Medieval sound

Soundscape – the sound of the environment around us – is becoming a popular field for exploration. Whether it is the hum of the city or forest birdsong, there are numerous examples around the web for you to explore and enjoy.

But it is not only modern soundscapes which are the subject of research.

Dr Mariana Lopez of the University of York Film & Music Department recreated the soundscape of 16th century York as part of the UK’s Being Human Festival.

The soundscapes included church bells, animals, music – the sort of soundscape you would have encountered if you had wandered the streets of York during one of the Mystery Plays some time during the 15th and 16th centuries.

The installation ran in Bedern Hall in York between 18-21 November 2016. Click here for full details. There will be a stereo version of it on the University of York website soon.

 

Passive, active, single

No, it’s not the title of the latest Richard Curtis rom-com. Passive, active and single refer to the three primary ways of designing hi-fi and studio loudspeakers.

Most loudspeakers feature multiple drive units, each of which has a restricted bandwidth. For instance, in a typical two-way design the bass/mid unit may cover 50Hz to 3000Hz and the smaller tweeter will take over from there to around 18000Hz. How the two units are connected defines whether the speaker is a passive or active design. A single, full-range speaker is one drive unit which endeavours to cover the whole frequency range, from 50Hz to 18000Hz.

All three have advantages and disadvantages – the art of successful speaker design is knowing which compromises are acceptable and designing accordingly.

PASSIVE LOUDSPEAKER

These dominate the hi-fi market. They use passive (non-powered) crossovers featuring components designed to operate at tens of volts and high current. This makes the components large and expensive, particularly if close-tolerance parts are used. Even at relatively low powers, the components can exhibit significant harmonic distortion which would be deemed unacceptable in an amplifier or other electronic hi-fi component. Furthermore, at higher powers, the components may heat up, their values alter and the crossover point – carefully calculated and designed for, often with computer modelling – may move, leading to more distortion.

Finally, the crossover appears after the power amplifier,and effectively decouples the drive units from the amplifier, allowing no electrical damping and control over the movement of the cone or dome.

ACTIVE LOUDSPEAKER

Technically, these are a huge improvement over passive loudspeakers. The crossover is powered, like a preamplifier, and uses small voltage components, making them cheaper, closer tolerance and cooler running. An active crossover can be designed and manufactured much more accurately than a passive crossover. The amplifiers come after the crossover and are connected directly to the drive units, allowing much greater control and damping. Distortion is a magnitude less than with a passive system, something one would think all hi-fi enthusiasts would strive for.

The main disadvantage over a passive speaker is the requirement for a second power amp. However, the power amps themselves can be smaller – they are precisely matched to the drive unit with no requirement to drive high-current loads. Many systems – for example, Linn, Meridian, AVI, Bang & Olufsen and Genelec – fit the power amplifiers within the loudspeaker cabinet, leading to a further cost saving in expensive metalwork for the amplifier.

Despite these advantages, the active speaker shares with its passive counterpart a number of significant problems.The sound is still generated by two or more separate sound sources, leading to a lack of focus. The units themselves may be wildly dissimilar in both design (cones and domes or ribbons) and materials. The units may have different transient responses, as you might expect when trying to match a lightweight dome to a heavy plastic or paper cone.

Would you be happy to listen to a piano solo split between a church organ and a harpsichord?

SINGLE-DRIVER LOUDSPEAKER

Despite their apparent simplicity, these can be amongst the most sophisticated loudspeakers available. The sound is generated by one drive unit, usually from one point in space and manufactured using one material. The sound is more focused, coherent and natural than the best active or passive speakers. There is none of the distortion and poor damping of the passive speaker and they avoid the complexity of the active.

But a high-end, full-range speaker is not the easiest or cheapest thing to design and manufacture. The Jordan Eikona 2 is the culmination of decades of research and development. The proprietary materials used are expensive and specialist in nature, many of them hand-tooled.

So the single, full-range driver has many advantages over the active and the higher cost of the drive units is offset by the need for only one power amplifier, the choice of which is entirely left to the end user.

The results are worth it. Listen to the Jordan Eikona 2 and instead of a loudspeaker, you are listening to music.

Electromagnetic soundfields

DT880

We wouldn’t normally recommend that you turn to headphones rather than the Jordan Eikona speakers, but here’s something which might tempt you.

BBC Radio 3 has posted a short video of a binaural recording with a difference. Specially adapted wireless headphones allow the recording artist to ‘hear’ electromagnetic fields from LED displays, security systems and other electronic devices.

It’s a fascinating listen. It works best on headphones but also works well if you sit between a pair of Eikonas and turn the speakers inwards to face your head.

You can watch and listen to the video here.

 

Eikona VTL loudspeaker from BK Electronics

Eikon_Pair_White_close

Following on from the review of the BK Electronics VTL kit, we are pleased to be able to announce that BK now have a complete VTL speaker system available.

The loudspeakers are supplied in white or black, with satin or piano gloss finish and are fitted with magnetic, clip-on grilles. The result is very elegant.

Prices are £894.95 for satin finish and £1014.95 for gloss.

Full details on the BK website.

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A history of Ted Jordan’s VTL Loudspeaker

eikona kit pair

Following on from last week’s customer testimonial to the BK Electronics VTL kit, we thought we’d go into further detail about the evolution of the design.

Ted Jordan designed the VTL loudspeaker enclosure in the early 1990s. It used the Jordan JX92S full-range drive unit and saw commercial success as the Konus Essence. It has enjoyed a long life among manufacturers and DIY constructors and continues to do so with the arrival of the Jordan Eikona 2.

The transmission line loudspeaker is an evolution of the acoustic labyrinth, first produced commercially by Stromberg Carlson in the 1930s. Arthur Bailey added a port in 1965 (Non-Resonant Loudspeaker Enclosure Design, Wireless World 1965) and a new enclosure species was born. The advantages of the transmission line over a reflex or sealed enclosure include more extended bass, better suppression of resonances and greater power handling.

The basic idea is a speaker at one end of a pipe with a hole at the far end. The pipe may be more or less heavily damped depending on design. The VTL is a type of transmission line known as a coupled cavity. The rear of the drive unit fires into a cavity which feeds into a long, damped pipe. Above a certain frequency, the cavity decouples the driver from the pipe and the enclosure behaves like an optimised sealed box.

Robert Fris is generally credited with inventing the coupled cavity TL with his Daline (The Daline, A Decoupled Anti-resonant Line Loudspeaker, Hi-Fi News, November 1974), but in fact Ted Jordan described something similar four years earlier. Ted’s article for Wireless World (Loudspeaker Enclosures, January 1971) described the evolution of the infinite baffle via the sealed box, reflex and horn to a box with long, damped line (see diagram below).

More recently, George Augspurger’s AES paper (Loudspeakers on Damped Pipes, JAES, vol 48 no. 5, 2000) computer-modelled TL alignments and concluded that the coupled cavity is a very successful option.

The Eikona VTL remains as Ted envisaged it; a compact, floor-standing enclosure which is smaller and easier to accommodate than most transmission lines. The wide baffle goes against the modern trend of narrow-fronted enclosures but it gives more weight and realism to the lower registers, particularly on piano and voice.

Ted enclosure evolution

Project – BK Electronics Eikona VTL transmission line

VTL 04.1

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.

VTL 02.1

Project – MLTL30 Eikona transmission line loudspeaker

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.

blog-djinn-02-1

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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Firm Foundations – the Concrete Baffle

This is a contributed blog from Jonathan Espley of Matteis Loudspeakers. He has been a long-term user of Ted Jordan’s full-range drive units and is a passionate advocate of ultra-rigid, concrete baffles. These concrete baffles appear in his own range of loudspeakers but are also available to home constructors. Jonathan describes the background to their development.

matteis-veneered

 Back in April 1982, Hi-Fi News & Record Review published an article, Tone Arms And The Twist. It suggested an alternative way of making a pickup arm. The idea was to use strategically-placed mass to provide stability for the cartridge at audio frequencies. In so doing, it removed the need for an ultra rigid arm and highly engineered bearings and virtually eliminated structural resonances. I rebuilt a Hadcock Unipivot arm to test the principle and it worked superbly well.

The loudspeaker drive unit and cabinet has a lot in common with the moving coil cartridge and pickup arm. The arm/cartridge converts mechanical energy into an electrical signal whereas the loudspeaker converts the electrical signal into a sound wave. In each case, the transducer should be held absolutely stable at audio frequencies.

High end pick-up arm manufacturers go to great lengths to engineer the arm to be as rigid as possible in order to extract maximum information from the record groove. Loudspeaker manufacturers design some superb drivers only to stick them in a highly resonant wooden box.

It’s not difficult to see where the main problem lies with conventional loudspeakers. The cone is driven in a backwards/forwards motion to generate the sound wave. This puts great pressure on the baffle to resonate in the opposite direction to the movement of the cone. Any movement due to flexure must be subtracted from the cones movement. Hence there is an inevitable loss of energy.

When it comes to side panels, they are solid in the front to back dimension and any resonance does not directly affect the motion of the cone and so has minimal effect compared to the baffle. I have built speakers with concrete sides and, believe me, it’s not worth worth the compromise as it’s very difficult to get an acceptable finish. 

matteis-baffle

I started experimenting with a concrete mould for the front baffle then tried reinforcing it to obtain greater rigidity. To cut a long story short, I ended up with a mould (shown below) that has reinforcement right across the baffle. The concrete does not take the strain as it is not stable enough at 30mm thickness. Every improvement to the reinforcement brought an improvement to sound quality. The main difference is a sense of presence to music. Stereo image is more sharply defined, giving a much more realistic presentation of a musical performance.

There is still a small residual resonance as the pressure to drive the cone against atmospheric resistance is so great that the whole enclosure moves slightly. It helps if the enclosure is deep and narrow with the base as deep as possible, with spikes to pierce the carpet.

I have a new enclosure design formulated which I hope will overcome this problem. It has some novel features and will be the basis of a future blog.

matteis-speaker

The Power of Radio 3

radio3-70-blog

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.