12" midbass speaker with 8-ohm voice coil

Outlet: Open Box

Item #: 236RTX128

Low Stock

Be the first to write a review

Your price: $89.99 each Earn up to 90 Rewards points

Add to Cart

+ Add to wishlist + Email me alerts for this product

New Stock: $99.99

View all associated offers

They'll hear you coming
Are you looking to play your music loud? If so, you'll want to check out MTX's Road Thunder Extreme speakers, which use PA system technology to bring concert sound levels to your car. MTX built the RTX128 12" midbass speaker to fill in the frequencies in between where your tweeters and subwoofers play. And, believe us — this incredibly efficient speaker will give you plenty of volume when you feed it some serious power.

RTX128 12

Built for high power
The RTX128 handles up to 300 watts RMS thanks to its hefty magnet, treated paper cone, and cloth surround. You can also easily run two of these 8-ohm speakers with a single amplifier channel, great news if you're installing two in each door. You can install this speaker in an enclosure if you want, but it works great in a free-air applications.

Note: This package contains one speaker. You'll need an external amplifier to drive this speaker properly — an in-dash stereo won't have enough power.

Product Highlights:

  • 12" midbass speaker with 8-ohm voice coil
  • treated paper cone
  • treated cloth surround
  • power range: 50-300 watts RMS (900 watts peak power)
  • frequency response: 66-5200 Hz
  • sensitivity: 96 dB
  • mounting depth: 4-15/16"
  • warranty: 1 year
  • Our 60-day money-back guarantee
Be the first to review this product
Great Gear Giveaway

Submit a review and then enter to win a $350 rewards card

Review this product:

Thanks for taking the time to share your experiences about this product. Please be sure to focus your comments on the product itself. Read our Review Guidelines for more information.

Your email won't be visible. Please use the email address that is associated with your order.
(e.g., JohnD) Your review will be signed using the display name and location
(e.g., Charlottesville, VA)

Click on a star to rate the overall product on a scale of 1-5
1500 characters left
  Attach a YouTube Review
Crutchfield Video Review Guidelines
  • Only submit videos that you made or are authorized to use.
  • Do not submit videos that contain music, video or visuals that are copyrighted and belong to someone else.
  • Please see our Review Guidelines for more information.
500 characters left
500 characters left

Hands-on research

What's in the box?

Download owner's manual

  • One 12" Midbass driver
  • Specification sheet

Product Research



  • Fs (resonant frequency): 60.9 Hz
  • Qms (mechanical Q at Fs): 10.375
  • Cms (suspension compliance): 0.133 mm/N
  • Mms (diaphragm/coil mass, including acoustic load): 51.434 g
  • Rms (suspension's mechanical resistance): 1.898 kg/s
  • Vas (equivalent compliance volume): 52.90 liters
  • Xmax (maximum linear peak): 0.8 mm
  • D (cone diameter): 10.24"
  • Sd (cone area): 520.93 cm² (0.052093 m²)
  • Vd (peak displacement volume): 0.042 liters
  • Qes (Electrical Q at Fs): 0.771
  • Re (voice coil DC resistance): 5.50 Ω
  • Le (Voice coil inductance): 0.642 mH
  • Bl (force factor): 11.86 Tm
  • Qts (total Q at Fs): 0.718
  • η0 (reference efficiency): 1.492%
  • Peak Power: 900 watts
  • SPL: 96.0 dB
  • Frequency Response: 66 Hz to 5.2 kHz
  • Recommended Crossover: 70 Hz high pass


5 Year Warranty Terms: This product carries a 5-Year Prorated Warranty with the following terms:

  • Years 1-2: Products found to be defective in materials or workmanship during the first two years will be, at Mitek's option, repaired or replaced by Mitek at no charge. The warranty period does not renew, but continues on from the original date of purchase.
  • Years 3-5: The purchase price of an item which becomes defective after the first two years and prior to the end of the warranty period will be prorated and credited toward the purchase of a new MTX product. The amount of proration is determined by dividing the original purchase price by the number of months in the warranty period (60), then multiplying the result by the number of months remaining in the warranty period.

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.