Foreword / YouTube Video Review
This speaker was sent to me by the owner in used condition.
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 with respect to the technical merits and subjective notes I had during my listening sessions.
For help understanding the data, I encourage you to watch this video which discusses the implications of (some of) the data shown below:
Information and Photos
Some specs from the manufacturer can be found here.
- Impedance: 4 ohm
- Recommended Amplifier Power:: 25-400W
- Bass/Midrange:: 2 x 5.25” Polypropylene
- High Frequency Driver:: 3 x 1” Soft fabric dome
- Frequency Response:: 80 Hz – 20 kHz, ±3dB
- Sensitivity:: 90 dB, 2.83V/1m
- Grille Dimensions (HxW):: 14.17 x 12.51”, 360 x 318 mm
- Baffle Dimensions (HxW):: 13.93 x 12.24”, 354 x 311 mm
- Wall Cutout (HxW):: 13.03 x 11.33”, 331 x 288 mm
- Mounting Depth:: 3.74”, 95 mm
- Weight:: 18.8 lbs / 8,5 kg
MSRP is approximately $2100 USD each, though, this product is now discontinued (from what I can tell) and is available for much less.
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:
This speaker was measured using the Klippel Near Field Scanner Baffle module, permitting accurate “infinite baffle” results. Per Klippel’s documentation (here):
“By scanning on 2 hemi-spheres in front of the speaker, room reflection as well as diffraction effects from the baffle can be removed, providing accurate half space data."
The test baffle has a sealed volume of approximately 2ft³, though, this speaker is sealed and my baffle wall enclosure has no further effect on the low-frequency response already imparted by the speaker’s internal enclosure. If you would like to see the construction of my baffle, please watch this video.
The reference plane in this test is between the middle tweeter and the midranges (per the manufacturer spec).
I tested the speaker primarily with the grille off and the majority of the data provided is without the grille. But the grille on SPIN result is also provided.
CTA-2034 (SPINORAMA) and Accompanying Data
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.
Response Linearity and Sensitivity
Impedance Magnitude and Phase
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.
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. However, I did perform some “sanity check” listening tests to verify that the data made sense. To do so, I built an 8 foot by 8 foot baffle in my garage. This isn’t large enough to reinforce the entire bass but my concern was more to make sure the data made sense with what it showed in respect to the overall timbre and tonality in the lower midrange and up, along with checking for off-axis consistency. Take this for what it’s worth and understand these are just notes and that the listening was performed in mono (I was only supplied one speaker for review). With those caveats in mind, here is what I heard which does line up with what the data shows:
- Somewhat neutral above the midbass region (above about 300Hz).
- Some lower vocal resonance. Data shows a +6dB bump centered on ~150Hz which backs up what I heard.
- When moving to the side of the speaker, there is a hole in the sound on one side but not the other. Data shows asymmetric horizontal which backs up what I heard.
Due to the multi-woofer/tweeter design, this speaker has a weird dispersion that will sound different depending on which side of the speaker you are on. In other words, if you sit right in front of it you will hear a different sound than you would to either the right or the left, rather than the speaker radiating the same side-to-side. This is going to make placement non-trivial and orientation moreso.
That’s it for the written review.
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