Earlier on in the year we started playing around with SPL (Sound Pressure Levels) box designs. Researching, designing, building and testing them until our ears almost bleed at times and then we came across one design we were happy with.
This design was used in the states and produced some MASSIVE SPL numbers in a little Honda CRX, we duplicated this design and with this box and four entry level 10″ Sony Subs we managed a 149.9dB in ABTEC3. You can read all about that HERE
Since this design worked so well on four entry level 10’s we thought why not try a similar design with some 12″ JBL GTO1214 SVC sub-woofers! Oh course first we had to re-calculate how much air-space would be needed to accommodate the 12’s, so off to our trusty box-builders house it was with our MAD plan!
After many hours of cutting, drilling, gluing and screwing our box-builder had the box ready for us to pick up. On the way back to the office there was a noticeable difference in cabin pressure even at low levels, I couldn’t wait to have the subs run in so we could test them!
A good fourteen days later the JBL 12’s were nicely run in so it was time to give them a burp and see what SPL numbers they could do in the Mitsubishi Pajero (ABTEC1). With the Sony XAV-622 Head-Unit, Digital Designs X1 Cross-Over and the Digital Designs M3 Amp the entry level JBL GTO1214 12″ Subs managed to get 147.2dB. This wasn’t a bad number but it wasn’t the magical number we were after!
At this point the thinking caps went back on and the conclusion was the same as any madman would say, “We need MORE POWER!”. So many phone calls were made and an extra battery and a Digital Designs M4a was ordered from the states!
A couple of weeks later two Digital Designs M4a‘s and one Digital Designs Z18D1.5 turned up and as much as I want to go on about the DD Z18 I will leave that for another blog. So another few days pass-by with the M4a next to my desk taunting me and if you have ever seen one you would know how monstrous this amp is! And just to let you know, this amp is almost four feet long!
After removing the DD M3 amp from ABTEC1 our MD started installing the extra battery as I tweaked the settings of the DD M4a before installing it behind the drivers seat. At first I had doubts the amp would fit but when we test fitted it, it was like it was made for ABTEC1!
Now for the fun part, testing! We must of spent a good five to ten minutes finding the optimal frequency which surprisingly was 54Hz and after 2 low volume runs it was time to turn the M4a up and do a power run!
After the first power run I was lost for words! We managed a very respectable 150.5dB @ 54Hz, the fun wasn’t over yet tho as we agreed to do 4 runs in a row. To my amazement we did another 3 runs at 150.5dB and the excitement definitely was and still is high!
To finish this off, here is a video of the the 4th run we did!