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Category: BMW Sound System

Alpha One BMW Speakers & Amp – All You Need to Know!

Radoslaw Zbroinski

Sep 7, 2023

Alpha One BMW Speakers & Amp – All You Need to Know!

Want to improve your BMW audio system but don’t know if our Alpha One upgrades are for you? You’re in the right place! We’ve collected the questions most frequently asked by our customers and prepared this article for your convenience. 

After reading this article, you’ll learn everything you might want to know about Alpha One Speakers and Amplifiers. We’ll also explore the factory sound systems installed in BMWs, checking if it’s really worth replacing them.

So, let’s dive in!

PS: most of the questions and answers were covered in one of our FAQ videos, so if you’re short on time or prefer watching to reading, check it out below.

What Are the BMW Factory Audio Setups? 

Before we get into upgrading the stock sound system of your BMW, it’s worth taking a quick look at the options it could come equipped with from the factory. There are 4 most common BMW audio systems that are available in standard or as an option: Base, Hi-Fi, Harman Kardon, and Top Hi-Fi

If you’re interested in a more in-depth look at them, be sure to read our Harman Kardon vs Hi-Fi vs stock audio comparison. Meanwhile, here’s a brief overview of their characteristics. 


The Base (or Stereo) is the lowest-tier BMW audio option you could get. In its iDrive 6 version, this system has just 6 speakers: 4 midrange ones and 2 underseat subwoofers. It has no tweeters nor does it have a dedicated BMW amplifier. Although the iDrive 7 variant gets the same number of speakers, they are all powered by the Receiver Audio Module (RAM) that acts as a receiver and amplifier, which slightly improves the underwhelming sound quality. 

Hi-Fi System (S676A)

The Hi-Fi option (S676A) is an improvement over the Base system. It has 9 speakers, which include 2 tweeters and an additional midrange speaker in the dashboard. Additionally, it features an 8-channel BMW amplifier installed in the trunk, which is the reason why it’s more powerful than the Base. Similar to the Base system, the iDrive 7 version of the Hi-Fi option also utilizes the RAM. 

Harman Kardon (S674A)

The third BMW audio option worth mentioning is the Harman Kardon Hi-Fi system (S674A). It features a slightly stronger amplifier, but it employs the same number of channels as regular Hi-Fi audio – they also differ in the number of speakers and the head unit coding. 

Despite the same name, the S674A Harman Kardon system is different from the S688A option. The former was created for small chassis cars, like BMW 1 or 2 Series. It doesn’t sound as good as the S688A sound system, but still is an upgrade over the S676A setup. 

Just like with Base and 676 Hi-Fi, the 674 HK system is different for pre-iDrive 7 cars. There, it is powered by an amplifier fed with an analog signal from the head unit. It is also different in the latest variant re-introduced in 2023 in the U11 X1 chassis where it is powered by RAM.

Top Hi-Fi (S677A) and Harman Kardon (S688A)

Lastly, we’ve got two of the best factory audio options for BMWs: the S677A (Hi-Fi System Professional) and S688A Harman Kardon surround sound systems. 

There are some differences between the two, the main being that the S677A is an earlier design, but they both have a similar layout and amplifiers. Interestingly, some late production E-Series and early production F-Series BMWs could come equipped with either of the two options. Out of all setups discussed, this one’s the most capable. It’s usually equipped with 16 speakers (2 powerful 8 Ohm subs, 7 mid-range speakers, and 7 tweeters). 


Just like with the above systems there is a generational gap between the electronics powering the 688 HK-branded systems between pre-iDrive 7 and post-iDrive 7 vehicles. The earlier version sounded better – it was powered by a single 600 W max output power amp fed with a digital optical input signal. 

On iDrive 7 and 8 BMWs, the same system has only 464 W of max power. While it is also fed with a digital input signal passed through DSP processing, the sound is not as natural or pleasant as in the old system. Here, it’s powered by a seven channel RAM for midrange and tweeter channels, and a separate booster module to power the underseat woofers. 

Read our article about the Harman Kardon sound systems to learn more about this option.

BMW Speakers & Amplifier Upgrade – Alpha One FAQ

Now that we’ve established the baseline and know what are all the available stock options, let’s talk business. Namely – how to improve upon what BMW is giving us. You probably already guessed it, but there are many ways to go about it. If you’re considering following the path of our Alpha One BMW speakers and amplifier upgrade, it’s likely you’d want to know everything when it comes to specs or characteristics of our products. 

And that’s why we’re here! Join us as we explore the most frequently asked questions regarding BimmerTech’s Alpha One. 

Will the speakers fit all BMWs?

Our speakers will fit most BMW models produced after 2008. If you want to be sure that your car is compatible, you can always enter your VIN on our website to check. There are a few exceptions though where our speakers don't fit, e.g., for certain BMWs with uniquely designed speakers 

Will the amp fit all BMWs?

Will the amp fit all BMWs?Similar to the Alpha One speakers, our Amplifier will fit most 2008+ BMWs equipped with the Base stereo, Hi-Fi (S676A), Hi-Fi Professional (S677A), Harman Kardon (S674A and S688A), and Individual Audio (S752A). We’re also constantly working on expanding the list of compatible vehicles, so be sure to decode your VIN on our website and check if we’ve got something for you at this point.

What is the total wattage of the amp?

Depending on the factory-installed audio (either Base, Hi-Fi, Hi-Fi Professional, Harman Kardon, or Individual Audio), our amplifiers will have a different peak total power output. For info on specific wattage, visit our Alpha One page and decode your VIN. Regardless of what it replaces, Alpha One amp is always significantly more powerful than the stock amplifier.

Does the amp require additional coding?

In most cases – no, it doesn’t. However, if you are upgrading from a base stereo system that had no amp from the factory, coding will be necessary. This does not apply to base stereo upgrades for BMWs with iDrive 7. No coding is needed for that stock option. 

How do I install the system on a BMW with the Base sound system?

Since the Base doesn’t have tweeters and an amplifier, the installation is slightly more complicated than for Hi-Fi or Harman Kardon Systems. While our kit is still plug-and-play even in this case, there are just a few more harnesses to run. You also might need to source a few trim pieces on your own, especially if your BMW is lacking grilles for the tweeters.

If you would like to see an example of the installation, we actually have a video on our channel upgrading the audio system of an E70, which had the Base audio. If you have a Base stereo system in a BMW equipped with iDrive 7, the amp installation process will be exactly the same as for a 676 Hi-Fi car. 

Are the speakers plug-and-play? Do they need any cutting or splicing?

Yes, they are a 100% plug-and-play! All of our connectors connect directly to the existing BMW harnesses.

Should I perform the installation or take it to an installer?

You will have to take off a lot of panels and connectors. We can provide you with all of the tools you need with our BimmerTech DIY Essentials Kit and Trim Tool Kit, as well as all of the knowledge you need with detailed PDF instructions. In most cases, we also have installation videos on our YouTube channel for your BMW or a similar model. 

However, if you don’t feel comfortable doing all that, you can find a list of our recommended dealers near you right on our website or visit our Orlando showroom.

What are the sizes of the speakers?

What are the sizes of the speakers?While the construction and materials of our speakers far surpass what BMW offers, the size of their baskets remains the same as the factory ones. This way, the acoustic properties of the vehicles work well with the sizes and everything remains plug-and-play. 

When it comes to the diameter of the midrange speaker’s cone, it is the same as OEM. For our woofers and tweeters, it depends – some of the factory-installed ones are absolutely tiny compared to the Alpha One replacements. 

Do I need all of the speakers?

If you want to take full advantage of the upgraded system, we recommend getting a complete set. That being said, it isn’t required. We offer kits to meet both your desires and budget: from the simple Woofer Set, through the Front & Woofer Set, all the way to the complete speaker upgrade. You’ll definitely find what you need!

We do suggest getting all of our speakers if you have the Alpha One amplifier since the factory speakers may not be able to handle the additional power and can blow or produce distorted sounds. 

What are the speakers made out of?

Our tweeters and mids feature aluminum cones for prolonged life and high output, while our woofers have paper cones for superior movement when reproducing these low tones. Each speaker is constructed with neodymium magnets which are stronger and more powerful than typical ferrite magnets, which are the same types of magnets used for refrigerator magnets.

Should I get the speakers, amp, or both?

This really comes down to your personal preferences and needs. To take full advantage of what Alpha One can offer, you’ll definitely want the amp and speakers. If you don’t usually crank the volume up too much but want a fuller and more custom audio experience, our amp should be enough. If you are looking for a little more headroom and a clearer listening experience, our speakers will do the trick. 

Remember though: your factory amp can’t drive the Alpha One speakers to their full potential, while the Alpha One amp can overdrive factory speakers if you increase the volume too much; this is why we suggest both. If you have a vehicle equipped with the Base stereo we strongly recommend upgrading both the amp and the speakers for best results.

Still not sure what to choose? We have a detailed guide that will help you decide if either one of the two, amplifier or speakers, is the right choice for you. Be sure to read it!

How does it compare to competitors?

Unlike our competitors, we don’t like to trash-talk other brands. All we can say is that we offer more plug-and-play kits for newer BMWs that others don’t and that there is a difference in the sound quality and service you get from BimmerTech. Our amps also come pre-tuned for either OEM or Alpha One speakers.

Is it worth the upgrade?

Although the complete Alpha One system might seem a little bit pricey, the old saying “You get what you pay for” fully applies to it. With our upgrades you get superior audio quality and service, turning the sound system into a proper music listening experience. Whether you are upgrading from the Base, Hi-Fi, Hi-Fi Professional, Harman Kardon, or Individual Audio – we know you’ll be pleased.

How does the custom tuning work on the amp?

How does the custom tuning work on the amp?When purchasing an Alpha One Amplifier, we ask you to fill out a questionnaire that will tell us what kind of music you listen to and how you like it playing. Based on that and knowing the acoustic properties of your BMW’s interior, we will tune the amp before we send it to you, making it sound just the way you want.

Can I tune it with the iDrive system alone?

The iDrive system will still give you access to the basic equalizer. While that allows for some customization, you will not get the precise control that you would from the amp’s DSP itself. Comparing the DSP of the Alpha One Amp to the adjustments available in the iDrive menu would be like comparing a single grain of sand to the Pyramids of Giza, in terms of their size. Sound tuning in iDrive just won’t cut it.

Can you change the tune after I order it and does it cost anything?

Yes, we can change the tune after it’s been ordered. Each amp comes with a USB cable that allows you to connect a computer to your amp to access the tuning. If you are unhappy with your tune, our audio experts can provide a new tune for you free of charge.

How does the Alpha One system compare to Harman Kardon?

Simply put, it’s better. With Alpha One, you get clarity from your speakers, crisper highs, cleaner mids, and more punch from your lows. If you have a BMW with the S674A Harman Kardon option, upgrading the amplifier alongside the speakers will pump in even more power, optimized stereo imaging, smoother frequency response, and more customization possibilities than before. 

What is ASD Deactivation for?

Active Sound Design, or ASD, pumps artificial engine noise through your car's speakers, to emphasize the vehicle's sporty feel. If you prefer to keep things natural or your upgraded stereo is making all that noise a little too intense, deactivating your ASD will take care of that. We offer this coding service on our website, while for certain iDrive models, you can insert a harness into the ASD module that will bypass it entirely. If you want to learn more about it, check out our blog about BMW Active Sound Design.

Why do you need to keep the old amplifier in while adding the upgrade to MGU (iDrive 7) cars?

Alpha One Audio UpgradesFor iDrive 6 and older vehicles with Base stereo, 676 Hi-Fi, and 674 Harman Kardon, the analog audio signal was generated by the iDrive head unit and then passed on to the amplifier in the trunk. On top of that, the 676 and 674 factory amplifiers' functions were to amplify audio signals for the speakers. Since that was all they did, replacing the factory amp with a superior Alpha One device was the way to go.

With iDrive 7, the headunit no longer outputs an analog audio signal. Instead, the audio signal is delivered to the RAM (Receiver Audio Module) via an encrypted digital signal. This means that the analog audio output can only be sourced from the RAM, so it has to stay installed. The RAM is also responsible for a lot more than just putting out audio: antennas and microphones are connected to it too. If you have a hybrid BMW, it is also responsible for generating pedestrian warning sounds. Overall, if you remove the RAM, many features will stop working in your BMW.

Alpha One Audio Upgrades – Perfect for Your BMW!

We hope that this article brought you the information you were looking for. Still have some questions regarding our Alpha One Speakers or Amplifier? Contact our sales team – they’ll be happy to answer and assist you in choosing the Alpha One upgrades perfectly suited to your car and your needs. 

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