In this article, we are going to talk about the compact Sundown Audio SFB series amplifiers. The SFB series is a fairly newer amplifier lineup in the Sundown arsenal and there are still some questions out there that car audio lovers have about them. I am going to attempt to answer some of the most asked questions and give you some technical specs of these amplifiers to shed more light on their construction and performance.

What are Sundown Audio SFB Amplifiers?

The SFB in the Sundown SFB series amplifiers stands for, quite simply, Sundown Full-Bridge. In order to understand what the term “full-bridge” means, we need to discuss both a typical half-bridge amplifier, a full-bridge amplifier and how they work. I will try to keep this as simple as I can so that it is easy for most individuals to understand. 

  • Half-Bridge Topology

In a half-bridge amplifier, the positive speaker terminals provide the output signal, while the negative speaker terminal is tied to the ground. When the output voltage on the positive terminal fluctuates from high to low, it creates an overall voltage difference, causing the speaker to react accordingly. 

  • Full-Bridge Topology

In a full-bridge amplifier, the typical positive and negative terminals are done away with. In layman’s terms, both the positive and negative terminals are active. This means that when there is a positive output voltage on the positive terminal, there will be a negative voltage produced on the negative terminal creating the voltage difference needed to get the speaker to react. By utilizing the full-bridge topology, the SFB amplifier can produce high power with less voltage across the rails.

SFB Facts and Benefits

Most of the full-bridge amplifiers in the car audio market today are Brazilian-made amplifiers, this is not the case when it comes to the SFB series. The SFB series amplifiers from Sundown Audio are produced in China. The SFB series amps are produced in China to keep the amplifiers at a very competitive price point for their power ratings. This does not mean they are cheaply made. If you are familiar with the Sundown Audio brand, you know all of their products are designed and built to perform exceedingly well. 

Because these amplifiers utilize the full-bridge topology, they offer high power ratings in a much smaller package than similarly rated half-bridge amplifiers. This is because the internals of the SFB amplifier is similar to having two half-bridge amplifiers strapped on a single board. This allows the amplifiers to be produced with fewer components keeping their dimensions smaller. 

In all amp dyno tests that were performed on this series of Sundown amplifiers, the result was the SFB amplifiers outperforming their power ratings by substantial amounts. You can find some of the amp dyno results of the SFB-1000D in a YouTube video from Williston Audio Labs by clicking HERE.

The Cons

There aren’t many negative points to go over in regard to the SFB line, but there are a few things to consider when purchasing these amplifiers. The SFB line cannot be run with an impedance lower than 1 ohm. For most users, this should not be an issue, but keep that in mind when it comes to your subwoofer’s voice coil configuration because any impedance lower than 1 ohm will damage the amplifier.

In addition, because the SFB line utilizes the full-bridge topology, these amplifiers cannot be strapped. You can, however, use a (gain-matched) two-amplifier setup to power a dual-voice coil subwoofer as long as the impedance of the coils is not below 1 ohm.

SFB Full Line-Up

The SFB series amplifiers are available in a wide range of RMS ratings. So no matter how big or small your build is, there is an SFB amplifier for you. Here are the SFB amplifiers available at the time of this writing.

SFB Amplifiers




600 WRMS @ 1 ohm

350 WRMS @ 2 ohms

250 WRMS @ 4 ohms


1000 WRMS @ 1 ohm

850 WRMS @ 2 ohms

500 WRMS @ 4 ohms


1500 WRMS @ 1 ohm

1200 WRMS @ 2 ohms

650 WRMS @ 4 ohms


2000 WRMS @ 1 ohm

1500 WRMS @ 2 ohms

950 WRMS @ 4 ohms


3000 WRMS @ 1 ohm

2000 WRMS @ 2 ohms

1100 WRMS @ 4 ohms


5000 WRMS @ 1 ohm

3200 WRMS @ 2 ohms

2200 WRMS @ 4 ohms


8000 WRMS @ 1 ohm

5000 WRMS @ 2 ohms

3250 WRMS @ 4 ohms


13500 WRMS @ 1 ohm

8100 WRMS @ 2 ohms

5500 WRMS @ 4 ohms


200 WRMS/CH @ 1 ohm

125 WRMS/CH @ 2 ohms

75 WRMS/CH @ 4 ohms


500 WRMS/CH @ 1 ohm

300 WRMS/CH @ 2 ohms

200 WRMS/CH @ 4 ohms


1050 WRMS/CH @ 1 ohm

590 WRMS/CH @ 2 ohms

350 WRMS/CH @ 4 ohms


CH #5 1000 WRMS @ 1ohm (CH 1 – 4) Not supported

300 WRMS/CH + 500 WRMS @ 2 ohms

200 WRMS/CH + 250 WRMS @ 4 ohms


If you are looking to get a cost-effective Sundown Audio amplifier that produces big power in a small footprint, I highly recommend the SFB line for you. As described previously in this post, there are plenty of benefits to installing an SFB amplifier in your vehicle. Also, being Sundown Audio, you know these amplifiers will provide the power you need to give your system the power it needs to be loud.

The SFB amplifiers are available on the DOWN4SOUND SHOP website. The amplifiers and the technical specs and can be found by clicking HERE. 


About The Author Brandon L

comments (1)

Your email address will not be published.

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>