JBL covers Prophet’s Mosque piazza
Published: MEA
SAUDI ARABIA: A column line array system from JBL has been installed to cover the piazza at the Prophet’s Mosque in Madinah. The project was handled by audio consultant Ahmad Tekin Topuzdag who has served as the sound system manager for the two holy mosques for over a decade.
‘Due to extreme sun and heat, a few years back the entire piazza of Prophet’s Mosque was installed with 250 26m x 26m umbrella-like canopies, designed by SL-Rasch GmbH. Altec Lancing Horn speakers were already installed around the perimeter of the mosque to cover the piazza and surrounding areas,’ explained Mr Topuzdag. ‘However, after the installation of the new shades, the sound from the horn speakers was blocked and reflected by the new umbrellas.’
The degradation of the sound quality in this area was noticed by officials from the mosque, and an acoustic study was requested to find a temporary solution and improve the sound in general in this area. ‘The 73 horn speakers installed around perimeter had a limited frequency response of 500Hz to 10KHz,’ recalled Mr Topuzdag. ‘Therefore, Topuzdag Acoustic Consultancy took the opportunity to implement a much better frequency response in the piazza with a new sound reinforcement system.’
The initial measurements showed that the 257,000 sq-m piazza would require a further 130,000W to provide a uniform 84dBA coverage throughout. With this in mind, Mr Topuzdag designed a new system based around products from Harman Professional.
The new system centres on 140 JBL CBT 70J-1 line array column speakers with a further 85 CBT 70JE-1 extensions to provide extended bass response. ‘The JBL CBT 70J-1 series speakers have a perfect frequency response of 60Hz -20kHz as well as J shaped curving. This gives the speaker unique passive asymmetrical coverage resulting in even front to back SPLs,’ explained Mr Topuzdag. ‘Due to this, those pilgrims standing virtually underneath the cabinets do not get the disturbingly loud sound that you would expect from such powerful speakers.
‘However, the open area needed a punchier sound, therefore an additional +3dB in the 100Hz to 400Hz frequency range was required,’ continues Mr Topuzdag. ‘This was solved by adding 85 JBL CBT 70JE-1 woofers to the system.’
The 225 JBL CBT speakers are powered by 32 Crown CDi 6000 amplifiers. ‘The overall power of the system is almost 160,000W which actually exceeds power requirements of the speakers,’ said Mr Topuzdag. ‘However, this extra power was required to compensate for loss of power over long cable runs. In certain areas we had to lay 500m of cable to reach some speaker locations.’
The entire system is controlled by a single BSS Blu 160 signal processor. According to Mr Topuzdag, this equipment was particularly useful when it came to using different delays for different speakers.
The final part of the system is 225 140V/600W custom made line matching transformers from Edcor. ‘Each speaker had to pair with an Edcor custom made transformer to match the high amplifier voltage output,’ explains Mr Topuzdag. ‘With such great distances we couldn’t use the speaker’s native 8-ohm impedance.’
The result the new system has produced is something Mr Topuzdag is clearly very proud of. ‘Once the system was set and we went live, the result was amazing. Not only did we have uniform SPLs throughout the mosque’s piazza, we also achieved a perfect balance of the entire frequency range,’ he smiles. ‘As a result we now have an STI better than 0.7 (for male weighting) in many locations. In fact, outside the mosque now sounds better than inside thanks to the JBL CBT 70JE-1 woofers. This is especially true with bass preacher Sheikh Ali Hudayfe and baritone preacher Sheikh Abdul Muhsin al Qasim performing.’