Crossover Design for Speakers

Cross over Design for SpeakersCrossover DesignIn terms of crossover design, there are two distinct fillings in agile or supple crossovers. Passive crossovers are the most common implementation, since precisely iodin amplifier is needful. In this case, filters comprising hands-off components (inductors, capacitors and resistors) are partd to ensure that the illuminate frequency range is supplied to each driver. Low-pass, high-pass and band-pass filters are commonly used and wishing to be matched to ensure that the frequency roll-offs compliment each other, such that in the crossover zone(s) the combined acoustic output of the drivers maintains a flat frequency response.In terms of these passive filters, it is the localize of the filters used that is the primary consideration. A first frame filter has a roll-off of -6dB per Octave and a Butterworth characteristic. prototypal come in filters are undesirable for two reasons a +3dB peak is introduced at the centre of the cr ossover band and the crossover bandwidth is large due to the tranquillise roll-off, which means the drivers need to be capable of handling a great frequency range. thus far, first roam filters require the least components, incur less(prenominal) place loss as a result and do non introduce a phase change in the output.Second order filters are the most commonly used type in passive crossovers, since they are relatively simple solely solve the problems associated with first order filters. The roll-off is -12dB per octave and the filters may be designed with a Linkwitz-Riley characteristic which maintains a flat frequency response across the crossover band, unlike the combine of Butterworth filters.Third order filters offer a roll-off of -18dB per octave, however there is a problem of phase separation in a two-way frame there is a phase shift of 270 degrees which can result in lobing and tilting of the coverage pattern (DellaSala, G. 2004). Some designs such as the DAppolito co nfiguration1, which uses one-third drivers, actually make use of this phase separation in order to minimise lobing, however the DAppolito configuration is notoriously interlacing and catchy to implement well without precise driver measurements.If a high-order crossover is desired, fourth part order filters are by chance the best choice. Although they are more complex in terms of design and require more components, the advantages are a small crossover bandwidth (roll-off is -24dB per octave) and a 360 degree phase shift wherefore no phase correction is required. Passive crossovers beyond fourth order are generally not considered. Borwick (2001, p.267) notes these are seldom used in passive crossover designs because of their complexity, cost and insertion losses.The other preliminary to crossover design is the fighting(a) crossover. In this case active filters (normally establish around op-amps) are used to divide the input signal into the required frequency bands prior to amp lification the crossover has multiple outputs and a separate power amplifier is needed for each frequency band. Some audiophiles complain that active crossovers (which normally employ high-order active filters) are not a in effect(p) choice, due to the poor flying response of high order filters. However as Elliot (2004) notes, the additional control that the amp has over the drivers behaviour improves the transient performance, and especially so at (or near) the crossover frequency the most tiny frequency point(s) in the design of any loudspeaker.Apart from the increase complexity and multiple power amplifier requirement, active crossovers are far superlative to their passive counterparts in almost every way, although some purists may disagree. solid quality op-amps are cheap, as are the required resistors and capacitors (since these do not need to handle much power). The active solution means frequency response is no longer defined by the quite mingled combined resistive, ca pacitive and inductive load of the passive crossover and drivers. olibanum the frequency response of the crossover is independent of dynamic changes in the load. Furthermore, the active crossover makes it easy to tune the crossover dynamically with most commercially available active crossovers one can simply dial in the required frequency bands.Efficiency is improved with active crossovers, since no power is lost by the amplifier in driving passive inductors or resistors. The amplifier likewise has the best possible control over transient response, since there is nada between it and the driver other than cable. Thus the amplifier can respond flat and presents the maximum damping factor at all times, regardless of frequency (Elliot R. 2004).In view of the above one may then wonder wherefore passive crossovers continue to remain so popular, since it seems far more synthetical to implement frequency division before amplifying the signal. Ease of installation is perhaps the main f actor. Almost all commonly available hi-fi arrangings use speakers with passive crossovers. For the consumer this makes things easy the speakers are simply connected to the amplifier and installation is complete.In contrast, turnkey active solutions for the average consumer are not forthcoming, although rack-mounted professional active crossovers can be obtained for quite reasonable prices (around 150 for a quaternate order 2 way Linkwitz-Riley design)2. However, these require a fair mensuration of audio engineering expertise to set up correctly and the typical home listener simply does not possess this knowledge.For the high-budget client want the best audio reproduction, active crossovers are certainly the best option the technical advantages have been seen to be numerous. This is offset by the fact that the system will be far more complicated to correctly install, but it is assumed in this case that complexity of installation is of little apprehension to the high-budget cli ent who is unlikely to handle the installation themselves in any case.For the low-budget client, the best solution is the passive crossover. It is a simple option, only requires one amplifier and yet produces acceptable sound quality. It is far from the best solution, but adequate to(predicate) if a competitive price point is desired.In conclusion, all but a few dyed-in-the-wool purists will agree that the active crossover is a superior solution in terms of quality and control. What it lacks in chasteness is outweighed by a far superior level of control over frequency response and the drivers themselves. However, due to issues of complexity one can endure that the traditional passive crossover shall continue to lead a rose-cheeked existence in the majority of loudspeaker designs.SourcesBorwick, John. (2001). Loudspeaker and Headphone Handbook, central Press.DellaSala, G. (2004). Filter Crossover Types for Loudspeakers, Audioholics Magazine.Dickason, V. (1995). The Loudspeaker Design Cookbook, Audio Amateur Publications.Elliot R. (2004). quick vs Passive Crossovers, Elliot Sound Products.Rossing, T. (1990). The Science of Sound, Addison-Wesley.11 DAppolitos across-the-board 1983 paper may be obtained here http//www.aes.org/e-lib/browse.cfm?elib=117622 For example the Samson S-2 http//www.inta-audio.com/products.asp?partno=sto-oth-sam2w