can be very effective given suitable positioning, but it must be kept away from boundary walls. It can sound more welcoming than many of today’s bright, analytical high-end speakers, and so deserves a serious audition.
Originally published in the December 2008 issue
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