So you all know me for my preference for accurate musical reproduction (SQ).
I've helped with SPL focused competition vehicles over the years.
Now comes a hybrid for a long-time friend (25 years and counting). We'll call him "The Brian".
A van that will be SQ for most of the time and SPL for some of the time.
Equipment is as follows:
Head Unit: Clarion C500
Front Comps: JL Audio C5
Front Amp: Boston Acoustics GT-475
Sub: Fi 18BL
Sub Amp: Massive Audio N4
AGM battery up front, AGM battery rear, 1/0 wiring.
originally, the HU and comps are installed. I will redo them totally.
I put in a new amp rack and wired up the N4 already.
I loaned The Brian a sub (Vega 124) in an enclosure - one i normally use for my HT.
We have the 18BL.
The GT-475 is on it's way.
So, the first thing with a hybrid SPL vehicle is determining where the vehicle will peak - this can be mathematically determined or empirically determined. We did both.
Before we get into math, let's start with the testing (done last night).
I created a 20Hz-100Hz sweep with a total duration of 5 minutes.
I used TrueRTA, a ECM8000 mic, and a SoundDevices USBpre to measure response in real-time.
I placed the mic at the passenger windshield corner - isolated with foam.
I removed bass boost and EQ, and removed crossover and minimized subsonic filtering.
Using the HU, amp, and Vega124 in a "sealed" enclosure (vent was closed off) I played the sweep.
I measured peak SPL on the RTA in an insulated garage with a low noise floor.
I repeated the measurement with a few sub locations (both driver and passenger rear corners) - Magenta and Yellow lines.
I then removed the sub from the van, placed it on sawhorses, and measured the response near-field (1 meter) - Blue line.
The graphs below are the results:
We can see the blue line follows the typical closed box response curve.
In the van, we get a peak at 45Hz.