RS-Arch-II. Process

Project of built-in home theater speakers.

Front, rear speakers, center channel, 2 subwoofers. Finishing – stone veneer.


The first pair of front speakers in the process:

The body of the speakers is made of MDF 19 mm thick, the front panel is 22 mm thick. Inside 4 stiffeners tighten the whole body into a monolithic structure, all elements are assembled with the help of rails and glue. The inner volume is evenly filled with sound-absorbing material. Acoustic design – closed box with a capacity of 42 liters.

Scan Speak Discovery Series drivers. A pair of 8-inch midbass drivers with a fiberglass diffuser and a high-frequency driver with an annular diaphragm and a central waveguide. The drivers are arranged according to the D`Appolito scheme, ie the high-frequency driver is located between two identical medium-frequency drivers. As you know, this layout of the speakers (vertical in this case) is characterized by an extended diagram in the horizontal plane and narrowed in the vertical. Built-in speakers have limitations in the exact orientation of the acoustic axes on the listener, so the D’Appolito scheme compensates for this limitation.

Sound settings on filter layouts. Testing of various schemes of “filtering”, selection of denominations of details, measurements of characteristics and control of live sound.
Final setting and filter scheme: mid-bass speakers are connected in parallel via a 2nd order filter with a cutoff frequency of 1.1 kHz, the high-frequency driver also has a 2nd order filter with a cutoff frequency of 2.6 kHz. The distribution frequency of the filters is 1.3 kHz. All drivers are connected in phase.



Setting up crossovers of the central channel.
The speaker system has significant dimensions: width 1750 mm, depth 400 and height 110 mm. The case is made of MDF panels 19 mm thick. The inner space is divided by diaphragms and stiffeners. It will soon have a matte black finish and a decorative grill with hidden magnetic mounts. In the photos, the speaker is set in a vertical position at the time of adjustment. Its design position is horizontal.

Configuration.
Scan Speak drivers: two 8-inch subwoofers are located at the bottom of the speaker system, 4 midrange and 1 tweeter with a ring aperture are on the front panel. Acoustic design of the bass section – a closed box with a capacity of 42 liters, medium and high-frequency drivers are located in a separate isolated volume.
The filter scheme is 3.5-way. The process of setting up filters begins with simple schemes with their gradual complication if it gives a positive result for the sound. In this case, the classic 3-way filter scheme was initially envisaged, but evolved to 3.5-way. There are 2 pairs of speakers in the midrange: one pair adjacent to the high frequency driver operates in the frequency range 280 Hz… 2.4 kHz, the other pair of midrange speakers is limited to 1 kHz. This scheme added a number of advantages, in particular a better diagram and a more uniform frequency response without the need for additional corrective circuits. Final version of filters: bass and midrange speakers are enabled through 2nd and 3rd order filters with a distribution frequency of 280 Hz, mid-high frequency distribution is organized by 1st and 2nd order filters at 1 kHz and 2.4 kHz.
The nature of the sound is as close as possible to the front channels, which we also developed for this project of built-in speakers.


Rear channels for mounting in the ceiling structure.
The crossovers for these speakers are tuned in draft boxes, closed acoustic design with a capacity of 5 liters. Structural restrictions on the height of the suspended ceiling of 95 mm were solved by the selection of speakers with a minimum depth of the magnetic system and the absence of the rear part of the body (its role is performed by the floor plate). Boxes of the same volume and size have already been installed on the design sites in the ceiling structure at the facility.
Loudspeakers have a 2-way configuration: 6.5-inch mid-bass Scan Speak driver and 1-inch Seas tweeter with a miniature neodymium magnetic system. The filters have a 2nd order configuration with a distribution frequency of 3.6 kHz. Frequency range: 100 Hz – 20 kHz with frequency response uniformity +/- 2 dB. Power – 50 watts. Sensitivity – 89 dB/1W/1m. The midbass drivers in these speakers use the same model as our RS-One monitors which have proven themselves perfectly.
The speakers are collapsible, the main body that forms the acoustic design of the bass speaker is hidden in the design of the suspended ceiling, the front panel with speakers and crossovers is removable. Fastening of a round decorative frame is made by means of the hidden magnets (under them openings on perimeter of the forward panel are provided). Subsequently, this part of the body will also be painted white.

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