New & Reviewed

Built & Tested: SB Acoustics Micro-C Speaker Kit

Daniel Koch

Issue 39, October 2020

Our friends at The Loudspeaker Kit have sent us another bookshelf speaker kit for review, and it boldly came in ‘Lamborghini Orange’! With that kind of bravado, are these speakers as good as they think they are?







WOOFER: 4” ceramic cone.

TWEETER: 3/4" soft dome.

SIZE: 262 × 170 × 132mm, 3.7kg.

The range of speakers at The Loudspeaker Kit is not exactly what you would call ‘consumer’. These are premium products aimed firmly at the audiophile. Last year we reviewed a complete build kit, where the cabinets came flat-packed, and we were pretty impressed with the quality of both the kit and the sound it made. This time around, the cabinets are pre-assembled and finished in a gloss finish similar to car paint. They can be ordered in satin or gloss black or white, or the gloss-only Lamborghini orange supplied to us. The product is made by SB Acoustics.

The book-shelf-sized monitor kit is a set of cabinets, pre-made crossovers (which were very, very nice), and drivers. They are a two-driver speaker with a ¾-inch tweeter and a 4-inch mid-woofer. The cabinets are designed with a bass reflex port, where the bass is directed from the top rear of the cabinet down a full-width channel and out a front-facing port. The whole assembly looks pretty good, and is completed by some high-quality foam rubber feet which enabled us to test the units on a glass table with no ill effect.

As before, we are not going to perform laboratory tests on these speakers. No Thiele and Small parameters, no sensitivity measurements, or frequency response analysis. That’s all been done and the data is available. We’re not questioning it. We just want to know how well they go together, and how good they sound. The numbers mean little to many people, unless they have that level of knowledge. Most people just know what sounds good, and what’s lacking. Before we test, however, we have to build.

Building The Speakers

Unpacking the box revealed that the cabinets were in their own box, well-protected with foam and bubble-wrap, with another box having the components securely packed in. There was no room for movement to generate transit damage of parts. The kit is well-thought-out, even having two different types of screws: Phillips drive pan-heads for the tweeter and hex drive cap screws for the woofer. A hex key was included.

If you apply basic care, the instructions are quite clear. Assembly is straightforward but differs from the manual at one point. The crossover fits on the internal panel, which is spaced forward as part of the enclosure’s bass reflex port. There is a false floor as well, part of the same acoustic channel. The holes are pre-drilled for the screws, and the screws are embedded in plastic stand-offs which double as screw retainers. Tighten until there is no wobble on the stand-offs but overdoing it will crack them.

The instructions declare that the wires from the binding posts to the crossovers should be soldered, and are pictured as bare ends. The supplied crossovers, however, had substantial eyelets pre-soldered to the input wires, and these go straight onto the binding posts. Just make sure the plastic washer goes under the eyelet, and the securing nut on top of the eyelet. It is worth applying a small amount of glue to the case where the binding posts go through, mainly for sealing. Also, note the orientation of the holes for the wires before you tighten the nuts. The binding posts themselves are a very high quality plastic-encapsulated version.

With the crossovers installed and the binding posts connected, install the damping material. The suggestion to cut the speaker damping material before assembly is neither here nor there, but we cut before. We used Uhu clear glue to tack the material in place. Be careful to look at the diagram carefully, as it may not be immediately apparent, depending on your experience, about where this stuff goes. For example, one piece is tacked to the false floor and lays over the crossover, but the crossover is not shown on the diagram, implying that the material goes against the internal panel. This is mutually exclusive with the location of the crossover. Similarly, another piece gets folded to attach to both sides of the box and over the other piece. This is also not immediately clear in the diagram. Perhaps a front and side elevation would have helped here.

After the damping material is in, draw the wires through their respective openings. We had to fold back the damping material to read the labels, so spare yourself the trouble and write it somewhere (or take a photo) first. On ours, the back and yellow pair was the tweeter and the black and red pair was the woofer, but wire colours may change so check first. As with all good quality speakers, the terminals are different sizes to ensure correct polarity, and the crossover wiring is pre-terminated with the appropriate spade terminals. We did find a couple fit a bit loosely, so a gentle crimp with pliers was employed. These wires are subject to vibration inside the cabinet so don’t be tempted to accept even slightly loose connections.

The last challenge was installing the drivers. We found that on both cabinets, the tweeter’s screw holes needed drilling out. Two were not drilled at all, and the others suffered from being filled with the two-part paint used on the cabinet finish, and a bit of swelling in the MDF. The same can be said of the woofers, although the screw holes were better formed here. The issue, in this case, was the separation of some of the MDF, which impacted screw alignment. It was pretty minor and we didn’t even bother redrilling these. And that’s it, the speakers are assembled!

Amplifiers, Audio Sources and Set-Up

We are testing these with an in-house amplifier. Last time we still had a valve-fronted solid-state amplifier also from The Loudspeaker Kit, which has since been given away as a prize. So we used an Onkyo HT-R693, which claims a Frequency Response of 5Hz to 100kHz.

That’s more than adequate when human hearing is around 20Hz to 20kHz for a newborn, and around 50Hz to 16kHz by the time you reach your mid-twenties. It only gets worse after that. Total Harmonic Distortion for this amplifier is given as 0.08%. Of course, you can find amplifiers claiming lower figures, but as with the frequency issue, there is a point where the human brain just can’t tell the difference, and 0.08% is below that point. So that said, we were pretty happy with the amplifier available.

One thing that is worth noting, however, is audio sources. We played a very big range of music from Bach to the Beatles, Enya through to AC/DC, Metallica to Aretha Franklin singing a capella. More importantly, however, we made sure we used sources with high sample rates. When MP3 downloads were the most common source of music, some files were as low as 64kb/s. 128kb/s was common, and you often had to look for 320kb/s. By contrast, the WAV files used on CD encoding are usually 1411kb/s. They also have more samples taken across the audio range as well, resulting in much more sound information captured.

This theme extends to digital streaming, such as Spotify and YouTube. On YouTube, the set video quality rate defines the audio bit depth and rate, and therefore the quality, regardless of the actual image quality. Setting to the highest quality in the video settings means the highest quality sound. Of course, there are pitfalls if the source material was uploaded in low quality.

All that had to be done to set up the test was connect our audio sources to our amplifier using high-quality cables and Bluetooth set to the 4.2 standard (which carries much more data than the old standards), and use decent-gauge speaker cable to connect to the binding posts which we secured tightly, ensuring no stray strands of wire.

"I heard details in a Pink Floyd song that I’ve listened to since my teens that I have never noticed before."

The Test Results

Well, they do sound good! Do they sound good enough to justify the price? That depends on a few things, like how good your hearing is in the first place, and what you’re willing to pay for a set of bookshelf sized monitor speakers.

One thing that became apparent is the speakers have a serious presence. The sound really gives an impression of depth. They have a sound like actually being there where the music is being made. There is clear intonation, details can be heard that cannot even on reasonably good headphones. I heard details in a Pink Floyd song that I’ve listened to since my teens that I have never noticed before. In fact, the Pink Floyd tracks really did put the speakers through their paces. Full of such dynamic sounds all at once, and many, many small audio details, both studio and live tracks took on a very real feel. The Aretha Franklin a capella test also showed how well these speakers performed. That track sounded like a live, up-close performance, the kind performed in small venues without needing a microphone. Having said that, the late great Aretha could probably have sung in a stadium without a microphone.

That’s the biggest take-home point about these speakers. They are able to render a very clear, undistorted sound at even the highest sampling rates, and make it sound very real. Someone in the office even described it as ‘3D’. It was so clear in fact, that those with sharp hearing could even tell when we changed to lower quality (but still good) tracks.

The bass response from other music is also impressive, though there is a limit to even the best 4-inch driver and it was noticeable in certain tracks. However, it was far less obvious than it is with some of the other speakers we have around. We were impressed enough that we kept listening after the test without bothering to connect a subwoofer. The neighbours were listening too, whether or not they liked it.

Shopping List

Speaker kit available at The Loudspeaker Kit: