Armed with a Bazooka BTA6100 amplified subwoofer, we help fix one of the biggest weaknesses of the new Toyota Prius.

The SAS Bazooka BTA6100 package

With all the accolades bestowed on the new Toyota Prius, one would think the carmaker hasn't overlooked any details in designing this most high tech of high tech production cars. The car certainly has more than its share of gee-whiz technology: Its super-quiet operation during full-electric mode, its coolant thermos that keeps the gas engine warm for three days, the locks that detect your presence as you approach the car (the optional SmartKey), a stability control that purports to detect when you're oversteering - and self-corrects the wheel angles via its electronic steering mechanism (S-VSC), the continuously variable automatic transmission, and (in Japan only) an automatic self-parallel parking option. That's a pretty impressive list.

Low Tech Fi in a High Tech Car

With all this technology going into this car, it's perplexing how mediocre its sound system is. The Prius can be had with one of two systems: A "premium" six-speaker system with separate woofers and tweeters in the front doors and full-range speakers in the rear doors; or an optional JBL nine-speaker system, with a center voice speaker on top of the dash and two-way woofers and tweeters in each of the doors.

Neither system offers anything approaching state-of-the-art sound. Curiously, the JBL system is not all that much better than the standard "premium" system. The extra speakers in the JBL system go toward speech articulation (the center dash speaker is mainly for the talking navigation system) and tweeters for the rear passengers. Neither system has a subwoofer.

As can be expected, what's missing from both systems is any semblance of real bass from the speakers. Consequently, the sound is rather shallow - sort of like what you'd expect from a small compact stereo system.

As it turns out, the sound system ranks among the top (albeit few) complaints of discriminating Prius owners (the other complaints being the alloy wheels that look like plastic wheel covers and not being able to match the EPA gas mileage ratings).


Some room for improvement in the Prius

Addressing The Problem

To address the sound system problem, LA Car, Southern California's online automotive magazine, turned to its sister publication, LA Audio File. Both publications have staff members with considerable experience - i.e., the former technical director for Nakamichi USA, an audio equipment reviewer for The Sensible Sound, members of the Audio Engineering Society, and an OEM engineer for the Mark Levinson and Pioneer systems that go into the Lexus and Scion line of vehicles, respectively.

For this project, we couldn't help noticing that one of the popular factory-authorized optional accessories for the Scion is the Southern Audio Services (SAS) "Bazooka" subwoofer. Our audiophile panel came to a consensus: Given the physical similarities between the four-door hatchback Scion and the four-door hatchback Prius, fitting an amplified Bazooka subwoofer to the latter is a logical choice.

Withstanding the Test of Time

SAS is the company that popularized the bass tube subwoofer design (they hold the patent on it), and they've been developing, refining, and building the Bazooka subwoofer for over twenty years. Because Bazooka has withstood the test of time (and its status as an official Toyota supplier brand), we chose to go with an amplified Bazooka subwoofer for our Prius project car.

One of the little-known beliefs held by some Bazooka specialists is that the smallest units with the 6-1/2 inch driver have the best bass articulation of the bunch. The bigger units offer a bigger sound. However, if you're after the cleanest bass reproduction, have a relatively small vehicle, and don't have a need to really crank up the volume, consider one of the small Bazookas. We did just that in choosing the BTA6100.

The BTA6100 is one of two amplified Bazooka bass tube subwoofers with a 6-1/2 inch driver (the other being the BTA6200). Both the 6100 and 6200 have frequency responses that go down to 39 cycles per second (right about the range of the lowest note of a stand-up acoustic bass instrument). Where the two significantly differ is in power output (100 watts for the 6100 and 200 watts for the 6200), crossover range (fixed at 85 hertz for the 6100, variable from 80-250 hertz on the 6200) and price ($199.95 versus $279.95).

We thought about installing the unit ourselves. After all, there are some very capable Prius teckies doing everything from installing full-electric (EV) buttons to back-up cameras for their cars. However, that doesn't describe most Prius owners, and taking apart the Prius dashboard is not something we want to wish on anyone. In the end, we opted to have the installation done for us.


Circuit City Roadshop personnel Serrano, Incledon & Medina

Just What We Needed

We chose to go with Circuit City. First of all, because they're national in scope, and reader can replicate our results. Second, they carry the Bazooka line, and are familiar with its installation. Last, but not least, Circuit City charges a flat rate of only $55.99 to install this subwoofer into the Prius (in the Los Angeles area - elsewhere it's $55.99-60.99, depending on the market) . Given the myriad of dashboard parts that require removal to get to the central sound system assembly, it's a pretty reasonable price for the installation (check out Metro Toyota of Cleveland's Prius XM Radio installation instructions to get an idea of what's involved).

Location, Location, Location

Armed with an SAS Bazooka BTA6100 powered subwoofer, we took our project car to Circuit City's new Roadshop facility in West Covina. There, we met sales and installation manager Javier Serrano, who went to great lengths to discuss the pros and cons of various installation locations for the Bazooka.

We considered the cavity under the trunk area, but the Roadshoppers thought that'll result in a muted sound. Also considered was the area above the lid on top of the cavity, which will make the subwoofer unit easily removable. Bazooka's standard recommendation is to have the unit mounted longitudinally and firing into one of the rear corners of the trunk cavity. "We recommend that orientation because it works in every vehicle we've encountered," says SAS Bazooka Product Specialist Derek Tircuit. "It's almost like an eternal truth that we can pass along. However, other orientations will work." 

Serrano lobbied for the area just behind the rear seats, but that's just above the hybrid car's battery pack. Roadshop installer Michael Lopez disassembled the trunk area, however, and found that the battery pack is protected by dual barriers. Thus, the installer can affix the subwoofer onto the first surface without penetrating the second barrier that protects the battery pack. The location also places the subwoofer away from the trunk opening, making it less obtrusive in day-to-day use. Most importantly, it allows the unit to be adjacent to two surfaces (the trunk floor and the rear of the seats, while firing into a corner of the trunk cavity (corner loading is strongly recommended by Bazooka). We went with the Roadshop recommendation.

The end result certainly looks attractive. All the wiring is neatly tucked away and hidden from view. In order to avoid having to splice too many wires, Circuit City used Bazooka's optional 1761 interface harness, which fits certain model Toyotas. In the Prius, Lopez switched the remote wire that turns on the amplifier over to the the accessory lead. "Otherwise, the harness works fine," says Lopez. Circuit City installed the subwoofer with the optional SAS chrome mounting rings, which adds some nice contrast to the black Bazooka. In the event the seats need to be folded down for expanded cargo use, a simple Allen wrench will disengage the subwoofer tube. For those who stick with the tie-down straps that come standard with the subwoofer package, it's even easier.  


The Bazooka is neatly tucked away

What About the Sound? 

In a word: Transformed. The subwoofer does what it's suppose to do. The bass enhancement on pop recordings is subtle, with great extension where the material actually has extension. On certain concert organ or electronic music, you feel - mot merely hear - the bass registers. When the musical signal has no bass, the subwoofer stays out of the way. 

More importantly, the midrange is now dramatically more open sounding. With the Bazooka's crossover network cutting off the lower bass from the midrange-woofer drivers, they are free to reproduce the midrange without having to do double duty on the bass. The result is a cleaner sound overall. The Prius now has a sense of transparently and immediacy that is lacking in the factory system.

On a few recordings, we detect a slight trough in the mid to upper bass. This is more a fault of the factory woofers, in that they just don't product much sound in that region. We have the BTA6100, which has a crossover network fixed at 85 hertz. We suspect that this is not even a factor with the more expensive BTA6200, with its variable frequency crossover network. In any event, it's only noticeable on a few recordings - and subtle use of the bass control on the factory system mitigates this anomaly. 


Keep an Allen wrench handy for quick removal

The other thing we notice is that the subwoofer reveals the variations from recording-to-recording much more readily than the stock system. The Bazooka has a subwoofer output control, so you can adjust the amount of volume that the subwoofer puts out relative to the satellite speakers. However, while the output can sound just fine with one recording, another recording may sound like it has a bit too much bass. Again, the Prius' bass tone control (which thankfully affects the midrange minimally) is quite helpful. What will help more is a remote subwoofer output control. Such a control is, in fact, an optional accessory for the Bazooka.

The Bottom Line

Music is now more enjoyable in the Prius. There is a sense of realism to the music that transforms what was once ordinary to sound that is now extraordinary. The scale of sounds coming out of the system is larger, more life-like. Playing "Pops Hoedown" off of the Telarc Round-Up CD with the Cincinnati Pops Orchestra yields a palpable "you are there" quality. The same quality is heard and felt when playing "Take Five" off of the Columbia SBM Master Sound CD of the Dave Brubeck Quartet's Time Out. Play No Doubt's "Hella Good" (The Singles 1992-2003, Interscope Records), and all hell breaks loose as the Prius-Bazooka system belts out some clean, powerful rock n' roll. 

We find no adverse affects to the addition of the subwoofer - no detectable impact on battery drain, battery charging, or fuel economy. We do find ourselves looking forward to hearing the audio system in the Prius - something we never did before. Trying out various CDs, we are continually amazed now much better things sound - now that the Prius is armed with a Bazooka.  
    
- Roy Nakano
  
   


Editors' Note: This article also appears in L.A. Audio File's sister publication, LA Car, where it is entitled, "Project Prius: Breaking The Sound Barrier." LA Car is a World Wide Web journal of Los Angeles and its car culture. To view LA Car, aim your Web browser to www.lacar.com