Tom Bowlus’

This Article Was Originally Published On: July 1st, 2014 #Issue 14.

The MAS-210Flex is part of the Michael Arnopol Soundworks “Electric Bass” line of enclosures. As mentioned in the “in-hand” review, this enclosure – and all Big E Loudspeaker designs – employ(s) the Manipulated Vortex Waveguide™ (MVW) alignment, which is explained by Thomas Ewers and Stephen Regier in the article, The MVW Story, immediately following this review.

The 210Flex comes loaded with an impressive array of drivers: two Eminence Kappalite 3010LF woofers, two 6.5” Faital W6N8-120 midrange drivers, and two Ciare 1.26ND TW tweeters. The woofers were held in place by four bolts, secured by the very nice Sigma UltraGrip T-nuts. Wood screws can lose bite over repeated use, and while I did have trouble with two loose T-nuts in Cab Lab reviews from issue #13, these Sigma UltraGrips are really nice, and I would not expect them to come loose in any situation. Great choice. The midrange drivers appeared to be secured in similar fashion, but I was not able to remove them (the gaskets may have “glued” the frames to the baffle, and I did not want to damage the Faital drivers or the enclosure, so I let them be). Likewise, Mike had warned me that installing (and, hence, removing) the tweeters is a very complicated affair, so I left them in place, as well. The Eminence woofers have a nice gasket run around the inside edge of the frame to make for a tight seal against the front baffle.

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There are separate grills for the midrange/tweeter section of the cab and for the woofer section. Both grills are nicely done. The smaller, top grill is cut at an angle to match the slant on the top part of the cab. Foam is adhered to the top and bottom edges of the grill, and the right and left edges are pressed against thin strips of carpet (velcro?) to fight vibration. This grill is held in place by four long screws. The larger grill for the woofer section is held in place with eight of these same screws, and all of them have black, snap-on cap covers for a clean “Philips-head-free” look. The metal for the woofer grill is bent around (and then screwed into) two wooden “rails,” which include an angle cut to match the angle on the front baffle where the cab “flares out” to form the side ports. Very nice touch. The woofer grill also has foam attached to the top and bottom edges to help fight unwanted vibration. I also liked the fact that holes had been drilled through the wooden rails, exactly lining up with the perforation holes in the grill, to help align the screws holding the grill in place.

The exterior surfaces of the cab are coated in what appears to be a fairly thin (but completely covering) layer of Duratex paint. The MAS-210Flex has three handles. The top strap handle is mainly intended to be used while employing the cab’s “tilt-back and roll” feature. Speaking of this feature, the 210Flex has two built-in casters set in the two rear corners of the enclosure. They are good-sized and sturdy, and seem to work quite well. Two large rubber feet (also attached via T-nuts) are set at the two front corners. When stationary, the feet and casters give the enclosure a solid foundation. There are two Ampeg-style “dogbone” handles mounted on the sides. These handles were also held in place using bolts screwed into threaded inserts.

This enclosure is surely no simple build. There are a lot of obtuse angles, slanted surfaces and complex joints. The internal construction of the MVW alignment is also no simple affair. And that’s before we even get to the wiring of all those switching options! Certainly, in regards to both carpentry and wiring/soldering, this is one of the most complex cabs we have had an opportunity to evaluate. In an effort to keep the weight down, Mike has opted for thinner (12mm, or 1/2″), lightweight wood, and actually uses a combination of 1/2″ okume plywood for the outer case and baffle boards, and 1/2″ Italian poplar plywood for the internal construction of the woofer section. The internal construction of the midrange/tweeter section is made from even lighter 3/8″ okume plywood. Okume is a preferred plywood for marine applications, and it’s far from inexpensive. However, it is very light and strong for its size. Another great choice.

Looking at the interior of the 210Flex, there was no evidence of acoustic batting, but the complexity of the MVW alignment construction was apparent. Internal bracing in the woofer enclosure appeared to be mostly glued in place and appeared very sturdy. The interior wiring was extensive, and fairly tidy, using medium-heavy gauge, color-coded wire. Speaker leads were secured to the Kappalite woofers using screw-down binding posts. There are two sets of automotive-style light bulbs, made by Eminence, to provide protection. The two bulbs protecting the tweeter circuit are always on. The other two are positioned at the beginning of the midrange circuit, and are engaged when the Dark setting is selected. As these bulbs are pushed, they impart a gentle compression and a bit of tube-like warmth. The rear panel is fairly sparse, sporting only a recessed metal plate hosting two Speakon connectors. Remove the rear panel of the midrange/tweeter section and things get more complicated, revealing the crossover and wiring rig to handle all of those switch configurations. I was a little concerned, however, that the (already fairly thin) rear panel had to be thinned even more to accommodate one very large capacitor. If the enclosure were to take a solid hit in this area, I would be concerned about the possibility of internal damage.

In addition to our typical suite of measurements, we performed several additional tests to highlight the function of some of the MAS-210Flex’s switches. Fig. 1 is our standard on-and-off-axis chart (performed with all switches in their default settings), and Fig. 2 is our standard impedance curve chart. The additional tests are shown in Fig. 3 (which illustrates the high frequency response at all three Tweeter settings), Fig. 4 (which illustrates the effect of the in-phase and out-of-phase settings on the Voicing switch), and Fig. 5 (which illustrates the Neutral vs Bright settings). As we do in all of our Cab Lab reviews, all measurements were taken at 1m, using 1 watt of amplification. MAS and Big E Loudspeakers claim that additional performance benefits may be observed at higher amplification levels, but we did not run any higher-power tests to either confirm or refute these claims.

Fig 1 On and off-axis (15, 30, 45) frequency response

Fig. 1 On and off-axis (15, 30, 45) frequency response

Fig 2-impedance-curve

Fig. 2 Impedancen curve

Fig 3 Tweeter settings both off one tweeter default both on

Fig. 3 Tweeter settings: both off, one tweeter (default), both on

Fig 4 Voicing settings woffer sectoin in-phase default or out of phase

Fig. 4 Voicing settings: woffer sectoin in-phase (default), or out of phase

Fig 5 SW2 Settin Dark default or Bright

Fig. 5 SW2 Setting: Dark (default) or Bright

bass test
Flex Bass Cab

MAS-210 FLex


Configuration:2x10” woofer, 2x6.5" mid, 2x1” tweeter
Listed Impedance:4 Ohms
Rated Power Handling:900 watts
Inputs/Outputs:Two Neutrik® Speakon® jacks
Dimensions:26”w x 32”h x 14”d
Weight:79.6 lbs
Ports:Unique (MVW)
Baffle Board:12mm, 7-ply okume plywood
Cabinet:12mm, 7-ply Italian poplar plywood and 3/8" okume plywood (for midrange/tweeter enclosure internals)
Grille:Perforated steel (16-gauge)
Handles:Three (one strap-style on top, two side-mounted Ampeg-style "dog bones")
Corners:Metal, non-stacking
Driver Mounting:4 Sigma UltraGrip T-nuts


Woofers: Eminence Kappalite 3010LF
Cone Material:Treated paper, with cloth accordion surround
Voice Coil:Copper (3” diameter)
Magnets:Neodymium (11 oz.)
Midrange:Faital Pro 6.5” W6N8-120
Tweeter:Ciare 1.26ND TW
Mid/Tweeter Adjustment:Unique switching options (see below)
Protection:Bulb type (2 bulbs per woofer)
Speaker Connections:Screw-down binding posts
Crossover:3-way (crossover slopes and points vary with switching options)


Average Sensitivity (200Hz-900Hz):93.84 dBSPL (1 watt @ 1 meter)


Company:Michael Arnopol Soundworks
311 Laurel Avenue
Wilmette, IL 60091 USA
Telephone: 224 628 6162
County of origin:USA
Year of Origin:2013
List Price:$2,000
Street Price:$1,600
Test Unit Options:None
Price as Tested:$1,775
Available colors:Black, standard (custom colors available)
Available Options:None
Acquired from:Michael Arnopol Soundworks
Dates: January - March, 2014
Locales: Ohio
Test Gear (in-hand review):Reeves C225, Mesa/Boogie Strategy, Trace Elliot VA400, 1974 Ampeg V-4B, TecAmp Puma 900, Carvin B1500, Markbass F500,Carvin PB5, Bass VF4-P, F Bass BN5, Sadowsky WL4, MTD 535


1-5 (unacceptable to impeccable)


Features: 5
Tonal Flexibility:5
Ease of Use: 3.5
Tone: 4.5

In-hand Score 4.35average

On-bench Score 4.00average


Road Worthiness: 4
Cabinet Construction:4.5

Sonic Profile:

Lows: Deep, tight, powerful; somewhat warm, but clear
Mids: Able to dial in multiple midrange profiles; clear and articulate
Highs: Extended but smooth; simply beautiful


This cab can do it all, from a sonic perspective. The off-axis (and all around the room) response is very balanced and even. It is full and articulate, and generally smooth, though it can get more aggressive with certain settings.