TAD Micro Evolution One loudspeaker Measurements

Sidebar 3: Measurements

I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the TAD Micro Evolution One's frequency response in the farfield, and an Earthworks QTC-40 for the nearfield responses. My estimate of the TAD's sensitivity was 86.2dB(B)/2.83V/m, slightly higher than the specified figure of 85dB. Fig.1 shows how the impedance and electrical phase vary with frequency. Though the impedance has a minimum value of 3.9 ohms between 120 and 155Hz, and there's a combination of 5 ohms and –43° phase angle at 33Hz, the ME1 is a relatively easy load for amplifiers to drive.


Fig.1 TAD Micro Evolution One, electrical impedance (solid) and phase (dashed) (5 ohms/vertical div.).

The traces in fig.1 are free from the small discontinuities that would suggest the presence of panel resonances. However, when I investigated the enclosure's vibrational behavior with a plastic-tape accelerometer, I did find a mode at 367Hz on the metal plates that cover the sidewalls (fig.2), though this was not present on other surfaces to any significant extent. Also visible in this graph is a lower-level mode at 1130Hz; this was more pronounced on the top panel (fig.3). As both the frequency and the Q (Quality factor) of this resonance are high, I doubt it will have any audible consequences.


Fig.2 TAD Micro Evolution One, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of sidewall (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).


Fig.3 TAD Micro Evolution One, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of top panel (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

Tom Norton speculated that the woofer alignment was aperiodic in nature rather than being a traditional reflex (ported) tuning. The blue trace in fig.4 shows the summed output of the four slots to the front and rear of the metal plates on the ME1's sides. It peaks at 40Hz, as suggested by the impedance traces in fig.1, which coincides with the frequency of the notch in the woofer's output (red trace), as is to be expected with a traditional reflex tuning. The slots roll off above their passband, but don't fully support the woofer's midbass output. The crossover between the woofer and the coaxial drive-unit (blue trace) appears to be set at 440Hz, with fairly steep high- and low-pass filter slopes. The coaxial unit's response on the tweeter axis is relatively flat, though small peaks and dips can be seen throughout the treble, these perhaps due to spatially symmetrical reflections of the tweeter's output from the edges of the midrange diaphragm. There is also a slight discontinuity just above 1kHz in the midrange diaphragm's output.


Fig.4 TAD Micro Evolution One, acoustic crossover on tweeter axis at 50", corrected for microphone response, with nearfield responses of midrange unit (green), woofer (red), and port (blue), respectively plotted in the ratios of the square roots of their radiating areas below 350Hz, 1200Hz, and 230Hz.

Fig.5 shows how the outputs of the individual drive-units sum in the farfield, with the response averaged across a 30° horizontal window centered on the tweeter axis. The usual rise in output in the upper bass due to the nearfield measurement technique is very slight, suggesting that the TAD's woofer alignment is overdamped. And, as TJN found, the output rolls off rapidly below 50Hz. Higher in frequency, the slight discontinuity in the upper midrange is still apparent, and while the treble response is even, it appears to slope down slightly in the top octave compared with the trace in fig.3. The horizontal off-axis behavior (fig.6) is both even and very well-controlled, which tends to correlate with stable, accurate stereo imaging. However, the ME1 does become more directional than usual above 8kHz, explaining the difference between the traces in figs. 3 and 4 in the top audio octave. In the vertical plane (fig.7), the tweeter again becomes directional above 8kHz, but the speaker otherwise maintains its balance over a wide window.


Fig.5 TAD Micro Evolution One, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with complex sum of nearfield woofer and port responses plotted below 300Hz.


Fig.6 TAD Micro Evolution One, lateral response family at 50", normalized to response on tweeter axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.


Fig.7 TAD Micro Evolution One, vertical response family at 50", normalized to response on tweeter axis, from back to front: differences in response 45–5° above axis, reference response, differences in response 5–45° below axis.

In the time domain, the speaker's step response on the tweeter axis (fig.8) indicates that all drive-units are connected in positive acoustic polarity. Although the tweeter's output leads that of the midrange, which in turn leads that of the woofer, their outputs meld well, suggesting optimal crossover implementation. The cumulative spectral-decay plot on the tweeter axis (fig.9) is generally clean.


Fig.8 TAD Micro Evolution One, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).


Fig.9 TAD Micro Evolution One, cumulative spectral-decay plot on tweeter axis at 50" (0.15ms risetime).

Other than its limited low frequencies, TAD's Micro Evolution One offered excellent measured performance, not dissimilar to that of TAD's pricey Compact Reference CR1, though with reduced low-frequency extension. I am not surprised that TJN was impressed by its sound quality.—John Atkinson

Technical Audio Devices Laboratories, Inc.
US distributor: MoFi Distribution
1811 W. Bryn Mawr Avenue
Chicago, IL 60660
(312) 738-5025

AllanMarcus's picture

Is the "Micro Evolution One" from TAD some sort of remake of the Evolution Acoustics Micro One? If not, this naming is _really_ confusing, and Evolution Acoustics should be P-Oed.

spacehound's picture

One on the 'marketplace', the other on the speaker itself.

I am pleased to see that TAD has now become a serious player in high end 'domestic' speakers, and quite a popular one. It is good to see a 'real' manufacturer, as opposed to what I call 'a few guys in a garden shed' making speakers and selling them through tiny 'specialist' dealers that only hifi 'enthusiasts' ever visit.
And a major manufacturer such as Pioneer has FAR more resources to call on than the 'garden shed' (or as a maximum, some small industrial unit) manufacturers so is likely to make better speakers. Who are these 'garden shed' outfits? You can guess the two I mostly have in mind :-)
It works, too. I live near Southampton, UK. There are no less than three central 'high street' television/AV/audio shops that carry a small stock of TAD speakers or will quickly obtain them for a 'listen' as they have dealt with Pioneer for many years.

Why do I like it? It is enlarging the marketplace so 'legitimising' it to some extent. The small manufacturers cannot do those things.

The speakers.
As a fan of Tannoy dual-concentric (coincident) speakers I have known that Tannoy have been right all along for fifty years plus, and other manufacturers such as KEF, and now TAD, are confirming that correctness.
However, at 12,000 dollars the price is a nonsense. You can buy Tannoys with ten or twelve inch 'coincident' drive units for that and they sound amazing. And KEF are not far behind.

Whatever you say about this TAD it remains a small squeaky speaker with no real bottom end. No sane person will pay 12,000 dollars for that. It just isn't hifi, though I am sure it is as good as you will get in a small box. Even calling a six and a half inch driver a 'woofer' is nuts, though nowadays everyone does it.

For both of my reasons above, were I to change from my present Tannoys, TAD is the first place I would look, though not at these particular speakers.

prerich45's picture

This is Dave in Milton, nice review and nice measurements! The TAD looks really good with the Rel added on. I see you have given them the nod for Class A (Restricted Extreme LF)...with that said, you also mentioned that other companies can give the TAD's an sincere challenge. Would that statement lead me to believe that we may have other Class A (RE LF) speakers that are far less expensive than the TAD?

hb72's picture

thanks for interesting review! I see lots of text about bass and whether it is sufficient or not: here my thoughts about it:
31 squaremeters may be modest for US standards but is plenty for people living in large cities such as Tokyo, London, NY, also SF, people who also have & want to spend the dough on these beauties for their fancy city flats.

Also I'd like to invite friends of systems that reach below 40Hz (rather one octave pls, not a few semi-tones) to convince me about the indispensability of this very frequency range to great undivided enjoyment of (most) music (i.e. not earthquakes or car-crashes ..).

rzr's picture

This was a terrible review for a very nice loudspeaker. Stereophile has been losing it and this review continues to show this trend. Most of the article used either low-fi marantz, a home theater pre/pro in 2 channel mode, and an amp that has been out of data for over a decade. Why not go buy a $100 sony all in 1 box system at Best Buy to do the review?
The reviewer ups the ante and uses a better pre and amp from BAT, and guess what, the speakers perform better! Amazing when this happens. These speakers should have been reviewed using the BAT pieces 1st, then moved up to better upsacele pieces like the PS Audio BHK and Directstream DAC/Player and guess what, performance would skyrocket. If you want to continue to use a pre/pro and a proceed amp, you should think about going over to Sound and Vision.
The TAD corp should restrict you guys from reviewing any loudspeaker system that costs over $500 until you change your review process

supamark's picture

if you'd actually read the review you'd have noticed he explicitly states that he also works at Sound & Vision (hence the surround system). I've been reading Mr. Norton's reviews for like 30 years, I think he knows a little bit more about all this than you do.

Oh, and Kal Rubenson's review of the $4k pre/pro used:

Since you've demonstrated that you don't actually read through articles, Mr. Rubenson summed it up thus:

"...the decidedly improved analog outputs benefit all audio functions, including analog multichannel pass-through. If your concern is primarily for music playback, can you do better spending $1000 or so for a separate multichannel preamp? No way. It's easy to recommend the AV8802A, despite the bump in cost: It offers cutting-edge features and outstanding sound."

The more you know!

PS - pretty sure the pre/pro is lifted directly from the $7k McIntosh pre/pro with the *identical* back panel - both companies are in the Harmon corporate fold.