Harbeth P3ESR XD and the Nelson Bass Extender Stands
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A mishearing of “Harbeth Nelson” conjured up fond childhood memories of 4 O'Clock on Saturday afternoons in the 1980s - Dickie Davis introduces ITV World of Sport Wrestling. Big Daddy takes on Giant Haystacks. Invariably, the first piece of theatrical grappling is the full or Harbeth Half Nelson. The victim of the hold red faced, eyes bulging - tapping out in pain or near suffocation. But how do the Harbeth Nelson grapple with the lower octaves?
The Nelson reference is more prosaic than my overactive imagination, a reference to Nelson’s Column at London’s Trafalgar Square and there are certainly Corinthian design cues.
For years, Harbeth have designed arguably one of the the best iterations of the BBC Mini Monitor - currently the P3ESR-XD. Derived from the original LS3/5A BBC R&D specification request, note the credit on this whitepaper - non other than H.D. Harwood, the founder of Harbeth. The internet is awash with great stories of how this speaker legend came about. I’ve collected below some links that track the venerable history and the modern day offshoots.
Suggested Reading
Our colleague Rishi at Audio T Reading wrote an excellent review of the Harbeth P3ESR-XD which you can read Here.
BBC Research Department Report - The Design of the miniature monitor loudspeaker type LS3/5A
Mark Hennesy’s full history of Harbeth, which you can read Here.
A word on Frequencies
The common misconception is that a sub works on sub-hearing frequencies, i.e. below our hearing range of 20Hz - 20KHz and is a modern phenomenon of electronic music. However, this is not the case. If we look at the frequencies of orchestral instruments - some pipe organs reach as low as 16Hz, a grand piano’s lowest note is 27.5Hz. At the other end the piccolo chirps away at a maximum of 5KHz - still a long way off human hearing limit of 20KHz.
The Harbeth PSESR-XD speakers have a quoted frequency range of 75-20KHz - 75Hz is around an octave and a half above the lowest note on a piano - though room resonances and harmonics will allow for an impression of reproduction of lower notes.
The BBC spec sheet, was about the clear reproduction of the human voice for studio monitoring in a variety of conditions - production studio to outside broadcast back of a van. It was about uniformity of reproduction.
Filling in the Gaps
The Nelson Bass Extender incorporates a Harbeth 5-inch drive unit and 50 watts of digital amplifier power, speaker frequency extension from 35Hz to 75Hz resulting in exceptional bass control, great integration (notice how that upper frequency exactly matches the lowest frequency of the P3) and power output.
Essentially, removing the stress of stand selection, improving bass extension without the additional space and cabling of sub woofers.
Setup
One of our favourite combinations with the Harbeth P3, is the Naim Uniti Nova. The transparency, clarity and breath of presentation is really an enjoyable listen. Curiously, although the speaker does not reach particularly low frequencies, the way they roll off is so gentle that it only feels somewhat lacking in bass heavy electronic music.
What takes your breath away, is the mid range and upper frequencies. So perfectly balanced that there is no fatigue when listening and it really magically draws you in to the performance. Upping the ante to the Supernait 3 with NDX 2 then to the Naim 222 and Naim 250 still provides even more performance. The limiting factor is their diminutive size - a room dimension of 5m x 4m with standard 2.5m ceiling is probably their limit.
Placing the Harbeth on the Nelson Bass Extender stands raised the height by about 10cm compared to them being placed on a conventional 600mm stand. I thought this would upset presentation as my ear was now level with between the tweeter and mid range driver, not on axis with the tweeter, but really it did not matter.
More problematic was positioning. The advice from Harbeth is to start with the Nelsons at mid level bass on both stands and adjust from there. But getting the sweet spot was tricky. Push the speakers too far back and bass bloom flowered like a Hydrangea. Adjust the Nelsons volume to compensate and it felt like the bass fell away too quickly. The sweet spot was around 40cm from side or back wall and the Nelson volume on a 1/4, and a little more on the right channel, where there was more free space, in order to balance the presentation. This lays bare the Nelson issue - It negates a key advantage of a separate subwoofer–being able to place it optimally in a different location from the main speakers in order to reduce placement issues and blooms/nulls at the listener position.
Qobuz Audio T Bristol, Selected from Playlist:
Here is a selection of tracks we use for evaluating bass performance. The full playlist is available on Qobuz Here.
Sailing to Philadelphia - Mark Knopfler
Limit to your Love - James Blake
Veto, Tremours - SOHN
Man in the Long Black Coat (Album Version) - Bob Dylan
Never Come Back (Koreless Remix) - Caribou
Paper Tiger (Album Version) - Beck
Playing God - Polyphia
Chameleon - Trentemøller
THE EIGHTH NIGHT PART 1 - Mike Dean
Veto, Tremours - SOHN
Conclusion
Let’s be clear - this is a bass extender not a sub. We are talking about extending the range of the Harbeth P3 in an integral way that does not necessarily mean sub frequency theatrical slams, but lower octaves enhancement.
The clearest benefits are that bass extension works absolutely beautifully. One of the most curious advantages is in the way the whole soundstage benefits - clearer imaging, greater expanse of sound and depth in the whole frequency range and a book shelf clarity, speed and transparency with the reach of a floorstander.
Aesthetically, the footprint is unchanged and thus the visual marmite of separate subs is a household argument that will not be an issue.
If you are a Harbeth P3 or BBC LS3/5A model incarnation owner - this is well worth an audition.
Thank you for reading,
Justin - Audio T Bristol
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