Al-Azhar Mosque with RCF TTL-11A

The Al-Azhar Bekasi Mosque in Jakarta has earned a place in the record book of Italian audio manufacturer RCF by becoming the first large house of worship to install an RCF TTL11A active column speaker system. PT. Kairos Multi Jaya, a leading distribution and system integration company was responsible behind the design, supply, and installation of the mosques’ new sound reinforcement solution.


Leo Tanzil, chief engineer at Kairos Multi Jaya explained how Kairos came to be involved with the project: “A colleague who happens to own a sound rental business near the mosque was told that the Al-Azhar mosque wanted an audio system to help solve an intelligibility problem as worship- pers could not hear the sermon well due to a long reverb time and poor mid-low sound.” After the meeting with the mosques’ management committee, Kairos learned that the dimensions of the building is almost 40 meters wide by 50 meters length and with a 35 meters high dome situated right in the middle of the prayer hall.


The main issue raised by the management is that the voice reproduction from the previous system was not clear enough. The old system used 18 units of 12″ speakers distributed around the hall. “The old system was very low in intelligibility and when we measured the reverberation time – it was unacceptable. The T20 was 4 seconds at 130hz!” exclaimed Leo. One of the most common request when designing a sound system in a mosque is that the system should have a minimal impact with the architecture. The committee also requested that the system has to be easy enough to be operated by the janitors. The mosque needs to use the system a minimum five times a day for the prayers and so the system has to be automated for power-up an power-down modes. Keeping all that in mind with all the other information collected, the Kairos Project Team members of Karuna, Arief, Aurel, Reno and Erow, and led by Leo discussed about using a variety of speakers, however the building’s 50 meter length made it clear to them that the TTL11A was the perfect choice.


“This column is a perfect choice not only because of its accurate directivity but also because of its extended lows. The 8-inch neodymium woofers cover the sound down to 60Hz and the speakers will probably not be driven till their max SPL of 136 dB. This SPL can be achieved with a 9-channel amplification of total 4000 Watts,” explained Leo. It was no surprise that the team’s design proposal was unanimously liked by the committee members who approved of the slim design of the RCF column speakers. “When they asked us to demo the speakers, we knew that it would be the ‘deal closer’. They were so amazed with the clarity of the voice reproduction and also the reduction of perceived reverb,” said Leo.


The final solution uses just 4 RCF TTL11A column speakers on one wall to provide complete coverage for the whole area. The columns are tilted by 10 degrees, and now the reverberation is much lower than before due to its perfect directivity. Other elements in the system includes an Allen & Heath iDR-8 matrix processor with DSP, an Allen & Heath PL-10 to remotely control the iDR-8, Shure SM58 microphones, as well as Audio-Technica clip-on mics. “The iDR-8 allows presets for each of the five praying times, which is why the management and the resident engineer are very satisfied, because everything is now automatically adjusted,” added Leo. Being a “first-ever” installation for the RCF columns in a large house of worship and with its successful outcome, Kairos Multi Jaya will undoubtedly use this project as an excellent reference for future RCF-based solutions and will also promote this idea in other markets as well. “We have done many solutions for churches, ballrooms, function rooms, cafes and clubs, but on this occasion, we proved that the project team in Kairos Multi Jaya is also capable to deliver a great sounding installed system for a mosque which required us to focus more on a SPL distribution system with on/off automation” concluded Leo.