Avantone Gauss 7

Avantone’s newest monitors revive a classic speaker brand and channel the ’70s West Coast studio sound.

Avantone Pro appear to be creating a business out of mining the monitor archive. First it was their MixCube, an homage to the Auratone single‑driver compact monitor; then their CLA‑10 clone of the Yamaha NS‑10; and now the venerable old American speaker brand, Gauss, has found itself brought back to life under the Avantone umbrella. However, Avantone’s new Gauss 7 monitor bears no relation to products by the original Gauss company — Avantone have simply purchased the rights to the name and are planning a range of monitors that will use it.

Before I describe the Avantone Gauss 7 though, I’ll cover a little of the history of the original Gauss company. I write “a little” because it turns out that the Internet has a bit of a blind spot where Gauss are concerned, and there’s not all that much history to be found. It’s not even clear to me if the name, Gauss, was inspired by Carl Friedrich Gauss, the German physicist who gave his name to a unit of magnetic flux, or if that’s just a random coincidence. The basic story, however, is that Gauss were founded in the 1960s by some ex‑JBL driver engineers. They launched a range of 10‑ to 18‑inch‑diameter drivers and horn‑loaded compression tweeters, aimed at PA, guitar backline and US West Coast‑style main studio monitor applications. Gauss also subsequently launched some complete, JBL‑inspired, main monitors. They gained a reputation for engineering advances over their immediate competitors by introducing such innovations as double spider suspensions, direct‑wound aluminium voice coils and formers, and braided voice‑coil lead‑out wires. These are all relatively common features today, but back in the 1960s they were new. Gauss were sold in the 1970s to the parent company of Electro‑Voice and Altec, and then all three brands were sold on to the Telex manufacturing group (now part of Bosch), at which point the Altec and Gauss products were integrated into the Electro‑Voice range and the Gauss name in particular disappeared.

Despite the fact that there’s no direct link between Gauss now and Gauss back in its heyday, the philosophy of Avantone’s new Gauss 7 speaks of the values that are often identified with 1970s studio monitors: high electro‑acoustic efficiency and snappy dynamics prioritised over a ruler‑flat frequency response and low coloration. Having said that though, there wasn’t much alternative to high‑efficiency and somewhat unrefined tonal qualities when amplifier power was more limited than it is today and driver diaphragm and enclosure materials were relatively undeveloped. West Coast monitors of the 1970s were, in these terms, pretty much as far away as it is possible to get from, for example, the BBC monitor sound of around the same time.

Knocking On Seven’s Door

So, to the Gauss 7 itself. It’s a relatively plain‑looking yet neatly detailed two‑way nearfield monitor, of dimensions that ought to cause no problems in the vast majority of studio rooms — even small ones. The cabinet proportions quite usefully eschew the current trend for extended depth, which can only help with installation in cramped spaces. The attractively angular profiled and satin‑black painted MDF front panel carries a nominally 180mm (7‑inch) bass/mid driver and a 30 x 55 mm Air Motion Transformer‑style ribbon tweeter. Behind the front panel, the cabinet sports a ‘black ash’ veneer finish, and towards the bottom left of the front panel is an LED that illuminates in red and blue to indicate standby and normal operation respectively.

The Gauss 7 bass/mid driver is noticeable of course for its white paper diaphragm, which brings to mind not only the NS‑10 and the later Yamaha HS Series of monitors but also Avantone’s own NS‑10 clone, the CLA‑10. However, while the Gauss 7’s white diaphragm shares its paper pulp formulation with the CLA‑10 driver, Avantone Pro say it’s a completely different driver design, with a stiffer diaphragm, larger magnet system and a butyl rubber surround engineered to enable significantly greater diaphragm movement.

The Gauss 7’s AMT tweeter is an all‑new design.The Gauss 7’s AMT tweeter is a fresh design, Avantone say, rather than an off‑the‑shelf item. AMT tweeters differ from pure ribbon devices by employing electrical conductors ‘printed’ on a concertina‑folded substrate rather than using the (usually flat) aluminium ribbon itself as the conductor. In both cases the conductor is held between the poles of a magnet so it moves in response to the electrical signal. The primary advantages of the AMT devices are that, thanks to the length of the conductor, it doesn’t require the input transformer that a pure ribbon needs for impedance matching, and thanks to the large, effective radiating area that results from the concertina folding of the diaphragm, it’s much more efficient. AMT disadvantages are that, in comparison to a pure ribbon, they have significantly higher moving mass (although it’s usually still substantially less than a dome tweeter), and because of their physical diaphragm size they tend to display somewhat restricted high‑frequency dispersion. If you’ve had one eye on the nearfield monitor market in recent times you will probably have noticed the increasing popularity of the AMT ribbon, and there’s little doubt that they can be made to work extremely well.

Around the back of the Gauss 7 there’s a connection, control and heatsink panel. As far as connections are concerned, the Gauss 7 offers analogue balanced inputs with options of TRS jack and XLR sockets. There’s no digital input option. Controls comprise a ±6dB variable gain knob, and switches that engage flat or ±2dB high‑frequency shelf EQ options; and 0dB, ‑2dB or ‑4dB room boundary compensation LF EQ. The ‑2dB and ‑4dB options are suggested for wall and corner installations, respectively.

The rear panel hosts the analogue audio inputs, an input gain knob, HF trim switches and boundary compensation EQ controls.Before I leave matters of Gauss 7 control, if you’ve read many of my reviews you’ll know that I can get grumpy over variable gain knobs, because they introduce doubt over monitor level pair matching. Avantone Pro do actually acknowledge this in the Gauss 7 Quick Start Guide, and suggest that a sound pressure level meter or sound level metering app is used to confirm pair level matching at the listening position. I still think knob detents would be preferable though, firstly because that would mean that no messing about with SPL meters is required, and secondly, setting the level using a full‑band measure of SPL will potentially be skewed by listening position frequency response anomalies that result from differences between left and right monitor locations. For example, if one monitor is significantly closer to a corner than the other, that could result in significantly higher SPL at low and low‑mid frequencies. If the resulting skewed SPL is then measured and compensated by full‑band gain reduction on one monitor, it will then be quieter than its opposite speaker in the upper‑mid and high‑frequency band. One of the more subtle benefits of room/monitor optimisation apps such as Sonarworks, ARC or Dirac Live is that they can fix pair level matching issues such as these, but I still think knob detents or even switches would be better.

Along with the knobs, switches and sockets, a reflex port is also to be found on the Gauss 7 rear panel. The port is of a healthily large diameter (the larger diameter of a port, the more air volume can flow without turbulence) and fairly generously flared. Due to the relatively short cabinet depth of the Gauss 7, its reflex port tube takes a sharp 90‑degree bend downwards internally so that the length required to achieve the appropriate tuning frequency can be made to fit. Port tubes with bends are not unusual so the Gauss 7 is by no means alone in having one, however sharp bends do result in the earlier onset of turbulence. Having said that, bends can also suppress the likelihood of undesirable organ pipe resonance. I’ll investigate the Gauss 7 port with a little FuzzMeasure analysis...

Call The Fuzz

Diagram 1: The Gauss 7’s on‑axis frequency response (red trace), plus measurements taken 20 degrees above and below axis (green and blue traces, respectively)

And speaking of FuzzMeasure analysis, Diagram 1 illustrates the Gauss 7’s axial and 20 degrees vertically off‑axis frequency response, the latter measured both 20 degrees upwards and downwards. The main thing to notice is that the response through the crossover region between 2kHz and 5kHz is somewhat untidy. And where I’d normally expect one or other of the vertical off‑axis curves to display the results of driver overlap interference, in the case of the Gauss 7, both show discontinuities. Having said that, however, when measuring the Gauss 7 I found it was particularly sensitive around the crossover region to microphone position, which suggests that the bass/mid driver response is somewhat variable at the top end of the range, making managing its integration with the tweeter somewhat hit and miss. Such a characteristic is not at all unusual with paper‑diaphragm drivers, especially those engineered for high sensitivity and high volume level potential, as I suspect the Gauss 7 driver is. The second characteristic revealed by Diagram 1 is that, as expected, the AMT tweeter shows relatively restricted vertical off‑axis dispersion.

Diagram 2: A close‑mic measurement of the bass driver reveals a port‑tuning frequency of 50Hz.

Diagrams 2 and 3 reveal some characteristics of the Gauss 7’s low‑frequency performance. The first of the two diagrams illustrates a close‑mic frequency response of the bass/mid driver. And I mean really close; the mic was less than a centimetre from the diaphragm. Make such a measurement with a closed‑box monitor and you’ll see a pretty accurate measure of its low‑frequency roll‑off, and although that doesn’t work with a ported speaker, the technique still offers some useful information. The monitor’s port‑tuning frequency in particular is revealed by a sharp suck‑out. In the case of the Gauss 7, it’s at 50Hz, give or take. 50Hz is pretty typical for a monitor of the Gauss 7’s dimensions, but what is less usual is that the suck‑out is relatively wide and not particularly deep, which suggests that the port resonance is well damped.

Diagram 3: A close‑mic measurement of the Gauss 7’s port.

Diagram 3 illustrates the close‑mic response curve of the reflex port itself. There’s two things to note. Firstly, the port output extends significantly either side of the 50Hz tuning frequency, which confirms that the port Q is relatively low and that the Gauss 7 falls more into a ‘damped reflex’ category than a ‘squeeze as much bandwidth extension as possible out of the port’ category. To my mind this augurs well for the Gauss 7’s subjective low‑frequency performance. The second thing to note is not quite so positive and it’s that, despite the sharp bend in the port tube, the Gauss 7 does appears to suffer some organ pipe port resonance, as revealed by the peaks in the curve at 950Hz, around 1.5kHz, just under 2kHz and just under 3kHz. This series suggests the peaks are harmonically related. The most troubling resonance is the one at 950Hz because not only does it peak at only 8dB below the port’s low‑frequency output, it’s located at a frequency where the ear is extremely sensitive. I’d expect it to make a contribution to the Gauss 7’s subjective signature.

Diagram 4: A waterfall plot measured at the port exit.

To illustrate the port resonance in a little more detail, I generated a waterfall plot of the close‑mic port output, and that’s illustrated in Diagram 4. If you’ve not come across a waterfall plot before, it illustrates how a frequency response decays after the input signal stops. Resonant features are revealed by ridges running from the back to the front. In the Gauss 7 waterfall plot, the major low‑frequency port resonance dominates visually, but the 950Hz feature in particular is also unmistakably apparent.

The final FuzzMeasure curve, Diagram 5, illustrates data I’ve not presented previously in monitor reviews. The frequency response curves displayed are generated by attaching an accelerometer to the side panel of the enclosure to visualise how much, and at what frequencies, it vibrates in response to an input signal. Enclosure panel vibration is important because it can make a significant detrimental contribution to the subjective character of a monitor. The Diagram 5 curves show the cabinet accelerometer outputs of the Gauss 7 and of a BBC LS3/5A, with both monitors generating the same broadband acoustic output level. The differences aren’t insignificant and the Gauss 7 clearly has a less rigid and more resonant cabinet than the BBC LS3/5A — especially in the two octaves from around 400Hz to 1.5kHz where the ear is most sensitive and where so much musically critical information lives. Of course, in some respects, the comparison is unfair because an LS3/5A is not only a far more expensively engineered monitor, it was also specifically designed to reproduce acoustic sources as accurately as possible. Having said that, it’s also the case that the LS3/5A was designed not far short of 50 years ago, so it’s not as if the technology and techniques needed to minimise cabinet vibration are not well known.

Diagram 5: Measurement of cabinet activity taken with an accelerometer placed in the middle of a side panel. The Gauss 7 is shown in blue, and a BBC LS3/5A in red.

Listening In

Despite the fact that I most often in my reviews write about FuzzMeasure analysis before I describe how a monitor sounds, the actual process happens the other way around. It’s important I think that my initial subjective opinion is not influenced by a bunch of objective measurements. And speaking of my subjective opinion, on listening to a variety of CDs and Pro Tools mix sessions, the Gauss 7 revealed itself in general terms to possess a fundamentally usable, if slightly mid‑emphasised and bright tonal balance. I’d be reasonably confident of producing mixes that translate in overall balance terms right from the off, however I pretty quickly reached around to engage the rear panel EQ to drop the tweeter by 2dB. It worked better that way in my studio (I also engaged the ‑2dB LF boundary shelf). The Gauss 7 tweeter, since I’m on the subject, is a success; it is revealing of high‑frequency detail without particularly drawing attention to the fact.

The Gauss 7 reveals an impressive level of mix detail... and its subjective bass quality is notably impressive.

Generally the Gauss 7 reveals an impressive level of mix detail, due to some extent to its mid emphasis (NS‑10 style), albeit with a slightly flat and unfocussed stereo image quality. And its subjective bass quality is notably impressive for an inexpensive ported monitor. To my ears its designers have hit on a good compromise between bandwidth extension and dynamic character. Hand in hand with its low‑frequency performance, the Gauss 7 also impressed with its ability to play at surprisingly high levels without obvious signs of either distortion or compression. In that respect it reflects the original Gauss company’s philosophies well.

However, referring back to my FuzzMeasure analysis, it perhaps won’t come as a surprise to read that, along with the positives, I felt that the Gauss 7 is not without some subjective flaws. In particular, it displays to my ears a noticeable nasal and boxy character that colours voices and acoustic instruments. Feed it with less organic mix elements, synths and processed loops, say, and you may well not notice, but listen to naturally recorded voices, woodwind or acoustic guitars, for example, and the Gauss 7 imprints a degree of its own tonal personality on theirs. I suspect there’s three phenomena responsible: firstly the FuzzMeasure analysis suggests that the bass/mid driver diaphragm is somewhat uncontrolled towards the top of its band, and that could well result in a noticeable upper‑midrange signature. Secondly, the Gauss 7’s cabinet panels clearly play along with the music and, again, this is very likely to be audible (when the BBC LS3/5A was developed, even the variety of wood used for internal cabinet corner battens was found to be significant). And thirdly, that port organ pipe resonance is likely to play a part in the overall sound.

I’ve described some Gauss 7 flaws in that last paragraph, however it’s important I think not to get too hung up on them because the context of the Gauss 7 is, firstly, that it’s inexpensive, and there’s no such thing as a flawless inexpensive monitor, and secondly, that it’s intended to some extent to channel a West Coast vintage monitor vibe. And those monitors were flawed too. There’s also elements of the Gauss 7 that work really well for the price. Its low‑frequency performance is good, it plays loud without trouble and its tweeter works well, so if the vintage vibe appeals, and your mix work doesn’t require the last word in midrange tonal accuracy on voices, the Gauss 7 is an appealing option. I probably wouldn’t want to mix a BBC radio play or a Mozart string quartet on the Gauss 7, but an Eagles tribute band? Absolutely.