Changelog
2/2/19 - Expanded the Keele/Dayton CBT entry and placed it in the main list.
27/1/19 - Expanded the NHT, Technics SB-C700, KS Digital and Arendal entries. Added the Gradient Audio Finland entry into the main list.
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There is a "State-of-the-art Loudspeakers" thread on this forum already. A slight semantic distinction from that thread and my intention here has to be made from the outset. The focus is not on absolute pinnacle performance from cost-no-object speakers. Instead, I hope to share about more affordable loudspeaker designs and manufacturers that have a demonstrable commitment to releasing evidence-based designs consistent with acoustical physics and psychoacoustics, even if they do not quite reach the levels of unsurpassed excellence often appearing in that other thread. There is a surprising variety of driver configurations and design choices in the list that follows - much more so than proponents of subjective intuition-led audio reproduction often assert when they speak of a "boring" homogeneity/convergence arising from evidence-based audio.
However, the nature of divergence in the loudspeakers I describe here is, in my view, consistent with what one might call a
"reasonable pluralism". I will attempt to point out the different priorities of each design and the relative compromises their designers accept. However, what all these designs share is a spirit of progressiveness, advancement and commitment to making rationally-defensible engineering choices - and are most importantly well-priced. From my perspective, it is actually the conventional "hifi" market that is far more homogeneous in its stagnation of design format - think passive flat-baffle "monkey coffins" without any care to match dispersion.
Note: the list is unsorted, work-in-progress (hence the empty entries) and largely stream-of-consciousness for now. If this thread gains traction, I will probably reformat it with a taxonomy based on driver configuration (2-way, 3-way, coaxial etc.) and expand my descriptions. At least one speaker in every listed manufacturer's line has been independently tested to measure well. Special mention has to be given to German magazine Sound and Recording for world-class measurements for several speakers. They deserve all the support we can give for their contributions. You can do so by
purchasing a PDF collating measurements of over 80 speakers (mostly active monitors). You can read more about their measurements in
this thread.
Neumann - The German studio legend, now under Sennheiser, has a
line of active monitors that have impeccable horizontal dispersion (note: refraining from using the more technical term "directivity" in the interests of making this piece accessible). The designs show a clear lineage tracing back to manufacturer Klein+Hummel, which Sennheiser bought over, rebranding their loudspeakers as Neumann products and releasing new designs under the Neumann name. There is existing material on ASR about the importance of at least smooth horizontal dispersion for accurate (and likely preferable) playback from Toole et al.
The Neumanns are perhaps some of the most conventional speakers you will see in this thread. The entire line uses the multi-way non-coaxial driver configuration that dominates audio. However, they use computationally-optimised waveguides (see
here for explanation on what a waveguide is, as well as the importance of seamless horizontal dispersion at least) to ensure a seamless transition in dispersion. Tools like computational fluid dynamics have been used to minimise any sort of anomalous movement of air (think port chuffing and baffle diffraction) within the physical limits intrinsic to the size of each speaker. This explains the complex port shapes and seamless baffles (either cast aluminium or polycarbonate) with no edges. Incredibly advanced construction techniques compared to boring old veneered MDF boxes. All their speakers are excellent, but it is the two babies in the line - the KH80DSP and KH120A - that are conspicuous value leaders for their performance level. The KH80DSP is the latest design. It uses a DSP crossover. It has a 4-inch midwoofer, which basically restricts it to very nearfield or desktop use. However, it is perhaps at the absolute limit of loudspeaker engineering for its size. This is a speaker, that when tested independently at a German acoustics lab,
achieves a +/-0.6 dB (you read that right) on-axis response out of the box (scroll down for measurements). It is flat to 60Hz and has a -6dB point at 52Hz - great for the size. Distortion is state-of-the-art, which allows maximum SPL to be above 90dB right down to 60Hz. It has linear phase response even at crossover due to the use of FIR filtering. The crossover works in tandem with the waveguide to achieve absolute seamless and uniform horizontal dispersion. It has vertical dispersion as good as possible for a non-coaxial, non-symmetrical driver placement (aided no doubt by tight centre-to-centre spacing made possible with the tiny woofer). All that for $1000 a pair. It is pricey, but (in my reckoning) commensurate with the amount of R&D. Did I mention the hiss (always a complaint against active monitors) of the KH80DSP is not just inaudible in the typical sense of being masked by room noise? No, it was tested at
0dbA/1m - just about the absolute threshold of human hearing acuity under any circumstances. The KH80 upstages its older, larger brother, the KH120A, which is designed similarly (and measures quite similarly), but is "only" +/-1.2dB on-axis, has a bit more vertical lobing due to the larger midbass driver, uses an analog active crossover and doesn't have FIR filtering. Still a
very good value as I've outlined. Hopefully a KH120DSP is in the works.
Genelec - A famous name. Much of their product line is like Neumann's. Smooth, seamless low-diffraction enclosures, smooth dispersion for their non-coaxial loudspeaker designs. Neumann is slightly more accurate. Genelec is sold in more places.
Here are polar maps of the most common 2-way Genelecs (provided by the company) compared to the Kali LP-6. However, they have released
'The Ones' - comprising the 8331A, 8341A and 8351A in order of size. This uses coaxial driver loaded in a large waveguide, crossed to double oval-shaped woofers that fire out of slots made by the large waveguide and the rest of the cabinet. There is no baffle in the conventional sense to speak of. The
entire front of the speaker is a waveguide. Sound and Recording has measured the
8331A and
8351A. At the bottom of
this post, I explain the advantages and disadvantages (have edited it from the original for clarity):
Kali - I don't need to introduce them, there is a thread on this forum already. Their story (top designer, blank slate, budget positioning) is well-known, the design well-optimised for its constraints. I have heard reports of both hiss and no hiss. But the
acoustic radiation of the speakers is otherwise beyond any reproach for the price and even much more (see my link early in the post about waveguides and dispersion to understand how to read a
polar map). There are some minor response anomalies to consider though,
like a slightly-depressed treble.
KS Digital - A highly under-the-radar active monitor manufacturer outside of Germany. Their speakers tick a lot of boxes. Coaxial. Sealed. Active DSP with class AB amplifiers. FIR filtering for linear phase at crossover. Aluminium enclosures (with hardwood trim). German-made even. All that for around KEF LS50 passive pricing. Scarcely believable, right? The model I'm referring to, the
C5 Reference, uses a 6.5-inch SEAS Prestige coaxial driver imported from Norway. This entry is special, because it is the C5 Reference inspired this thread.
Sound and Recording measurements here.
It has
some issues but there is, as I wrote, a broader significance to this product:
KSD also has a newer
line that load the coaxial tweeter in a rigid waveguide, reminiscent of Presonus and the old Altec coaxials. I have not seen detailed measurements or indeed much information at all about it.
NHT - I think their fairly long history means they should really be in the "usual suspects" section below. However, the brand was in the woods for a short span in the 2000s, before re-emerging with a direct-sale model. They also seem to have a mediocre reputation among pure subjective audiophiles for their ho-hum Chinese OEM provenance, nondescript aesthetic and association with home theatre (all of which do not predict any acoustic property of their speaker design).
Their speakers are highly well-designed across the entire line and (in a welcome departure) sealed. The idea of a well-engineered flat-baffle 3-way is to offer near-seamless dispersion wider than a waveguide speaker. Waveguides narrow dispersion to help achieve a seamless transition between drivers with a large disparity in radiating diameter. The larger driver's dispersion gradually narrows with higher frequency (and shorter wavelength). Sound path length differences between different points of the radiating surface at HF become significant relative to the wavelength of the frequencies in question.
This necessarily entails acoustic interference (due to the addition and subtraction of out-of-phase signals) that accumulate into highly-attenuated SPL at oblique angles compared to on-axis - ie. a narrowing of the net acoustic radiation a.k.a dispersion with increasing frequency. A flat-baffle 3-way with carefully chosen driver diameters splits the difference so the dispersion mismatch is small enough to be almost eliminated (at least on the horizontal plane of the design axis) through optimising driver placement and crossover topology. This is evident in the
NHT C3, as well as the
Philharmonic BMR.
What of flat-baffle 2-ways? The mismatch in dispersion is very large, and minimising it requires crossing tweeters lower and woofers higher than they'd be comfortable with in virtually all circumstances.
Arendal Sound - Another direct-sale Scandinavian brand, but Arendal hails from Norway instead of Sweden like XTZ. They sell a line of
high-SPL speakers, . They provide
on-axis and off-axis curves as well as impedance response. Drivers are integrated well with a deep waveguide and good crossover. That sort of waveguide promises narrower dispersion but higher SPL capability (together with what look like beefy woofers), which is good perhaps for rooms with harsh specular early reflections from sidewalls. Unfortunately we don't know what smoothing technique they used for the curve, but the graphs don't seem excessively-smoothed.
Technics - The venerable brand's return to high-performance audio was muted, not least because What Hi-Fi gave a two-star review for their coaxial SB-C700 that has no basis in empirical reality. I will not dignify that site with a direct link on my pose.
Stereophile measured them. These are way better designed than the LS50 passive. LS50 has shelved up response (+3dB within the listening window per NRC measurements at Soundstage Network) from 2-5kHz. That's stupidly bright. Its the result of a dispersion mismatch at the crossover frequency - rather ironic because coaxials provide a better basis for smooth-dispersing speakers to be engineered. In contrast, the SB-C700 is totally seamless in dispersion and flat throughout the crossover range. Going by raw driver performance, the Technics is only very slightly behind the Genelec seamless coaxial that covers the midrange up and the KEF Uni-Q. As a complete speaker, the SB-C700 leaves the LS50 (and the other 2-way KEF coaxs without a separate woofer) in the dust. In fact it is
to my knowledge, the best implementation of a pure 2-way coaxial, despite using a passive crossover. It extends cleanly (see
distortion measurements in the third pic of the first post) right down to its 48Hz tuning frequency, giving up little in bass performance to a non-coaxial midwoofer of similar size.
The "peaks and dips" are mostly artifacts of the normalisation technique as mentioned in the KS Digital entry. Also the midwoofers are much larger (6.5-inch vs 5.25 for LS50), which means more headroom and bass extension. In my opinion their white low-diffraction curved enclosures and flat aluminium honeycomb midwoofer look a damn sight better than the LS50's industrial design too.
Gradient Audio Finland - Read up on Jorma Salmi's contributions to audio engineering, talking about his wide-ranging research publications would be beyond the scope of this thread. Suffice to say he, like Siegfried Linkwitz, was concerned about room-agnostic performance and optimising designs using both in-room measurements and a solid foundation in engineering. To this end, Gradient's top offerings are dedicated to exotic driver configurations that achieve unconventional polar patterns like cardioid, dipole or a mix of both. All their speakers are built in Finland using birch ply. Their entry-level offerings are the
Gradient Five standmount and
Gradient Six standmount, both of which using SEAS coaxials customised to their specs and passive radiator bass loading. I have no measurements and only an useless subjective report that they did not sound severely coloured in my experience and were enjoyable on and off-axis. Their flagship, the
Revolution mixes cardioid (in the midrange below baffle step), dipolar (in the bass) and monopolar (in the treble) radiation. They use dual 12-inch woofers mated to a coaxial acting as MF/HF. The
1997 version of the speaker is exemplary for its era and still good by today's standards. It has been incrementally-revised to keep up with driver and active crossover advances of course. The Revolution now is not that of 1997. The Five and Six use the same coaxial as the current Revolution, except those are used "full-range".
Note that even way back then, the custom coaxial they specced does not have any major on-axis dips below 10kHz, and only one at 16kHz, which is more than can be said for some coaxial drivers today (not that it should be a problem IF it fills in immediately off-axis). The
in-room response John Atkinson measured falls within +/-1.3dB at 1/3-octave, one of the best results Atkinson ever measured. Robert E. Greene of The Absolute Sound
reports similarly in his own room.
Constant Beamwidth Transducers (Dayton/DB Keele) - There are two CBTs you can buy as manufactured products: the CBT36 kit and the CBT24 kit/
complete speaker, both offered by Dayton. The CBT24 is on sale for $1495/pr as of February 2, 2019. For mini-monitor money, you can get a bleeding-edge driver array, albeit limited by driver performance. I would personally love to see someone stick in Vifa TG9s or some other widebander with smoother dispersion and FR. Rick Craig of Selah Audio also does custom CBT work at a much higher price range. The CBT
isn't a line array. Despite its looks it is as far as one can get from a line source. The curvature and gradually-decreasing SPL (called "shading") emitted by drivers as one moves up the array come together - as someone described brilliantly on DIYAudio -
a "slice" (like an orange) of the wavefront of a perfect point source placed on the ground plane. Project an imaginary line backwards from each driver at the angle at which the driver is pivoted. Do you see the slice of a sphere now? Exceptionally uniform coverage both vertically and horizontally. No floor bounce because the speaker is on the ground plane. Floyd Toole mused that it could be the
"perfect" surround loudspeaker due to the uniformity of coverage allowing similar sound over a larger seating area.
There is more discussion on another ASR thread.
Note that the CBTs will require subs and ideally DSP to equalise driver response. Don Keele (ex-JBL, designer of the JBL biradials before the CBT array for audio) has an excellent lecture series that examines the properties of CBTs:
<<<<<<<<<<<<<<<<Entries below are work-in-progress>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Danley - Horns, linear phase, point-source. You get the idea.
HEDD - ADAM's co-founder starts a new firm. AMT active monitors, all assembled in Berlin (starting to see a German slant here...). More expensive than ADAMs of a similar design made offshore (T5V and T7V). Unfortunately, the only third-party measurements I could find were from
Russian sources with measuring conditions I'm not so sure of. They have a VST plug-in that linearises FR and phase (HEDD Lineariser). They also use ICEPower for amplification. Add-on support for either Ravenna or Dante is available through slot-in modules. Clever I think. Trivial to add a card if either protocol takes off, but one isn't left with a white elephant if it doesn't.
Merovinger - Custom installer from Germany with a DSP coaxial speaker using an air-motion transformer tweeter. I know the Fluid Audio FPX7 does so too, but the DSP for Merovinger seems more extensive. It is used to linearise both phase and FR, as well as time-align. Need to do more research on these. Intriguing.
ME Geithain - Coaxial, cardioid and active. From, you guessed it, Germany.
ABACUS Electronics - Germany again. Active speakers, preamps, power amps and streamers with built-in Acourate functionality.
The usual suspects (residual category for evidence-based brands that seem to be well-known, so I'll get to them last or simply leave this list unelaborated. Lots of information available from a Google search anyway) - Salk, Philharmonic, ELAC, Ascend, Selah, Seaton Sound, PSB, B&O, Revel, JBL (LSR and Synthesis), ADAM, Buchardt Audio, Vanatoo
