Foreword / YouTube Video Review
These speakers were sent to me by Parts Express. I was not paid for this review, however, I believe Parts Express is unlikely to ask for this stuff back since it’s a DIY build.
Also note the bottom section of this review will have some additional stuff that you might be interested in with respect to the DIY aspect of this speaker and verification of the completed speaker’s results.
The review on this website is a brief overview and summary of the objective performance of this speaker. It is not intended to be a deep dive. Moreso, this is information for those who prefer “just the facts” and prefer to have the data without the filler. The video below has more discussion.
< coming soon >
Information and Photos
Specs from the manufacturer can be found here.
- The Samba speaker kit offers revealing and accurate response with incredible detail
- Incredibly flat response throughout the crossover region, ±1.5 dB from 500-15,000 Hz
- Full 6 dB of baffle step compensation for powerful bass response, even away from a wall
- Denovo Audio CNC cut MDF cabinet panels make the enclosure easy to assemble with minimal tools
- This kit includes almost everything you need to build a single high-end bookshelf speaker, including: a knock-down cabinet, drivers, crossover components, and damping material.
The current price is approximately $165 USD each.
Below you can see the kit pieces laid out, getting ready to be built.
CTA-2034 (SPINORAMA) and Accompanying Data
All data collected using Klippel’s Near-Field Scanner. The Near-Field-Scanner 3D (NFS) offers a fully automated acoustic measurement of direct sound radiated from the source under test. The radiated sound is determined in any desired distance and angle in the 3D space outside the scanning surface. Directivity, sound power, SPL response and many more key figures are obtained for any kind of loudspeaker and audio system in near field applications (e.g. studio monitors, mobile devices) as well as far field applications (e.g. professional audio systems). Utilizing a minimum of measurement points, a comprehensive data set is generated containing the loudspeaker’s high resolution, free field sound radiation in the near and far field. For a detailed explanation of how the NFS works and the science behind it, please watch the below discussion with designer Christian Bellmann:
The reference plane in this test is at the tweeter.
Measurements are provided in a format in accordance with the Standard Method of Measurement for In-Home Loudspeakers (ANSI/CTA-2034-A R-2020). For more information, please see this link.
CTA-2034 / SPINORAMA:
The On-axis Frequency Response (0°) is the universal starting point and in many situations it is a fair representation of the first sound to arrive at a listener’s ears.
The Listening Window is a spatial average of the nine amplitude responses in the ±10º vertical and ±30º horizontal angular range. This encompasses those listeners who sit within a typical home theater audience, as well as those who disregard the normal rules when listening alone.
The Early Reflections curve is an estimate of all single-bounce, first-reflections, in a typical listening room.
Sound Power represents all of the sounds arriving at the listening position after any number of reflections from any direction. It is the weighted rms average of all 70 measurements, with individual measurements weighted according to the portion of the spherical surface that they represent.
Sound Power Directivity Index (SPDI): In this standard the SPDI is defined as the difference between the listening window curve and the sound power curve.
Early Reflections Directivity Index (EPDI): is defined as the difference between the listening window curve and the early reflections curve. In small rooms, early reflections figure prominently in what is measured and heard in the room so this curve may provide insights into potential sound quality.
Early Reflections Breakout:
Floor bounce: average of 20º, 30º, 40º down
Ceiling bounce: average of 40º, 50º, 60º up
Front wall bounce: average of 0º, ± 10º, ± 20º, ± 30º horizontal
Side wall bounces: average of ± 40º, ± 50º, ± 60º, ± 70º, ± 80º horizontal
Rear wall bounces: average of 180º, ± 90º horizontal
Estimated In-Room Response:
In theory, with complete 360-degree anechoic data on a loudspeaker and sufficient acoustical and geometrical data on the listening room and its layout it would be possible to estimate with good precision what would be measured by an omnidirectional microphone located in the listening area of that room. By making some simplifying assumptions about the listening space, the data set described above permits a usefully accurate preview of how a given loudspeaker might perform in a typical domestic listening room. Obviously, there are no guarantees, because individual rooms can be acoustically aberrant. Sometimes rooms are excessively reflective (“live”) as happens in certain hot, humid climates, with certain styles of interior décor and in under-furnished rooms. Sometimes rooms are excessively “dead” as in other styles of décor and in some custom home theaters where acoustical treatment has been used excessively. This form of post processing is offered only as an estimate of what might happen in a domestic living space with carpet on the floor and a “normal” amount of seating, drapes and cabinetry.
For these limited circumstances it has been found that a usefully accurate Predicted In-Room (PIR) amplitude response, also known as a “room curve” is obtained by a weighted average consisting of 12 % listening window, 44 % early reflections and 44 % sound power. At very high frequencies errors can creep in because of excessive absorption, microphone directivity, and room geometry. These discrepancies are not considered to be of great importance.
Horizontal Frequency Response (0° to ±90°):
Vertical Frequency Response (0° to ±40°):
Horizontal Contour Plot (normalized):
Vertical Contour Plot (normalized):
Horizontal Polar (Globe) Plot:
This represents the sound field at 2 meters - above 200Hz - per the legend in the upper left.
Vertical Polar (Globe) Plot:
This represents the sound field at 2 meters - above 200Hz - per the legend in the upper left.
Impedance Magnitude and Phase
### Group Delay
Harmonic Distortion at 86dB @ 1m:
Harmonic Distortion at 96dB @ 1m:
Dynamic Range (Instantaneous Compression Test)
The below graphic indicates just how much SPL is lost (compression) or gained (enhancement; usually due to distortion) when the speaker is played at higher output volumes instantly via a 2.7 second logarithmic sine sweep referenced to 76dB at 1 meter. The signals are played consecutively without any additional stimulus applied. Then normalized against the 76dB result.
The tests are conducted in this fashion:
- 76dB at 1 meter (baseline; black)
- 86dB at 1 meter (red)
- 96dB at 1 meter (blue)
- 102dB at 1 meter (purple)
The purpose of this test is to illustrate how much (if at all) the output changes as a speaker’s components temperature increases (i.e., voice coils, crossover components) instantaneously.
Comparison vs Simulation
Once my testing of the completed speaker was finished I then disconnected the crossover and measured the response of the individual drivers (while still attached to the cabinet). Using KLIPPEL’s Near Field Scanner “Export” module I then exported the magnitude+phase of each driver as a text file (360° vertical and horizontal in 10° increments). I imported those files to VituixCAD along with the impedance phase+magnitude and used the crossover schematic provided by Parts-Express to see verify the performance and then to tinker a bit to see if I could improve the crossover and overall performance. You can see this matches nearly perfectly to the measured performance of the completed speaker.
While I am not providing my own crossover suggestions, you can find discussion on this in my Facebook group (link at the bottom of this review). Additionally, I also have a link to the raw data should anyone be interested in trying their own hand at simulating the crossover and possibly making tweaks. That data can be found here (dropbox link). Just make sure you flip the polarity of the tweeter in the simulation! Long story on why the polarity is wrong… but just make sure you don’t forget to do that!
Flipped Tweeter polarity
Does the polarity of the tweeter look like it’s wrong, causing the dip at the crossover region? Yea, I thought so, too. But, it’s not. Because when you do flip the polarity of the tweeter this is what you get:
Parting / Random Thoughts
As stated in the Foreword, this written review is purposely a cliff’s notes version. For details about the performance (objectively and subjectively) please watch the YouTube video. But a couple quick notes based on my listening and what I see in the data:
- Linearity could use some crossover work. Due to the dip in this region these speakers tend to miss upper midrange detail and “bite” or “dynamics” to the sound.
- Output and distortion look quite good until about 100Hz. Even at 96dB @ 1m the distortion is less than 1% above this region. Though, compression at 102dB/1m show issues. The distortion, however, is quite low at about 0.30% above 100Hz at 96dB/1m.
- Bass is good and, with an anechoic F3 of about 50Hz, extends down to around 40Hz in room (mind the volume, as I said above).
In terms of build quality and construction, the speaker kit was super easy to build. I do suggest you purchase crossover boards from Parts Express. These boards cost only about $5 for a pair and make wiring components much more tidy and easier than drilling out scrap MDF. You can see what this looks like in the picture at the top of this review. There are no enclosure resonances and the enclosure itself is braced and the kit comes with some stick-foam padding which is also a nice plus. Everything went together extremely well and while clamps are suggested, they aren’t entirely necessary. Definitely a fun first project if you’re looking to get into DIY.
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