Equipment Review No. 1 July-August 2001
Bag End Infrasub-18 Powered Subwoofer
Bag End Loudspeakers
Description and Specifications: 400 Watt 18" forward firing sealed powered subwoofer. Input channels (RCA jacks) for left, center, and right with high pass outputs at 12dB per octave (-6 db 95 Hz), one pair of speaker level inputs, level adjustment, polarity +/- switch, detachable power cord, and master on/off switch on back of unit. Rated frequency response is 8 - 95 Hz +/- 3dB. Built-In overload protection is provided to prevent damage due to overdriving the sub. 23.5" H x 21.25" W x 18.25" D. 1 year warranty.
Equipment Used: VAC D/A converter MK II, PS Audio P600 power generator, Philips CDC-935 transport, Meridian 568 Preamplifier, Krell KST-100 Amplifier, Audio Research LS-3B Preamplifier, Revel F-30 speakers, and Audioquest, MIT, and Music Metre cables.
I. Placement. The manual consists of a double-sided sheet of paper. Unfortunately, it does not contain any useful information about speaker placement for the Infrasub-18. I suppose that your dealer would be able to help determine the best location given your specific system. If you are like me then you have read several conflicting opinions on where a single subwoofer should be placed in a rectangular room. I started off with the sub in the front left corner. I ended up with it 1' away from the front and 8-10" away from the sidewalls near the right corner next to my equipment rack.
II. Hookup Choice #1. Bag End recommends connecting the output from the front channels of a preamplifier (if available) directly to the subwoofer, and then utilizing the high pass outputs back into the main amplifier. The subwoofer itself has no crossover adjustment. If you don't run a cable back to the main amp and make connections in this manner, then the bass information from the Infrasub-18 and the main speakers will overlap. This could possibly entail very long cable runs to and from the subwoofer, and could get expensive depending on the quality of cable used. For Part I of the review I connected a pair of Audioquest cables to the left and right inputs on the subwoofer and used a pair of Music Metre cables back to the amplifier. When I disconnected the sub for comparison I used the Audioquest cables directly into the amplifier.
III. Hookup Choice #2. Another possibility would involve connecting the subwoofer output from a surround unit to a single input on the Bag End subwoofer. This means that the subwoofer could receive a smaller bandwidth, and allow the main speakers to receive lower bass information. This connection would normally allow a selectable high pass crossover for the main speakers, and an adjustable low pass crossover for the subwoofer depending on how flexible the surround processor/ preamp is. This was the setup used for Part II of the review.
IV. Adjustment. There are only two controls on the back of the subwoofer. One is the level adjustment, and the other is the phase switch. I adjusted the level by ear with the use of the Stereophile Test CD #2, tracks 3 and 16. I also made use of the HFN/RR Test Disc II, tracks 43-48. After some crude adjustments I listened to a few recordings to make sure the level was appropriate. With a 17 Hz tone from the test disc I had a slight rattle in the room from who knows where. At 20 Hz my rack was vibrating and I could feel a throb in the room. At 31.5 Hz there was even more output and the floor was shaking. At 50 Hz there was significant output and in my room this was the most output across the frequency range based on placement of the subwoofer and my listening position. I played with the phase but there was more output in the 0 degree setting (as opposed to the 180 degree setting), so I left it there.
V. Finish. Normally I don't comment on the look of the products I receive unless the look is closely related to the application or claim of the product itself. I felt it necessary to mention that the vinyl covering was already starting to peel in the back left corner of the subwoofer. The Infrasub-18 is offered in a few wood finishes that would push the price of the subwoofer to over $2000. It may be worthwhile however, if the subwoofer is to be in plain view alongside nicer furnishings. From a distance it was not a problem for me, but I usually expect a little more from a speaker in this price range.
Listening-Part I: This section contains comparisons between the output of my stereo preamp into the Bag End subwoofer and out to the amplifier, and direct connections bypassing the subwoofer and running the speakers full-range.
(1) I put on R. Strauss's "Intro to Also Sprach Zarathustra" and J. Strauss "Banditen Galop" from the Telarc Sampler Volume 3. These pieces have extended deep bass and good dynamic range. I found the bass to be deep and taut, well integrated with the Revel F30's, and dynamics were excellent. Everything sounded very good from the start except for whatever it was that was rattling in my living room. I moved a few things around and got the rattling down to a minimum. I felt the urge to play everything really loud. My neighbors might not have been so happy about it though-it was 11:30 at night!
(2) Next I listened to track 1 from Donald Fagen's Nightfly. I felt that the bass was somewhat localizable. It seemed that the crossover might be the reason, but with this connection there was no way to check this. See Part II for further details. Overall I was very impressed with the quality otherwise.
(3) From the Diva CD I listened to Peggy Lee singing "Fever." Bass was clearly emanating from the center of the main speakers on this cut. Unfortunately, Peggy wasn't the only one with a fever-this time it was my fireplace cover (which is metal and glass) vibrating away. By opening it partially I was able to eliminate the rattling. I began to realize how much care must be taken in what goes into a room with a subwoofer capable of the quantity of low bass that the Bag End offers.
(4) After listening for a few days, I began with the critical listening sessions. I wanted to determine if and how much signal loss might be present as a result of my connecting the subwoofer between the preamplifier and amplifier. I put on track 5 from Elton John's Tumbleweed Connection on MFSL. With the subwoofer in the system the low bass had better definition and trailed off more naturally. There appeared to be a slight reduction in high frequencies, and everything seemed just a bit toned down. I checked levels with and without to make sure that the subwoofer wasn't lowering the signal level. I was surprised to find out just the opposite. It seems that when the subwoofer was connecting in between the amplifier and preamplifier, the level was slightly increased. I was able to adjust the volume to compensate. The Revels have a bit of extension in the highs that may not be entirely accurate, so it tended to be easier to listen to the system with the Bag End in the system due to a shift in tonal balance. But without the subwoofer the soundstage width increased and vocals became more natural and 3-D. The sound was bigger and brighter, with a better sense of space. That there was a reduction in bass goes without saying. Note: When I turned off the power on the Infrasub, there was a loud thump. No harm was done, but it was quite startling.
(5) I became more concerned about testing for the loss due to using the internal crossover in the subwoofer. There was no doubt I was gaining an improvement in low bass, in dynamic capability, and pure output, but at what cost? I tried David "Fathead" Newman playing "Night of Nisan" from Atlantic Jazz Flutes. With the subwoofer in the system I was tapping my foot in time with the music and really enjoying myself. When I disconnected the Bag End, the hiss on the recording became more apparent, there was a reduction in low bass, and the sound was not quite as involving. However, there was definitely a slight loss of transparency that occurred when the subwoofer was connected between the amp and preamp. I couldn't determine if it was due to the cables, but I'd guess it was not.
(6) I began to feel that I should check out some familiar recordings that I know have deep bass content just to see how much improvement there was. I put on tracks 1 and 2 from Pink Floyd's Dark Side of the Moon. I have never heard bass this deep in my room before. It felt as if the big "heart" was in the room beating away with the walls bending before it. When the throbbing stopped, in came the mid bass. The bass power was almost scary. Without the subwoofer in the system there was still a good amount of low bass (as the Revels have 10" woofers already), but it was not room shaking. The output level was lower and you could tell the speakers were working harder. The speaker also sounded congested at a higher level. That could have been due to overworking the amp. As I said before, with the Bag End in the system I could definitely play music louder. Instrumentation did improve a bit without the sub. I still go by my recommendation to connect the subwoofer outside of the amp-preamp chain when using revealing equipment and speakers.
Listening-Part II: This section contains listening tests using the internal crossover in the Meridian 568 preamp set to 60 Hz for both the high and low pass signals to the main speakers as well as the Infrasub-18. The Meridian not only offers adjustable crossover frequency in 1 Hz steps, but also allows different adjustments for the high and low pass. In addition, there is a separate subwoofer level depending on which surround/ processing mode is being used (i.e. a setting for stereo, a different setting for Dolby Digital, etc.)
(1) I listened to the "1812" Overture by Tchaikovsky on Telarc from 12 minutes to the end. With the direct connection to the main amp I felt secure that I was not losing a bit of information in the upper ranges while the subwoofer easily handled all the low bass information. Since the range of the subwoofer was narrower, setting the level on it was not as critical as before. Also, I gave myself a way to adjust the level electronically whereas before I could only adjust the level from the back of the subwoofer itself. Since I had such a wide range of adjustability on the Meridian, I could have chosen just about any crossover point. I would think that a standard 80 Hz setting would work fine with just about any speakers and this is a very common setting on almost every surround unit I've ever used. I would think that the people that would be considering the purchase of this subwoofer probably have sophisticated enough equipment that would allow this kind of flexibility. If you are stuck with a stereo setup that does not allow crossover adjustment, and you are not interested in getting an electronic crossover, then it would be worth your while to make sure that there is not an unacceptable amount of loss of resolution when using the internal crossover in the subwoofer.
(2) With track 3 and 4 from Moby's Play, I was certain that I had found the setup I liked. I was hearing everything on the recording with better bass than ever before. When the low bass wasn't present then the Bag End was silent, and when the bass came in it was really there! I like the fact that the Bag End had a slightly more restricting frequency response, because integration with the rest of the system was even better than before.
(3) One song that really has a good bass line is track 8 from Me' Shell Ndegeocello's Peace Beyond Passion. I got super clean upper bass coming out of the Revels, the mid bass overlapped nicely, and the low bass just shook and thudded exactly as I wanted it to. And like before the bass level wasn't that critical. Whether I moved it up or down a little it still blended extremely well.
(4) I decided I should revisit the Donald Fagen track off the Nightfly album mentioned in Part I-(2). The bass level seemed lower at first, but then I realized it was more defined and I was hearing it from between the speakers and not over in the corner. This seemed to solve the problem with being able to localize the bass.
(5) I tried Cannonball Adderley's Somethin' Else on MFSL, track 1. This recording doesn't have all that much low bass, but there is some midbass, and the Infrasub-18 was doing a nice job and not coloring the sound. In fact, you'd think that it wasn't even playing-at first I even had my doubts! So I turned off the main amp and listened to just the base line on the Bag End. I could hear the individual bass notes and the sound climbing up and down in frequency as well as shifts in volume and sustain. Everything was working properly.
(6) Lastly I listened to Toccatta & Fugue in D by Bach and Prokofiev's Romeo and Juliet (Montagues & Capulets) both from the Telarc Sampler #1. I experimented as in (5) by turning the main amp on and off to listen to the contribution made by the Bag End. With the organ piece, the bass was so intense I could feel air moving about 2' away from the subwoofer. My rack was shaking, as was the Bag End on the floor during certain moments in the cut. The bass on the second piece was not as powerful as the first, but was still presented very nicely.
Conclusion: When I first received the Bag End I felt like a little kid the first time your parents leave you home alone and you feel free to play and have a good time. This is how it all began. When most people think of 18" woofers they probably imagine loud obnoxious car stereos booming down the street at 1:00 in the morning. Or maybe what they have in their mind is a big ugly box with one-note bass. That is not the Infrasub-18. It produced bass-deep, tight, clean, controlled bass is what came out of this subwoofer. I easily reached the limit on my power amplifier before the subwoofer came even close to overloading audibly.
When connected via the internal crossover and then to the main amplifier, the Bag End integrated very well with my main speakers. There was a slight loss in transparency with the subwoofer connected to my amp, but this was eliminated with a direct connection from the subwoofer output of my preamp. This is my only hesitation in recommending this sub, and it is a small one. Only on a few recordings was there indications where the bass was coming from, and this too was eliminated when the crossover frequency was lowered. With more experimentation with placement it is possible I could have even better performance, but I was more than happy with the quality of sound with the subwoofer in the corner of my listening room. If you are in the market for serious low bass, then this subwoofer is a must audition. For the quantity and quality of bass produced, the Bag End is a very good value.
- Brian Bloom firstname.lastname@example.org
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