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Volume VIII Number 1
June 2000


BAG END INFRASUB-18 Subwoofer Review

The BAG END INFRASUB-18 subwoofer immediately gets your attention upon removal from the shipping container. It's large and it's heavy. Ninety-two pounds of speaker measuring in at 23.5"h x 21.25"w x 18.25"d. Remove the front grill and take a step back as you face the action end of an 18" driver. A driver this large even gets oohs and ahs from normally battle hardened, unflappable audiophiles who have been around since the CBS LP/RCA 45 war! Very, very impressive looking hardware. But hey, where's the instruction manual? Would you believe the instructions are written on the metal back panel! That's the complete instructions not just the identification of the controls and connectors. If you ever lose the instructions to this speaker you probably have lost the speaker!

Removing the INFRASUB from its shipping container is as easy as falling off a cliff or falling out of a box. The folks at BAG END are due an award for knowing how to pack a speaker for easy removal (and repacking) from the shipping box. There's no miscellaneous assortment of packing material consisting of numerous assorted sizes of cardboard pieces that resemble a jigsaw puzzle. It's these same cardboard pieces, assuming you've kept them all and remember how they go back into the box, that defy being reinserted in proper position and direction when you are repacking the speaker for shipment. BAG END uses a liquid foam packing material which, once it hardens, conforms exactly to the shape of the speaker. The speaker literally falls out of the box during unpacking and falls into the box during repacking! Why more speaker manufacturers don't use this type of packaging is beyond me; if it's a cost issue I suggest they eliminate the expensive and useless spikes included with most speakers and opt to go for easier packing and unpacking.

The controls and connectors for the INFRASUB are located on the rear black metal panel. And there's two pleasant surprises, at least for me. One, instead of the auto-sensing on/off function found on most subwoofers the INFRASUB has a good old fashion on/off mechanical switch. I prefer to do my own turning on and off for any piece of electronic equipment under my roof, not to mention the fact that you can easily turn the subwoofer on or off as you integrate it with the primary speakers. And two, instead of a permanently attached power cord the INFRASUB has a plug-in power cord. This makes it much easier to move the speaker about without a power cord getting in your way or accidentally being pinched under this behemoth.

The remainder of the controls and connectors on the rear of the INFRASUB's rear panel are as follows: three RCA line input jacks, volume control, speaker level spring loaded connectors, a two position polarity switch (labeled + and - with + being the indicated normal position), and three hi-pass level RCA jacks. All of this hardware mounts to a rear aluminum panel which-judging from the fact that the panel gets warm during operation-acts as a heat sink for the internal 400 Watt power amplifier. The nominal input impedance of the INFRASUB is given as 4 ohms. The black finish speaker enclosure (3 ft3 sealed box) is made from " Medium Density Fiberboard (MDF) and there are no feet on the bottom of the cabinet, making the movement of this behemoth on a carpeted floor (mine) almost a pleasure; for those who think spikes make a difference don't panic, I'm sure BAG END will supply feet, including the "spike" variety!

Before proceeding it should be mentioned that BAG END makes much ado that the INFRASUB uses what is called the Extended Low Frequency (ELF) design concept. I'll spare you the details but there are stated benefits for the ELF system, none which catches the eye more quickly than a stated low frequency extension listed as 8 Hz.! BAG END is quick to point out that , "...it is not audible nor does it have enough acoustical power for you to feel it." Why go to 8 Hz then? BAG END's stated benefit for the low frequency extension is, "...the improved phase response, one of the main benefits of an extended subsonic acoustical response, is preserved..." My own subjective impression of all this technical babble is that BAG END goes lower than any subwoofer I've heard. More about that later.

My listening was done with two sets of speakers (one set a time, of course!) integrated with the INFRASUB. They were the Polk RT7 bookshelf speakers and the Carver Platinum Amazings. My subjective listening impressions follow.

The Pollk RT7s (-3 dB points at 23 kHz and 49 Hz) integrated beautifully with the INFRASUB. I am not into Home Theater (which isn't the same as multi-channel sound) so all of my low frequency material was strictly of the natural kind that emanates from a symphony orchestra. No nonsensical baloney (perhaps BS is a better description) from this guy about while playing the sound of an airplane it caused my mother-in-law to proclaim that the damn airplane almost hit the house. Or I had to get up and check to see if the airplane had just landed on the roof. Phew! Ten years of being associated with the military in Germany makes one acutely aware that the sound of planes, tanks, and weapons of various caliber are, at best, only approximated by even the best of systems.

Once I dialed in the INFRASUB with the Polks the result was a desire on my part to just setback and listen. No, it didn't cause me or my mother-in-law to wonder where the symphony orchestra was but it sure as hell was a fine approximation of the real thing. Regularly attending the Baltimore Symphony concerts at Meyerhoff Hall lead me to listen to the Baltimore Symphony via the recorded route (all CDs, all but one on the Telarc label, and all but two of the Baltimore Symphony). There's something about the addition of a good subwoofer-integrated properly with the primary speakers-which causes the whole frequency spectrum of a symphony orchestra to be heard as it is heard in a concert hall. And it's more than just the obvious extended low frequency response enhancement. To wit: If I turned off the INFRASUB while listening to a bass drum being pounded the diminishment of bass was obvious. However, if I turned of the INFRASUB at a point in the performance where there wasn't any bass it was still obvious to my ears, a hole was created at the lower end. My guess (an educated guess, but still a guess) is that there's subsonic information created as a result of a combination of the orchestra's sound and the acoustical characteristics of the hall. And so there's no wondering...if it can be heard then it should be measurable.

The combination of an inexpensive set of Polk bookshelf speakers and the INFRASUB is sound I could easily live with. Two of my reference CDs (Stravinsky's Rite of Spring, Yoel Levi conducting the Atlanta Symphony, Telarc 80266 and Havhaness' Mount St. Helens Symphony, Gerard Schwarz conducting the seatlle Symphony, Delos 3137) were listened to with and without the INFRASUB. Spectacular sound! If I can leave the reader with only one thought it would be don't believe the popular audio myth (propagated by manufacturers of expensive and small speakers and reviewers who live in apartments) that there's nothing of any importance below 40 Hz!

I had only my reference Sunfire True Subwoofer Signature for comparison purposes and the INFRASUB definitely was better (albeit a very small better) at filling in the bottom portion of a symphony orchestra's sound spectrum. Using test CDs and rough measurements indicated that the INFRASUB is good down to at least 12 Hz and probably even somewhat lower! I realize that's quite a declaration but I'll live with it until the measuring masters prove me wrong (or prove me correct!). As of today I don't think there's any consumer friendly subwoofer (as compared to a subwoofer built into the garage, attic, basement, or some other room in the house) which goes lower. Quite a feat. My tip-of-the-hat to BAG END.

The other side of the coin is when I connected my Carver Platinum Amazings MK IVs in parallel with the INFRASUB. Oh, still fine sound, mind you, but without the physical limitations of the small Polks keeping me in check (output power wise) I was able to play music at extremely loud levels, approximating more closely than with the Polks the sound intensity of an actual performance. Nothing wrong here, in fact the sound was quite good. But when compared to the sound of my Sunfire True Subwoofer Signature (very important-at the same levels!) I preferred the sound of the Sunfire subwoofer. Why? Again, I don't have the instruments to measure with but I would bet a lot of money that what I prefer in the Sunfire/Carver speaker combination-as compared to the INFRASUB/Carver combination-is lower levels of distortion with the former; again, I'm using my ears and a subjective impression in this declaration. And again, if I am wrong I'll hear about it and if I'm correct no one will say anything! Hey, if you can't take the heat then get out of the kitchen, huh!

Okay, I'll admit to playing a sound effects CD, the lifting off of the Space Shuttle Discovery from Cape Canaveral, Sonic Booms 3, Bainbridge 6289. The microphones and associated equipment were located only 4,000 feet from the launch pad and were installed the day before the launch, to be turned on automatically, as no humans are allowed this close. You want loud and low? How about sound averaging (!) 144 dB and a low frequency measured at an unbelievable 1/8 Hz! No, I didn't get up to check and see if the Space Shuttle Discovery was outside my house! But the resulting sound was impressive! Very impressive. And the winner is the Sunfire/Carver combination of speakers. The IFRASUB/Polk duo was limited by the need to spare the lives of the Polks, and the INFRASUB/Carver combination just couldn't go as loud. I can't get too excited about the results as I play the Space Shuttle liftoff maybe twice a year and the symphonic repertoire almost daily.

So, Joe, what's the bottom line with the INFRASUB? At $1,495 they aren't exactly inexpensive but with (I think) the best low frequency extension of any commercially available subwoofer the price is more than reasonable. Ten years ago this kind of performance was just a dream, and 20 years ago there were knowledgeable people saying that anything below 20 Hz was not possible in any reasonable size box and certainly not in any box that would fit into a living room. Again, one heck of an accomplishment on the part of BAG END.

Integrating the INFRASUB with smallish type speakers results in performance that almost defies believability. But when mating the INFRASUB with larger speakers (and the higher sound pressure levels that will invariably follow) I would want to compare before I purchased. Perhaps mating the INFRASUB with something other than the Carver Platinum Amazings MK IVs would result in a different listening experience on my part. All of this said I want to put things into proper perspective. If I had to live with the INFRASUB I would do so knowing that better-if there is such a thing-is nothing more than a personal opinion!

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