Stand Loudspeaker Reviews

TAD CE1TX loudspeaker Measurements

Sidebar 3: Measurements

I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the TAD CE1TX's behavior in the farfield, and an Earthworks QTC-40 mike for the nearfield responses. The mesh that covers the coaxial drive unit can't be removed, but the measured behavior was taken without the grille covering the woofer.

Fig.1 Tad CE1TX, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

Tad specifies the CE1TX's voltage sensitivity as 85dB/2.83V/m, which is 2dB lower than average; my B-weighted estimate was within experimental error of that figure, at 84.7dB(B)/2.83V/m. The speaker's nominal impedance is specified as 4 ohms. My measurement, taken with Dayton Audio's DATS V2 system, indicates that the impedance magnitude (fig.1, solid trace) drops slightly below 4 ohms in the lower midrange, with a minimum value of 3.61 ohms at 124Hz. The magnitude is higher than 8 ohms in the very low bass and for almost the entire treble, however. The electrical phase angle (dotted trace) is occasionally high, which means that the equivalent peak dissipation resistance, or EPDR (footnote 1), lies below 3 ohms from the midbass region through the upper midrange and in the top audio octave. The minimum EPDR values are 1.45 ohms at 35Hz, 2 ohms at 60Hz, and 2.03 ohms at 861Hz. Its low effective resistance and lowish sensitivity mean that the CE1TX needs to be paired with amplifiers that can deliver both voltage and current.

Fig.2 Tad CE1TX, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of metal plate that covers one of the sidewall (measurement bandwidth, 2kHz).

The impedance traces are free from the small discontinuities in the midrange that would indicate the presence of panel resonances in the enclosure. The wooden cabinet did seem extremely inert when I rapped it with my knuckles, and when I investigated these panels' vibrational behavior with a plastic-tape accelerometer, I didn't find any resonances. However, a fairly strong resonant mode at 588Hz was present on the metal plates that cover the reflex vents on the sides of the enclosure, with a lower-level mode slightly lower in frequency (fig.2). As these modes are both relatively high in frequency and have a high Q (Quality Factor), their effect on music should be minimal.

Fig.3 Tad CE1TX, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with the nearfield midrange (green), woofer (blue), and port (red) responses respectively plotted below 400Hz, 800Hz and 500Hz.

The Tad speaker's impedance-magnitude plot has a low-frequency saddle centered just below 40Hz, suggesting that this is the tuning frequency of the reflex-loading slots between the wooden side panels and the metal plates. The woofer's nearfield response (fig.3, blue trace) has the expected notch at this frequency, and the port's output (red trace) peaks sharply between 30Hz and 60Hz. The port's upper-frequency rolloff is clean overall, though some low-level peaks are present at 150Hz and between 200Hz and 500Hz. The woofer's output rolls off above 150Hz with what appears to be an 18dB/octave slope, and the midrange unit's output, measured in the nearfield (green trace), rolls off below 300Hz with the same third-order slope. The crossover frequency between these two drivers appears to be close to the specified 250Hz.

The complex sum of the midrange, woofer, and port responses is shown as the black trace below 300Hz in fig.3. The usual boost in the upper bass, which will be due to the nearfield measurement technique, is absent, which suggests that the Tad speaker's reflex alignment is tuned for articulation and low-frequency clarity rather than bass weight. The black trace above 300Hz in fig.3 shows the CE1TX's farfield output, averaged across a 30° horizontal window centered on the tweeter axis. The balance is even but with a slight lack of energy in the presence region and some small peaks and dips above 7kHz, the latter due to the coaxial mounting of the tweeter.

Fig.4 Tad CE1TX, 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.5 Tad CE1TX, 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.

The Tad speaker's horizontal dispersion, normalized to the response on the tweeter axis (fig.4), is similarly uneven in the same HF region but is otherwise well-controlled. The lack of presence-region energy in the on-axis response tends to fill in to the speaker's sides, which suggests that the CE1TX's treble balance will be neutral in all but very small rooms. As expected from use of a coaxial drive unit, the vertical dispersion (fig.5) is very similar to that in the horizontal plane.

Fig.6 Tad CE1TX, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).

Fig.7 Tad CE1TX, cumulative spectral-decay plot on tweeter axis at 50" (0.15ms risetime).

In the time domain, the CE1TX's step response on the tweeter axis (fig.6) shows that the tweeter's output arrives first at the microphone, followed by that of the midrange unit, then that of the woofer. All three drivers are connected in positive acoustic polarity, and the decay of each unit's step blends smoothly with the start of that lower in frequency, which suggests optimal crossover implementation. Other than some small ridges of delayed energy in the top octave and some ripples in the upper midrange, the speaker's cumulative spectral-decay ("waterfall") plot (fig.7) is superbly clean.

When I reviewed Tad's Compact Reference CR1 standmount, which employed a similar array of drive units, in January 2012, I was impressed both by its sound quality and by its measured behavior. I wait to read what Herb Reichert thought about the Tad CE1TX's sound quality but, as with the original CR1, this loudspeaker's measured performance is superb.—John Atkinson

Footnote 1: EPDR is the resistive load that gives rise to the same peak dissipation in an amplifier's output devices as the loudspeaker. See "Audio Power Amplifiers for Loudspeaker Loads," JAES, Vol.42 No.9, September 1994, and stereophile.com/reference/707heavy/index.html.

COMMENTS

max SPL

Submitted by JRT on May 18, 2023 - 7:27pm

The specs in this review and in TAD's marketing webpage do not include maximum SPL, which is useful in determining the maximum signal crests which can be accomodated relative to a specific propagation distance and Lref (reference level). The 200W maximum power handling is presumably a thermal limit rather than a nonlinear distortion based limit or mechanical excursion based limit, and that thermal limit is presumably relative to a longish time averaged interval of music signal rather than accomodating signal crests without significant mechanical clipping.

Looking at KEF's published specifications for the Blade Two Meta for comparison, KEF lists max SPL at 116_dB, but with no SPL filter weighting or other conditions mentioned.

Audio Engineering Society has recently published AES75-2023,
"Abstract: This standard details a procedure for measuring maximum linear sound levels of a loudspeaker system or driver using a test signal called Music-Noise. In order to measure maximum linear sound levels meaningfully and repeatably, a signal is required whose RMS and peak levels as functions of frequency have been shown to be representative of program material. Various existing standards define noise-based test signals which, like Music-Noise, have incorporated the knowledge that typical program material has a diminishing RMS level with increasing frequency, but Music-Noise uniquely also features a relatively constant peak level as a function of frequency, so that the crest factor (peak level – RMS level) increases with frequency, which an analysis on a large variety of music and other content has revealed is an important additional characteristic of typical program material. The specified procedure determines a loudspeaker’s maximum linear sound levels by incrementally increasing the Playback Level of Music-Noise until a stop condition is met: either an unacceptable change in the transfer function’s magnitude or an unacceptable change in the coherence of the transfer function."

I appreciate the measurements already included in these reviews, appreciate the significant effort that goes into providing those, and understand that J.C.Atkinson is not likely in need of more work to keep himself busy. That said, it would be better to see max SPL IAW AES75-2023 included in Stereophile's published measurements of loudspeakers, not only because the data itself is very useful, but also because publishing that would bring added useful considerations to the reader's attention, get them thinking more about accomodating signal crests without clipping, electrical or mechanical, in high quality playback.

More information about M-Noise and related measurements are detailed at the following link.
https://m-noise.org/

Julia Wolfe

Submitted by AaronGarrett on May 18, 2023 - 10:12am

That Julia Wolfe recording is great! I'm on a Grisey kick at the moment. I don't know if it's your kind of thing but I'm totally hooked on this https://i.imgur.com/gXcAeQZ.png

Puzzled

Submitted by Nirodha352 on May 18, 2023 - 10:27pm

So… low impedance and sensitivity don’t matter anymore after having been branded bad boys by reviewers for ages?

A speaker I'd love to have ...

Submitted by Long-time listener on May 18, 2023 - 10:31pm

...if I could afford it. But first, if I'm paying $32,000, I'd ask that they make it less ugly before they deliver it to me. Its visual design is discombobulated and all-over-the-place: There is a white ring around the upper drivers, and a black ring around the lower; there is an unpleasantly cheesy, orangish wood veneer coupled with metal side panels. At the very least, change the white ring to black to bring some unity and harmony to the visual design.

Just because the sound engineers can produce a good-sounding speaker doesn't mean they can produce one that looks good. Sheesh. For $32,000?

Trademark Design

Submitted by funambulistic on May 19, 2023 - 8:48am

It seems all of TAD's speakers use the white/silver ring on the mid/tweet - it is kind of their thing. I tend to agree with you on their choice of wood as it is not for me. I would prefer something darker, like walnut. The ME1 (smaller version to the CE1) comes in piano black or silver, which would be a nice option on the CE1. Going up the line, the Reference models come in Beryl Red (meh) or Emerald Black (nice!).

Submitted by tenorman on May 19, 2023 - 7:22pm

A midrange more or less reminiscent of the best horns?

Submitted by orfeo_monteverdi on May 19, 2023 - 1:39pm

[please forgive my poor English]

First of all, please note the question mark in the title, as well as the words "more or less" and "reminiscent", as I am aware that, otherwise, the title could trigger reactions (after all, we are talking about a 4 Ohms low sensitivity speaker).

Many thanks Herb for this thouroughful review. Always a pleasure to read you, sincerely.

I listened to the 1st European pair a few months ago, at a dealer's. It was a burnt in pair, touring in Europe. The dealer is still waiting for his own pair.

The partnered electronics may not be have been ideal, but what I could hear later in the afternoon, just before attending a concert the same evening, became interesting. It is that experience, which specifically focused on the midrange, that I wished to share.

I listened to lieder (piano and baritone voice here) through the CE1-TX. Though there were no horn speaker under the hand to compare, I was struck by two things: the "rightness" of the piano (no high bass/low-mid emphasis which usually makes sound the left hand on a Steinway like a Harbeth - I own a pair of Harbeth M30.2 Anniversary, I'm definitely not trying to shock anyone here).

But most of all, I was struck by the incredible clarity, expressiveness and naturalness of the voice. We played at concert volume, at least subjectively (I sat approx. 3,5m-4m away from the speakers). Then, 120 minutes later, I was sitting right in front of the German baritone Benjamin Appl, 10th row (in a concert hall endowed with a very good acoustics - remember? I'm the "posh tippler", as you nicknamed me ;-) And Benjamin Appl sang exactly the same piece of music I heard on the CE1-TX two hours earlier (I had chosen them purposely for the TADs of course). The way the CE1-TX is able to project voices (in the best sense of the word) in a nearly "live concert way", is astounding; voices remain perfectly natural though, without coarseness or "astringency". And this reminds me a little of bit of horns (the best ones, not the fatiguing ones). To reach such a sound pressure level and expressiveness, a powerful amplifier might be required, though your feedback on what the low-powered First Watt Sit3 (30W facing 4 Ohms) is capable of with that speaker, is really intriguing and, for the prospect, is worth investigating.

Of course, one must not (or should not) play at such high sound pressure levels in town, with neighbors. Therefore the importance of another point: how do the CE1-TX behave at low, even very low level? (Steve Guttenberg in his YT video review seems to say that they still sound great at low level, even at very low level).

The speakers should come back at the dealer's in a few weeks. I will be able to assess them more thoroughly. They seem definitely promising, maybe even one of a kind.

Another point that struck me in your review was that the Harbeth 30.2 Anniversary (that I own, in a 2nd system) is the one speaker this TAD "reminds [you] of most"; not the Joseph Audio Pusar Graphene (which has nevertheless a higher-grade Scanspeak tweeter than the M30.2; the treble of the M30.2 is very good -you even wrote "gorgeous"-, but in absolute terms, I find that it lacks "magic" and air by comparison - the TAD, by contrast, are champions here). The TAD CE1-TX may remind me a little of my M30.2 Anniversary too (just a little, as far as I am concerned), but the CE1-TX are quite a different animal for sure. It seems they convey music in a unique way for their size. To be confirmed...

Kind regards from Europe.

PS: I live in such a tiny country that there is no need to be a tippler, even less to be posh, to access great concert halls just next door ;-)
Nevertheless, I like "posh tippler". I keep it. Thanks!

Lively. Vivid.

Submitted by laxr5rs on May 25, 2023 - 10:12am

If you ever hear me attempt to describe speaker performance with words like that, poor cold water on me and tell me I'm hopped up on goofballs. The subjective review is a ghost story.

Shake Sugaree

Submitted by Idano-nuttin' on December 8, 2023 - 12:45pm

Jerry Garcia first recorded 'Sugaree' on his eponymously named first solo album 'Garcia'. Different altogether than EC's song. Also, if Herb's friend had never heard (of) EC, how did he know 'THAT was how that recording was supposed to sound'? These may be fabulous sounding speakers, but like most standmounts, not pleasing aesthetically in the least.

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Stand Loudspeaker Reviews

TAD CE1TX loudspeaker Measurements