Want to build a portable bluetooth speaker?

Then maybe you should read this Dayton Audio KAB-250v3 review till the end. Is this a worthy mini amplifier? In short, yes it is. But you have to be aware on the way you choose your drivers and how you design your speaker box. I made a mini loudspeaker box, and as I guide you through my build, I will talk about what to look for. I’m not going to stress about the box build itself. So no panel dimensions and stuff. The result was merely mediocre, so there is no point in copying my design. Anyway, I will tell you what to look for and how to implement this BT amp properly. As a result, you will end up with an awesome build


What’s so cool about this amplifier board is that it comes with all these different modules. So, before we get into the Dayton Audio KAB-250v3 review, let’s talk about what you can connect to it. You have battery packs, connectivity boards, mounting plate etc. In addition, these are all connected to each other using molex plugs. In conclusion, no soldering or anything difficult, just plug and play. Here’s what you should be interested in :

  • Dayton Audio KAB-250v3 – This is the board itself. (Amazon affiliate paid link)
  • Dayton Audio KAB-INT – This is an additional board that has some connectivity options. It gives you the option for an auxiliary jack connection, 2 USB ports for charging devices on the go, and a button to turn on and off the bluetooth module. (Amazon affiliate paid link)
  • Dayton Audio KAB-BE – This is very useful for a number of reasons, in terms of convenience and safety. However, I will also list what’s wrong with this design. (Amazon affiliate paid link)
  • Dayton Audio KAB-AB – Aluminum Bracket. Very useful to tightly plant the board somewhere in your loudspeaker box. However, when making a portable speaker, space is an issue. This bracket is quite larger than the actual board, and needs additional space.

In conclusion, for convenience sake, you got all these extra modules that can make your life so much easier. We’ll get to them soon enough.

Wiring and extension boards

Using the diagram that they provide might be confusing, so I devised my own diagram which you can easily follow.

wiring diagram dayton audio kab-250v3 review

If you look at the diagram, I think you are smart enough to find it self explanatory. I want to talk about the extension boards. There is another one available, which is not in the diagram. However, I find it redundant because it includes things like Aux-in (which is available in the KAB-INT board) . Also a volume knob is present, which I also find useless, because you will use the volume on you mobile phone, or whatever input device you have. It is useful if you plan on making something for home use. Having said that, I have some things I want to mention about the boards. Because part of the Dayton Audio KAB-250v3 review is the actual extension boards themselves.

The Dayton Audio KAB-INT

  • The aux-in is a worthy addition.
  • The 2 USB ports can be used to charge mobile devices. You cannot use it to play music from USB sticks.
  • You have a button to turn off bluetooth discovery. This is pretty useless and annoying. I say annoying because it has 2 LED’s : one green and one red. If you turn off BT, the green one turns off. However, the red one stays on regardless. Furthermore, if you are on battery power you cannot turn off that LED. If you choose to install the on/off switch, when you turn the whole board off, that LED turns off as well. So make sure you find a spot for that switch as well. Otherwise you will have that red LED on, even when you are not using the speaker.

The Dayton Audio KAB-BE

  • The battery pack can hold 3 batteries which are wired in series. Most of the time you will find 3.7 V batteries. Know that this the nominal voltage. When the battery is full it will have 4.2 V. In conclusion, you will have total of 12.6 V. Pretty far away from the 24 V this amp is capable of.
  • But wait, you can daisy-chain them. You will find that each board has 3 connectors. It doesn’t matter which one you use, they do the same thing. Either you use it to connect to the main amp board, or use it to connect more battery boards in parallel. That’s right! Hooking up more battery boards will not increase the voltage, rather it will increase the total available play time.
  • Even with this downside, that you can’t increase the voltage by using more boards, I still encourage you to consider this board. The main reason is safety. It provides protection for the batteries. First of all, it balances the voltage between the batteries if one is weaker than the others. And second, and most important, it stops the charging when it reaches the rated voltage. If you hook up a Li-Ion battery to a power source, it will recharge indefinitely. After it gets full, the battery will overheat and explode. Don’t play with batteries.

The on/off switch comes with the board, and in my opinion, it’s not optional. If you get KAB-INT board you need the switch to turn off that red LED. Otherwise, it’s still good to shut down the board, as you might hear a light hiss in your speakers when it’s not playing anything.

As for power, many laptop power bricks will do. It would be convenient to buy a female power jack for easy connection.

My portable speaker build

Before we get to the Dayton Audio KAB-250v3 review, let’s check out my build, so you know what I’m on about. I used 4 mm MDF. I stacked 2 or more boards for added stiffness where needed. Like the front speaker baffle, for example.

If you are interested in how to make the magnetic grill, check out this article.

The speakers are placed in a sealed enclosure, each speaker in its own chamber. This made the enclosure as small as it could be. However, I think there are better options out there for a more fuller sound. I wanted a small footprint and this was the best solution.

If I were to make an enclosure again I would seriously consider a passive radiator. Bass reflex enclosure are not really an option because the small cavity demands long ports and you don’t want any air to be blown around the speaker. The passive radiator solves all these issues and it’s a welcome addition, as it extend the lower bass performance for little money.

Dayton Audio KAB-250v3 review and conclusion

So how does the KAB-250 perform?  Well it depends on what you are going to use it for. If you want to use it for a portable speaker you have to take few factors into consideration. I already made one. So, would I change anything about my design? Probably everything.

First of all, if you look at the specs, you think that the amp will put out 50W at 4 ohms. That’s what I thought. And I chose some 30W , 3.5″ speakers. However, the problem is that by using the available battery packs, you can only feed the amp 12V. And boy, you are going to hear a lot of distortion at high volume. This distortion is 100% from the amp itself. The amplifier doesn’t have the voltage requirement to put out the rated power.

The solution is to make your own voltage regulator and add more batteries in series to reach the 24V. Please note that you need 6 batteries for this and an additional 6 batteries if you want to extend the play time on the go. Listening at max power will seriously drain your battery juice. Another option is to get smaller speakers. As a result, some 2″ 10W speakers would be more than adequate.

Let talk about heat. This thing generates heat like a radiator in a slavic country in winter time. I’m talking about max volume. Even though it was running on just 12V the thing was getting hot as the box was warm to the touch. It didn’t shut off, or anything, but the only ventilation it had was some holes I did, hoping for a better BT reception. If you plan to make this amp sweat, make sure it has adequate ventilation. If I ran it at 85%, no problem with heat.

The reception is good. Heard people having issues, but not me. The thin 4 mm MDF panels didn’t obstruct the reception that much. I even went several meters away, with no break-ups whatsoever. If you experience choppiness or interruptions, make sure you have full batteries. Starving the amp may cause choppy playback.

In conclusion, my Dayton Audio KAB-250v3 review is a favorable one. Just design your project carefully if you go for a portable speaker. If you plan to use it at home for some mini speakers and power is not an issue, make sure it has enough ventilation and you are good to go.


  1. Image source : link.