To build a small monitor as “Do It Yourself (DIY) kit” has been on the wish list for a long time. One of my successful small monitors are the Kiwi loudspeakers. Bass and tweeter show their excellent characteristics in a very small cabinet. Is it now possible to achieve this excellent sound again with the same tweeter and a different bass with different construction and material?

A couple of “Kiwis” are available for comparison, but the SAM loudspeakers still have to be built by my friend Samuel. The following instructions will help you, Samuel, and your father to build your own loudspeakers. Although you get prefabricated parts, you need a lot of patience for gluing, damping, sanding, painting and careful installation of the drivers and crossover. A few days of effort will be needed to construct them, but I am sure that the sound will give you, your brothers and parents a lot of joy. But beware, you can also put the volume too loud and that not only harms the ears, it can also destroy your loudspeakers. Have fun with building your first loudspeakers!

Case construction

For the SAM I decided to develop a compact speaker. For listening, you put it on a stand so that it’s about at ear level, or you put it on a shelf or on your desk. This even supports the bass, which then sounds a bit deeper.
The cabinet is calculated to consider the space for the crossover, the magnets of the speakers and the bass reflex tube. This allows the bass to show its full potential. With such a small cabinet, a volume of 0.5 litres more or less has a big influence on the sound.

Bass cutout

The inner section of the bass has been widened at an angle of 45 degrees. With a small 10 cm driver the rear sound can escape into the cabinet with very little resistance and compression. As this driver has a very small transition from the basket to the diaphragm, you have to make sure that there is still enough wood to hold the screws tight. The construction of the bass driver allows for maximum expansion and we can benefit from it in terms of sound quality.
The interior of the tweeter and the terminal has also been widened. The compression is not relevant here, but we avoid sharp edges which can reflect in a disturbing way. These are details but in sum it helps to get the maximum out of the speakers.

Bass reflex tube

The length and diameter of the bass reflex tube influences the lower frequencies in the bass and has a very large influence on the overall sound. A compression occurs inside the bass reflex tube. To avoid this, you can increase the diameter but then you must adjust the length, which can have a disturbing effect on the fundamental. Nevertheless, one must calculate an optimum which was considered on the SAM cabinet. The bass reflex tube is considered in the construction, so that no separate plastic tube is needed. Due to the compression in the bass reflex tube, a lot of air is circulated and can generate flow noise. To avoid this, the edges have been rounded at the beginning and at the end.

Construction drawing

In the case construction all measurements are given in millimetres. In addition, all wooden parts have a letter so that cutting to the right size and assembling are easier. To avoid possible difficulties, I recommend assembling all parts before building the case and compare them with the drawing. For the SAMs all wooden parts are already cut to size and the recesses for the chassis, the terminal and roundings are precisely milled out. Holes in the correct dimensions have already been pre-drilled to the screws for mounting the chassis. This procedure is recommended for MDF, as it is a pressed wood and, compared to other woods, it yields and breaks less easily. Additionally, you must be careful not to overtighten too much at the end and then the screw will not hold properly.


With a cabinet it is important that it is stable. For this small cabinet 16 mm thick MDF was used. The advantage of MDF is that it has a high density and therefore absorbs sound well. It is also an advantage for painting work. Alternatively, you can also use birch chipboard. A thickness of less than 16 mm should not be used. A higher material thickness helps to have a quieter cabinet. Inside the case where the chassis are mounted, it is important that the large walls are glued with insulating material. Bonding additionally reduces the insulation, i.e. the penetration of sound through the wall. Depending on the material selected, the insulating material also acts as an attenuator. This means that the sound is additionally absorbed in different frequency ranges depending on the material density.

For the walls I use a self-adhesive insulating mat which is green coloured, Damping 10 from Intertechnik. To the respective edges it may have a distance of one centimetre each.
For the damping outside the inner the walls I use two different types of damping material:
• There is one small mat of white colour (called Bodum) which will be placed into the cabinet after the green damping 10 on the top.
• After this I use half a bag of the fluffy black material (called Sonofil) per case. When laying, I also make sure that the damping material is cut and fixed accordingly at the edges and bottom. This leaves enough air behind the chassis in the cabinet and in front of the bass reflex tube. It is important that the air to the bass reflex tube is open, so that the sound of the bass flows through at full speed and is not damped. We don’t want less bass.

No damping material Damping 10 is required on the back of the inner housing, as the crossover is mounted there.


For the cabling very high quality copper cable with a diameter of 1.5 mm2 will be used. It is flexible and not stiff, and the assembly is easier. The cable length should be generous. This means that you have enough space for soldering or plugging in the chassis as well as for the crossover outside the cabinet.
The cables for the drivers and the terminal are soldered to the crossover. For the connections to the chassis and the terminal I recommend using the mounted plugs. The soldering offers again a better contact, but you have to be careful not to burn the thin wires or to damage the sound irretrievably if the coils overheat. So, pay attention when soldering. The DIY kit has finished crossovers and they are prepared with gold-plated plugs. No soldering is necessary.

Speaker chassis


For the bass I use the Wavecor WF110WA01-4 Ohm loudspeaker. This small driver achieves a resonance frequency of 76 Hertz, which is not so low. Depending on the use of the crossover parts, a cabinet volume of just under 4 litres and bass reflex insert can produce an amazingly low frequency of just 55 Hz (-6 dB). With a linear excursion of 4 mm of the voice coil, the small chassis is designed with a long excursion to be loud even at low frequencies. The efficiency is 85 dB, which is an excellent value. To hear a little louder, however, you need a little more power from an amplifier with a 4 Ohm loudspeaker. The special feature of the bass is that neodymium magnets with cooling fins are used. Neodymium has a high magnetic power in a very small space. When the chassis is strained, the neodymium can heat up and the magnetic force suffers. Therefore, the cooling fins are generously designed. With all these measures, the magnet behind the diaphragm is kept so small that the airflow can circulate in a streamlined manner.

The bass driver is almost free of resonances up to the high frequency range. Thus, one could easily intend a separation at 3000 Hertz, where the bundling of the sound at different angles begins.


The tweeter (Wavecor TW022WA04) is a smaller dome unit with a voice coil diameter of 22 millimetres that lies exactly in the middle of the usual 19- and 25-millimeter tweeters. In addition, the tweeter has a wide surround, which increases the effective cone area and sometimes also the level stability. This dome tweeter has a particularly wide omnidirectional sound distribution and, thanks to the intelligently designed volume chamber behind the magnet system, the resonance frequency is only 800 Hz which is very low. Thanks to the use of neodymium magnet, the construction could be kept very small and optimally designed for ventilation. Without ferrofluid, which is normally responsible for cooling the coil, this tweeter can already be used from 2 kHz. The diaphragm can follow the signals quickly and exactly without this low resistance of ferrofluid. All these characteristics as well as excellent measured values promise a clear, spatial and stress-free sound.

Crossover and measurements

Influence within the cabinet

The construction of the crossover in these high-quality drivers is always a challenge. Small changes in component values can be seen immediately in the following measurements. This means that with such great and in this example good-natured drivers, you can very quickly achieve good measured values, but it takes time to get the best out of it. The cabinet geometry has a big influence on the frequency response. The higher the frequency, the more the sound is bundled and interference from edges becomes visible in the frequency response. Therefore, I recommend using the mass of the cabinet also in the width. A deviation of plus/minus 10 percent is unproblematic. In my construction a 8 mm round phase was used at the edges. This reduces the interference and the cancellation of the sound at approx. 3.8 kHz, which can be measured with an axial frequency response.


With a narrow cabinet we encounter another phenomenon. In the bass the sound pressure rises massively from 500 Hertz and in the tweeter the sound pressure rises from 3 kHz in the lower frequency range. These two humps are called baffle steps and should be eliminated by notch circuits for an even frequency response. Not only axially up to 6 dB volume are balanced over more than one octave, but also under measured sound pressure frequency response of 30 degrees a balanced and even behaviour is achieved. Without these notch circuits, a much larger coil value would have to be used, especially in bass. The baffle step is thus lowered but not eliminated. Now you would have a frequency response hole between 200 and 800 Hertz. And in this range voices and instruments get a lot of energy and with a broadband sink it doesn’t work much physically. So, it’s worth using a few more crossover parts. I used a 12-dB filter design for the bass as well as for the tweeter. With a crossover frequency of 2000 Hertz I am far away from the limits of the drivers with both drivers. With the steeper filter design of 12 dB for bass and tweeter I was able to tune an optimal sound addition with -6 dB point in the crossover range. Thus the conditions for an unlimited sound should be guaranteed. The linear tuning of the frequency response was implemented with a slight drop from the bass to the high frequency range. Between 1 kHz and 5 kHz, special care was taken to ensure that there was no overheating. The reason for this is that with such high-quality drivers and crossover components used, the sound is incredibly open and detailed at the beginning, but when listened to for a long time it is annoying or intrusive. Therefore, it is important that the frequency response hole at 3.8 kHz is allowed and not eliminated during axial measurement due to the geometry of the cabinet. With the 30-degree sound pressure frequency response, it is easy to understand that these interferences are no longer present. Otherwise we would have a measurable and audible highlighting of this frequency range, which would annoy the sound over time. The published sound pressure frequency responses are shown in a higher resolution than usual. This makes them look a bit more restless compared to one is used to from magazines, where the frequency response can appear very smooth. No loudspeaker is perfect.

Selection of crossover components

For the crossover we have the disadvantage of a small compact speaker where you can’t use every size of component. Nevertheless, we selected this quality driver and have used high-quality components at the sonic relevant places. The difference with better components is that everything sounds a bit better and more natural. The change of the sound is difficult to describe, because this is usually not visible in the measured values. It simply sounds a bit more open, fluid or right to the point. SAM’s crossovers are already assembled and can be connected to the chassis with gold-plated pole terminals.

Comment on measurement

The loudspeaker has a sensitivity of approx. 83.5 dB with slight fluctuations of approx. -1.5 dB. The frequency response remains stable with a horizontal shift of 15 degrees and only decreases minimally. Even at 30 degrees you can see that from 5 kHz there is a small frequency drop of about 3 dB, which is excellent. Due to the good dispersion characteristics, the loudspeakers do not have to be angled strongly in order to obtain a good imaginary stereo image.

The waterfall spectrum represents the three-dimensional oscillation of the diaphragms. The lower the frequencies are, the more the decay in the lower frequencies is usually delayed. SAM has a delayed midrange and a slight bass reflex and membrane resonance anomaly at 800 Hz. The latter can also be seen very well in the frequency response. In the treble you can see a very fast and excellent decay.

SAM needs a stable amplifier as a 4 Ohm loudspeaker, which can supply current. The minimum impedance is 2.4 Ohm at 135 Hz. The two impedance peaks in the bass are typical for bass reflex speakers. Usually they are even a bit higher, but due to the impedance linearization (because of the baffle step) in the fundamental range, the impedance peak is damped at 75 Hz. If you install too much damping material, you will also notice a low impedance peak in the bass range. In the waterfall spectrum you would notice a shorter decay, but the music would sound dull due to the high damping. The SAM was damped in several test series to such an extent that the fundamental tone and thus more character can be heard, especially with voices and a uniform and lively sound image is produced over the entire frequency response.


After completion, the loudspeakers are placed at a small angle to the inside and at a distance of 1.5 m to 3.5 m from the listener, connected and released.

To be able to judge the sound of a loudspeaker in the end, it is worthwhile to run the loudspeakers over several hours or days. The moving parts of the drivers change over longer periods of time, as do the crossover parts. This is particularly noticeable with bass, which changes over time and can sound deeper, for example.

Samuel now comes your task: you can judge the sound of your SAMs and if you know them well then you can compare it with the “Kiwi” loudspeakers. Try to find out which are the strengths of each box. Make yourself a scheme with a rating. For example

• Do the SAMs favour a music style (classical, blues, jazz, pop, rock etc.) or doesn’t it matter at all what you hear with them?
• How do voices sound? Women with bright voices, men with bright or dark voices? Do you hear the typical character of the voices?
• How do individual instruments sound and can you even detect the body and name of a brand? For example, a piano (Steinway, Bösendorfer, Yamaha) or a violin, flute etc.?
• Can you distinguish between several instruments and voices or does everything blur?
• Does everything sound so spatial that you can assign the instruments to a certain position, more left, middle or right or further back?
• How does it sound at low volume? Do you still hear details or only when it gets louder?

Well, Samuel, please write down how you experience the SAMs and then we will publish your sound check here on the homepage. Maybe your brothers, Daddy and Mum also have an opinion.


Frequency response 0 (red) and 15 degrees (green)
Very linear response after 2 kHz

Frequency response 0 (red) and 30 degrees (yellow)
No overheating and light lowering of frequency

SAM Impedance

Impedance Curve
Low impedance at 135 Hz with 2.4 Ohm

SAM Waterfall Spectrum

Waterfall spectrum
Mid section delayed, treble excellent fast settlement


Design of Crossover

Component parts

In the following the most important components are listed, which are needed for the construction of a loudspeaker box. Not all components are listed in detail, since every DIY enthusials can incorporate his own ideas.

SAM component parts

* Basis for mounting the crossover. I recommend shortening the width from 102 mm to 90 mm, so that the crossover can be inserted through the bass cutout and mounted in the cabinet on the rear wall.

Assembly tips

Before you assemble the cabinet, please read the assembly tips completely.
The wooden parts for the cabinet have already been prefabricated as a DIY kit. You only have to glue the parts together. Before gluing, I recommend putting the wooden parts together with the enclosed wooden connection lamellos. This will give you a good impression of what the box must look like and you will not make any mistakes when gluing.
In addition, I recommend that you stick the prepared damping material to the inner walls first before the gluing process. If the cabinet is already glued, you only have the openings of the speaker chassis and that is very difficult to stick the greenish damping material in the right position. Please note that the designation of the insulation material corresponds to the designations on the wooden inner walls. The assembly is documented on the photos. The green damping material has a protective foil on the adhesive surface. With a sharp knife you can carefully cut the protective foil and then try to lift it away from the adhesive. This is a lengthy process and requires a lot of patience. The adhesive surface is then pressed against the inner wall so that it sticks over the entire surface. It additionally calms the cabinet and dampens the sound in the interior.
Wood glue is usually used for gluing, which can be seen on the photos. Alternatively, polyurethane glue can also be used, but you should avoid skin contact. When gluing, you should make sure that the glue is used sparingly in the area of the bass reflex part so that no or little glue quicks into the interior of the bass reflex when pressing the pieces of wood. In all other places, over-swelling of the glue is desirable, but must be wiped off with a damp cloth or dry household paper, as subsequent removal by sanding is laborious.

SAM Overview of dyi parts
SAM construction front and back

Construction front and back

SAM construction side view

Construction from side view


SAM damping
Damping of the box with different material