Car amplifiers can generally be broken down into 3 categories:
Mono or single channel amplifiers – used for subwoofers
4 channel amplifiers – used for interior speakers
5 channel amplifiers – used for a combination of interior speakers and subwoofers
When shopping for the best car amplifier, it is important to pay attention to the following specifications:
RMS power ratings
Total Harmonic Distortion level or THD
All the amplifiers I recommend here are excellent quality. You will see they have relatively low total harmonic distortion level, typically less than or equal to 1%. They’re also rather efficient and come in a compact size. I’ve also listed physical dimensions for your reference as well.
Check your specs
Note, all of the amplifiers I recommend follow CEA-2006 Compliance regarding RMS rating guidelines:
Number of Watts X Number Channels RMS @ Number of ohms at 14.4 volts
Make it a point to look at an amplifier’s RMS power rating and see at what impedance or ohms it is rated at. Some less than stellar car amplifier companies out there will advertise an unrealistic power handling rating just to grab your attention. Oftentimes it’s only when you look at the owner’s manual do you find these ratings are listed at an unrealistic impedance such as .5 or 1 ohms.
For interior speaker amplifiers, generally speaking, you’re always going to be running the amp at 4 ohms. For subwoofers, you want your final impedance to stay in the range of 2 to 4 ohms. Anything less than 2 ohms is typically too little resistance for an amplifier to handle effectively. When you run a car amplifier below the specified impedance capability, you risk both sound quality and damage to your amp.
So pay close attention to those RMS ratings when shopping for an amplifier. For reference, RMS stands for Root Mean Square. Simply put, it is an approximation of continuous average power.
Power vs Size vs Sound Quality vs Budget
For this post, I’ve included a basic $ rating system in the amplifier comparison charts to give you an idea of cost against power, overall size and sound quality. Here is the key for that simple rating system:
$ = $75 – $150
$$ = $150 – $250
$$$ = $250 – $400
$$$$ = $400 & up
Best Mono Car Amplifiers
In the mono amp category, the more popular amps are in the 500 watt power handling range. In our shop we sell both the JL Audio JX 500/1D and the Alpine MRV-M500. Either amp is a great choice when you need a 500 watt mono car amplifier. If you are also installing the optional bass knob, JL Audio’s RBC-1 is slightly easier and cleaner to install. It’s slightly smaller so it’s easier to dismantle and mount in a stealth manner than Alpine’s RUX-KNOB.
If you need something slightly more powerful, like in the 600 watt range, I recommend the JL Audio XD 600/1 v2. It’s a great compact little amplifier that is very efficient and reliable. For a 1000 watt RMS mono amplifier, consider the JL Audio JX 1000/1D. The JL Audio JX 1000/1D puts out 1000 watts RMS at 2 ohms, but only 500 watts RMS at 4 ohms. Alpine’s PDX-M12 on the other hand has a regulated power supply and will consistently put out 1200 watts RMS whether you have a 2 ohm, 3 ohm or 4 ohm load. If you need a high output mono amplifier with a small footprint, the Alpine PDX-M12 is the way to go.
All of these amps are great options with various power handling ranges. They’re all compact and efficient. The KTP-445U is the most compact and efficient of all. Aside from power output and physical size, there is also an audible sound quality difference between all of these amps.
If you were to compare the KTP-445U to the built in amplifier of an Alpine head unit (about 18 watts x 4 RMS) you would notice a considerable difference in output, clarity and vibrancy. Yet, when compared to the JL XD 400/4 v2 amplifier, the Alpine KTP-445U sounds rather flat. If you had the opportunity to listen to these car amplifiers on a sound board (like I do) you would notice the XD 400/4 v2 sounds more lively and vibrant. If you then compared the JL XD 400/4 v2 amplifier to the Alpine PDX-F4 amplifier you would find the PDX-F4 is even more vibrant and has greater detail and subtle nuance.
Best Car Amplifier – 4 Channel
RMS @ 2 ohms at 14.4 Volts
90 x 2 (bridged to 4 ohm load per channel)
200 x 2 (bridged to 4 ohm load per channel)
200 x 2 (bridged to 4 ohm load per channel)
RMS @ 4 ohms at 14.4 Volts
45 Watts x 4
75 Watts x 4
100 Watts X 4
Sound Quality Rating
Physical Size L x W x H
7-7/16'' x 1-1/2'' x 2-1/12''
8-9/16" x 7-1/8" x 2-1/16"
10-1/8'' x 7-9/16'' x 2''
Gauge Power Wire Recommended
Minimum 18 Gauge
Minimum 8 Gauge
Minimum 4 Gauge
5 Channel Car Amplifiers
5 Channel car amplifiers are a convenient option for anyone looking for a space saving, total system amplifier. In my shop, we sell both Kenwood and Alpine 5 channel amplifiers. The major differences between these 5 channel car amplifiers is their power capabilities and overall size. They all have great sound quality and provide warm, rich and natural tonal qualities. The Kenwood has a very small footprint along with pretty impressive power output – note there is no optional plug in bass knob for the Kenwood. If you purchased this amplifier, you could always install a universal bass knob, like the PAC Audio LC1. That’s what we do in our shop when we sell and install this amplifier.
As you can see, there are a variety of choices and options out there when shopping for the best car amplifier. Space constraints, desired RMS power output, sound quality and budget can all factor into your decision making process when selecting the best car amplifier. I hope this post has made it a little easier to select the best car amplifier for your unique needs and vehicle application.
Still confused about the best car amplifier for your needs? Feel free to post a question in the comments and I’d be happy to clarify any details and answer any questions. Thanks for reading!
If you own a 2007 up JK 2 door or 4 door Unlimited, you know what I’m talking about. At lower volume levels the Jeep Wrangler stereo is tolerable. However, as soon as you try to crank it up – like when the is top off – forget it. You can’t turn it up loud enough to hear over the wind noise.
You may also notice this other annoying peculiarity in your Jeep Wrangler stereo. As you turn the volume up, the only frequencies that seem to get any louder are upper mid range and treble frequencies. The bass level stays kind of flat. This self attenuation feature is to prevent you from blowing stock speakers and to save Jeep the cost of having to replace them under warranty.
There are a number of things working against you with the factory Jeep Wrangler stereo. Luckily, it’s relatively easy to overhaul this system and do a Jeep Wrangler stereo upgrade.
Where to start with your Jeep Wrangler stereo upgrade?
We see a lot of Jeep Wrangler’s in our shop and for the most part, we’re replacing and upgrading everything – head unit, speakers, amp, subwoofer. I realize, that’s not always in everyone’s budget and for a lot of people out there, you may have to do your Jeep Wrangler stereo upgrade in different phases. I recommend you start with what is going to give you the biggest impact and biggest improvement overall – the subwoofer.
Even if you installed the best 6.5″ speakers money could buy, they would still be incapable of reproducing the natural frequency range so effectively produced by an aftermarket subwoofer.
When adding a subwoofer to a upgrade a Jeep Wrangler stereo, most of my customers are looking to keep the installation discreet for a couple reasons.
There’s not exactly a ton of extra cargo space in these things to begin with.
They’re such easy targets for theft (I will address this as well later on in the post – there is an easy way to add an alarm to these vehicles. I recommend you protect your investment and you can do so without any additional remote control. The alarm I recommend works off the factory key).
For a Jeep Wrangler stereo upgrade, I highly recommend installing JL Audio’s Stealthbox subwoofer.
They offer it for both the two door model and 4 door unlimited. Check it out.
Note – if you have the factory subwoofer enclosure in the Unlimited model (2011 and up), you will also want to purchase these two additional Mopar parts to replace the trim that goes around the seat belt bolt. A plain (without subwooofer) passenger side rear cargo trim panel (part #1PU12DX9AG) and a cover for the upper seat belt / roll bar (part #1PU18DX9AD) from Jeep/Mopar parts. If you have the rear 12 volt outlet as well, you will lose that feature.
If you start your Jeep Wrangler stereo upgrade by adding one of these options, you will also need to add a separate amplifier as well. Additionally, if you’re going to be running this off the stock head unit, I also highly recommend using Audio Controls LC2i line output converter. This product helps to correct any factory attenuation that occurs in the signal being fed to your new amplifier and subwoofer. In this scenario, with the factory Jeep head unit maintained, we’re still receiving audio signal from the factory stereo. The same factory stereo that limits the increase in bass frequencies as you turn the volume up. Because of that attenuation feature, it’s beneficial to have a line output converter that is designed to integrate with such a head unit. The Audio Control LC2i will provide a more seamless and smooth increase in subwoofer volume as you turn your stock volume knob up. If you’re doing an aftermarket head unit at the same time, don’t worry about this aspect. Replacing the stereo also addresses this annoying attenuation feature.
Either way you go with your Jeep Wrangler stereo upgrade, you will want to have a separate subwoofer control knob.
I think this is a must in any installation, factory head unit or aftermarket. Especially if you listen to a variety of music. Every recording is different; some songs have more bass, some have less. A bass knob gives you an easy way to tweak the bass level on the fly from song to song for ultimate listening enjoyment. In the Jeep Wrangler, there is room right in front of the center console behind the shifter for such a knob.
Let’s talk amplifiers for your Jeep Wrangler stereo upgrade
Okay, so hopefully I’ve convinced you to invest in one of the subwoofers discussed above in order to upgrade your Jeep Wrangler stereo. And by now you realize you will also need an amplifier to power it up. If you see yourself also eventually upgrading and amplifying the speakers (highly recommended) then you’ll want to buy yourself a nice, high powered, yet small, 5 channel amplifier. Remember, space is limited in these vehicles.
My favorite amp for a Jeep Wrangler stereo upgrade is the Alpine PDXV9.
This baby puts out 100 watts X 4 RMS to the interior speakers and a whopping 500 watts RMS to the subwoofer. For comparison, most stock head units put out around 10 -15 watts RMS per channel, aftermarket head units are around 18 watts RMS per channel. So in terms of power and output, this is a huge upgrade.
If you’re building your system in stages, you can always wire up the amp for the subwoofer channel only until you invest in some higher quality interior speakers. The bass knob for this amp is the RUX-KNOB, pictured above in my own Jeep Wrangler center console area.
There is room to mount the amp under the passenger or driver seat in either the 2 door or 4 door model.
If you’re feeling a little sticker shock on the price of the amp, I do have an alternative suggestion. Consider purchasing an Alpine head unit like the CDE-153BT and using the Alpine KTP-445A power pack amplifier. It’s very tiny, compact amplifier that is easy to install and it will boost power to your interior speakers to 45 watts x 4. It’s designed specifically for Alpine head units. It’s pretty easy on the wallet too. You could then purchase a mono or single channel amplifier such as JL Audio’s XD 600/1V2 for the Unlimited enclosure or the XD 300/1V2 for the 2 door enclosure. Both of these JL Audio amps will work with the HD-RLC bass knob.
Let’s talk about your source for your Jeep Wrangler stereo upgrade
One thing I always stress with customers in my own shop is this. The source of your music is like the heart of your stereo system. You could buy and install the best car audio speakers and amplifiers money can buy, but if it’s all being pushed through a crummy, basic stock head unit, it’s like taking two steps forward and one step back. You’re still limited to the sound quality and capability of your source. Technically speaking, you could install something like JL Audio’s Cleansweep processor and keep the stock head unit. However, it’s really not the same as an aftermarket head unit. That’s just cleaning up and leveling out what’s already there. The Cleansweep is not really capable of improving detail and resolution. That still comes down to your head unit’s digital to analog convertor.
Desirable features like detail, richness and vibrancy come across in the quality of your head unit’s digital to analog convertor. Because of this, I highly recommend replacing the stock head unit. If you have the budget, I recommend you go for a nice double din touch screen head unit.
Having the large touch screen just makes it so much easier to access and search all your music sources. Connect an iPod and search by artist, playlist, song title, etc. Stream Pandora from your phone and search by channel and category.
Whether you decide to go for a single din or double din head unit, you need to be aware of some key features that will be beneficial to your Jeep Wrangler stereo upgrade. When shopping for head units, look for features like these:
3 high voltage RCA preouts 4-5 volts (the higher the sensitivity here, the more kick and efficiency you will get out of your amplifier)
Bluetooth (seriously, everyone should have this feature by now. It’ so convenient and in some states legally required for making and receiving calls. Android users – this feature will also allow you to stream your music pre-amp level which is better sound quality than through a head phone jack connection)
USB (best sound quality for iPod or iPhone. In general, try to avoid connecting any device via headphone jack. When you connect via the head phone jack, this uses the amplifier in the device, as well as the amplifier in your stereo – so it’s like amplifying an amplifier – not the cleanest way to listen to your tunes)
Steering Wheel Control Capability (most Jeep Wranglers stereos have this and it’s a really nice feature to retain – consider PAC Audios RP4-CH11 to make your installation easier)
Okay, so we’ve addressed the subwoofer, the amplifier and we’ve addressed your source for your Jeep Wrangler stereo upgrade. Now let’s talk about speakers. The stock Jeep Wrangler stereo system was redesigned in 2007. This redesign eliminated the previous standard issue front 4″x6″ speaker housing. We can now accommodate a standard 6.5″ component system.
Thanks to the assistance of one of Alpine’s engineers, who worked with Jeep on this redesign, Wrangler owners now have standard sized speakers front and rear.
The rear sound bar accommodates 6.5″ coaxial speakers.
Previous model Jeeps were very limited in speaker size and thus potential output – it’s not exactly easy to find a good quality, high power handling 4″ x 6″ speaker. Luckily for 2007 and up Jeep Wrangler owners, it’s pretty easy to find good quality, high power handling 6.5″ speakers.
Pick the best of the best
When it comes to purchasing car stereo equipment for your Jeep Wrangler stereo upgrade, I always recommend to cherry pick among brands. Alpine tends to excel in those PDX series amps – they’re the best sounding, high powered, compact amplifiers I’ve heard in the past 14 years. JL Audio tends to excel in their XD series amplifiers and their American made subwoofers and Stealthbox enclosures.
Every company excels in a couple areas. It varies from brand to brand and price point to price point and that also changes from year to year. However, when it comes to speakers, I recommend choosing a company that specializes in speakers.
Morel is one such company, they excel in speakers. That is all they do. From $100 speakers to $10,000 speakers and everything in between. So for speakers in your Jeep Wrangler stereo upgrade, I recommend Morel.
Morel has a few different series speakers in their line up and I will describe the pros and con’s of each.
Morel Maximo Series – Entry level
The Morel Maximo series are considered entry level, but they’re an excellent value and perform well against other entry level brand speakers. The tweeter is very detailed, yet still smooth and the mid range is a clear improvement over stock. These speakers are pretty efficient and will perform with limited power output. However they can also handle a decent amount of power and thus perform even better with proper amplification. In the front, you could do the Maximo6 and in the rear, the Maximo6C. The mid range is not as clean as what you will find in the next level up from the Tempo series. However, you will still find these speakers give you a night and day difference in performance and quality over stock.
Morel Tempo Series – Mid level
These are some of my favorite speakers that we sell in our shop. The tweeter is very smooth and mellow, and the mid range is very warm, clean and punchy. However, these babies really need an amplifier to perform and achieve their full potential. Capable of 110 – 120 watts RMS, that Alpine PDXV9 will do them well. In the front, you could use the Tempo6 components and in the rears, the Tempo6c coaxes. If you prefer more detail in your tweeter, consider the Hybrid series.
Morel Hybrid Series – High end
The Morel Hybrid series speakers are really quite awesome. The tweeter is very open and airy, yet incredibly smooth and delicate to the ears. The mid range is clean, accurate, warm and natural. This is what we have in our own Jeep Wrangler, but honestly there’s no way I can appreciate the full quality of these when the top is off. Here in Connecticut, we typically have the top off for only 3-4 months out of the year, so we definitely have plenty of time during the rest of the year to appreciate their performance and quality. In the front, you could use the Hybrid 602’s and in the rear, the Hybrid Integra 602’s.
Ultimate performance and quality does come at a premium price. For practicality purposes, many of my customers choose the Tempo series or Maximo series and are quite happy with their choice. Keep in mind, speakers are just one piece of the puzzle in your Jeep Wrangler stereo upgrade.
Installation gear for your Jeep Wrangler stereo upgrade
Whenever you install an aftermarket amplifier in a vehicle, you will need quality power and ground cable, a fuse, fuse holder, speaker wire and RCA cables. Always choose 100 percent oxygen free copper. We use Stinger wire and Stinger RCA cables in our own shop. If you’re installing the amp under the front passenger seat, you can get away with 6 foot RCA’s.
Metra and Best Kits both make a double din dash kit for this car, however we prefer the fit and finish of the Best Kits BKCDK642 kit.
Depending on whether or not your car has steering wheel controls, you will probably want to buy a PAC Audio interface harness. The C2R-CHY4 is fine if you do not have steering wheel controls (provides retained accessory power, turns on any stock amp if equipped and if being retained) or go for the combo piece RP4-CH11 if you do have steering wheel controls.
Sound deadening material – Dynamat definitely helps to cut down on rattles and reverberations in all vehicles. I highly recommend it to any customer who is upgrading their stereo. In the Wrangler, I would recommend a Trunk kit and a Wedge pack. Definitely do the back cargo area and sound bar area. It really does improve sound quality, cut down on rattles and road noise. Overall, it helps to give you a cleaner bass and mid range response.
Protecting your investment – get an OEM style alarm for your Jeep Wrangler
These vehicles are easy targets for theft so you want to think about protecting what you’ve invested in your Jeep Wrangler stereo upgrade. Consider the add on alarm available from DEI aka Directed Electronics (parent company of Viper).
The 3903T is an aftermarket alarm designed to work with your factory Jeep key. It adds basic alarm features such as a shock sensor, starter kill relay and it also comes with a standard outboard 6 tone siren. Besides the 3903T, Jeep owners should really add the 508D proximity sensor.
When properly installed, the 508D creates a radar bubble around the vehicle. The sensor can be installed under the center console. You really want it towards the center of the vehicle for best performance. If that field is disturbed – say by someone reaching into the open vehicle – the alarm goes off. It’s a great theft deterrent.
It’s very important to have this type of product professionally installed. You need to adjust the proximity field to the point where it is effective and not over sensitive. It’s easy to over do it. If the radar bubble is too large, the alarm will go off anytime anyone walks by your car in a parking lot.
Here is another cool product to consider from Tuffy. Keep in mind, it does require modification to the JL Audio Stealthbox Unlimited enclosure. That enclosure sits higher than the Tuffy security deck is designed for (speaking from experience here).
In my own 2 door Wrangler, we’ve removed the backseat and have fabricated a custom down firing subwoofer enclosure mounted where the backseat was. Next Spring, we will be installing the Tuffy Security Deck. Note, if you have the 2 door like we do with backseat removed, you will want to order the 4 door model security deck to cover the full cargo area.
Jeep Wrangler Stereo Upgrade Conclusion
As you can see, it’s not that difficult or complicated to upgrade the stereo in a Jeep Wrangler. We do it all the time at our shop in Brookfield, CT.
If you have to build your system in phases, I would recommend starting with the subwoofer. Add in the frequency range that you’re missing. Next step would be an aftermarket head unit. This gives you more output and control over the stock speakers. Most aftermarket head units have crossovers built in. This feature will allow you to filter out the bass that would normally go to the stock speakers. This will allow them to play only mid range and treble frequencies while the subwoofer plays all the bass. After that, I recommend upgrading your speakers and lastly, make sure you amplify those speakers.
The end result? Investing in these quality car audio products, and having them properly installed and tuned, will do wonders for your Jeep Wrangler driving experience. When you upgrade the stereo in your Jeep Wrangler, you’ll be able to crank it up and actually hear and enjoy the stereo system.
Hello everyone! I’ve been meaning to write this for a long time, so sorry for the delay between posts. At Sounds Incredible Mobile, I get plenty of customers who like to install their equipment themselves. I’m all for that, unless they don’t know what they’re doing and they blow something up because of improper installation. So, if you’ve got a nice amp and sub you want to install, but you’re afraid you don’t know what you’re doing as far as tuning goes, this article is for you.
So what are all these adjustments and dials on the side of the amp? What do they do?
Low Pass Filter. This is the 1st thing you’re going to want to adjust. If you’ve got a car with decent sized speakers, like 6.5″ or 6×9, you’ll want to set this to about 80 hertz (lo-pass). If your head unit has built in crossovers, you want to set those at 80 hertz (hi-pass) as well. This way your interior speakers are playing 80 hertz and up, the frequencies they’re most capable of playing and your subs will be playing 80 hertz and down. This way everything is playing as efficiently as possible and each component is playing the frequencies they’re designed to play. If your speakers are smaller than that, you may want to set the cross over on the amp and head unit around 90-100 hertz to make up for what the smaller speakers can’t really reproduce. Once that is set, we can move on to gain.
Gain is not a volume knob, that’s a very important thing to remember when it comes to tuning. In fact, it’s so important, it bears repeating: gain is not a volume knob. It’s a sensitivity level adjustment. It’s about matching the sensitivity of your deck’s subwoofer preout to the amplifier. Let’s say you have a basic head unit with a 1.8 Volt preout. The amplifier is not going to be as sensitive to a 1.8 Volt preout as one with a 4 Volt preout. So you want to match the sensitivity. Minimum on an amp gain is usually 5 Volts, Maximum is usually around .2 Volts. Even your cheapest aftermarket head unit is usually at least around 1.2 Volts, so even then your gain should never be maxed out.
If you’re going speaker level in, you’d probably be surprised to learn you’re probably around 5 Volts, so even with a stock head unit, you shouldn’t have to crank the gains. If it sounds like you need to, please read an earlier post about adding an amp and sub to a stock system. If you get the wrong speakers for the source of the signal or if you have a stock amplified system, you may need to tweak a few things to get the sensitivity right.
A good rule of thumb is to never put the gain up more than 3/4, but if your deck is on the higher voltage side, less should be sufficient. Remember, distortion is what kills subs and speakers. It’s a lot harder to hear distortion on bass than it is on interior speakers. And certain songs may distort at certain volumes while others do not, so it’s something you really have to pay attention to in order to avoid damaging your equipment. So crank the volume, put on a variety of music, and slowly bring up the gains to a point where it sounds good, but you don’t hear the subs flubbering or distorting.
Bass EQ. What exactly is Bass EQ? Frequencies have wavelength, a frequency of 45 hertz has a wavelength of about 25 feet. This means in order to hear the full cycle of a 45 hertz wave, that wave has to travel a full 25 feet. The distance from your subwoofer box and your ears is probably less than half that distance (This is why I love time correction/time alignment!). The other issue you run into in a car environment is incidental sound waves. That 45 hertz sound wave is not only trying to travel to the front of the cabin, but part of it is going to hit the other walls of your trunk and bounce back towards the front. Some of these sound waves will put that 45 hertz frequency out of phase due to the timing of the sound waves.
By boosting that frequency, we help to make up for any phasing issues that may occur due to cabin design. It helps to play around with the placement of the sub before actually turning this adjustment up. Sometimes you have to use Bass EQ just to correct phasing issues that occur due to road noise. This is definitely true if you find your system sounds good when you’re not moving, but your bass disappears as your drive.
Bass boost adjustments are usually tuned around 45-50 hertz on amplifiers, so they are boosting the playback of that particular frequency. Bass Boost or Bass EQ adjustments should be done last after all other adjustments have been done and subwoofer positions have been tested as it’s really an attempt to correct for poor cabin acoustics.
The car is a tough environment for acoustical bliss, but it can be achieved with some technical understanding and some time and patience.
Ohm. What is an ohm? How does a 2 ohm load effect an amp? How does a 1 ohm load effect an amp? Or a 4 ohm load?
The ohm load effects power output in amplifiers as well as sound quality.
Subwoofers can measure 2 ohm, 4 ohm or 1 ohm. 2 ohm, 4 ohm and 1 ohm impedance’s will make the same amplifier put out different amounts of power and can greatly affect the way your car stereo system sounds and performs.
This article discusses the various subwoofer configurations available such as single voice coil 2 ohm, single voice coil 4 ohm, dual voice coil 2 ohm, dual voice coil 4 ohm, as well as series and parallel wiring and how each will effect the measurement of ohms.
All speakers have a measurement of resistance, called impedance which is measured in ohms. Car stereo speakers are typically 4 ohm. You will find car stereo subwoofers in a variety of configurations like single voice coil 2 ohm, dual voice coil 2 ohm, single voice coil 4 ohm, and dual voice coil 4 ohm.
Dual voice coil means the subwoofer has two positives and two negatives, which give you the flexibility of wiring the subwoofer two different ways giving you two options for final impedance. These variations do not make one speaker more powerful than another despite what many consumers may think. However, the varying impedance will make a difference in what type of output an amplifier will have.
As the ohms drop, the amplifier will unleash more power, but with less control. This is an important aspect to remember. Failing to understand this concept is probably the main cause of self installed amplifiers shutting down and going into protection mode.
You will notice, when you buy an amplifier, or are looking at the specifications of an amplifier, you will typically find 2 or more ratings. One output at 4 ohms, and another output at 2 ohms. The output at 2 ohms is always higher because when the resistance is lower, you allow more output. All mono amplifiers are stable at 2 ohms, very few are stable at 1 ohm.
So what kind of speakers can we hook up to a mono amplifier? Let’s use an Alpine MRP-M500 mono amplifier as an example. This amp is rated at 300 watts at 4 ohms and 500 watts at 2 ohms. In order for us to get maximum output out this amplifier, using only one subwoofer, we would have to use either a single voice coil 2 ohm subwoofer or a dual voice coil 4 ohm subwoofer wired in parallel.
If we had two subwoofers, we would need each subwoofer to be a single voice coil 4 ohm wired in parallel to the amplifier. Or we could have two dual voice coil 2 ohm subwoofers with each woofer’s voice coil wired in series, then paralled to the amplifier.
Let’s take a look at this JL Audio 10W6 which is a Dual Voice Coil 4 ohm subwoofer as an example for the different wiring schematics on Series and Parallel:
Parallel is when you tie two positive and negative terminals together wiring them positive to positive, negative to negative, and then wire that straight into the positive and negative terminal of the amplifier. When you wire speakers in parallel, you are cutting the impedance in half. So a dual voice coil 4 ohm subwoofer wired in parallel is now measuring a 2 ohm load:
To understand Series, visualize a dual 4 ohm voice coil. You have two terminals side by side: Positive and Negative for voice coil #1 and then Positive and Negative for voice coil #2. To series this subwoofer, you would have to connect positive from voice coil #1 to the amplifier, then connect negative from voice coil #1 to the positive of voice coil #2, and then connect negative from voice coil #2 to the amplifier. This doubles the impedance. If we do this to a dual voice coil 4 ohm subwoofer, the impedance will be 8 ohms:
The problem that many people run into, is running an amplifier with the incorrect impedance. Let’s say we were to use that same dual voice coil 4 ohm subwoofer with a 2 channel amp bridged. When you bridge a 2 channel amp, you hook up left positive and right negative. You might assume you are simply wiring it as a mono amp, which in a sense you are. The important difference that is often overlooked is when you bridge an amplifier, the amp sees half the impedance at the terminal which means that 2 channel amp would see only 1 ohm. This is extremely low for a 2 channel amplifier, it would be unleashing a lot of more power than it was designed to along with very little control which would in turn cause the amplifier to heat up very quickly and shut down going into protection mode. Over time this will damage the amplifier.
For a 2 channel amp to work properly bridged, it needs to see an 8 or 4 ohm load at the terminal, this will ensure the amplifier will work properly and not overheat and shut down.
If you own an amp and you’re in the market for subwoofers, make sure you know what final impedance your amp needs to see. And vice versa, if you own subs and you’re in the market for an amp, know what impedance your subs are so that you purchase an amplifier that will give you optimum performance. It helps to talk to your local independent car stereo shop, but if there aren’t any in your area, just email me and I’ll make a recommendation for you. If you enjoyed reading this post, please spread the love. Tweet it, like it, stumble it, or use any other social sharing weapon of choice. Thanks for reading!