Historically, shallow-mount subwoofers have compromised performance for minimized mounting depth. However, the car audio fanatics at Rockford Fosgate knew that car audio enthusiasts want big bass that would fit under the seat of a pickup truck or in the corner of a sedan. Their solution for those serious about their music is the Power Series slimline subwoofers. These are no ordinary stubby subwoofers. Instead, they’re packed with more performance-improving features than any sub we’ve seen in recent history. We’ve got the amazing T1S1-10 on the Test Drive Review bench for a close look!
Rockford Fosgate Slimline Subwoofers
The top-of-the-line Power Series includes a pair of 10-inch and 12-inch slimline subwoofers. The Product Specialist at your local authorized Rockford Fosgate retailer can recommend the correct combination of single 1-, or single 2-ohm drivers to allow your amplifier to produce its rated power.
The Power Series Slim subwoofers are based on a sturdy die-cast aluminum chassis with cooling vents and fins integrated into the back to help keep the motor assembly and voice coil cool. Speaking of the voice coil, the T1S1-10 features a 2.5-inch diameter anodized aluminum former and has windings wrapped around the inside and outside. Rockford Fosgate calls this its Dual Wound design. The tinsel leads from the coils are integrated into the spider to keep them quiet at high excursion levels. Massive spring-loaded speaker terminals will easily accept 10-AWG speaker cables. The release buttons for the terminals are on the sides of that respective basket spoke, keeping them concealed.
The motor assembly for the T1S1-10 is based around a neodymium magnet assembly for incredible magnetic field strength from an impressively small and, more importantly, shallow package. The first unique performance feature I ran into was the Split Yoke Motor Technology (SYMS). This patent-pending motor structure allows for massive voice coil excursion from this reduced-mounting-depth chassis design. In addition, as you can see from the image below, the top of the T-yoke has channels that allow the motor assembly to move rearward without restriction. With an Xmax specification of 15 millimeters in each direction and a mounting depth of only 3 inches, it sounds like that tech works.
Another feature that dramatically improves clarity is the Integrated Copper Cap Heat Sinking Shorting Ring (IDHS). We know that’s a mouthful. So, what does this copper ring do? Moving coil loudspeakers function on the magnetic field created by the current flow through the voice coil winding. The interaction of the magnetic field and the fixed magnets on a speaker push the speaker cone outward or pull it inward, based on the direction of the current flow. Based on the same physics principle, when a conductor passes by a magnet, current is induced in that conductor. In a speaker, the cone’s motion induces unwanted currents in the coil that oppose the efforts of the amplifier. The addition of the copper cap helps to short-circuit and dramatically reduce that unwanted current. The result is a subwoofer with very low inductance that delivers impressively clear and detailed bass. The effect is most prominent in the midbass region, making the woofer easy to blend into the rest of the speakers in your car or truck.
The 1-ohm, single voice coil T1S1-10 and its brother, the 2-ohm T1S2-10, are rated to handle 500 watts of continuous power, and they have a 1,000-watt peak power rating. Of course, the specifications are compliant with the ANSI/CTA-2031 standard. The fins and cooling vents help to ensure that the motor assembly stays cool. There is also a vent in the center of the T-yoke for additional cooling and pressure release under the dust cap.
On the front of the driver, Rockford Fosgate includes a removable cast aluminum trim ring that conceals the mounting holes and slots. The ring is finished in a satin black powder coating, and there’s a handsome raw aluminum machined edge at the bottom. The mounting slots for the subwoofer are what they call the FlexFit basket. Your installer can fine-tune the installation so the logo on the dust cap is aligned perfectly with other subs or your vehicle. There are 10 large hex-head screws holding the sub in place in the sample enclosure I was sent. While we are talking about mounting, a foam gasket is integrated into the mounting surface to help it seal tightly with the enclosure. Though seemingly simple, this gasket is another impressive sign of Rockford Fosgate’s attention to detail.
The subwoofer’s cone is made from a proprietary mixture that includes carbon fiber, glass fiber and pearl mica. The result is a cone that’s rigid while offering excellent damping characteristics. These criteria are crucial to delivering bass that’s clear and detailed, especially at high excursion levels. In addition, the cone features an aluminum dust cap with the Rockford Fosgate logo printed on the center and a handsome silver accent ring where it’s bonded to the cone. The spiders, cone and voice coil former are attached using Rockford Fosgate’s Encapsulated Voice Coil Coupling technology (EVCC). They describe EVCC as being connected from the top and bottom of the former to provide a stronger, more rigid and more reliable connection than conventional gluing would deliver. The result is a further improvement in longevity and reliability.
In terms of system compliance, the T1S1-10 uses an injection-molded foam surround that includes Rockford Fosgate’s Vertical Attach Surround Technique, which helps maximize the moving surface area of the subwoofer. Finally, a pair of progressive Nomex spiders control cone motion and keep the assembly centered in the magnetic gap.
Quite simply, I know of no other shallow-mount subwoofers that have this much technology built into them. If you’ve read many of our technical articles here on BestCarAudio.com, then you know I’m a big fan of speakers and subwoofers that are laden with distortion-reducing tech. So I’m excited to hear this subwoofer!
Let’s Talk About Application
A subwoofer is only as good as the enclosure it’s installed in. If it’s too small or too large, you may not like the resulting bass performance. Rockford Fosgate has optimized the T1S1-10 for small sealed enclosures. They sent me the subwoofer installed into a cool bed-liner-covered enclosure with a gross internal volume of 0.801 cubic foot. The driver is specified as having a displacement of 0.03 cubic foot, so the net volume is 0.77 cubic foot or 21.8 liters.
Once removed from the enclosure, I set the subwoofer up on my test bench and measured the Thiele/Small parameters with my Woofer Tester 2. I then applied a 27 Hz, 14.4 volt signal to the sub to begin the break-in process. Some subwoofers change very little during the first few hours of play time, while others change dramatically.
While the sub is getting some exercise and rattling all the test equipment on my bench, I took a look at the Thiele/Small parameters and enclosure designs provided in the owner’s manual. The graph below shows the suggested sealed (0.8 cubic foot) and vented (1.5 cubic feet tuned to 40 Hz) frequency response plots. The sealed enclosure has a predicted Qtc of 0.94 and an F3 frequency of 43.1 Hz. While the Q is a little higher than would be considered “SQ,” this will add some efficiency to the system. For those less geeky, that means the sub will be louder with the same amount of power. The low F3 frequency is cool, and should make this a lot of fun! On the ported side, the 40-hertz tuning frequency adds 8 dB of boost at 50 Hz, 9.2 dB at 40 Hz and 6.2 dB more output at 30 Hz. That’s like having an amplifier that’s 6.3 times as powerful at 50 Hz, or similar to having four subwoofers in a sealed enclosure! Epic! I’m not shy about saying that most pickup truck owners should consider a single sub in a vented enclosure under the rear seat where possible. The improvement in low-frequency output, even over multiple woofers, is staggering.
The stiff suspension of the T1S1-10 also means that it might be a good candidate for infinite baffle installations. I modeled the driver in a 20-cubic-foot sealed enclosure, which is typical than a large trunk. The massive 15 mm Xmax spec allows for up to 700 watts of power handling at all bass frequencies, and the Qtc was nearly ideal at 0.789. Likewise, the progressive spider design used on this woofer will help control cone excursion at high power levels. Hmm. The free-air resonance of the driver is a little high, though. Nevertheless, the Product Specialist at your local authorized Rockford Fosgate retailer can explain the benefits and drawbacks of this type of installation.
Anyways, back to the break-in. After letting the subwoofer play on my desk for six hours, I repeated the electromechanical measurements. The equivalent compliance value increased from 13 to just shy of 15 liters. The resonant frequency dropped from 40.5 to 37.3 Hz. Again, I’d call this an insignificant change. What does this mean? The T1S1-10 sub is ready to go, right out of the gate!
Last but not least, I took an impedance and phase sweep of the subwoofer with my Woofer Tester 2. The graph shows the nice, low inductance of the driver, thanks to the copper cap/ring assembly. In addition, there are two small resonances from the cone, surround or dust cap that show up – one at 500 Hz and another at 2 kHz. Both are well outside what would be audible with a typical low-pass filter set at 60 or 80 Hz.
Auditioning the Rockford Fosgate T1S1-10 Subwoofer
With the testing and inspection complete, I loaded the subwoofer back into the enclosure and headed for my listening room. I just purchased a new amplifier for driving subwoofers. The amp is capable of delivering a voice-coil-melting 2,500 watts of power into a 1-ohm load. Unfortunately, I don’t have a linear power supply large enough to provide that in this room, but suffice it to say, the amp won’t care about driving this low-impedance driver. Oh, and the sub is only rated for 500 watts, so the 80-amp supply I have will be just fine.
With the subwoofer placed between the tower speakers, I cued up a set of test tracks. I’d recently asked my Facebook friends for some song suggestions for testing subwoofers. They replied in droves! So, here’s what I heard from these new tracks and the Power Series Slim 10-inch subwoofer from Rockford Fosgate.
Up first was “Don’t Cry – It’s Only the Rhythm” by Grace Jones, suggested by Mike Pesdirz. Just before one minute into the song, a deep multi-layered bass line with notes down to 30 Hz kicks in. The T1S1-10 had no problem rendering the music with a combination of impact, energy and transparency. You could hear and feel the bass, but localizing the subwoofer’s location was nearly impossible. That’s a sign of excellent low-distortion performance.
Up next was Infected Mushroom with “Eat it Raw,” based on a suggestion by Matthew Kim and Bryce Lewis. I was having flashbacks to bopping my head like a scene from “A Night at the Roxbury.” Nevertheless, the dance beat comes in at 30 seconds into the track. It’s tight and deep, yet once again, was rendered effortlessly. This track has some crazy imaging happening and would be a good demo in a car.
Andrew Davison’s suggestion, “Be Like That” by Kane Brown, Swae Lee, and Khalid, is a more modern track with a solid bass line. The beats center around 25 Hz at their lowest, which is a little hard for a single 10 to reproduce in a 20-by-30-foot room. Nevertheless, it was there, and the rest were clean and clear.
A suggestion by Andy Wehmeyer was “Blast!” by Marcus Miller. This track has massive presence. The sound came from the entire end of the listening room. The Rockford Fosgate subwoofer had no problem keeping up with the drum and slap bass. Each impact and string vibration was well defined. There was a slight overhang present in the higher bass notes that I might attribute to the high Qtc of the system, but it was far from sloppy or boomy.
My friend Jamie Edmundson suggested the track “Torus” by Sub Focus. Just after the one-minute mark, the track comes to life with waves of rolling bass that get down to about 40 Hz. At the three-minute spot, the bottom drops out, and bass information extends well into the single digits. There’s a 10-hertz infrasonic filter on my sub amp that is pending deletion. After that, this track would rock or be dangerous. I like it either way. The T1S1-10 kept up with the signal with effortless clarity.
Second from last in this listening session was “Such Great Heights” by Postal Service, as proposed by Jamie Prince. The electronic bassline covers a range of frequencies and has a great beat. The high Q of this sub in this enclosure added a tiny bit of overhang, but it wasn’t significant.
Lastly was Tool’s “Chocolate Chip Trip,” as suggested by Keith McCumber and Wayne Smedile. This is an epic demo track. The intro starts with chimes, bells and beeps that portray a sense of height and depth. At 1:23, the bass starts coming in and goes deeper and deeper. Once in full swing, Daniel Edwin Carey’s double kick drum is nothing short of amazing. Of course, I knew this because the Rockford Fosgate T1S1-10 had no problem keeping up.
Performance and Feature Summary
A shallow subwoofer has a lot of things working against it. Typically, there isn’t much room for a long-excursion motor to allow the sub to play loudly. Rockford Fosgate’s Split Yoke Motor takes care of that. I’d attribute the subwoofer’s transparency to the well-damped and rigid cone design and the Integrated Copper Cap. Two of my favorite full-size subwoofers use the same technology.
Rockford Fosgate owners love listening to their music loud, so the high-Q design of the woofer makes sense in that it will add additional energy to increase the efficiency of the system. In addition, the cone weight and suspension compliance have certainly been optimized to let it play down into the bottom octave of the audible music range with excellent output capability.
In conclusion – this subwoofer sounds fantastic. I’d want a slightly lower-Q design. With that said, the majority of consumers will appreciate the boost in overall efficiency from this design. This translates to “It’s loud, and you’ll like it!”
If you’re shopping for a shallow-mount subwoofer for your car or truck, there are none on the market (that I know of) with the features and technologies built into the Power Series T1S1-10. Frankly, it would be best if you experienced this before you spend money on anything else. You can find an authorized Rockford Fosgate dealer by using the locator on their website. For more information on their fantastic car audio products, please give them a follow on Facebook, Instagram or their YouTube channel.