Typical venues have uneven low frequency response. The modal response of rooms at low frequencies causes large peaks and dips in the overall response of a system. EQ is not effective in eliminating these response anomalies.

Ai advocates solving this problem in a more natural way. By using multiple subs distributed around the room, low frequency response can be smoothed out. Placing multiple subs in multiple locations, each sub will excite the room’s modes in a different way. While the response of each would still have the anomalies suggested above, the total combined response is much smoother than any of the individual responses. In essence, they balance each other out, resulting in a much smoother overall response. In addition, utilizing two types of subs: ultra low frequency (ULF) and broadband (BB), broadband having a higher cutoff frequency, further helps to even out the response.

The ESP Sub line uses single band pass cabinets that give the driver a shallow roll off above and below the tuning frequency. Using a single band pass design gives a combination of desirable characteristics: a less complex crossover, high power handling, shallow roll offs, higher efficiency, as well as lower overall distortion due to the driver’s output being acoustically filtered. The ESP Subs use a multi-tuned port that smoothes the overall response of the sub.

These subs have been designed to mate with the main ESP speakers with an absolute minimum of external processing. The passive versions of the ESP Sub line do need external filtering to eliminate unwanted high frequencies, but the requirements are easily met with common equipment used in sound reinforcement or monitoring applications. The active versions have integrated electronic crossovers to fulfill this function.