Project – BK Electronics Eikona VTL transmission line

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Ted Jordan’s VTL transmission line remains our most popular enclosure for the Eikona 2 full-range loudspeaker. It is a compact,floor-standing design which is 30 cm wide but only 10 cm deep and very room-friendly. It is perfectly happy working near walls and room boundaries and is a neat solution to high quality music in the home.

One of our customers, Steve, has just completed a VTL kit from BK Electronics. Steve is a very experienced hi-fi enthusiast and has owned some of the best loudspeakers available, including the famous QUAD ESL63. We’ll let Steve take up the story as he began auditioning the Eikona VTL:

“I’ve only had about an hour’s listening, I started with the subwoofer frequency sweep off YouTube to just see how low it would go, and it does go low! Solid output to below 40Hz and the lowest frequency reproduced is 32Hz and this is from a 4″ driver…

“I listened to a selection of my test tracks to listen for various different aspects of the sound quality. … Being a single driver speaker with no crossover to muck things up, the clarity and transparency are crystal clear and uncoloured. The stereo image and focus, even with just a few feet between the speakers, is superb.

“The midrange – particularly vocals and solo instruments like piano – have an amazing clarity and naturalness. Every aspect of their performance is as good as if not better than anything I’ve had before…

“I must admit to be a bit in awe as to what a 4” driver is capable of; these things reproduce percussion unlike any other speaker I’ve heard, drums and rim shots are so crisp and powerful, it’s a revelation, as for bass, these transmission line cabs just can move so much air, it seems like alchemy!

“The old adage of hearing stuff you’ve never heard before in your music is certainly true with these, the size of the soundstage and imaging is the best I’ve experienced in 40 years interest in hi-fi.”

Part 2 looks at the background to Ted Jordan’s VTL enclosure. Meanwhile you can see the plans here.

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Project – MLTL30 Eikona transmission line loudspeaker

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Eikona MLTL30 v2

The MLTL38 transmission line loudspeaker is very popular with users of the Jordan Eikona 2 fullrange driver.

The name MLTL (mass-loaded transmission line) arises from work by Martin J King, comparing computer-generated loudspeaker models against built and tested transmission line speakers. Martin produced a set of MathCad spreadsheets which enabled users to virtually build, refine and measure of this type of enclosure.

The MLTL is an enclosure dominated by a combination of quarter wave resonance and port mass. Adding a port allows the designer to shorted the transmission line’s length. Other parameters can be adjusted in the software to arrive at optimum results. One advantage of the MLTL is that the area behind the speaker unit can be damped, suppressing mid- and high frequency reflections, in a manner which would be detrimental in a typical reflex enclosure.

It’s a system capable of very high quality results. The new MLTL30 is designed specifically for the Jordan Eikona 2. It doesn’t go as low as our MLTL38 but the shorter cabinet may be more domestically acceptable. The graph below gives the MLTL30’s calculated response.

Plans for the Eikona MLTL30 can be downloaded here. As always, if you build an enclosure we are happy to see photographs and feature them on our Facebook page.

ML30 blog graph

Project – the Eikona 2 Djinn Open Baffle speaker

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The Open Baffle (or dipole) loudspeaker has a long history, with famous UK examples from Wharfedale and QUAD. At its most basic, an OB speaker consists of a drive unit on a flat board, the rear of the driver being open to the air. Whilst this may eliminate the colouration characteristic of some box enclosures, it has the disadvantage of introducing an acoustic short-circuit; sound from the front of the speaker saunters round to the back and happily cancels out all sound below a certain wavelength. The wider the board the speaker is mounted on, the lower in frequency the cancellation will take place.

In recent years, there has been a resurgence of interest in Open Baffles, particularly in the DIY community. At the end of 2016, one of our customers contacted us with details of his OB design, using the Jordan Eikona 2 and a Dayton Audio pro-audio 38 cm woofer.

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It is a distinctive design, featuring slot-loading for the woofer and an unusual edge-of-baffle position for the Eikona 2. At first sight, it looks as though the design cannot possibly work. But the designer has begun with specific aims and a carefully considered rationale to achieve them. The end result is both clever and genuinely interesting.

The Djinn OB Project is currently being documented on this DIY thread on Audiocircle.

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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

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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 the recording industry magazine Sound-on-Sound.

 

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

Audio Building Blocks 1
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Since original publication of this series, we have added a further three Eikona array loudspeaker designs:

Triangular Linear Array

Transmission Line Array

Pentagonal TL Array

Audio Building Blocks 3

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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

Audio Buildings Blocks 1

Audio Buildings Blocks 2

Audio Building Blocks 4

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.

Audio Buildings Blocks 1

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