YG Acoustics Sonja 1.3 loudspeaker Measurements

Sidebar 3: Measurements

Because of the YGA Sonja 1.3's bulk and mass, I performed the farfield measurements, using DRA Labs' MLSSA system and a calibrated DPA 4006 microphone, only on the Sonja 1.1 module. For the nearfield and spatially averaged room responses of all three modules, I used an Earthworks QTC-40 microphone. The Sonja's voltage sensitivity is specified as 88dB/2.83V/m. However, my estimate was significantly less than that, at 85dB(B)/2.83V/m. The Sonja 1.3 needs a big amplifier to reach the appropriately high SPLs of which it is capable.

The 1.3's electrical impedance is specified as 4 ohms, with a minimum value of 3 ohms. Fig.1 show the measured impedance. It ranges between 3 and 6 ohms most of the time, with slightly greater values in the bass and in the upper midrange. However, not only does the magnitude remain between 3 and 4 ohms throughout the midrange, with a minimum magnitude of 2.73 ohms at 281Hz, but the electrical phase angle is significantly inductive in the midrange, with a combination of 3.8 ohms and +45° phase angle at 814Hz. This speaker needs to be used with an amplifier capable of delivering both amps and volts in quantity—I suspect that the hardness I noted at sustained SPLs above 100dB was simply due to the amplifiers clipping into the demanding impedance. Fig.2 shows the impedance and electrical phase of the Sonja 1.1 module alone. As the input signal is high-pass filtered with a series array of capacitors, this results in the Sonja 1.1 becoming a highly capacitive load in the upper bass and below. Yes, the speaker's output is rolling off by the time you reach the combination of 4.2 ohms and –60° at 70Hz, but music has a lot of energy in this region. The Sonja 1.1 is thus an even more difficult load than the Sonja 1.3, and needs to be used with an amplifier capable of delivering large currents without flinching.1


Fig.1 YGA Sonja 1.3, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).


Fig.2 YGA Sonja 1.1, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).

The traces in figs. 1 and 2 are free from the small discontinuities that would indicate the presence of enclosure resonances; investigating the vibrational behavior of the Sonja 1.1's cabinet with a plastic-tape accelerometer, I found nothing untoward, other than a very mild mode at 815Hz (not shown). However, the 1.2 and 1.3 cabinets emitted faint, metallic-sounding bonks when tapped, and with pink noise I could hear faint whistles from the woofer enclosures when I listened with a stethoscope. The accelerometer revealed the 1.2 cabinet to have relatively strong resonances at 580 and 795Hz, the 1.3 cabinet at 560 and 795Hz (fig.3). Although these frequencies are well above the passbands of the 1.2 and 1.3 woofer enclosures—you would not, therefore, expect them to be excited with music playing—I could faintly hear the midrange resonances when I used a stethoscope to listen to the woofer enclosures while the speaker played pink noise. This is presumably due to the very tight mechanical coupling between the three enclosures. YGA's Yoav Geva does say that these panel vibrations above the woofer crossover frequency are due to the speakers being sited on a nonrigid floor, which hinders efficient draining of the vibrations to ground.


Fig.3 YGA Sonja 1.3, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of 1.3 woofer unit side panel (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

Turning to the YGA's frequency response, the Sonja 1.1's acoustic crossover in the farfield is shown in fig.4. The two midrange units (red trace) offer a superbly flat output in their passband, handing over to the tweeter (blue trace) just below 2kHz. The tweeter's output is basically flat, but with some small peaks and dips evident. (A response graph supplied me by YGA, taken in the NRC's anechoic chamber in Ottawa, was identical in this respect.) The acoustic filter slopes appear to be close to fourth-order low-pass for the midrange drivers, third-order high-pass for the tweeter. The midrange units roll out below 100Hz, reaching –6dB at 65Hz, as specified.


Fig.4 YGA Sonja 1.1, acoustic crossover on HF axis at 50", corrected for microphone response, with summed nearfield responses of midrange units (red) plotted below 400Hz.

Fig.5 shows how the Sonja 1.1's individual responses sum in the farfield, averaged across a 30° horizontal window centered on the tweeter axis (blue trace), to which is added the combined response of the Sonja 1.2 and 1.3 modules (red trace). Despite their different enclosure shapes, the 1.2 and 1.3 behaved identically; the summed nearfield outputs of the 1.2 and 1.3 roll off below 30Hz and above 50Hz. With the spatial averaging evening out the tweeter's behavior in its passband, the Sonja 1.1 offers an astonishingly flat farfield response.


Fig.5 YGA Sonja 1.3, anechoic response on HF axis at 50", averaged across 30° horizontal window and corrected for microphone response (blue), with nearfield responses of Sonja 1.1 module (blue) and the sum of the 1.2 and 1.3 modules (red) plotted below 400 and 200Hz, respectively.

Whether or not a flat on-axis response corresponds to a neutral balance in-room depends on the speaker's radiation pattern. The Sonja 1.1's lateral dispersion, normalized to the tweeter-axis response, is shown in fig.6. Other than in the top octave, the YGA's output generally drops smoothly and evenly to its sides, but there is a slight off-axis flare evident at 5.5kHz. However, this is mainly due to a small suckout in the on-axis response filling in to the sides. In the vertical plane (fig.7, plotted across the full ±45° window rather than the ±15° I sometimes use for large, cumbersome speakers), the vertical dispersion is disturbed by a lack of energy developing more than 10° above and below the tweeter axis. This will be due to destructive interference between the spaced midrange units, and confirms my listening impression that the Sonja's tweeter needs to be aimed at the listening position.


Fig.6 YGA Sonja 1.1, lateral response family at 50", normalized to response on HF axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.


Fig.7 YGA Sonja 1.1, vertical response family at 50", normalized to response on HF axis, from back to front: differences in response 45–5° above axis, reference response, differences in response 5–45° below axis.

The red trace in fig.8 shows the Sonja 1.3s' spatially averaged response in my listening room, with the response of the Vandersteen Treos I reviewed in March shown in blue. (Both traces were generated by averaging 20 1/6-octave–smoothed spectra, taken for the left and right speakers individually using SMUGSoftware's FuzzMeasure 3.0 program and a 96kHz sample rate, in a vertical rectangular grid 36" wide by 18" high and centered on the positions of my ears. This eliminates the room acoustic's effects, and integrates the direct sound of the speakers with the in-room energy to give a curve that I have found correlates reasonably well with a speaker's perceived tonal balance.) Both speakers benefit from the 32Hz diagonal mode in my room, but whereas the Treos rolled off below that mode, the Sonja 1.3s extended at full level to well below 20Hz. There is still a lack of energy between 70 and 120Hz, which leaves the YGAs' lows sounding slightly disconnected from their midrange, but the upper-frequency regions are generally even. Compared with the Vandersteens, which are no slouches in the treble, the YGAs have a slight excess of energy in-room between 5 and 15kHz, which may well correlate with the somewhat analytic-sounding balance.


Fig.8 YGA Sonja 1.3, spatially averaged, 1/6-octave response in JA's listening room (red); and of Vandersteen Treo (blue).

Turning to the time domain, the Sonja 1.1's step response on the tweeter axis (fig.9) indicates that the tweeter and midrange units are all connected in positive acoustic polarity. The decay of the tweeter's step smoothly blends with the start of the midrange step, correlating with the excellent frequency-domain integration of their outputs seen in fig.4. The two woofers' step responses (not shown) confirm that these, too, are connected in positive acoustic polarity. The Sonja 1.1's cumulative spectral-decay plot on the tweeter axis (fig.10) is superbly clean.


Fig.9 YGA Sonja 1.1, step response on HF axis at 50" (5ms time window, 30kHz bandwidth).


Fig.10 YGA Sonja 1.1, cumulative spectral-decay plot on MF axis at 50" (0.15ms risetime).

Finally, I very rarely examine a speaker's distortion because of the difficulty of doing so with absolute accuracy outside of an anechoic chamber. (Ambient noise and the room's acoustics are both interfering variables.) Out of curiosity, however, I did look at the Sonja 1.1's linearity. This is a low-distortion speaker. A 500Hz tone at a high continuous SPL of 95dB at 24" generated just 0.1% of third harmonic (fig.11), while the distortion harmonics were even lower than that with a 1kHz tone at the same SPL (fig.12). In this graph, the second and fourth harmonics are the highest in level, at –66dB each (0.05%). With a stimulus higher in frequency, the tweeter produced about 0.2% of second harmonic at this same high SPL.


Fig.11 YGA Sonja 1.1, spectrum of output on HF axis at 24", 500Hz at 95dB SPL (10dB/vertical div., linear frequency scale).


Fig.12 YGA Sonja 1.1, spectrum of output on HF axis at 24", 1kHz at 95dB SPL (10dB/vertical div., linear frequency scale).

The YGA Sonja 1.3 offered the excellent measured performance you should expect at its price.— John Atkinson

Footnote 1: The 1.1 is also available without the high-pass filter.
YG Acoustics LLC
4941 Allison Street, Unit 10
Arvada, CO 80002
(801) 726-3887

joelha's picture

It's amazing to me how often high priced equipment elicits contempt.

If you don't like the equipment, don't buy it.

But why the contempt and mockery? Is there something about people spending lots of money on high-end product which makes you unhappy?

Do you stand out in front of Lamborghini dealerships upset at the purchases made there yelling "Hey, you could have bought a nice Mercedes instead. What are you, stupid?"

Notice to contemptuous posters: The buyers of high-end product are spending their money, not yours. And even if the'yre the most foolish people in the world for doing so, why do you care so much?

In the case of the YG Sonja 1.3's, they sound absolutely remarkable. I've owned some very high-end speakers in the past and none of them, in my experience, matches them. They do reach realistic sound levels and convey a realism I've found to be virtually unique in the hobby.

I speak from experience as I own a pair.

For those who find my purchase unacceptable, I apologize for the upset my greater enjoyment (and support) of our hobby is causing you.


MVBC's picture

setting a strawman is typical response to pointing out troubling facts based on technical attributes. Your comparison with a Lamborghini is ill advised since sports cars engines are tuned to provide the best weight/power ratio, which 85 or 88 db/2.83V/m for a speaker is not.

JohnnyR's picture

A $108,000 speaker that requires a special amp to drive it because of the horrible impedance and phase response isn't a well thought out or well designed product.

joelha's picture

I've used Krell and Halcro amps to power the Sonja's.

What's so special about them?

And as for your being glad I spent the money instead of you . . . so am I.


JohnnyR's picture

had problemns driving the speaker. Go back and read what he reported in the measurement section. Why is it that both YG and Wilson have probelms with speaker impedance dips, is crossover design the weak part of their company?

jmsent's picture

Any speaker that has a crossover point this low between woofer and midrange is going to require some pretty large inductors and caps to get the job done. This, in combination with the paralleled woofers and a very low resonance frequency is going to result in a very tough load to drive. The same can be said for Wilson's designs, except that they use reflex enclosures. It's nothing new. I had a pair of the original B&W 801's that were well beyond the current capabilities of most amplifiers of the day. At least today, there are behomoths from the likes of Pass and others that can drive the YG's. Personally, I don't think designs like these are well suited to passive crossovers. A well executed active design in this configuration would make much more sense technically, but alas, the "high end" market rejects such products.

GeorgeHolland's picture

As you suggested, using an active design (wasn't the model that came before this active?) Using drivers with higher impedance voice coils so that the parallel combination doesn't dip too much. Using a better crossover design. Using a single larger woofer, a 15 inch instead of two 10's although it's the midrange drivers that are the culprits with their parallel impedance dipping too low around the 200Hz point, fix that problem and it would be okay.

Please understand I am not saying the YG is a horrible speaker but for the money it should be better in this case. Frequency response wise it's very good, the tweeter looks a bit ragged for the price. If they addressed the impedance problems then it would be a lot better. KEF years ago had a model that was virtually flat in impedance across the frequency range.

joelha's picture

If low distortion and remarkably flat frequency response are hallmarks of a weak crossover design, maybe you should re-read the measurements.

In spite of any issues John Atkinson may have had with driving the speaker in one instance, he still concludes with "Class A, all the way".

Have you even heard the speaker?

Between your theory regarding weak crossover design and my first-hand experience, I'm going to have to go with my first-hand experience.

And if you can find something better, at any price, please let me know what it is so I can audition it.


JohnnyR's picture

which may be partly attributed to the crossover design along with driver choices made by the designer and builder have already been mentioned above. Maybe YOU should re-read the measurements yourself. Ignoring the faults already pointed out isn't going to make it any better, sorry.

Atkinson gives out a lot of superlatives to undeserving components, in MY opinion that have problems which are convienly ignored, again MY opinoin.

Sorry again but that "theory" you mentioned is based upon educated scientific knowledge not from some one who just spent too much money on a speaker and was "wowed" by it.  Congrats on liking your new toy, flaws and all.

Have you checked out the two links posted earlier with the open baffle speakers? Have you listened to those?

ChrisS's picture

Comrade JRusskie,

How does your opinion compare to first-hand experience and measurement? Do you think that anything that happens solely in your imagination has any bearing on the real world?

joelha's picture

So let's see, Atkinson is wrong for being so impressed with the Sonja's, I'm wrong for being so impressed by the Sonja's, and you, the one of us three who hasn't heard them, knows better.


And yes I've heard the Linkwitz's and with all due respect to those who love them, in my opinion they're not in the same league.

I'll offer a theory of my own: It really bugs you when anyone spends six figures on an audio product.

Too bad.

I'll continue to enjoy my "toy" and you can continue to be annoyed.


anomaly7's picture

Having heard YG's at shows, I'm convinced they sound as good as they look.

If only you had an online contest where I could win a pair of these...

ChrisS's picture

"When you ain't got nothing, you got nothing to lose
You're invisible now, you got no secrets to conceal.

How does it feel
How does it feel
To be on your own
With no direction home
Like a complete unknown
Like a rolling stone?"

Comrade JRusskie, since you revealed long ago that you have nothiing valid to contribute to the discussion of audio products, you are now just simply annoying.

Patrick Butler's picture

While transducer design has come a long way in the last 50 years, we are still not close to designing and manufacturing anything that could be described as a perfect transducer.  State of the art designs are merely that- the best examples of the art as currently exists.  They all have problems.  The best works are artful compromises, and anybody that tells you differently is selling something.

lap's picture

I just want to say that I greatly appreciate all of you out there that are so worried about someone like me who has "wasted" my money on a pair of YG speakers. I currently own Anat lll Signatures.  Although I do own my own house, my own cars and actually have enough money in the bank to retire now if I wanted to it's very comforting to know that there are so many financial experts out there looking out for me....and audio experts to boot.

pulsetsar's picture

I was wondering about JA's decision to use the Vandersteen Treos (about $6k) in this review as a comparison in the measurements section. Was it just fresh in his mind or was he so impressed by those speakers he felt the need to compare them to ones almost 2 orders of magnitude more expensive! Having heard the Treos I have to agree that they are pretty awesome. Since I wasn't able to find anything else in their price range that could compete, by my ears, I put in order in recently for a pair with Richard Vandersteen himself answering the phone when my dealer called him - talk about service!

John Atkinson's picture

pulsetsar wrote:
Was it just fresh in his mind or was he so impressed by those speakers he felt the need to compare them to ones almost 2 orders of magnitude more expensive!

Mostly the former but definitely some of the latter too,

John Atkinson
Editor, Stereophile

brettmendes's picture

I always find it interesting how dedicated certain people in the audiophile community are to complaining. It's not like some 18 year old kid is saving his pennies to purchase a pair of these. There's no one who's going to save up $100K and then spend it on a pair of speakers. So who do these malcontents think they're defending? The speakers are bought by those that can afford them. I certainly can't and am unlikely to ever be able to. But I still can be curious about them, and these reviews satiate my curiosity. Isn't that part of the point of reviewing them in the first place? 



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