Hifi Pig caught up with Joe Jouhal, the founder and designer of the JoSound range of loudspeakers and Inès Adler, head of Voxativ, at the Munich High-End earlier this year. We’d been interested in Joe’s loudspeakers since we heard them at the Paris Show in September 2102 and so we thought we’d take the opportunity to ask a few questions about his designs, his philosophy on loudspeaker design, a bit about his background as well as the involvement of Voxativ. The “interview” here is a combination of transcribing the recording we made during the interview, conducted in the evening after the show, and a series of follow up calls and e mails.

It’s clear speaking to Joe that he’s been passionate about sound reproduction from a very early age. In the 1970’s when most teenagers were reading comics and football magazines he was reading NME and Wireless World and was seemingly fascinated by the articles about amplifier and loudspeaker design.

By 1976 when he went to university he’d already heavily modified a Thorens TD 150, built his own transistor based amplifier and made his own loudspeakers.

With limited funds available he hooked up with an old school friend and ended up working weekends at Nottingham HiFi Centre. In the back room of the shop many designs for loudspeakers, amplifiers and turntables were theorised, old valve amps repaired and much fun was seemingly had.

In the early eighties Joe, who was looking for gainful employment, was offered the chance to manage the Nottingham city centre branch of the newly relaunched Superfi.

In the mid 80s Joe entered the world of computers and there he stayed for the next 23 years until he was offered an exit package that gave him a good deal of spare time in which to tinker with a pair of loudspeakers that needed upgrading. Being a fan of everything from Saint-Saens to the Sex Pistols nothing seemed to work and so he decided to build his own with the design goals of them being accurate, with a stable soundstage, dynamic, airy, non-fatiguing, engaging, good with all genres and built using sustainable materials…oh and they’d need a high WAF too.

So what Joe did was look at his design goals and the speakers that offered the characteristics he wanted and then worked backwards from there – Electrostatics were out due to young children being around and horns would be too large. The name Jordan-Watts kept cropping up and he set on down the path of transmission lines. Joe decided to trawl the internet for Ted Jordan to see if he was still making loudspeakers … and he was … the Jordan JX92S.  In a simple box enclosure Joe was sure that this was the driver he’d been searching for but bass was lacking and so the idea of a single driver (and all the inherent benefits therein) transmission line loudspeaker began to germinate.

The actual shape of the line usually used could be referred to as a tapered line, but Joe decided to go with what is in effect a reverse pseudo-tractrix horn (the driver goes in the wide end as opposed to a horn where the driver is placed at the narrow end). The final transmission line contains no angular bends all – bends are radial. Prototypes were built and listening tests began but despite much refinement the loudspeaker still lacked the air and space around the music he was looking for. Ideas of an upward firing tweeter helped as did inverting the enclosures and putting them on stands. However they still had very low WAF and weren’t exactly drowning in green credentials.

The “Eureka moment”, for the styling, came when Joe was visiting the Jersey Maritime Museum with his children and saw a ship’s wheel. It was obvious to him that the drive unit needed to be housed in a pseudo sphere and the transmission line could be used to support it. Much modelling on the computer followed and a design came into being with the transmission line now resembling a “J” and the drive housing an “O” spelling…hence JO Sound.

Now, many loudspeaker enclosures use exotic woods but what would prove to be more eco-friendly? Joe looked at recycled glass & resin composites, recycled plastics, recycled paper composite and bamboo. The only product that proved sonically acceptable and with the necessary green credentials ended up being bamboo, but whilst certainly sustainable it wasn’t a cheap option.

The chosen bamboo (moso) is sourced from sustainable, panda friendly, sources. Moso is a grass that grows so rapidly that it can reach maturity in 5 years and can grow upto 20 metres in height. When it is harvested, the leaves are trimmed in situ and left to act as fertilizer for the re-growth. It will regenerate and be ready to be harvested again in 5 years, without the need for re-planting. So there was the final jigsaw piece in place but could they be made commercially? Well it would certainly seem so and suitable partners were sourced and on 23^rd March 2011 the first production batch was collected and the JO 45 was born – it’s a single driver, 85dB loudspeaker that has a frequency response of 40 Hz to 25 KHz and stands 1134mm in height and weighs in at almost 40Kg.

At AudioWorld 2011 Joe had the good fortune to finally meet up with Inès Adler of Voxativ, the Berlin based loudspeaker manufacturer and after visiting Voxativ’s demonstration room Joe knew that he had to design a product based on Voxativ full-range drive units. Over the course of the summer of 2011 Joe designed their top of the range model, the JO 33 and the Jo 15 Big Sub.

The JO 33 is a single driver, full range, quarter-wave transmission line using a reverse tractrix profile for the transmission line offering a sensitivity of 96dB and a response of 20Hz to 20KHz in a package standing a little over a metre in height and weighing in at 92Kg each.

The JO 20 Big Sub is a stereo sub with two discrete channels powered by the Hypex PCS 400 plate amplifiers. Joe says that these incorporate DSP based processors that allow very precise control over the frequency response curve and time alignment and it can be tuned to take room modes into consideration and tailoring it to the listener’s individual environment. Having witnessed the Big Sub it’s certainly a beast of a subwoofer with two 10inch aluminium drivers and two ten inch passive radiators powered by two 400W class D power amplifiers.

In the summer of 2012, Paul Morris (JoSound’s sole distributor in France, Belgium, Luxembourg and Switzerland) asked Joe to produce a more affordable speaker. This meant cutting down the manual effort in the production of the speaker as well as the development of a hybrid bass-reflex and transmission line loading system that we refer to as “pseudo-bass-reflex”. The result was the Cartouche 30 that was unveiled to the public at the Salon HiFi Paris 2012 where we first bumped into JoSound and their speakers. It uses a 4” paper driver running full range with a sensitivity of 85dB in an enclosure standing 1234mm high and weighing 32Kg. The captive cables that were a trademark of the JoSound range were done away with and more conventional binding posts added. Again, as before, the Cartouche 30 was well received at a number of the European hifi shows with some listeners actually looking for a concealed sub – such was the bass response.

At the New Music show where JoSound and Voxativ were exhibiting just a couple of rooms apart, Joe and Inès had the opportunity to really listen to each others product. It was apparent to Joe that by using rear horn loading, he would be able to get the best out of the Voxativ drivers. Inès for her part loved the look and quality of finish and the improvement in sound quality in the JoSound loudspeakers since the first time that she had heard them.

Joe says that he’d been intrigued by the performance of the Voxativ horns, because of their bass extension surpassing what he thought was possible from a conventional horn. Inès and Joe discussed how this was achieved with Inès explaining that she had developed her own horn theory that she called Acoustic Stealth Technology (AST). AST is apparently based on the science used to make stealth fighters invisible to radar through the use of wave reflection. Her designs are based on extensive computer modelling of wave propagation and energy transmission within the horn. The result was that a much more compact design could be achieved for any required performance level when compared to traditional horn designs.

Joe spent much time modelling wave propagation for JoSound’s trademark “pseudo-sphere” that appears on all models except the sub-woofer and Cartouche range. Here the relationship between the diameter of the round section and the radius of the filet on the front and back of the “pseudo-sphere” enable a very close approximation to the radiation pattern to that of a sphere of the same diameter, but again with a much smaller overall volume….clever stuff!

So was born the concept of “Voxativ by JoSound” and it was sealed with a hand shake.

Inès provided Joe with a design for an AST horn and Joe set to work on turning this into a product that incorporated the JoSound “pseudo-sphere”. On seeing the horn design, the image that popped into Joe’s head was that of the sun over the Great Pyramid and having found styling inspiration for the Cartouche in ancient Egypt, he immediately set to work on “Ra”. It’s certainly a very individual design!

Independently, Inès was busy developing the new Voxativ product, the diminutive π (Pi), which features a smaller version of the AST horn, whilst Joe was developing the Cartouche AC 1.5 using the new ferrite motor driver from Voxativ. Joe and  Inès decided to exhibit jointly at HighEnd 2013 in Munich, where the π (Pi), Ra and Cartouche AC 1.5 would be officially launched to the Hifi world.

The π (Pi) and Ra both possess an unusual trait, they can accept any of the Voxativ drive units from the AC 1.5 to the AC-Xp Permendur field-coil drivers enabling an easy upgrade path for users. The original intention was that Ra would only be offered with the AC-X field coil driver, but such was the quality of the performance of the Voxativ AC 1.5 it was decided to leave it there for all of the Munich Show. You can read what we thought about the Ra here but the π (Pi) was also very well received by public and trade alike.

It was good to see the Voxativ and JoSound teams working so harmoniously together at Munich and I’m sure this format will be repeated at future shows, despite the two companies essentially being in competition for the same market. Although we didn’t get an opportunity to listen extensively to the Voxativ kit on show at Munich a leading USA magazine included Voxativ in their Best of Show nominations for HighEnd 2013

A huge thanks to both Joe and Inès for taking time out of their hectic schedule to speak to Hifi Pig. We’ll be reviewing some loudspeakers from the JoSound range in due course and hope to have the opportunity to do like-wise with Voxativ kit.