Abstract: A loudspeaker apparatus 1 includes a loudspeaker unit 3 and an installation device 2. The loudspeaker unit 3 includes drivers 22 and 23 and an enclosure for the drivers composed of front and rear members 20 and 21. The loudspeaker unit is detachably mounted to an installation device 2, which, in turn, is secured to an installation surface 11 to which the loudspeaker apparatus is to be installed. The loudspeaker unit is mounted rotatable about its center axis 25. The drivers have respective sound radiation center axes 22a and 23a, which are oriented to intersect the center line 25 at a predetermined angle &thgr;. Thus, the direction in which the drivers radiate sound can be changed by rotating the loudspeaker unit about the center axis.

Abstract: An A/D converter provides a high conversion accuracy even when an input analog signal is at a low level. The A/D converter (10) comprises a first line including a first A/D conversion unit (ADC1) connected to an input terminal (1) applied with an analog signal, a second line including a first amplifier (AMP1) connected to the input terminal (1) and having an amplification ratio of 2m (m>0), a second A/D conversion unit (ADC2), and a second amplifier (AMP2) having an amplification ratio of 2−m, and a combination of a switch and a level detector (SW, LDET) for connecting an output of the first line or an output of the second line to an output terminal (2) in accordance with an output level of the first line.

Abstract: A throat device for interconnecting at least two drive units and a horn is provided. The throat device comprises a substantially straight body member having one end to be coupled with the horn, and at least two curved branch members coupled with the other end of said body member such that no phase interference occurs in a high frequency sound range.

Abstract: A speaker horn including a first and a second pair of side walls. The first pair of side walls has a first section and a second section between first and second ends, and the second pair of side walls has a third section and a fourth section between third and fourth ends. The first pair of side walls has, in a first plane including the central axis of the horn and perpendicular to the side walls of the first pair, a shape defined by the following equation:y=a+b.multidot.e.sup.cxwhere a, b and c are constants and have values different in said first and said second sections, and the second pair of side walls is, in a second plane including the central axis of the horn and perpendicular to the side walls of the second pair, linear in the third section and an arc in the fourth section.

Abstract: An automatic mixer apparatus is described which comprises a plurality of channels each including a level detecting circuit, a comparator and a voltage control amplifier, a gain control circuit for controlling the gains of the voltage control amplifiers of the respective channels and a mixer circuit for mixing signals from the voltage control amplifiers. The level detecting circuit detects a level of an aural signal received at the corresponding channel and the comparator operates to compare the detected level from the detecting circuit and a reference level. When the detected level is higher than the reference level, the comparator outputs a comparison signal to the corresponding voltage control amplifier to turn on. The gain control circuit receives the comparison signals from the whole comparators and outputs a gain control signal to the respective voltage amplifiers whereby the gains thereof are controlled in accordance with the number of the comparison signals received at the gain control circuit.

Abstract: A method of transporting mud, in which mud agitated and fluidized is supplied, while being pressurized by a pressurizing vane, through a check valve to a mud supply portion, and in which pressurizing air is supplied to the mud supply portion in a mud transporting direction to transport the mud in the mud supply pipe by the air pressure. According to this method, the mud can be continuously transported without large discharge noise.

Abstract: A method of and apparatus for continuously dredging sludge deposited on an underwater bed, at a high density of the sludge, according to which digging and scooping devices are placed in an airtight hood opened at its bottom, which is applied on the intended underwater bed and into which air is then introduced to obtain a condition in which water is removed out of the hood, and the digging and scooping devices are then put into operation, whereby dredging is effected at a high efficiency in that the content of water in sludge being dredged is suppressed to a minimum, the sludge being transferred under pressure in a state of containing substantially no additional water than it naturally contains.