2003-2008 Honda Pilot Bass Transfer Function

[Toy Civic]

Hello. I've been a novice car audio guy for about 17 years. I recently retired from 20 years in the US Navy and and now am attending the Installer Institute in Holly Hill, FL. (near Daytona Beach) to become a pro car audio installer.

I've read about and always known the concept of the bass transfer function of any particular vehicle, but never did it to any vehicle. I'm sure the majority of cars with aftermarket audio installs never had the transfer function measured either. The time and money involved are high and many shops do not have the correct equipment to properly do this.

So this past week, I was finally able to do a transfer function reading on my 2004 Pilot EX-L. We used a JBL GT804 subwoofer in an optimum sealed enclosure hooked to a mono 100 watt amp and ran test tones from 25hz to 100 hz in 5 hz steps. We used an Audiocontrol SA-3055 RTA meter to measure frequency ressponses.

We first measured the open air acoustical response, then the in car acoustical response using the exact same equipment and subwoofer. The subwoofer was placed in the same corner and pointed the same direction as the factory subwoofer location. I recorded the numbers and then plotted them on the simple graph seen below.

The solid line in the graph represents the open air acoustic response and the dashed line represents the in car acoustic response of the 03-08 Pilot. These are not to be interpeted as actual dB numbers. These are meant to establish frequency curves at ANY desired volume from 25 hz to a desired low pass crossover point usually no higher than 100 hz. You will notice a HUGE bass spike centered at 45hz at +13.5 dB above a reference line, and mild bass losses centered at 75hz at -4dB below a reference line. Even of you have an aftermarket subwoofer box placed in another part of the cargo area expect a MOSTLY similar response.

Moral of the story is that vehicle acoustics are the main reason stereos sound the way they do. The cabin gain at certain frequencies, especially our Pilots, should be seriously looked at and factored in when designing a subwoofer system. If ever replacing or upgrading the subwoofer using the factory location, use this frequency response graph as a guide when deciding what subwoofer and enclosure type to use. The overall goal of any audio system is not just to play certain bass frequencies loudly, but to have fairly flat and smooth frequency response of all bass frequencies. EQ helps, but should be the last thing tuned in a sound system.

[nsaspook]

I checked mine a few years ago during my sub upgrade.
Yaswu