JoSound are based in Jersey and make rather distinctive single driver loudspeakers and we’ve been lucky enough to review their Cartouche and Ra models over the last few years. Hifi Pig met up for a chat with Joe Jouhal from JoSound at the end of this years High End in Munich where he was demonstrating his latest Horus loudspeakers.
Hifi Pig: Your loudspeakers have an interesting and distinctive shape. Where does the shape come from and what inspired you to take such a different design approach.
First let me take the opportunity, to thank Hifi Pig for taking the time to visit us, we do appreciate it immensely, as we can see how hard this show is on journalists physically. Rather you than me!
The answer to your question is simple, but I will add a bit of perspective:
Many people have described the styling of JoSound products as “Art Deco”, which was a movement that flourished from the 1920’s to the 1940’s and was based on “visual styling”. Thus the styling of “Art Deco” objects, visually pleasing as it may be, is contrived, in that the object did not need to look that way in-order to function. This is something that we do not do.
Our design philosophy is more akin to “Bauhaus”, here, form always follows function. So an object looks that way because that is what is needed for it to fulfil its purpose. So, in a way, our “styling” is purely accidental. We may appear to have a house style, but that is simply as a result of using the same principles on all our designs.
Our products look the way that they do because they would sound different in any other shape. We are engineers not stylists.
Hifi Pig: A round front baffle is somewhat unusual, are there sonic benefits to this design feature?
The flat round baffle has long been associated with poor sound distribution in room and very prone to beaming. As Dr Harry Olson’s work in the early 1950’s showed. However his work also showed the ideal shape is a sphere.
Our baffles are round, but not completely flat, also the radius of the filleting on the outer edge is critical in relation to the radius of the baffle and the gentle curvature of the baffle. These parameters are all calculated based on our proprietary mathematical model that we call the “pseudo-sphere”. The aim is to get as close to the performance of a sphere without the associated physical bulk.
We do not 100% match the performance of a perfect sphere, as there is a distinct sweet-spot for listening, and in that seating position, the sound stage should be rock steady and almost holographic.
Hifi Pig: You have used single driver designs exclusively in all your loudspeaker designs. What do you think are the benefits of single driver speakers and do you think they have any associated problems that need overcoming in other areas of the overall loudspeaker design.
I have an affliction. I can walk into a room, hear a pair of loudspeakers and tell you the cross-over frequency or frequencies to within 30 Hz, as witnessed by Wolf Von Langa when I popped into his room to hear his excellent A5000 field-coil driver in the Pure Audio Project open baffles.
Passive cross-over networks have serious phase issues at the cross-over points, the capacitors, resistors and inductors all sap dynamics, in my view. As these dynamics are the very soul of music, we strive to extract the maximum that we can. A good full-range driver, coupled with a well designed enclosure, with no cross-over in the way will give a very dynamic performance that is close to the point source ideal.
The downside, enclosure design is critical and you may have to sacrifice some low end performance. With poorer quality full-range drivers, you have issues at the low end, high end and sometimes even in the mid-range, the so called “shout”. A very common fault is a rising top end and this present on some very expensive single driver designs.
So if you want to use just one driver, you really have nowhere to hide. Your driver selection must be right and your enclosure design has to be bang on the money, if you want great sound.
Hifi Pig: I note you’re using a new brand of driver. Why the change?
As you know, from mid 2011 to 2014 we built our range, ostensibly, around drivers from our previous supplier, in 2013 and 2014 we invited them to share the JoSound room at various shows, including both the HighEnd shows over that period. We even collaborated on a joint design that was kindly reviewed and much liked by Hifi Pig.
At every show that we conducted, we allowed them to have the prime position in terms of optimal placement, as their product was more expensive, and should thus be afforded the best opportunity. Late in 2013, they launched a wooden coned driver with an Alnico motor, their best sounding driver, in my opinion. It worked very well in our jointly designed enclosure. Shortly after HighEnd 2014 I received an email formally ending our collaboration and notification that they will no longer supply us with any drivers.
So I started looking for a new supplier, and I am glad to say that we have found a driver manufacturer who matches our own values. Our new supplier is AER Loudspeakers of Stuttgart, which is headed by a real gentleman by the name of Filip Keller.
Filip’s drivers, at every price point, are better sounding than the equivalent from my previous supplier. So I am actually very glad to have been cut loose from my previous collaboration, it set me free, through necessity, to design Horus.
Hifi Pig: Could the construction of the Horus be described as a back loaded horn loudspeaker and if so can you explain to Hifi Pig readers a little more about how you came to its design. Is it folded, what length is the horn…etc. Have you used HornResp, another program, or is it mostly done by ear?
As they say “necessity is the mother of all invention” and after losing the ability to produce my top end product, I had a real need to fill this now gaping void in my range.
The horn on Ra, was not my design but that of my previous driver supplier. So I wanted to design my own horn, but I wanted it to be compact, not a trait that bass horns are noted for.
I studied as a chemical engineer, with a penchant for fluid dynamics, and ended up spending 30 years in IT with a serious leaning to software development. Since 2010, I have been modelling my loudspeaker designs using my own software and the model has been refined based on actual measurement of the end product. Based on the measured parameters, the model, after much number crunching, now generates an ideal bass loading as a transmission line, bass reflex and horn (exponential and tractrix). In reviewing the results using the parameters for the AER MK11 driver, which they sell as a mid to high driver that should be crossed over no lower than 200 Hz, we ended up with a set of results which set me on the path to designing the loading regime for Horus.
I know that a lot of manufacturers make claims about their technology being “unique”. In the case of Horus all that I will say is that I do not know of any other loudspeaker that has this loading regime, is it “unique”? I’ll leave that for others to decide.
In essence, Horus is designed in a way that there is a confluence of three loading regimes in its dual ported bass loading. It is a curtailed downward firing exponential bi-horn, At the same time the averaged diameter of the ports produces the same loading result if calculated as a bass-reflex. Additionally, it equally behaves as a transmission line tuned to the free air resonance frequency of the driver. So what is it? It’s all three.
Unfortunately, all bass horns and transmission lines suffer from resonances created by harmonics from the fundamental note. Luckily back in the 1950’s John Karlson came up with a way of solving this issue. Sometimes referred to as the Karlson resonator. The profile that forms the support for Horus is in fact a modified Karlson resonator. As a result there is no damping material in Horus.
I am obviously not going to give out the precise geometry of the workings of the cabinet, but I have given any good DIYer, with the appropriate level of mathematical ability, enough information to be able to have a good stab at a copy.
When Filip Keller heard his MKII driver in the Horus at HighEnd 2014, for the first time, he looked around it and then asked me which woofer was I using inside the cabinet as none was visible outside and my response was “good, but unusual mathematics”. His response “Wow, I never imagined this was even possible with this driver.
Hifi Pig: With Horus you have said you can order the speakers with the “base” level driver and work up through the range with sonic improvements as you go. How does this work with speakers having different Thiele/Small parameters?
A common mistake that loudspeaker designers get fixated on if the famous Thiele-Small (T/S) parameters. For a start they only apply at very small excursions. Our modelling is not based on these, but more aligned to the Klippel type approach.
If you want chapter and verse on the reality of T/S parameters visit EJ Jordan’s website and find his article entitled “The Parameter Games”. Ted Jordan is a great loudspeaker designer, and one of my personal influencers.
Quite simply we measure drivers in real life conditions and feed our own set of parameters into our own model, which through constant refinement generates a 95% match with actual measurement, in the case of the Horus MK.
We have modelled all the AER drivers in the Horus cabinet and they all work. This has been verified through actual measurement.
Do we rely on modelling and measurement alone? No, before launching any new product, we and our listening panel spend considerable time in verifying that the product does actually play music well. We have made minor changes to designs based on listening.
Hifi Pig: You use bamboo as the main construction material in all your loudspeakers. Why is this?
There are three real reasons:
Firstly, when I founded JoSound, my children asked me to not chop down any trees or cause any harm to our environment, in-order to make my products, I agreed. This restricted me to recycled sheet material and bamboo, which is a grass. We chose a variety called “moso”, which is the fastest growing species.
Secondly, acoustically bamboo is a superb material, it has been used to make musical instruments for thousands of years. We use laminated bamboo, where the style of lamination allows us to produce an acoustically inert cabinet, so all you hear is the driver and the port output.
Finally, I hope you do agree, it does look beautiful.
Hifi Pig: We’ve been in your room here a few times over the period of the show and the sound has become more dynamic over time. What changed?
That is a great question. OK, when we set-up on the Wednesday we had 2 changes from the previous year, we went up one level on the O2A loudspeaker cable and used the Ultime cables this year and also we were using the Transrotor ZET-1 turntable with an Audio-Technica Art-7 cartridge. For digital, we had some of the RM Remaster processed files to play with as well as the original CD rips. We were very happy with the sound.
So what changes did we make. On Thursday night we managed to pick up the new driver for the Horus B3 model (our current top of the line), this driver was specifically designed by Filip Keller of AER loudspeakers, for JoSound. DIYers can buy his BD 3B, on which this driver is loosely based, but not this special JoSound edition. When we tried it, despite having no burn in, it was already significantly better, faster, smoother more dynamic. So we left it in.
We then ran this system as is until Saturday afternoon.
Audio-Technica (AT) launched their fabulous new cartridge, the ART-1000. This is an old design, that some have tried to produce but never managed to do it justice. Finally, technology and production practices have improved such that AT have been able to produce it and I for one am glad that they did.
Having the ART-7 in our room meant that their staff were coming in our room to hear what it sounded like. Late on Saturday morning Clive Atkins and Koizumi-San, from AT, came and listened to the ART-7. We got talking and I mentioned that I would love to hear the ART-1000 on my system and maybe next year they might loan us one. Clive responded with “I’ll see what I can do” and they left. A couple of hours later they both returned. Koizumi-San was cradling an ART-1000 in his hand very carefully, it was one of only 28 in existence right now and this was number 10 and destined to be owned by Clive. They asked if I would be willing to make a live change to the system and switch to the ART-1000. I broke my own rules and agreed, with the proviso that they had to set it up. They obliged and we switched over to the ART-1000, again with no burn-in but wow, yet more speed, more attack and very smooth. So we continued with it until the end of the show.
So the answer to your question in a nut shell is what you heard was a driver and cartridge match made in heaven, both burning in together and getting better, faster, more dynamic and smoother with every minute of play time.
Normally at the end of the show we turn of the system at 18:00 if there is no visitor in the room, not this year, we were enjoying the sound so much that we let the music play and popped the cork and sipped prosecco whilst listening to great music.
Sadly, we had to return the cartridge, I have to get one!
Hifi Pig: What components in your system do you consider to be key?
Putting a good system together, is about listening and changing on component at a time and evaluating each change. This is very much our way.
As a result, what you hear is a true sum of its parts and no one item can be singled out our set-up this year worked incredibly well together. Here is what it was composed of:
Transrotor ZET-1 (turntable)
Audio Technica AT-ART7 (cartridge)
Audio Technica AT-ART 1000 (cartridge) from late Saturday afternoon
Aurorasound VIDA (phono-stage)
Tranquil PC Media One (media player)
AMR CD 777 ( CD transport)
AMR DP 777 (DAC)
The Bespoke Audio Company (passive preamplifier)
Arte Forma Due Volte (mono-block power amplifiers)
PS Audio P10 (mains regenerator)
JoSound Horus MK (loudspeakers) on Thursday only
JoSound Horus B3 (loudspeakers) Friday onwards
All cabling is with the O2A interconnects
We also hosted files that had undergone the RM Remaster treatment, it works.
Can I be a little cheeky and thank all the people who visited our room and all from Audio-Technica, Aurorasound, Tranquil PC, AMR, The Bespoke Audio Company, Arte Forma, PS Audio, O2A and RM Remaster, for making the components that all added up to a beautiful sound.”
Hifi Pig: What’s next for JoSound? New models?
For some time, we have been considering producing a range that reflects a more modern appearance, by making a coloured lacquer finish. But high gloss lacquers all fail the eco credentials test that my children set me.
However, we have now found an eco friendly 100% recycled product that we will launch at next year’s HighEnd. It will be called Gemini, it will be based on the Horus design, with a different look, as the material has different acoustic properties to bamboo.
Work is continuing on our own turntable, and as you know I already have a crazy sub-woofer, but next year we will have one with the speed to match Horus and Gemini and the extension to play the lowest organ notes (16 Hz) with real power.
Having recently hooked up with a gentleman of some repute in our industry who suggests that he has resolved the issues of phase alignment in a passive cross-over, you never know, we might even turn up with some smaller and cheaper models using multiple drivers.