The Power of Radio 3

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Here at EJJ HQ, we’re big fans of Radio 3, the BBC’s classical music station. The station has an enviable reputation for quality broadcasting which goes back seven decades, with many notable innovations in both drama and music.

In that time, the station has also been at the forefront of audio developments. These include the introduction of stereo broadcasting in 1962, experimental quadraphonics in 1974, and more recently, binaural and 4-speaker surround sound from recent BBC Proms. In addition to broadcasting on FM and DAB, evening concerts are available in ‘HD’ quality via the Radio 3 website. This is a 320 kbps AAC stream that – in terms of audio quality – BBC recording engineers say matches the direct output from the concert hall mixing desk. If you follow the BBC Research Blog you’ll discover more interesting ideas under investigation, including object-based sound and surround sound with height (via Ambisonics).

This year, Radio 3 celebrates 70 years of broadcasting, from its beginnings on 29 September 1946 as The Third Programme. As part of the celebration, historian David Hendry gathered 70 memorable moments from the station’s archives and these have been spread across the schedule over the last four months.

Now you can now find these gems gathered together in one place on the BBC Radio 3 website. They’re well worth exploring – click here to view the selection.

 

Project – Aurora 400 2-way system

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One of the more unusual projects we’ve been involved with this year has been an two-way Aurora 400 system.

The initial enquiry came from a long-standing Jordan customer who was using one of Ted’s Linear Array designs. Each array consisted of four JXR6HD units crossed over to a JX150 Jordan bass system.

The electronic crossover was custom-designed by the customer and BBC engineer and is a first-order design, -3dB point at 275Hz. Our customer was intrigued by Ted’s claim that the Aurora reflector loudspeaker produces better stereo than the already superb imaging of the Linear Array.

As with all the Jordan Aurora designs, the cabinet was bespoke. Our customer chose contrasting veneers for the cabinet and reflector, an effect which is both striking and attractive.

The Aurora 400 takes the place of the Linear Array and is wall-mounted just above the bass enclosure. As sensitivity of the Auroras is lower than the array, gain adjustment of the crossover was needed to equalise the frequency response of the entire speaker system.

Our customer has connections to the audio industry and is a very critical listener so it was gratifying to receive his comments on the Aurora 400 system:

I’m impressed by the Aurora performance as bass reflex full-range speakers but as I don’t need the bass frequencies, I can put in much more stuffing than would work with a bass reflex design … “

“Impressions of the Aurora speakers is that they are better than the line array … the Auroras are quite special; very clean … they have better presence than the JXR6HD line array, so I’m impressed with the sound!”

For more details of the Jordan Auroras, see here.

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A New Jordan Eikona Loudspeaker

Taliesin Side-by-Side

We have just received exciting news from our American dealer, Ars Harmonia.

In addition to selling the Jordan Eikona full-range drive units, Ars Harmonia manufacture high-quality loudspeaker enclosures. They have had great success with the Jordan VTL and now they have launched their own, exclusive design, the Taliesin.

This loudspeaker follows a similar form-factor to Ted Jordan’s elegant VTL transmission line but is slightly larger at 99 cm tall, 34.5 cm wide and 15.24 cm deep.

The unique Taliesin enclosure was designed by Paul Kittinger using Martin J King ‘s famous MathCad loudspeaker  modelling software. The cabinets – one in solid cherry with bird’s eye maple and the other in walnut – were hand-built by Bruce Pea.

The first two pairs are already at dealers. Contact Bruce at Ars Harmonia for more details.

Walnut Taliesin - No Grill

Project – Classical Jordan DCR

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A very nice email arrived this week from one of our customers. He has just completed building the Jordan Eikona DCR loudspeaker design and is thrilled with the results:

“They sound fantastic. Very natural on the human voice (my wife is a classical singer, so listens to lots of song, opera, etc). They fit really well in the kitchen, either side of a chimney breast. Sound is seamless, much improved on the stack of 4x 50mm Jordan units & bass each side they replaced. Very much enjoyed making them, now enjoying listening to them and plan to make another pair…”

The DIY plan for the Jordan DCR enclosure is available on our website here

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Loudness Wars

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For over a decade, music producers have been fighting a loudness war.

Louder is more exciting and superficially appealing. This is important when you are competing for the attention of the music-buying public. It also helps overcome ambient noise if you are listening to music whilst in a vehicle.

Rather than just boost the ultimate sound pressure level of a piece of music, the trick employed is to bring the quiet parts up to match the louder sections. In this way, the overall dynamic range is reduced. The listener loses a dimension that is part of the complexity and richness of music.

This may be one reason why some enthusiasts prefer original vinyl releases to CD or streaming counterparts; it’s nothing to do with the carrier format, it’s how the music has been mastered. It’s certainly true that in some recordings we’ve explored, the remastered, more modern release can lack the dynamic range of the earlier – to the extent that we default to the earlier version wherever possible.

Here is an excellent primer on the loudness wars, viewed from the production perspective and published in industry magazine Sound-on-Sound:

http://www.soundonsound.com/sound-advice/dynamic-range-loudness-war

Audio Building Blocks 4

 

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One of Ted Jordan’s most popular systems was the Linear Array. This vertical arrangement of four Jordan 50mm units gave many of the benefits of a taller, floor-to-ceiling line source but at much lower cost.

The 50mm Module Array required an additional bass system but a Jordan Eikona Array is a stand-alone system. Four Eikonas are equivalent to a single 250mm bass unit in terms of cone area but have lower mass, faster transient response and greater sensitivity. This makes an Eikona Array a compelling alternative to the industry standard of speakers with passive crossovers and large, heavy bass units.

The design can be realised in a number of different ways. One of the simplest and most elegant is a reflex enclosure. By adjusting the height of the Array for seated listening, we arrive at a floor-standing loudspeaker which is 1200mm high, 340mm wide and 125mm deep. The cabinet can be constructed from 18mm MDF or Baltic birch ply. In general we prefer ply as it is more pleasant to work with, weighs less and is more robust. We recommend fitting a low-profile grille as it protects the drive units from dust and inquisitive fingers. Arguably it also has a psychological benefit as it’s easier to concentrate on the music when you aren’t distracted by moving cones.

In use, the speakers should be turned-in 60 degrees so that the listening axes cross in front of the listener. This gives the most stable stereo imaging, with a wide listening angle; central images remain central as you move left or right. The system sound integrates at distances above three metres so these are not near-field loudspeakers but work very well in larger rooms. The increased sensitivity over a single Eikona system makes the Array a good match for high quality, lower-powered tube amplifiers.

A full plan is available here.

Eikona Linear Array specification:
Size (external) – 1180mm (h) x 340mm (w) x 125mm (d) excl. base
Impedance – 6 ohms
Sensitivity – 92 dB/watt
Peak power handling – 400 watts
Minimum amplifier – 4 watts

blog - Eikona Array Reflex

A triangular, sealed-loading version of the Linear Array is featured here.

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Audio Building Blocks 3

speaker-Eikona 9 array blog

Last time we looked at a line array speaker system using 16 Jordan Eikonas per enclosure. Whilst capable of terrific performance, a 2.5m high loudspeaker may be more than many people (and rooms) require.

One of the requirements when assembling a loudspeaker array is to ensure that the total impedance of the drive units does not fall below that of a single unit. The next stage down from 16 units is – somewhat counter-intuitively – nine. Using the Eikonas in this way provides a system with 95 dB/watt sensitivity and 121 dB peak SPL and the opportunity to dispense with the cabinet altogether.

Mounting the array on a flat panel gives us a classic open baffle speaker with the benefit of no internal standing waves, fewer panel resonances and a cleaner sound. It also introduces a major drawback; an acoustic short circuit.

Below a certain frequency – approximately 500Hz for a 30cm wide panel – sound from the front of the speaker will leak round to the back, be out of phase and start to cancel out. This cancellation results in a 6dB per octave, which is considerably less than the 24dB/octave of a reflex enclosure. The array’s increased sensitivity and power handling means we can use equalisation to extend the bass below 500Hz. How low depends on the maximum loudness we’re trying to achieve. Nine Eikonas have the same cone area as a single, 30cm cone but for high SPL or large spaces, it might be prudent to add a pair of dedicated bass units.

The CAD drawings show a customer design for just such a system for installation in a church. The wall-mounted panels are manufactured from Perspex with the wiring loom bonded onto the surface. The panels fold away when not in use and the whole effect is extraordinarily elegant. It could easily be adapted to a home environment.

Next time we’ll conclude this short series with an enclosure project for a four Eikona array.

speaker 9 array in church-FTL2

CAD drawings © David Smith, Fathomtree Ltd

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Audio Building Blocks 2

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In 1962, Ted Jordan designed the Jordan-Watts Module to work as both a stand-alone loudspeaker and a versatile audio building block. He revisited this idea, 50 years later, with the development of the Jordan Eikona. Combining a high quality, full-range driver in multiples or with other units gives tremendous design flexibility.

For example, one approach is to use the Eikona in a vertical line array of multiple units, which offers three significant advantages over the use of single, larger speaker units:

“1. In practice one small cone is more efficient at low frequencies than one larger one and both the efficiency and the power handling increase with the number of units used.

2. Irrespective of the power requirements the intrinsic quality of the individual unit is retained.

3. By closely mounting the units one above the other the advantages of a ‘line source’ are secured which overcomes, to a large extent, the problems of poor room acoustics.”

(Derive from First Principles, by E.J. Jordan, Gramophone magazine, April 1964)

At the Bristol Hi-Fi Show in February, there was a demonstration of a pair of reference-quality loudspeakers costing £13,750. They were large floor-standing speakers with a sensitivity of 90 dB/watt, 500 watts power handling and a maximum SPL of 116 dB/metre.

How does the Eikona compare?

As we’re building this ourselves, let’s be extravagant and use 32 Eikonas for a pair of 2.5m-high, line source arrays. Each array features a combined cone area equivalent to a 38cm bass unit but with the moving mass and transient response of a single Eikona. The array has a sensitivity of 98 dB/watt sensitivity, 1600 watts power handling and a peak output of 124 dB – more than enough to handle a full orchestral crescendo at realistic levels.

These figures give freedom to balance enclosure size, sensitivity and bass extension to almost any domestic requirement. For example, a column design would occupy minimal floor area, reach down to 20Hz, be immune to many problems with room reflections and be capable of truly world-class performance. And all for less than half the cost of the loudspeaker at Bristol.

Of course, not all of us have the room or budget for a loudspeaker on this scale, so in part 3, we’ll examine how the Jordan Eikona can form the basis of a more modest instrument and dispense with the cabinet altogether.

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Jordan-Watts Module 02

One of the major design aims with the Jordan Eikona 2 is to provide a loudspeaker that is more than a full-range driver. The Eikona is a versatile building block which can be scaled to work across a range of future applications.

The Eikona draws upon a heritage which goes back to Ted Jordan’s original design work at Jordan-Watts in the 1960s. The Jordan-Watts Module was a metal-cone drive unit launched at the Audio Fair in 1963. It could be used alone, in multiples or with additional bass units in a variety of enclosure sizes and types. It was flexible enough to reach a range of performance targets and markets.

To arrive at this radical loudspeaker, Ted went back to first principles. He threw out much of the accepted wisdom to arrive at what he regarded as a better solution.

In an article for Gramophone magazine (Derive from First Principles, April 1964) Ted described the problems facing loudspeaker designers and the techniques he used to overcome them. He used a controlled-flexure aluminium cone with a diameter of 100 mm in order to balance high frequency extension with good bass. A tangential suspension system of three silvered beryllium-copper cantilevers gave a bass resonance of 41Hz with a power handling of 12 watts.

Ted wrote: “For conditions where this is insufficient, any number may be used together to achieve the required capacity. This approach offers three distinct advantages over the use of single, larger speaker units.”

In the next blog, we’ll look at these advantages – and how they allow the Jordan Eikona to compete head-on with £16,000 reference loudspeakers.

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