Bag End: M-6 Time-Align monitors, Infrasub-12 PRO subwoofer

When Bag End sent me a three-piece system featuring their new M-6 studio monitors and Infrasub-12 PRO subwoofer, I lugged the heavy boxes over to WMBR Radio (where I used to DJ and engineer live recordings) for my colleagues there to use and test. I had little interest in auditioning these speakers myself. But a couple months later, the engineers at WMBR submitted their review, and I became immediately intrigued with the Bag End system when I read words like "stunning," "remarkable," and "blew away everything else" in the writeup. So I lugged the heavy boxes back to my studio and gave the system a fair shake myself. In the process, I realized how useful a subwoofer can be in "tuning" a room, even if high-quality, full-range speakers are already being used. Let's start off with the review from WMBR, and I'll butt in again afterwards to share my own opinions and revelations. (M-6 each $630 MSRP; Infrasub-12 PRO $2080; www.bagend.com) -AH

We've been big fans of Bag End's line of home audio gear for some time at WMBR studios, so we were naturally excited at the opportunity to check out products in the manufacturer's studio line. Our three-piece demo system consisted of an Infrasub-12 PRO subwoofer and a pair of M-6 Time-Align nearfield monitors as satellites. The sub is an active unit, employing an amp capable of driving its 12'' driver with 400 Watts RMS. The nearfields are passive. We happened to have a Gemini power amp available, and it performed admirably with the M-6's. While we would have liked to test a few different amps, we had little trouble discerning the characteristics of the system with the Gemini.

Setup of the system was very straightforward. The few frequency-shaping and volume controls are all located on the subwoofer; like most passive speakers, the nearfields don't have any settings themselves. The sub's crossover rolls off the lows starting at 80 Hz on the satellites. The Infrasub-12 PRO is designed to be flat down to 8 Hz, but if your source music has too much noise in the sub-bass (e.g., if the music was produced on a system unable to reproduce low frequencies, and therefore, too much sub-bass noise was unknowingly left in the mix), you can switch in a cutoff at 20 Hz. Whether you have the cutoff set at 8 or 20 Hz, given the amount of power required to deliver high volumes at such low frequencies, it would still be possible to overload the sub's 400 W amp. But the designers at Bag End came up with a unique approach to managing signals that have too much low end to reproduce without distortion or damage. The typical method is to employ a limiter or compressor to reduce the amplitude of the signal below the fixed crossover frequency. This can result in pumping or sudden "holes" in the bass whenever the limiter or compressor engages. The Infrasub-12 PRO, on the other hand, utilizes a Dynamic Filter circuit that moves the cutoff frequency of a high-pass filter from 8 Hz (or 20 Hz according to the high-pass switch) upwards to prevent overload. In other words, if a signal with too much low end would require more power to reproduce than available, the Dynamic Filter will temporarily slide the cutoff up to a frequency that will allow full-volume reproduction of the bass content above that frequency. Bag End's reasoning for this approach is that it sounds much more natural and musical to remove just the lowest frequencies while keeping the rest of the bass unaffected than it is to hear all of the bass drop in volume. A remote LED indicator (connected to the sub via an included XLR cable) tells you when this is happening. In practice, we rarely managed to engage the dynamic filter at our normal (but at times loud) recording volumes.

Once we had the Bag End system set up and volume- matched, we were universally impressed. The clarity of the satellites is about what you'd expect from a high-quality monitoring system; all the mids and highs are very sharp and well-defined, which helped pinpoint even the most minor problems with the room setup or mix. Imaging capability is where the M-6's blew away everything else we'd ever used. The trademarked Time-Align design, along with the dual-concentric driver placement (the tweeter is actually inside the woofer) ensures that the portion of the signal reproduced by the M-6's woofer reaches your ear exactly in phase with the portion reproduced by its tweeter-no matter where you're sitting within firing range of the speaker. The result is a very tangible sense of space. This translated into a vast improvement in fine stereo- imaging control, immediately noticeable to everyone who listened to any of the final mixes we did on the system.

The subwoofer was pretty beefy for our small control room, and we had to spend some time tweaking the gain on it so it didn't completely overwhelm the satellites. Once we'd gotten it where we wanted it, the level of detail it was able to deliver in the low end was stunning. This subwoofer actually gives you a reasonable amount of control in shaping the sub-50 Hz regime, with good spectral detail and a response that extends well below the limits of any of our ears. It was a big change from our usual monitoring setup (which doesn't include a subwoofer), and it took all of us some practice before the low end of our mixes translated well. But once we'd spent some time with it, the increased low-frequency control made a huge difference in the quality of our final mixes.

Both the M-6 monitors and the Infrasub-12 PRO subwoofer are remarkable pieces of engineering. The care taken in their design is obvious, and the payoff was a tangible improvement in our mixes, particularly the imaging and low-frequency detail. When purchasing any monitoring system, you have to consider the price/performance ratio (and don't forget the cost of an external amplifier if needed), but to us, the quality and performance of this system certainly justifies the premium price.

-Bryan Cord, Ramsey Tantawi, Nick McCarthy, Kyle Bittinger; www.wmbr.org

Well, I have to agree with what's said above, especially in regards to imaging. I've since purchased a pair of M-6 speakers for my home (and so did reviewer Ramsey). Some of you may recall that I'm a fan of ADAM monitors and that I had a pair of ADAM P11A's installed in my living room. I've now swapped these out for Bag End M-6 speakers. Why? I still love the P11A's (and they're now on my desk in my home office, where I've set up an Isobox with two rackmount computers so I can do editing and production at home). The P11A's sound great, but their sweetspot wasn't big enough for my home theatre, which is wider than it is long. With the M-6's Time-Align and concentric-speaker design, the sweetspot is HUGE! Granted, I don't feel that I get the extreme high-frequency detail with the M-6 that ADAM's unique ribbon tweeter design gives me, but that's a compromise I'm willing to make for a bigger stereo field and incredible midrange clarity from the M-6.

I also purchased an Infrasub-12 PRO subwoofer to supplement the ADAM S3A's in my studio, and it did wonders for the low-end response in my control room. If you've been following my reviews on acoustic treatment, you'll remember that I've been fighting a low-frequency null that manifested itself as a major dip in the speaker-room response at mix position from 63-72 Hz. That "hole" started out about 18 dB deep. With various types of bass trapping, I was not only able to reduce the width of the hole significantly, but its depth shrunk to about 10 dB, which is pretty respectable considering that this hole was the only large peak/dip measured in the smallish (18 ft long) room. Now, with careful installation of the Infrasub-12 PRO, I've effectively filled in that hole completely. I'm proud to report that my speaker- room response measures within ±4 dB of flat from 25 Hz to 18 kHz (frequency-limited by the accuracy of the measurement device) at mix position. And throughout the room, the bass response is fuller, tighter, and pretty much all there. (See www.kimcheerecords.com/articles/studioacoustics/ for plots.) Some of you are probably asking, "How is this so?" The ADAM S3A supposedly has a frequency response of 32 Hz to 35 kHz ±3 dB. Why would you need a subwoofer to deal with an anomaly at 63 Hz?

The problem with relying on nearfield monitors to reproduce the extreme low-end is that the optimal position for the nearfields in terms of imaging and detail (everything but the low-end) may not be the best place for the bass to be generated. The low-end response of the room is most likely to be affected by standing waves as a result of the size, shape, and materials of the room. Standing waves are what cause the peaks and dips in the low-end response. By separating the low-end driver-the subwoofer-from the main left & right monitors, you can move the low-end driver to a position in the room that least excites the room modes (without it sitting in a null point) and therefore causes the fewest standing waves. With the assistance of a room-mode calculator, I was able to position the subwoofer optimally for the best speaker- room response. -AH