Out of stock

Q Series

$509.00 $379.00

Handmade in USADue to COVID-19 all orders can have upto 45 business days lead time

The Q is the Q

SKU: Q Categories:

The 2019 Q-Ferrite Series of subwoofers continues the tradition of the Q series being our sound quality reference line. Featuring a 4 stack ferrite motor structure and 34mm of Xmax that allows for incredibly detailed, tight, and powerful bass. Triple progressive 10″ spiders keep the incredible linear excursion of this sub under control, while the stitched extra heavy lead wire feeds the giant voice coil. With the bulk of the parts being pulled from the Q-Neo series you can think of the Q-Ferrite as the functional equivalent but less expensive version of the Q series. Not every customer wants or needs the Neo version of the sub or the added expense. The Q-Ferrite series gives you all the same features such as pole chamfer, cooling channels, stitched leads, 10″ progressive spiders, 34mm of Xmax, and a carbon dustcap but at a reduced cost without sacrificing performance.

Working well in a variety ported, sealed, and bandpass enclosures, you do not have to give up your trunk to have strong bottom octave foundation for the rest of your system. The New 2019 Q-Ferrite series keeps with the Q tradition of incredible bottom octave performance and sound quality.

  • Dual 1 and Dual 2 Ohm

  • Cast 6 spoke basket

  • Wrap around gasket

  • Kraft pulp fiber reinforced cone

  • Dual layer wide foam surround

  • Push terminals or Hybrid option

  • Extra heavy lead wire

  • FEA optimized motor

  • High Flux density design

  • 3” diameter 4 layer coil (Flatwind option)

  • 4 stack magnets

  • Triple progressive spiders

  • 34mm Xmax

  • Machined in house at Fi
Weight 55 lbs
Dimensions 20 × 20 × 16 in

Thiele-Small Parameters

  Q12 (F) Q15 (F) Q18 (F)
Coils DUAL 1 | DUAL 2 DUAL 1 | DUAL 2 DUAL 1 | DUAL 2
Fs 33.3 Hz | 32.7 Hz 30.7 Hz | 30.6 Hz 27.9 Hz | 27.9 Hz
Re 0.9 | 1.8 0.9 | 1.8 0.9 | 1.8
Qms 7.75 | 7.85 8.38 | 8.29 9.01 | 9.17
Qes .40 | .41 .46 | .47 .53 | .54
Qts .38 | .39 .44 | .45 .50 | .51
Mms 249g | 256g 313g | 319g 409g | 414g
Cms 0.981M/N | 0927M/N 0.836M/N | 0.830M/N 0.803M/N | 0.801/N
Sd 480cm^2 | 480cm^2 810cm^2 | 810cm^2 1210cm^2 | 1210cm^2
Vas 29.6 l | 29.9 l 76.8 l | 75.9 l 164.6 l | 164.2 l
Spl 86.2dB 1W/1m | 86.1dB 1W/1m 88.7dB 1W/1m | 88.5dB 1W/1m 90.0dB 1W/1m | 89.9dB 1W/1m
Bl 15.13 N/A | 21.4 N/A 15.13 N/A | 21.4 N/A 15.13 N/A | 21.4 N/A
Xmax 34mm (One Way) 34mm (One Way) 34mm (One Way)
Rms 1750W 1750W 1750W

Technical Specifications

  Q12 (F) Q15 (F) Q18 (F)
Overall Diameter 12.500” 15.625” 18.750”
Cutout Diameter 11.125” 14.125” 16.750”
Mounting Depth 9.000” 9.250” 10.00”
DriverDisplacement 0.08cuft 0.09cuft 0.1cuft
Sealed Box .5-1.5 cuft 1.5-2.5 cuft 2.5-4 cuft
Ported Box 1.8-2.5 cuft @ 33Hz 3-5 cuft @ 33Hz 5-7cuft @ 33Hz

This is a complete list of options; not all options are available on all models.
See drop down selections for options available with each speaker model.

P Chamfer: This is a chamfer on the end of the pole, it helps to bring the air down around inside of the motor and helps cool the coil better. It also helps relieve the pressure underneath the dustcap. We recommend at the bare minimum to get this option if you choose this series of woofers.

Hyper Pole: This is an extended version of the standard P Chamfer. It has 1.250” more pole and chamfer resulting in an increased compression ratio for better cooling.

Cooling: Self explanatory, the cooling channels are machined into the inside of the sub to help cool the coil FAR better. But there are some things that you sacrifice. There is less metal inside of the motor so it is a little weaker. If you are looking for a fart/burp only scenario for SPL we suggest that you do NOT get this option. Stick with only the P chamfer. Now if you are looking for a daily sub to beat on and you have less then 2000 watts then this is the option for you. 2000+ watts you need to look into the BTL series.

Flatwind: The flatwire coil option simply helps the power handling of the sub. The coil has more surface area to dissipate heat and will take more power then the regular round wire coil that comes in the ‘stock’ version of the sub. This option will also make the sub tend to be more prone to ‘peaking’. If you are looking to do an SPL install we highly recommend that you use choose the flatwound coil option. In testing it is louder then the regular roundwire coil and takes the thermal abuse much better.

BP: “BP” option which was a machined aluminum compression plug to the pole which helps channel all of the air under the dustcap around the coil for better cooling. To aid with this increased airflow we also added 6 axial cooling channels in the top plate. Along with increased thermal capacity comes the addition of an extra spider and a changed spider pack. All of these features increase power handling from 200-500 Watts depending on the application.

High QTS: This option is for users who intend on using the subwoofer in only a sealed enclosure.

Low QTS: This option is for users who intend on using the subwoofer in only ported enclosures.

Extra Spider: This option adds an additional spider to the spider pack to help with mechanical power handling and keeping the moving assembly under control.

I Heat Ring: This option is a machined aluminum ring in the gap that lowers the inductance of the voice coil which allows it to play up a little higher in the frequency range and have better overall transient response. Please note that you can NOT select low Qts and the I Heat Ring options together.

Internal Lead: This option is for 8 lead coit per coil, increasing the current flow from coil to terminals.

Inner Heat Sink: Its a machined aluminum ring in the gap that lowers the voice coils inductance (allowing it to play up higher and have a little better overall transient response). It also reduces the volume inside the magnet gap of the motor increasing air speed with the cooling as well as allowing the coil to kick off heat to a more receptive thermal mass rather than magnets.

Daily or SPL: Simply put, if you plan on listening to any type of music you MUST choose the daily option. If it is strictly for a fart/burp scenario then choose the SPL option. The reason we have these options is the gap tolerances between the two are different. The gap in the SPL woofer is much tighter and FAR less forgiving in comparison to the Daily option. The Daily option simply gives the coil more wiggle room inside of the gap to deal with the non-linearity tendancys that you can get into when you are using a sub in a daily driving scenario. Typically SPL applications deal with 1 note and it does not change, therefore we can make the gap much tighter and get all of the motor strength that we can out of it.

Spider Spacer: Adding this feature mirrors the spider layers and in turn reduces rock ratio helping keep the voice in line at extreme excursion.

Universal: This option gives you the choice to later chance the impedance of your voice coils. You can change from dual 2s to dual 1s and vice versa by reconing them. If you do not choose this option your motor(s) will be optimized per the coil resistance that you have chosen. (Dual 2s will forever be a dual 2 motor, Dual 1 will forever be a Dual 1 motor).


Speaker Terminals

We have two terminal options on selected subwoofers.

Our Standard Push terminal using 144 strand count sewn tinsel leads Or our new Hybrid+ lead system with ring terminal attachment for high power systems.



We have 4 Dustcap options on selected subwoofers.

Our regular Dry Carbon composite dustcap and new Gloss Carbon. Both variants are available in 6″ and ‘Big’ 7″ diameters to further your customized experience with Fi.



We have a wide array of color options to choose from, with over 10 colors to choose from we’re sure you’ll find something to enhance the look of your Fi subwoofer.


Subwoofers & Recones are dispatched via FedEx Ground. Small goods such as sticker packs, various apparel items are shipped via USPS. Upon dispatch of your goods, order status will be updated from “test/pack” to “shipped” which is accompanied with tracking details.

General Information

All orders are custom made to your selected options.  Each order is machined from raw steel and hand made.  This normally takes 10-15 business days, but due to unforseen issues it can take longer. Fi will maintain reasonable communication should an item take longer than our normal 15 business days to make.  We also note for each item the current lead times (which can be longer than our normal 10-15 business days. Should an item take longer than normal, all refund policies still are in effect.

Delivery Location

Items offered on our website are only available for delivery to addresses in the US and Canada. We also accept orders from international customers who are shipping to addresses on an individual basis.  All items will ship direct from our Las Vegas, Nevada location.

Delivery Time

An estimated delivery time will be provided to you once your order is placed. Delivery times are estimates and commence from the date of shipping, rather than the date of order. Delivery times are to be used as a guide only and are subject to the acceptance and approval of your order.  Deliveries will be made through FedEx Ground unless otherwise noted.  Delivery times in the US generally take from 1 to 5 business days depending on how far you are from our facility in Las Vegas, Nevada

Unless there are exceptional circumstances, we make every effort to fulfill your order within [15] business days of the date of your order. Business day mean Monday to Friday, except holidays.

Date of delivery may vary due to carrier shipping practices, delivery location, method of delivery, and the items ordered. Products may also be delivered in separate shipments.

Delivery Instructions

We will only ship to the customers billing address.  No exceptions.  All orders are shipped with direct signature required.  We will not ship orders without direct signature, sorry if this causes any inconvenience.

Shipping Costs

Shipping costs are based on the weight of your order and the delivery method. To find out how much your order will cost, simple add the items you would like to purchase to your cart, and proceed to the checkout page. Once at the checkout screen, shipping charges will be displayed.

Additional shipping charges may apply to remote areas or for large or heavy items. You will be advised of any charges on the checkout page.

Damaged Items in Transport

If there is any damage to the packaging on delivery, contact us immediately.  A claim will need to be filed with Fedex.  In contacting us please have your order number (it has been emailed to you and is on the shipping label) and your tracking number (emailed to you and on the shipping label) ready to expedite the claims policy.


If you have any questions about the delivery and shipment or your order, please contact us.


    Best sounding sub I’ve purchased and work great for all music styles. It hits the lows better than I anticipated and my last sub was a v.1 sp415.

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