It is excellent for both stereo and home theater use and is versatile enough to work well in a variety of locations where Power Sound’s larger products might not fit.
POWER SOUND AUDIO S1510DF SUBWOOFER
- The Power Sound S1510DF Subwoofer can play more loudly than you’ll ever need.
- The downward-firing configuration ensures that the driver is protected from kids and pets.
- The multitude of controls on the plate amplifier ensure the best match to your satellites.
- If your room size changes in the future, the S1510DF can be tuned for the new room.
- No port means that there is no port noise and no peak in the frequency response.
- Colors other than crinkle black would be appreciated but aren’t available.
- The sub is designed to be run without a power ground to eliminate hum.
- The boxes are well-made but still light enough to move easily.
The Power Sound Audio S1510DF Subwoofer is a compact and well-built 15” subwoofer. The downward-firing driver of the S1510DF allows it to be used in locations where a front-firing subwoofer would not work due to clearance problems. It can be installed behind a sofa, in a corner, or in locations where there is no clear path for a front-mounted driver to fire. Although one loses the “cone cry” of having the driver pointed at the listening position, this is not a significant concern for the frequencies where a subwoofer works.
The Power Sound Audio S1510DF comes with wooden feet that provide clearance for the downward-firing woofer. They are designed for use on carpeted floors or hard floors, but if you have an older house with uneven floors (as I do), the sub can rock due to their rigidity. I first tried to remedy this by using Teflon slides. Although they made the sub easier to move while protecting the floor, they did nothing to compensate for the uneven floor. I finally ended up using some self-adhesive felt strips that cured my problem.
Power Sound Audio will include some soft, adhesive, hemispherical feet on request that have enough flexibility to cure the uneven floor problem, but I wasn’t aware of them until after the review was complete.
I requested the S1510DF because my previous Power Sound Audio S3601 could excite room resonances that a pair of subs in different locations would not. The generous Power Sound trade-in program (unique to them, so far as I know), made this both possible and economical.
On-board Plate, 960W RMS (2100W PEAK)
19-200 Hz +/-3dB
IN-ROOM BASS EXTENSION:
DIMENSIONS (D x W x H):
18″ x 17.25″ x 19.5″
Subwoofer, Review, 2019, Power Sound Audio, Sealed, S1510DF, Subwoofer Review 2019
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The Power Sound Audio S1510DF subwoofer is a sealed-cabinet design. There is some consumer confusion about the differences between sealed-cabinet and ported-cabinet subwoofers.
Ported-cabinet subs, by virtue of their design, have the potential to produce slightly higher volumes for the same amplifier power and cabinet size than sealed-cabinet subs. But despite this, ported-cabinet subs cannot be equalized to produce frequencies much lower than the port tuning frequency. Should a user try to reproduce sub-sonic frequencies using most ported-cabinet subs, the unloaded cone may “flap” uncontrollably causing either “port-chuffing” and/or driver damage.
Sealed-cabinet subs, by contrast, roll off sooner than ported-cabinet subs, but can be equalized (to a reasonable extent) for lower frequency response than ported-cabinet units. The roll-off of a sealed-cabinet sub is also more gradual at 6dB per octave than that of a ported-cabinet sub which rolls off at 12dB per octave below the port tuning frequency. The frequency response of the sealed-cabinet sub is also usually smoother than that of ported-cabinet subs, which are often tuned to provide a slight peak in frequency response at or just above their port tuning frequency. This peak increases the impact or “slam” of bass notes, but when exaggerated can also lead to “one-note-bass” where the peak frequency is excited by other tones above or below.
There are limits to the low-frequency response of even a sealed-cabinet sub. Those limits are imposed by the amplifier power available from the plate amp, the power-handling and excursion capabilities of the driver, and the propensity of the driver-cabinet combination to “double” (reproduce a tone of twice the frequency of the fundamental).
The Power Sound Audio S1510DF seems to be designed with a good compromise between output and doubling. I equalized mine to be flat to 20Hz (+3dB @ 20Hz) without doubling and without running out of power and clipping. That said, the ultimate volume capability is slightly limited with equalization applied, and if you want cathedral-level volumes at subsonic frequencies, then multiple subwoofers are recommended (I use two). With two subs installed, I needed no equalization for my listening tests.
Unfortunately, the Power Sound Audio S1510DF is available only in crinkle black finish. Although this does keep the price down (allowing a higher quality woofer and plate amplifier for the same price), it is not the most décor-friendly choice. It would be nice if wood veneers were available as extra-cost options. But pretty is as pretty sounds, and the sub’s performance certainly makes up for the lack of spousal acceptance factor – at least in my home. Your sensibilities or your significant other’s may vary.
Although Power Sound Audio’s CAD drawing of the S1510DF cabinet depicts no internal bracing, the construction seems heavy and tight enough that no box resonances were audible. A knuckle-rap on the cabinet sides does produce a livelier sound than one would hope for, but either the resonance frequency is above the usable frequency range of the subwoofer or it is sufficiently low in amplitude not to be audible in use.
The Power Sound Audio S1510DF Subwoofer weighs “only” 64 pounds. So unlike other more massive subwoofers, unpacking or lifting the sub is possible for me without assistance. But the ergonomics of actually lifting the sub out of its box make it advisable to have a helper. A safer method of unboxing is to open the top and then roll the carton over so it can be lifted off the subwoofer. Once unboxed, the sub can be righted and then slid to its working position.
The sub comes with four black, crinkle-finished corner legs that are integral to the cabinet itself. These are intended to provide adequate clearance for the downward-firing 15” driver to work without interference from the floor. The bare legs may be used on either carpet or on hard floors.
I first tried using my two Power Sound subs side-by-side on the front wall between the satellite speakers. This excited some noticeable room peaks, so I then tried stacking one sub (firing upward) on top of the bottom (downward firing) sub. This reduced the room peak noticeably. I also tried stacking the subs in the corner, and this worked well too. But I finally ended up with the subs just inboard of the right and left speakers where they seemed to provide the smoothest bass.
Experimentation is key in finding the best locations for subs in your room. But once that is found, there are additional tweaks that will improve the sub-to-satellite integration.
I first set up a sound pressure level meter at my listening position and set my satellite speakers to full-range. I then turned off the power to the subwoofer and adjusted the satellite volume to 85dB using the SPL meter. For this adjustment, I used a monophonic 80Hz test tone from a source. The purpose of this step is to establish a reference level for the system setup.
Then I turned off the power amplifier to the satellite speakers and turned on the subwoofer. I set the subwoofer plate amplifier crossover dial to its highest frequency. Using the same test tone, and without readjusting the preamplifier’s volume control, I adjusted the volume knob on the sub’s plate amp until I also had 85dB at the listening position. The purpose of this second step is to match the levels between the satellites and the subwoofer. Once set, I turned both the satellites and the subwoofer on, and set the crossover point on the AVR to 80Hz (the subwoofer’s crossover dial remains at its highest frequency).
Note that although the THX subwoofer crossover standard frequency is 80Hz, you can set it even higher if you wish. This gives multiple benefits including prevention of intermodulation distortion in the satellite woofers, reduction of amplifier current demands for the satellites, and creation of a generally wider and deeper soundstage. On the other hand, if you reduce your subwoofer crossover point to significantly below 80Hz, you’re giving up many of the advantages of using a subwoofer at all.
Once the satellite and subwoofer levels were matched, I then adjusted phase with the AVR’s 80Hz crossover active. Using the same 80Hz test tone, and the same SPL meter at the listening position, I adjusted the phase (“delay”) knob on the sub until I got the highest possible sound pressure level. This ensures time alignment between the satellite speakers and the subwoofer. The increase in bass tightness is definitely audible.
And finally, I adjusted the Room Size (damping) knob on the subwoofer’s plate amplifier until I achieved the best-possible compromise between pitch definition and low-bass extension from the subwoofer. Notice that this is the ONLY adjustment that I had to make by ear. All the rest of the adjustments could be easily measured.
And since the same SPL meter is being used for all the measurements, the absolute accuracy of the meter is completely irrelevant. You could use an SPL app on your phone and get EXACTLY the same results as if you used the very best of studio calibrated microphones. This is a relatively unknown but very curious and valuable fact.
Associated Equipment used in this review included:
- Mac Mini with Roon software and TIDAL streaming enabled
- Sonore Microrendu Ethernet to USB converter
- Arcam AVR550 used as processor and/or receiver
- Emotiva PA-1 monophonic power amplifiers
- Heathkit vacuum-tube customized monophonic amplifiers
- JL Audio CR-1 electronic crossover
- Schiit Audio Freya balanced vacuum tube preamplifier
- Thiel 1.6 loudspeakers
- Klipsch RP-600m loudspeakers
- Klipsch Heresy HWO loudspeakers
- Two Power Sound Audio S1510DF subwoofers
Subwoofer design and implementation for either home theater or stereo use involves finding the position for the subwoofer that produces the least room resonance. This can be done using a technique called the “subwoofer crawl.” It is achieved by locating the subwoofer in the normal listening position and then, with bass-heavy music playing, crawling around the periphery of the room to find a location that has the least overhang, distortion, and boominess in the bass. Most users prefer not to do this.
The second most effective method of achieving minimum room resonance it to use multiple subwoofers in different locations. The interference of the waves from the two subs generally reduces the amplitude of both peaks and dips in the room. I chose to use this option.
The third most effective method of achieving minimum room resonance is to use a room correction program (DIRAC, Audyssey, Anthem, and YPAO are common ones) to electronically reduce room peaks. Electronic room correction can also be used in conjunction with either or both of the previous options. Room correction is a standard feature on most AV receivers and processors.
Since the availability of room correction software is not certain for all possible subwoofer customers, the listening tests for this review were conducted without any electronic room correction. And although I did briefly experiment with parametric equalization to enhance the low-bass response of the Power Sound Audio S1510DF subs, all the listening notes were made with no equalization at all.
For bass testing, my favorite music includes:
Bach’s Toccata and Fugue in d minor is a perpetual favorite. When the pedal tones occur, the listener’s diaphragm should flex with the subsonic synthesizer tones, 16Hz according to the liner notes. Few subwoofers can strongly produce this frequency without significant equalization, but you’ll know when the subsonics are there. Do NOT try to equalize a ported subwoofer to this low a frequency. It may be damaged if you try.
Without equalization, the fundamental tones of the synthesizer were too low in amplitude to create body effects at “normal listening volumes.” You could get some diaphragm effects by turning up the volume to unhealthy levels, but if true subsonic performance is your goal, I’d recommend using a parametric equalizer to boost the 20Hz band. Just don’t overdo it!
While originally intended for car stereo, this cut produces some VERY strong low bass tones. Try this cut first with significantly reduced volume! Otherwise, your subwoofer(s) could be damaged (not to mention your ears). For whatever reason, this track DID produce noticeable flexing of the listener’s diaphragm, and the effect was noticeable without equalization.
The effect was so strong that my wife (at the opposite end of the house) immediately demanded that I stop playing the track. I suspect that the next-door neighbors felt it too…
Another very good bass testing cut is the Hungarian Rhapsody by Franz Liszt as performed by the Atlantic Brass Quintet. Although there are no subsonics to be had in this music, the low brass will give you a good feel for how cleanly and smoothly your subwoofer is interacting with the room. In my room, I heard no significant peaks or dips, and the tone definition was as good as I’ve heard.
I also like to listen to jazz with acoustic bass to evaluate subwoofer performance. Since the acoustic bass is a standard for both jazz and folk music, examples are plentiful. Some of my favorites include music by the Seekers, the Rooftop Singers, the Dave Brubeck Quartet, and the Pentangle. The pitch definition on all was exceptional.
Without equalization, here are the frequency response curves of my right and left Power Sound Audio S1510DF subwoofers measured from the listening position. At the time of testing, the right subwoofer was placed a third of the way along the speaker-wall from the right corner while the left subwoofer was placed hard in the speaker-wall left corner.
A word must also be offered about hum, usually caused by ground loops in the audio circuitry. In an ideal world, source components would provide isolated grounds for unbalanced subwoofer feeds and/or would offer balanced XLR outputs for hum rejection. The world is not perfect. The majority of AV receivers, processors, and outboard crossovers do not offer ground isolation or balanced XLR outputs. A few subwoofers offer balanced inputs, and the Power Sound Audio S1510DF is one of them.
Therefore, when connected by unbalanced (RCA) cables, the only option with most sources, it is not unusual for ground loops to cause subwoofer hum (particularly if cable-TV boxes are connected to the system). Subwoofers are also more likely to hum when both input jacks are used (connected separately to the source or when using “Y-splitters” to up the subwoofer sensitivity).
The most effective way I’ve found to prevent ground loops with unbalanced sources is to use a “ground-isolator” AC-plug on the subwoofer. This way, the subwoofer is “star-grounded” to the source component by the jacket of the signal interconnect. The Power Sound Audio S1510DF, however, already removes the grounding wire at its input IEC socket and does not need the isolator plug. It should be far more hum-resistant than many subwoofers.
The S1510DF also offers the convenience of using 12-volt trigger signals to wake from sleep mode. I did not use this option for two reasons – using the trigger wires just contributes to the volume of wiring behind the equipment rack and by placing the subwoofer’s power switch in the “auto” (middle) position, it will wake automatically when an audio signal is present.
THE POWER SOUND AUDIO S1510DF SUBWOOFER is reasonably-priced, compact, and offers very high value for the money. Although less-expensive subwoofers are available, most fail to offer the same quality, flexibility, and durability.
- Compact design with lighter weight than many other subwoofers
- Flexible positioning due to the downward-firing design
- Easier to integrate into a multi-use room due to the compact size
- Soft feet available on request for use on hard floors
- Some color options other than crinkle black
The Power Sound Audio S1510DF Subwoofer is the smallest and lightest sealed model in the company’s lineup. Despite its entry-level status, the cabinet is well-made and very inert, performance is very good with minimal doubling, and the price is reasonable considering its quality and value.
Although two or more of these subs will provide the smoothest room performance, most users will opt for a single sub. Placement becomes far more critical with a single sub, but that’s true of all subwoofers.
The large 15” cone area of the S1510DF allows for lower distortion and higher ultimate volume than most subwoofers that use smaller drivers. If these factors are important to you, then definitely check out the Power Sound products before settling for a lesser option. The Power Sound company offers a trial period and if this isn’t the sub for you, it can always be returned within the trial period.