Kerr Acoustic K320 mk.3

Hardware Review

Kerr Acoustic K320 mk.3
Friday, May 14, 2021
floorstanding loudspeakers
Jason Kennedy

Hi-fi as a hobby had its heyday in the 50s, 60s and 70s, an era when there were fewer luxuries to indulge in for the average man and large loudspeakers were not considered to be an obstacle to domestic bliss. As a result most of the people who appreciate good sound and make good sounding equipment grew up in that era, but there are a few exceptions and Jes Kerr is one of them, he started Kerr Acoustics in his mid twenties and is not yet 30. He did it the hard way too, building transmission line (TL) cabinets at home with the help of his dad. The cabinet supply side of the speaker industry is limited to one major producer in the UK so these are by far the most expensive parts, and when you bring the TL aspect in it gets even more prohibitive so you can see why Jes’ approach made sense in the first place. Now that Kerr Acoustics has been going for three years he has taken the easy/expensive route but the cabinets for his K320 floorstander are very nice and apparently sound better than their home made predecessors.

Jes puts the improved sound down to the greater rigidity that mitre joints bring to the party, but they were already pretty stiff because he uses birch ply rather than MDF/HDF, a material that can usually only be found in BBC based designs from the likes of Falcon and a few others. The problem with ply is that it’s expensive and difficult to machine, the benefit is high rigidity and an acoustic character that clearly has its adherents. The K320 is fairly typical in terms of height and width but quite substantial in depth terms, it’s not excessively heavy but substantial enough to discourage lifting, Kerr reserves that status for the range topping K100 with its 12 inch bass driver. I like the look of the 91dB sensitivity figure but not the 78kg mass on that one.

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The K320 runs a true ribbon driver (eg not an AMT ribbon) from Fountek that Jes modifies for this application, this tweeter has a 60mm long aluminium diaphragm and neodymium magnet. According to the spec it’s good for 1.2 to 40kHz which is impressively wide band and explains how Kerr has managed to marry it to the 6.5 inch Scanspeak Revelator mid/bassunit with wood pulp cone, the two crossover at just under 2kHz which means neither has to reach beyond its capabilities. The transmission line behind the main driver is 2.4m long and damped so that only frequencies below 100 Hz get to the vent at the front.

The crossover is fitted on the inside of a stainless plate on the back and a single pair of copper plated CMC terminals are provided for cable connection. Kerr provides 6mm thread spikes that disappear into the carpet giving the speaker a grounded appearance. The finish on the supplied pair was a richly figured oak but other wood veneer and paint finishes are available, the latter in any RAL colour which is unusual.

Sound quality
The Kerr K320 is an easy speaker to get used to, which from a reviewing perspective is a bad thing, what we want are clear characteristics to talk about. Here however is a speaker that quietly gets on with the job and delivers the music without adding to or detracting from it in a significant way and this is a good thing for the end user. The bass however is notable for being so prodigious when called for, placing this speaker with respect to spacing to the rear wall was tricky because most of the time they work well with a short gap behind them but when a track with serious low end comes along it’s apparent that a bit more space is required. They don’t exaggerate bass but neither do they hold back when proper low end comes along. 

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With its transmission line loading, minimal styling and slim profile the K320 might be mistaken for a PMC but the tonal balance is richer and more relaxed, the bass more generous and the treble a shade sweeter. And I like sweet treble as long as it reveals plenty of detail and projects a strong image whilst keeping the timing on the ball. All of which are the case here, I rediscovered an obscure album by Michael Ivey called B.Y.O.B. which is an unusually laid back concoction of hip hop and funk with powerful bass lines and a rambling style. The K320 managed to project the voices well, giving them shape and solidity whilst defining the rhythms being laid down by bass, drums and various other instruments and voices in the mix. Another more familiar album revealed more 3D solidity and real depth to the image and the bass, the reverb clearly rendered as it ebbed away. On Tom Waits’ Shore Leave (Swordfishtrombones) there is a physicality to the sound that when combined with strong tonal definition of instruments and voice makes it very real, the music being projected into the room extremely well. The Kerr achieves this by virtue of its 24/18mm ply cabinets that are clearly very stiff, and good quality drive units and crossovers that squeeze a lot of fine detail out of the incoming signal. 

I really like the way that the Kerr speaker reflects the nature of the signal it receives, one example of that was when changing from an RSX Prime power cable on the turntable power supply to a Naim Powerline, the change was very distinct indeed. The vinyl exchanging a sense of power for one of delicacy that worked a treat with the Waits and another jazz tinged classic in Joni Mitchell’s Sweet Sucker Dance (Mingus). The system also suffered a streaming downgrade when the Ansuz X-TC network switch went back, the English Electric 8Switch that replaced it isn’t as smooth or relaxed but has a musicality that goes some way to making up for this and still manages to deliver good depth of image and reinforces leading edges which brings the bass into tighter focus.

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Although not particularly sensitive the K320 responds with enthusiasm if you wind up the volume, Leifur James’ Red Sea is a slow builder but by the time things got going the level had reached a point I don’t often go to, yet the sound remained clean and calm as the sound filled the room and produced a huge vista that you could almost bathe in. It encouraged a few other lively tracks including Uptown Top Ranking with its easy groove and beautifully textured bass, and Trentmoller’s Chameleon. This had been recommended by another reviewer for its reflex port testing near square wave bass, something that this transmission line had no trouble in delivering with full depth and precision. 

To get an idea of the K320’s driveability the Angel 6 amplifier was switched to an Octave V70 with KT20 output tubes and a power rating of 50W into four Ohms, this produced a more fruity result with beautiful tone on saxophone and rather more generous bass, to the point where the speaker really needs to come further into the room to reduce low frequency output. But there is plenty of gravitas and a fluidity to the sound that goes a long way to making up for the lack of grip in the bass. And pulling the speakers further away from the wall did the trick, the emphasis remained on the midband but the bass no longer made itself obvious and the results were inspiring, the trumpet and sax on Matthew Halsall’s Fletcher Moss Park being precisely positioned in a clear acoustic and tonally superb. I really enjoyed Herbie Hancock’s Rhodes keyboard playing on Sweet Sucker Dance too, the tubes bringing out the shine and life in the instrument and an all round degree of articulation that was highly engaging.

In its Mk3 guise the Kerr K320 is a remarkable achievement for what is almost a one man band, and in the great scheme of things Jes Kerr has got to this stage in pretty short order. When you consider how much manpower goes into the creations of bigger brands four man years is not a lot, top marks.

Specifications: 

Type: Transmission line, two-way, standmount loudspeaker
Crossover frequency: 1.95kHz
Drive units:
Mid/bass – 165mm wood fibre cone
Tweeter – 60mm true ribbon
Nominal frequency response:  24 – 45,000 Hz
Nominal impedance: 6 Ohms
Connectors: single wire binding posts
Sensitivity: 90dB (2.83V/1m)
Dimensions HxWxD: 1020 x 195 x 395mm
Weight: 25kg each
Finishes: oak, walnut, rosenut, black oak, satin or high-gloss lacquer RAL colours
Warranty: 5 years

Price: 
from £7,495 /pair
Manufacturer Details: 

Kerr Acoustic Ltd
T 07884 493425
www.kerracoustic.com