In RDacoustic's own words.
Our mission: We created RDacoustic for love of music and the pursuit of its most believable presentation. Our philosophy is  to give people the real listening experience. Our products deliver perfect sound full of the finest details including excellent spatiality. Widebanders are not very common and that's a pity. Characteristics like high sensitivity and zero phase shift can make for an unforgettable playback experience within the comfy confines of an average living room. Our aim is to carry on the development of widebander speakers in various executions and variations to give our customers the best possible quality of hand-made choices.


Evolution and goal: Our flagship Evolution speaker comes after many years of experience and experiments with fullrange drivers. Our aim was to produce a still compact universal full-range system without any compromises. The primary requirements for the Evolution project were a perfect presentation of the mid and treble frequencies accompanied by detailed deep bass. We went through many prototypes of folded horns prior to reaching the final shape whilst performing a detailed analysis of the maturing prototype's many parameters. The final sound dictated the construction of the box.

With Lenka Filipová at Lešná castle for a little PR op.

Development: Over the years we found that the backloaded horn was the best solution. Gradually we simplified the horn, then increased baffle height of baffle up to 2.2 metres where the bass began to eclipse the overall output of the speaker itself. We were desperate to optimize/reduce the size of baffle whilst maintaining solid bass. The standing waves which appear with most horn constructions are minimized by the mutual tilt of our sidewalls and the inclination of the inner line. The curved horn itself has no sharp edges and its expanding cross section amplifies bass frequencies by more than 3dB. The throat chamber is stuffed such that only bass components progress to the actual horn. Hence there is no midrange information coming out of the horn to avoid cancellation, image ghosting and phase shift.


Advantages: In the Evolution you won't find any crossover and the single driver makes for a near perfect point source. Eliminating a crossover eliminates splitting up the bandwidth into separate bands which interferes with precise image localization and the precision of soundstaging. Not even the finest detail is obscured. That's difficult to achieve with crossovers. The first impression for most new listeners is a very significant midband accompanied by a wealth of detail. It is said that once exposed to a properly implemented widebander, one cannot go back to conventional multi-way speakers. A typical issue with widebanders is lack of proper LF support. This we have addressed with the evolution of our horn. We offer various colour options from the RAL range. The leather's tint and texture are picked from a sampler book. Other options include top-range WBT terminals and silver-plated hookup wiring.


Drivers: The quest for perfect sound never ends. That's why we remain very open to ongoing development and offering options. We can fit most 8" widebanders into our baffle. Each driver offers its own presentation. We cannot claim that one performs better than another, only that they are different. Purchasing an Evolution speaker is only the beginning. Then one experiments with drivers, hookup wiring, terminals and the Oris500 horn. The choice of driver often comes down to money. But it's misleading to think that the most expensive ones are automatically best. We offer three well-known driver brands.


Fostex are the ideal starter choice. We make small modifications to their FE206e to increase its spatiality and fine details to a level usually the providence of costlier transducers. Due to its bigger diaphragm, bass is represented very well. Many of our customers remain with this basic option to never perceive the need to upgrade to more efficient drivers. Voxativ's extraordinary drivers are more intense and accurate in the vocal range and their bigger motors increase overall precision. Lowther sits somewhere in between. Both Voxativ and Lowther offers a huge array of drivers which fit the Evolution. One general rule of thumb here is that the bigger the motor, the more detailed and precise playback becomes. Obviously this also gets pricier. The top-range Voxativ driver is €28'000/pr.

At Munich HighEnd 2016

Oris500: This front horn option attaches easily using four pegs instead of the driver's trim ring. It boosts the lower midrange by up to 3dB and makes the sound more directional, especially useful in overdamped rooms. During low SPL sessions, it creates an obvious increase in midband information. Conversely, it can become a disadvantage during louder listening.


Listening space:The Evolution speaker system is suitable for listening space from 18m² to 90m², depending on a given room's acoustics. Preferably the room should be well damped with no large flat reflecting surfaces, which could blur the midrange. Diffusers then are an obvious option. The advantage of widebanders is their balanced impedance. It means a level workload for your amplifier and that tube amps may apply.


Production process:The Evolution speaker is made from extra hardened molded MDF especially made for us. Right after its production, QC ticks off mechanical features, consistency and finish. CNC machining creates the individual parts which are then bonded into the final body. Lacquering happens in one continuous process after which the leather is installed, then the terminals and drivers. Final QC focuses on the acoustic and electrical parameters.


From the above we extrapolate two basics: one, because this is a fixed cabinet which serves all fittable drivers, optimization between horn line and transducer must by design be more general than specific; two, due to the usual unpredictable interactions between speaker/room and—this is especially so for widebanders—between amp/speaker, the 'perfect' Evolution incarnation for each customer must be determined in situ. That makes the model name fitting and reiterates the quasi DIY aspect of the widebander genre where experimentation remains ongoing. To stress this point further, the firm's David Piska informed me that "we will send you one pair of wooden front horns as an option. Those are very easy to install. Remove the driver trim rings and push the horns to the bungs." To be honest, I wasn't presold on this. Its influence would cover a relatively narrow band. That's how horns work. To end up with linear results would either require that the unassisted driver have a quite nonlinear response (in which case, why would the horn be optional?); or for a room to interfere so badly yet perfectly that the horn gains would offset its sins in mirror-imaged fashion. Either scenario seemed quite unlikely. As always though, the proof of the pudding would be in the eating.