Do we need adjustable crossover?
Home What are they? Active vs Passive Adjustable Crossover Analog or Digital? Frequencies, Slopes Filter Topologies FR Correction   < Tech << T-Line Speakers		Active crossovers are used mainly in professional sound systems or in very high quality home hi-fi systems. In all these applications, the use of active crossovers are justified by the necessity to reach maximum sound quality. The cost factor is not the number one consideration. Let's look at each case more closely. Studio Monitors. In recent years, more and more companies manufacturing studio monitor loudspeakers are using embedded active crossovers together with dedicated power amplifiers built right into the speaker cabinets. It is almost a de-facto standard now for studio monitors. The crossovers used in such systems are not adjustable and rightly so. Each loudspeaker goes through extensive tests and adjustments in the manufacturing process and manufacturers are not willing to let users ruin sound quality by adjusting crossover frequencies, filter slopes and even output levels for each driver in a system. All these parameters were meticulously calculated and optimized for each speaker and speakers were supplied in matching pairs. Any alternations will reduce sound quality and change the stereo image. Audiophile quality hi-fi speakers. The same considerations are applicable to these speakers as for studio monitors. The only difference is that hi-fi speakers are used in homes and sometimes not in the best sound environment. Therefore, some adjustments are permitted but only in a limited range and only for output signal levels. Sound reinforcement speaker systems. This is the only group of speaker systems where manufacturers are willing to give musicians access to adjustments of almost every parameter in active crossovers. The reason for this is simple: in most cases crossovers are made by a separate manufacturer and not by the speaker manufacturer. As a result, crossover manufacturers are trying to make universal units which can be used with almost any speakers available on the market. This approach gives disastrous results: a lot of high frequency drivers are permanently damaged because these crossovers have a frequency adjustment range of 1:10 or more and a high frequency driver which has a bottom frequency limit of 1200 Hz, and accidentally receives a 120 Hz signal at a high level. Not only can crossover frequency be adjusted, but in some models, the user can adjust the slopes of the filters, the delay time and compression driver equalization. In order to adjust all these parameters to correct values, the user must have extensive technical knowledge and special test equipment. This is not always the case. One more consideration must be observed: precision of the frequency adjustments and precision of the filter alignments. Parts used in dedicated crossovers are of high precision and usually of 1% or even better. Potentiometers used in adjustable crossovers are 20% or so. As a result, calibration of the crossover frequency on the dial is far from accurate. Same with filter roll-off characteristics (alignment). In 4-gang potentiometer with 20% precision of the value, difference between adjacent sections can be 30-40% and filter characteristics will be nowhere close to specified. Obviously, the dedicated crossover with carefully chosen parameters and all necessary corrections of frequency response and time delays will give much better sound quality than the unit with adjustable parameters. Not only because dedicated crossover will have optimum adjustments, but also because quality and precision of the parts will provide a better signal transfer. In order to build a universal device with adjustable parameters, the designer must compromise sound quality. Interestingly, if we take a look at the active crossovers made by the sound reinforcement speakers manufacturer, and designed to be used with certain speaker models, we will find that these crossovers are always of a non-adjustable type.