2-way floorstanding speaker systems
based on Scan-Speak Illuminator drivers
Project
Visualizations and drawings of various construction and finishing options
Production
work on the enclosures
The cabinet has a classic design and is made of milled MDF panels 19mm thick. To suppress internal resonances, the cabinet has stiffening ribs, the internal space will later be filled with sound-absorbing material.
The internal volume is divided into 2 compartments: a volume for the acoustic design of the mid-bass driver with a bass reflex port and a separate volume for the crossover boards.
Decorative grills are attached using hidden magnets.
Cabinets are decorated with veneer by hand and varnished in a painting chamber.
Production. Continued
Electrical part: crossovers, drivers, internal wiring
Crossovers are made from milled fiberglass boards with a thickness of 1.5mm. High-quality components are used: polypropylene capacitors, wire resistors, thick wire inductors on “air” cores. The production of final crossover boards takes place after the development and fine-tuning of prototypes.
Scan Speak Illuminator drivers have a number of design features: magnetic systems using neodymium magnets, paper cones of mid-bass drivers of variable thickness with a special molding that gives them a characteristic pattern. Aluminum baskets with a minimum number of streamlined ribs, which provide minimal resistance to air movement from the back of the mid-bass cone.
Tweeters with a ring diaphragm and a ceramic central “drop”. The framing of the small horns is made of soft dampers. The tweeter housing is made of solid aluminum.
Internal wiring of speaker systems is performed with copper litz wire cables of the required cross-sectional area, taking into account their directivity. Subjective sound examination demonstrates a number of advantages of such cables, which are manifested in the clarity and expressiveness of the sound.
electroacoustic measurements
Production. Final stage
Final assembly, testing
RS-Illu is our first speaker system development that uses one of the top Scan Speak Illuminator drivers.
What are the advantages of these drivers compared to, for example, the Seas Prestige, SS Discovery or Classic, which I know well? Considering the fact that Illuminator is several times more expensive than them. Advantages in frequency response uniformity, directivity width, sensitivity or power performance? No, that’s obviously not the point. The listed characteristics of the Illuminator drivers are very good, but they do not differ significantly from other 6.5-inch woofers and 1-inch tweeters if you compare their datasheet with others.
The first thing that attracts attention is the resolution, which is incredibly high in the entire frequency range. No hint of masking quiet sounds with loud ones or nonlinear distortion.
The second is the bass potential of the mid-woofer. It is really capable of going very low, it’s unexpected to hear convincing infra-bass from such little ones!
The third is the ability to overload. The sound does not lose its intelligibility and transparency even at extremely high volume levels (as for speaker systems of such a small size). The sound does not cause discomfort, does not fall into a mush, but remains as detailed and transparent as at moderate, comfortable volume levels.
To fully appreciate the aforementioned qualities of the “Illuminators”, I had to work quite a bit with the fine tuning of these speaker systems. With the first few versions of the crossovers, the speaker systems immediately sounded quite good, even with draft, rough filter settings: the tonal balance was even, with no noticeable colorations or frequency distortions. It seemed like we could stop at this stage. But one version lacked expressiveness and drive; the sound was clean, sophisticated, but somewhat detached and a bit “pop”. Another version of the filters gave the opposite sound: bright, assertive, and driving, but lacked the sophistication of the first options, subtle transitions, and halftones.
The challenge is to find a delicate balance between these two extremes. The culprit behind the tuning difficulties was the peculiar frequency response of the mid-bass drivers: a slope from the lower to the upper midrange of several dB. Very smooth curve without sharp drops, but extremely sensitive to the influence of filter settings.
The problem was successfully solved by step-by-step selection of cutoff frequencies and slopes of filter transfer functions using appropriate software and directly on draft crossover models with test measurements and listening. The final version of the crossovers is quite simple and provides the following formal characteristics: a 1.3 kHz crossover frequency, 2nd-order low-pass and high-pass filters with small correction circuits. The unevenness of the frequency response in the frequency range 40 Hz … 20 kHz is +/- 2.5 dB.
Fine-tuning crossovers is an undeniably necessary stage in creating and setting up speaker systems that should not be neglected. And thanks to the combination of the excellent characteristics of the Illuminator drivers and the fine, almost jewel-like setting of the crossovers, the RS-Illu really captivates with its sound: it fully reveals all the colors of the music and gives unique listening emotions!
Photo gallery
Photos of completed speaker systems
