Design Theories: Compound - Push/Pull Dual Drivers
| Compound - Push/Pull Dual Drivers | |
| Basic Theory | |
| Two drivers share an acoustic volume of air within a single enclosure. The best way to take advantage of this alignment is to mount one driver facing outwards with the other driver inverted and facing inwards. The drivers are then wired so that they are electrically out of phase while remaining mechanically still in phase with one another. Odd ordered harmonics are cancelled out by using this approach according to Vance Dickason. According to M&K who specialize is push/pull subwoofers claim that this approach cancels out even ordered harmonics. So take your pick. Either way, harmonic distortion is reduced in that any anomalies or variations in the two driver's spider, cone or suspension characteristics are canceled out by the other driver's inversely proportional anomalies and variations. The sound is said to be as accurate and pure as it can possibly be with each driver "correcting" the other driver. Option designs include having the two drivers share the same acoustic volume of air while maintaining the more traditional look of having both drivers fire forward into the listening environment. Though this does not have the same harmonic cancellation effect, all other characteristics between the two alignments is identical. Box volume must be twice that of a single driver. This can be easily modeled by taking the Vas of a single driver and multiplying it by two. The system has an increased efficiency of 3dB over a single driver. Power handling for the system is twice that of single driver. Frequency response is the same for a single driver in an enclosure exactly half the size. | |
| Advantages | |
| Increased output and power handling. Very high SPL capability. | |
| Disadvantages | |
| One single huge speaker enclosure that may be both unattractive and hard to move. Response it essentially identical to building two smaller enclosures of exactly half the size but without the versatility of placement of two separate subs. There are no real disadvantages to building this kind of enclosure as the speakers will behave just as they would in enclosures by themselves. It's very common to make MMT style speakers and use the two drivers in the same enclosure. | |
| Best Applications | |
| Where one sub just isn't enough. High power high output applications. If you choose to do the push/pull configuration, the sonic advantage may make this sub more suitable for audiophile music and critical listening experiences. | |
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Source: www.danmarx.org
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