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SQL 15 Series 2

(13 customer reviews)
$319.99 – $475.99

SQL-15 Subwoofers are sold as singles.

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Description

Sound Quality Loud

The SQL series stands as our best-ever produced subwoofer when it comes to performance-to-cost ratio. It’s engineered to offer a solid Sound Quality (SQ) foundation, complemented by the potential for gut-wrenching bass when needed. The SQL series, fully designed using Finite Element Analysis (FEA) simulation software, embodies its name, delivering Sound Quality Loud.

The motor topology of our SQL series is based on an SGLC overhung design. It employs a solid copper winding 2.75″ voice coil, which is wound on a split black anodized aluminum former. The choice of a 2.75″ diameter coil strikes the perfect balance between 2.5″ and 3.0″ coil diameters – it maintains less inductance than a 3″ coil while offering more motor force than a 2.5″ coil. The coil and overall mass balance have been meticulously calculated and verified through multiple Klippel test sessions, resulting in a 50 mm winding width coil (voice coil winding height). Nested inside the Y35 grade magnet structure, you’ll find a solid aluminum faraday ring that reduces inductance for enhanced transient attack characteristics.

Our SQL series is equipped with large 8 3/8″ dual Nomex spiders. They offer a uniform suspension compliance curve that minimizes suspension distortion over the linear stroke. These spiders are designed to stiffen up at or near the limits of Xmax to handle extra excursion when necessary. Dual mirror flat woven lead wires, sewn onto the top of the spider, ensure symmetrical compliance on both sides, effectively eliminating the coil rocking issues associated with single leaded spiders.

On the exterior, a stiff naturally dried, treated paper cone and tall roll rubber surround grace the top of the SQL series subwoofer. The paper pulp cone brings the ideal mass for improved low-frequency reproduction, while the tall rubber surround harmoniously complements the dual Nomex spiders, creating a perfectly balanced suspension curve. Click on the white BL/Kms plot adjacent to the subwoofer images to view the Klippel results.

Finally, the design of the enclosure and the overall performance of the SQL series cannot be overlooked. These subwoofers can operate efficiently in a very small sealed enclosure or in small to medium-sized vented enclosures. The low F3 points in the sealed enclosures of the SQL series enable them to play down to 8 Hz, making them unrivaled low-end performers even in compact sealed boxes. The immaculate output capability at full volume is directly attributed to their 28 mm one-way linear Xmax.

In sum, our SQL series subwoofers readily deliver clean, loud, and broad bandwidth performance, even in small enclosures. Elevate your audio experience with the SQL series.

Additional information

Impedance

Dual 2 ohm, Dual 4 ohm
Dust Cap Material

Paper, Carbon Fiber

Subwoofers Specifications

Quick Info

Weight28 lbs
Dimensions (OD)15.375 inches
Dimensions (Cutout)14.375 inches
Mounting Depth7.4 inches
Displacement0.16 cubic feet
RMS1000 watts

Thiele-Small Parameters

Re3.25 Ohms
Fs23.8 Hz
Qes0.45 –
Qms5.83 –
Qts0.42 –
Le2 mH
Sd130.17 square inches
Vas115 Liters
BL20.417 Tesla Meters
Mms388.55 grams
Cms115 µM/N
Xmax28.4 mm one-way 70% BL
SPL95 dB

Materials

Voice Coil Materialcopper –

Enclosure Recommendations

Sealed Enclosure Volume2 cubic feet
Ported Enclosure Volume4.25 cubic feet
Ported Enclosure Tuning22 Hz
Port Surface Area20 square inches

Additional Specifications

Distance from baffle to top of surround1.25 inches
Minimum clearance from top of surround to speaker grill.05 inches

13 reviews for SQL 15 Series 2

  1. Benjamin Galles (verified owner) –

    Ever since the JL Audio W6V1 came out in the early 90s, I have never purchased a subwoofer that was not a JL.. until I purchased an SQL 15 D4 last week. Let me tell you something.. I will NEVER buy another JL Audio woofer again! This woofer just absolutely SLAMS! I was absolutely astonished by how it hit those low frequencies so thunderously! I am writing this review only because I came back to order another one.

    You absolutely cannot beat this woofer for the price. But price aside, you cannot beat this woofer.. PERIOD!

    Like me, once you try it.. YOU WILL COME BACK FOR MORE!!!!!!!!

  2. Ron –

    I’m running each of my SQL-15’s in a ported DIYSG Kuda 15 4.75 cu.ft. net with a Crown XLS-1502 and pound out some serious bass, whether music or movie’s they handle with ease everything I feed them !

  3. Scott Irwin –

    I have just one sub so far. It’s the SQL15 D2. I put it in a sealed 2.2ft box. With the D2 wired in series I can take advantage of my Crown XLS2500 max rms output of 2400 watt in bridge mode. I use this sub in my bedroom with a pair of Infinity RS3 bookshelf speakers and made a center channel by using a crossover from some old Cerwin Vega’s and Bose satellites, so it’s a 3.1setup that works fairly well. The SQL15 D2 performs flawlessly it actually is better than the other speakers it’s paired with. I have other subs in the house, Klipsch RSW12 with a passive radiator,650w rms & 2400w peak also a 1500w active JBL PRX 718XLF in my music room. However The SQL15 D2 out performs both of these two Class leading speaker manufacturing power houses in quality and performance. So my hats off to Nick and company at Stereo Integrity for a great product.

  4. Casey –

    I’ve had the SQL-15 D4 for almost 2 years now. I’ve used one in both my home theater and car in a sealed 2.0ft^3 enclosure stuffed with poly-fil. In my home theater, I ran it off of a Crown XLi1500 wired in series bridged @ 8 ohms for 900W rms. In my car, I ran it off of a JL Audio RD500/1 wired in parallel bridged @ 2 ohms for 500W rms.

    This subwoofer does everything well! Plays music very accurately and digs deep while watching movies. I currently have the SQL-15 back in my car because I added a couple HT18v3’s to my home theater. I removed the IDQ12v4 that I ran for several years from my car and the SQL-15 does everything better.

    I listen to all kinds of music. The SQL-15 has no troubles blending in with my front stage with limited processing. It performs so accurate. It is not limited to certain music. It plays it all so well!

  5. Greg — Omaha (verified owner) –

    I purchased the SQL 15D2 and paired with a JP8 (about 1,000-1,200 watt amplifier) and it is just phenomenal. I got it a little under 2 weeks ago so have been breaking in all tuned up about 40% ish, gain not cranked. Playing all sorts of music and it is just great. Sounds good overall on many kinda of music, though obviously shines moreso still on those deep thumps or long low bass lines. But regardless performs flawlessly, loud and clear. Can’t wait to SMD tune it in about a week after break in really get it pumping. I’m a 2.3 cu.ft. Sealed enclosure. My liking is sealed. Still will take your breath away even at under half. I can tell it’s gone be fantastic once tuned. Wish I had gotten dual 4 ohm to be able to add another for easier single amp set up lol. I prolly will just sell my current once I get a new car in a year and restart with some funds from sale and get two @ dual 4 ohm. Regardless; WONDERFUL.

  6. Derrick Lyons –

    I purposely waited to write this review after months of listening. I have ran several different sub setups over the last few years. Everything from JL, Adire Audio, Resilient Sounds, Skar, Savard and Deaf Bonce looking for the best SQ and SPL mix. After much contemplating I decided to try the SQL 15. I decided to go larger than recommended for the enclosure size and landed around 2.8 net on a CAB 22 at 2 ohms. All I can say is wow! The SQL has something so special about it. It effortlessly reproduces low frequencies like no other sub all while maintaining accuracy and clarity. It has enough SPL sealed to compete with other setups I’ve ran ported. I am excited to take drives everyday because I know my ears will be happy every time. Thank you to Nick and the team for creating a gem of a subwoofer at a solid price point.

  7. Derik Veliz (verified owner) –

    For years I’ve been searching for the perfect subwoofer, I’m a fan of Sound Quality and tried many different subwoofers and box combinations, in just a small sealed 2 cubic feet box, my SQL15 out performs everything I’ve had before.
    Thank you for such a wonderful product.
    D.

  8. Jamal Ghazwani (verified owner) –

    I recently purchased two 15” SQL subs and had a custom ported box built for them, and holy s***.. These are quite literally the BEST subs I’ve ever ran. They sound absolutely pristine and hit the lows with such richness. Not to mention how accurate these play in such a huge, low tuned ported box. When I was shopping, at first it was hard for me to justify spending so much on just subwoofers, but now that I’ve heard them in all their glory, I couldn’t be happier with my purchase. I’d buy these over any other high end brand of speakers. You sir are a genius! These are on par if not better than any high end subs out there. I just wanted to say thank you so much for giving us customers such a great deal on these. You’ve really created something special here and I wanted to let you know just how blown away I am with your products. I wanted to personally thank you for your contribution to the audio world.

  9. Gary Love (verified owner) –

    It’s been a few months since I’ve gotten my 2 SQL-15s up and running in my theater. I replaced an SVS SB16Ultra and the difference is night and day. The SQLs are in a vented box assembled from the DIY Sound Group Cube-15 MAX Subwoofer Flat Pack. These are the clearest and deepest sounding theater subs I’ve heard yet. Even my wife was excited the first time she heard them. She always disliked the amount of “noise” that the SVS made and when I started building this pair was hesitant about it. After that first movie clip, she looked at me and said “That is what it should sound like, so clean!” I run these off of a Crown XLS 2502 at what is listed as 1200W X 2 at 2 ohms. I don’t think it’s pushing that much power, but it definitely never seems to strain and I’ve never even heard a hint of stress on the drives, much less any distortion.

    Next project… IB 24s … but that’s going to wait for the dedicated theater at the final retirement house.

  10. Headley –

    After scouring the car audio world looking for a more SQL subwoofer to put in my trunk, I came across the SI SQL, 12. Back in the day I have 2 Kove Armageddon 15’s in a sealed box and loved them, and then I was introduced to monstrous single sub setups, in ported boxes. I loved the spl’s and the deep low bass that they produced, but knew that i was missing the versatility that a driver that was in a sealed box could provide. I had a 12 inch Sundown ZV4 on a 2500 watt sundown amp, and loved it, but it missed so many frequencies in the upper registers. The ZV4 sub is amazing, but not ideal for SQ.
    I called SI, talked to the owner, and he told me that 2 15’s would make up for the lost DB’s of the ZV4 in a ported box. He told me to put each sub in a sealed 2 cuft box, separate chambers, and I would be happy with the output and SQ.
    I did, and…WOW!!!! WOW!!! WOW!! Tight, punchy, versatile, it hits every note, and it is LOUD when needed. Truly, It does NOT hit as low with authority as the ZV4. It hits the very low notes below 22 HZ and lower, but not as loud or present as the ZV4. But everything else, it outshines all the subs i have owned; the ZV4, DC Audio Level 4, Ampere Audio, Soundqubed, Skar ZVX 12, and a pair of C2 Audio Threatcon 12’s, all subs that I have owned over the past 7 years. What eas close to the SI SQL was a Diamond Audio D9 15 that I had in the trunk of a car, and an Elemental Design 13AV that I had in a Yukon Xl. Those sounded amazing too, but the SQL is just a touch better in accuracy and louder with less wattage going to it. The sensitivity is perfect.
    These subs have provided me with an option that I could not find before, a true SQL option that is truly for those of us who actually like music with structure, chord changes, build ups, climaxes, dimension, and I am not talking classical, but RnB, soul, old skool Hip Hop, and so much more. But, i did put on some decaf and it kills that too.
    If these subs had a face, they would probably be refined 42 yr old dude with a good job, 2 kids, and a love for loud quality music.
    Great job Stereo Integrity, masterful! And thank you!

  11. Kevin –

    Next level performance. I built a sealed box for the 15 and its absolutely beautiful. Deep and clear lows without having to compensate with a port.

  12. Colby –

    I am very impressed with the SQL subs. I’ve had my SQL15 for over a year now and absolutely love it! For reference, I was running a JL Audio W6 for a long time before switching. I had a 12″ W6 sealed that I really enjoyed but eventually decided I wanted to go bigger. I didn’t want to sell a kidney and my child to get the 13.5″ version so I started doing a ton of research on what’s on the market these days. I was just about to purchase a 15″ IDMAX when I came across Stereo Integrity. Everything I was reading was very positive and I liked the price tag, so I decided to get the 15″ SQL and I’ve never looked back. This thing is awesome!! It digs really deep, hits hard, and more importantly to me, it’s suuuper clean. I’ve ran it in a ported and sealed box and they both shine in their own ways. This thing in a ported box is just an animal. Crazy SPL and hits sub 20HZ notes with authority. At the end of the day though, I’m just obsessed with the sound of these SQL subs in sealed boxes. Are there subs out there that get louder? Of course. But I’ve never heard one that gets this loud with such great SQ. I think it has truly earned the SQL name. Plus the price just makes it even better.

  13. Jacob L (verified owner) –

    After running most of the other high-end woofer brands (JL,Morel,Focal) for the last 15 years, I wanted something different. Enter Stereo Integrity, and the SQL15. Running in a 2 Cu.Ft. sealed box on RF1500.1, this woofer is VERY good. Quick, accurate, loads of low end output all the way down to subsonic. And if you need a grille, the Memphis MG15 (for the MOJO15) fits like it was made for it.

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