MTX TH650.1D

TH Series mono sub amplifier — 650 watts RMS X 1 at 1 ohm

  • MTX TH650.1D


  • MTX TH650.1D

  • MTX TH650.1D

  • MTX TH650.1D

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Item #: 236TH6501D

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Original price $249.99
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Our take on the MTX TH650.1D

by Buck Pomerantz

My system has plenty of power. Who needs an amp?

You might think you don't need an amp because you have a 400-watt system in your car, or because your new stereo puts out 50 watts a channel. But those are peak wattage ratings, which may boil down to 15 or 20 watts per channel, using the more realistic RMS rating. An amp sends your speakers the power they need to deliver your music with clarity and impact, whether you're using factory speakers or high-performance components. And low-frequency reproduction requires lots of power, so an amp is an absolute must if you're adding a sub to your system.

MTX muscle from a TH Series amp

If you're addicted to great bass, then you know that MTX has been building great amps and subs for decades. Their TH650.1D mono amp mixes the latest advancements in amp technology with MTX know-how to bring you strong, clean power that you can rely on — day in and day out. This TH Series amp delivers up to 650 watts to your subwoofer system, with some cool features that'll make your life easier.

Flexibility and reliability

The TH650.1D can handle multiple subs, operating safely with loads as low as 1 ohm. What's this mean to you? 1-ohm stability gives you a little more flexibility as your system changes over time. You can send 250 watts RMS to a single 4-ohm sub right now, but you won't have to sell your amp when you add more subs later on. And, speaking of time, MTX designs their amps for reliability. All internal wiring is as short as possible, for the purest reproduction with low noise. And you'll find a handy clip light that helps you set your gain properly, so you know you're getting the cleanest bass possible.

Read more

TH650.1D mono amp

Tuning your bass

MTX includes a number of tools for tuning your bass. The low-pass filter sets up a 24 dB per octave wall that stops higher frequencies from reaching your sub. You can also adjust the subsonic filter to remove the extreme low frequencies, which helps your sub play louder and improves the performance of many enclosures. And this amp also features an old school bass boost, which allows you to kick in up to 12 dB of bump at 40 Hz for max bass when you need it. MTX includes a wired remote, so you can adjust the bass level from your front seat.


  • mono subwoofer amplifier
  • 250 watts RMS x 1 at 4 ohms (400 watts RMS x 1 at 2 ohms)
  • 650 watts RMS x 1 at 1 ohm
  • CEA-2006 compliant
  • frequency response: 20-200 Hz
  • adaptive Class D amp technology
  • clip light helps set gain
  • variable low-pass filter (40-200 Hz, 24 dB/octave)
  • variable subsonic filter (20-50 Hz, 12 dB/octave)
  • variable bass boost (0-12 dB at 40 Hz)
  • External Bass Control included
  • preamp and speaker-level inputs
  • Smart Engage turns on amp when signal arrives through the speaker-level inputs
  • fuse rating: 40A x 2
  • 4-gauge power and ground leads recommended — wiring and hardware not included with amplifier
  • 11-5/16"W x 2-1/16"H x 7-5/8"D
  • warranty: 5 years (free repair or replacement for 2 years; prorated replacement for years 3 through 5)
  • Our 60-day money-back guarantee

Hands-on research from the Crutchfield Labs (what are the Labs?)

Features and Specs
RMS Power Output (Watts x Channels) 250 x 1
Peak Power Output (Watts x Channels) 1300 x 1
Power at 2 Ohms (Watts x Channels) 400 x 1
Bridged Power (Watts x Channels) ---
Minimum Impedance Bridged N/A
Minimum Impedance Unbridged 1
Best Frequency Response 20-200 Hz
THD at Rated RMS Power 1%
Signal to Noise Ratio 75 dB
Input Voltage 14.4v
Amplifier Class D
Low-Pass Crossover Frequency 40-200 Hz
Low-Pass Slope (dB/octave) 24 dB/oct
High-Pass Crossover Frequency N/A
High-Pass Slope (dB/octave) N/A
Bass Boost 0-12 dB
Bass Boost Frequency 40 Hz
Fan Cooled No
Fuse Rating 80
Speaker Level Inputs RCA
Preamp Outputs No
Width (inches) 11-5/16
Height (inches) 2-1/16
Depth (inches) 7-5/8
Parts Warranty 5 Years (3-5 Prorated)
Labor Warranty 5 Years (3-5 Prorated)
Product Research
What's in the box?

Download owner's manual

  • Mono amplifier with two 40A ATO fuses installed
  • Two 10' speaker-level input wires (with RCA plug on one end and bare wire on the other)
  • Electronic Bass Control (EBC) module
  • 16' EBC cable (with RJ-25 plugs on each end)
  • 2.5mm Allen wrench
  • Owner's Manual (En/ Fr/ Sp/ Po)

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 open the box, verify contents, 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.



Overview: The MTX TH650.1D is a mono block Class D amplifier. It has anodized aluminum heatsinks to dissipate heat generated by the amplifier. The amp produces 250 watts RMS x 1 at 4 ohms, and 400 watts RMS x 1 at 2 ohms.

1 Ohm Stable: The TH650.1D is stable down to 1 ohms. At 1 ohms, the power output is 650 watts x 1.

Protection Circuits: The TH650.1D provides protection against overheating and electrical short circuits.

Gain: The amp's rotary gain control is continuously variable from 250mV to 5V to match the output of the source unit.

Crossovers: The amp features a built-in low-pass crossover, with a continuously variable cutoff frequency of 40-200Hz. It has a slope of 24dB/oct. In addition, the amp has a subsonic filter, which cuts ultra-low frequencies to minimize wasted power and protects speakers not capable of reproducing those frequencies. It has a variable crossover frequency of 20-50Hz, and a slope of 12dB/oct. Both filters are non-defeatable.

Bass Boost: The TH650.1D's bass boost circuit is variable from 0 to +12dB, and centered at 40 Hz.

Electronic Bass Control (EBC): The amplifier comes with the Electronic Bass Control (EBC) module that allows you to adjust the gain of the amplifier from the front of the vehicle. The EBC comes with a 16' cable which plugs into the RJ-25 jack on the amplifier.

Smart Engage: When the speaker-level inputs are used, the amplifier will automatically power on when voltage is detected on the input. No separate Remote Turn-on lead is required. This is especially convenient when adding an amplifier to a factory system without RCA outputs, or when adding an amp and sub in the trunk and you don't want to remove the head unit.


Line Level Input/Output: The line-level signals from the source unit are input using the stereo RCA inputs. The amp does not offer a line-level output.

Speaker-level Inputs: If the source unit lacks RCA outputs, such as a factory head unit, you can splice the two supplied speaker-level input wires into the head unit's speaker wires, and then plug them into the stereo RCA inputs.

Power Terminals: The TH650.1D features set screw terminals for power, ground and remote turn-on. The power and ground terminals will accommodate up to 4 AWG wire, while the remote turn-on terminal will accept up to 8 AWG wire. The set screws can be loosened or tightened with the supplied Allen wrenches. MTX recommends the use of 4 AWG power and ground wires with the TH650.1D.

Speaker Connections: The amplifier is equipped with set screw terminals for the speaker outputs. The terminals will accommodate up to 8 AWG wires, and can be loosened or tightened with the supplied Allen wrench.

EBC Port: The amp has a RJ-25 modular phone jack for plugging in the supplied Electronic Bass Control (EBC) module. The EBC comes with a 16' cable, allowing you to control the gain of the amp from the front of the vehicle.


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.
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MTX TH650.1D Reviews

Average Customer Review:

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Filter by rating:
5 out of 5

Always match subwoofer potential to amp wattage

Written By Soso, NJ, USA on Sunday, August 10, 2014
Crutchfield Customer Review (What's this?)
I had this amp pushing a Soundstream EXW12 rated for 250watts at 4 ohms. The amp worked fine at all volume levels when matched with this subwoofer at 4 ohms. I then upgraded to a 800watt Soundstream R3.12 Dual-Voice-Coil subwoofer. The TH650 was good for the R3 at loud volumes. I was getting the head banging rattles one would expect when running at 400watts, but I wanted to match my subwoofer's wattage rating with a amp that could push it to its potential. I exchanged my TH650 for a MTX TH1200.1D and am not looking for anything more.

Match the right subwoofer to this amp and you'll be satisfied.
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4 out of 5

MXT Madness

Written By Shane P, Springfield, MO on Thursday, September 12, 2013
Crutchfield Customer Review (What's this?)
This amp far exceeded my expectations. Running 2 12's at 1 Ohm, this thing will blow the roof of the car! It has arelly great design with a sleek finish. I wasn't sure if this was the amp i really wanted but after hooking it up, I'm more than happy
Clean, Good Looking, Powerful, Clear sound, Great compact design
The bass control knob it came with causes a cary amount of feed back where the system isn't even useable, but when unplugged, it works great. Who knows, probably something in my wiring
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5 out of 5

compact power

Written By snobillie, phx, AZ on Saturday, May 04, 2013
Crutchfield Customer Review (What's this?)
Was a little hesitant ordering this piece due to the other review. But, after the install, this thing pounds!! Wired it up using an audiocontrol Lc2 (another exceptional piece), powering a kicker compvx 10" @ 1 ohm, with a 1.5 farad capacitor. This little monster wants to tear this woofer apart! Had two of these previously with a dx1000, I submit that this setup if duplicated by two would crush the other system I had!! Granted, given the impedances change the power output....... overall, very satisfied! cant speak to longevity or thermal issues as it is only hours old, but so far so good! Crutchfield has been helpin me since the early nineties, another good purchase, Thanks!!!
Small, powerful,
none yet
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2 out of 5

Mtx th650.1

Written By One hardwood, Midwest on Saturday, March 09, 2013
Bought this to replace a mtx 4004 amp that I had running my mtx terminator subs. Well... Bad choice way less power than the 4004, which is rated at 100rms bridged for each channel so 200 total. This th650.1 is lucky to have 100 rms total. It's way over rated. That's not the norm for MTX. what a disappointment. Save your money buy something else. By the way I am 42 years old and have installed over 100 systems.
Rally small power
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