VOX 253 MTI

Art. No. 5987

Characteristics - Sound Properties

The VOX 253 MTI is the current highlight in the VOX series. The uncompromising approach, involving fitting the TI 100 8 Ohm as the low- to mid-range unit and the MHT 12 8 Ohm as the tweeter, worked highly successfully in the TOPAS. Following the basic design concept of the VOX series, this system is fitted with two TI 100 8 Ohm 's as low- to mid-range units and the TIW 250 XS 8 Ohm as the woofer.

One particularly convenient innovation is used for the first time in the VOX 253 MTI: it is now possible to tune the bass output level on the crossover unit. Depending on the acoustic properties of the room and personal preference, the bass output might be too strong, if the speakers are placed close to a wall, for example. The adjustment unit is mounted on the crossover unit directly parallel to the woofer and enables to listener to adjust the output level between 70 Hz and 150 Hz. The lower-frequency bass is not affected. Increasing the resistance affects the bass output: 10 ohms for a minimal reduction in bass and 3.3 ohms for maximum reduction. If the adjuster is left open (i.e. resistance is infinite), bass output reduction is deactivated.

frequency response

Construction

At first sight, the construction of the VOX 253 MTI looks complicated, which is why it is worth looking at each internal part individually first.

In the lower part of the cabinet, you can see the bass reflex tunnel, made up of the base and two upper boards. In the middle, there are five cross-reinforcements to prevent resonance. At the top of the cabinet, behind the cut-out in the acoustic baffle for the mid- to high-range unit, is the enclosure required for the mid-range cone, made up of two wooden boards. Three 8 mm holes will have to be drilled in the rear wall of the mid-range chamber for the cables. They should not be drilled directly behind the driver because otherwise there will not be enough depth available for the wires behind the magnets. The holes must be well sealed afterwards.

Fitting the TIW 250 XS into the side is a special feature. The mounting board for the TIW 250 (380 x 283 with a 235 mm cut-out) itself is glued in place from inside behind the cut-outs in the corresponding side-wall. This means that the bass driver can be recessed by 19 mm (19 mm = thickness of the boards). For optical reasons the side-wall cut-out must be made extremely accurately.

Two triangular reinforcing pieces are installed between the front panel and side walls to provide the required rigidity at the front despite the broad bevel.

The frequency crossover unit is mounted on the side-wall behind the bass cut-out.

Inner damping

The damping uses one mat placed in the medium range cabinet. The remainder is evenly distributed throughout the cabinet. The area above the tunnel opening (at the rear of the front panel) up to the lower edge of the reinforcement remains free. If, as a result of the acoustics in the room, the low-range bass is too powerful, damping this area will have a corresponding effect on the overall bass output level.

crossover

sketch