[The Feastrex wideband drivers from Japan have stirred up much interest since their introduction. When our foreign correspondent Warwick Freemantle reported that he was working on a speaker employing a Feastrex driver as main unit, I asked him to wield his pen. Granted, this now turns out a bit self-serving for Warwick because he's decided since to go commercial. However, not being a formal review but rather, an informal behind-the-scenes glance at an impending product launch, most readers will appreciate the difference. They'll enjoy the opportunity to learn more about it. Those inclined to cry foul and "crass capitalist propaganda and self promotion"... well, they should tune out just about now. - Ed.]


Some of you may remember that a year ago, I reported on the Guangzhou AV Fair in China and how very impressed I was when visiting the Melody factory in Shenzhen. Well, a lot of things have happened since then. The Melody brand has been refreshed in Australia with new dealers and a new marketing strategy pioneered by my outfit, Pure Music Group.


Parallel to this, my passion for single driver loudspeakers has been fuelled by the introduction of new drivers from Feastrex in Japan. Feastrex calls them full ranges but I eschew the use of that term because there is no single dynamic driver that can really cover the full range of music. I prefer the more technically correct expression of wideband drivers. I have always liked crossoverless single driver loudspeakers. Although this category of loudspeaker is flawed in many ways, they tend to have an ability to communicate the essence of music very well. I had been observing Feastrex for the last two years as they went through the birthing pains of bringing a new product to the market. The product has matured through a number of iterations and finally there are several versions available.

These include the D5x and D9x Series, each available in Naturflux, Monster Alnico and Field Coil versions. As the name suggests, the D5x family are 5" drivers and the D9x family are 9" drivers. The Naturflux magnetic circuit consists of a spherical magnet said to concentrate the magnetic flux more strongly into the voice coil gap than a conventional magnet does. These drivers are called D5nf and D9nf. The result is better bass control and extension than one normally hears from a driver with a conventional magnet. Next up in the range are the Monster Alnico drivers, the D5 and D9, which, due to their greater damping, do not produce bass as deep as their Naturflux counterparts but reveal more inner detail and generally have more transparency. At the top of the range are the Field Coil versions, the D5e and D9e. These have an electromagnet instead of a permanent magnet and require an external power supply to energize them. Varying the voltage supplied by the power supply allows the user to vary the driver's characteristics.


Mr. Akiyama, owner of Feastrex and Mr. Teramoto, his chief engineer, have worked tirelessly to create a product that is uniquely Japanese in conception and execution. I think it is more than just a loudspeaker driver being offered to the market. It is an expression of their desire to leave a legacy of having made the best wideband driver technically feasible at this point in time. By using materials that are only available in Japan, they have also built a product that nobody else could. In particular, the Washi paper as it has been made by Japanese artisans for centuries is used for the cones and voice coil formers. This material is ideally suited to loudspeaker manufacture (i.e. it is reputed to have near perfect dimensional stability regardless of humidity and temperature) and cannot be replicated by any other material.


I purchased a pair of D5 Monster Alnico drivers a few months ago. When we heard them for the first time, we were extremely impressed. That is an understatement. My friend Aaron was with me at the time and he is an owner of Zu Definitions powered by a Yamamoto A-08S equipped with EML tubes. He knows a thing or two about good sound. After we heard the Feastrex units, I had to practically peel Aaron off the ceiling, he was so excited and enthusiastic.

As I had intended to add bass support in the form of two 10" Australian-made bass drivers from SGR Audio in Melbourne, I was more interested in extracting ultimate transparency and high-frequency performance from the driver than the last bit of bass extension. This is why I chose to go with the D5 Monster Alnico driver over the D5nf. After measuring the driver, we decided that 200Hz would be the best point for us to actively cross (i.e. at line level) to the bass section. My friend Chris calls passive crossovers a "good place to lose music" and I have to agree. Fortunately Stuart Ralston at SGR Audio is a bit of a whiz with active crossovers. I don't mind admitting that I know nothing about crossover design. By dividing the signal before it enters your power amplifiers, the loudspeaker drivers are connected directly to the amplifier, with nothing in between but wire. This is the best way to divide the frequencies and not compromise any of the signal between the cracks. Stuart said it would be a piece of cake to design an active crossover integrated into his own solid-state amplifier to power the bass section. Presto, we could have our Feastrex running on valves from the active crossover and the bass section on transistors, all in a nicely sized cabinet which is domestically appealing. Stuart could also build into the active crossover whatever equalization was required, a nice plus. Note that the crossover and amplifiers are all analogue. There is no digital conversion anywhere.
SGR has developed some pretty special bass drivers. My friend Chris had given me the tip that these would make a good combination with the Feastrex driver and he was dead right. Originally SGR searched all the known sources for a good bass driver that met their requirements but nothing cut the mustard. They have a graveyard of bass drivers that either sounded terrible due to severe cone breakup or fell apart when pushed hard. So they commissioned their own to be built locally to their specifications, calling for less than 1% distortion, unusually low for a woofer. The box that houses them also has a lot of special features that SGR asked me not to divulge. The result is bass that seamlessly extends the incredible articulation of the Feastrex into the low bass. Unlike the sort of fake bass most people have been conditioned to mistake for real, this is pure clean bass without exaggeration or overhang. The SGR bass drivers can move an amazing amount of air with absolute control and their amplifier has the power to maximize this control. It is really not just a bass amplifier but rather, a high-quality full-range music amplifier that happens to do bass exceedingly well.
We embarked on a project to build one pair of loudspeakers. Alas, somewhere along the way, the project derailed from
something intended for just me to a loudspeaker we shall soon be offering to customers as well. I have received many expressions of interest so I feel compelled to follow this path. I have assembled the best people I know of to build the cabinets, drivers, electronics and everything else to do with this project. Due to the high quality we wish to maintain, these loudspeakers can only be built in small quantities.
Loudspeaker design is a blend of technology and personal taste. The designer must rank his priorities and design accordingly. The Feastrex drivers are a landmark achievement and other people including Feastrex themselves will produce their own interpretations of what constitutes the optimum use for these drivers. Again, taste will play a large role so I expect a lot of variety in these forthcoming designs. Full-range purists might cry foul because we are using active bass below a driver intended for full-range use but it is the best way to obtain genuine bass from a reasonably sized enclosure. Ours is but one view of how this can be done and we think it addresses many of the key aspects that are important to music reproduction.


I was in bed thinking about how the world could come to know about this loudspeaker and inspiration struck: what better way than return to Guangzhou and show it there? This is a speaker that will appeal to Asian music lovers wanting ultimate transparency in a room-friendly size but with full-range performance. That is not to say it would not appeal to all music lovers wanting the same attributes. Still, it seemed like a good excuse to return to Guangzhou. I rang Alex Wang of Melody and asked him whether his father Shi He Wang could be interested to cooperate with an exhibit. The answer took a few days but I was delighted to learn that it was in the affirmative. So now we are headed for the Guangzhou AV Fair to show off our creation. We have called the loudspeaker Sonic Purity RS-5a. That's code for Reality Series, 5" driver and 'a' for either active or Alnico, take your pick.

The boys at SGR Audio are putting the finishing touches to our show model in beautiful Phantom Black Metallic for the bass box and Dakar Beige Metallic for the head unit. We will be showing with Melody's new PM845 single-ended mono amplifiers so the sound will be very good. Melody normally takes out a nice size conference room so we will not be squashed into one of those small hotel rooms typical of hifi shows. The speaker model we are taking with us will allow attendees to see and hear it and make comments. We will take those comments to heart and refine the design before it enters final production. I think it is good to get feedback from potential customers before one commits to production. As I said earlier, how many units we can ultimately produce will be very limited because of the intense hand labor involved to achieve the quality we desire.


I will report back after the show about our coming out party. Hopefully all will have been good but I am certain that there will be trials and tribulations along the way.