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AUDIOPHILE AUDITION - web magazine for music, audio & home theater
 



  October 2004, Review 1 of 3 [2] [3]

Thorough Bass Inc. Magellan VIII SU Subwoofer & TBI 200 SU Subwoofer Power Amp (Plus Further Listening to Magellan VI )

MAGELLAN VIII SU PASSIVE BASS MODULE SPECIFICATIONS: 
FREQUENCY RESPONSE: 12 Hz – 160 Hz (–6db)
POWER CAPACITY: 175 W RMS (300W IHF)
SENSITIVITY: 87 dB 1w/1m  @ 25Hz
DRIVER COMPLEMENT: 8"  Low Mass Single Piece Convex Aluminum Cone
CONNECTION:  5-way binding Post
IMPEDANCE: 8 ohms
ACCESSORIES: Custom Brass Isolators – Standard Large Rubber feet
DIMENSIONS:
WIDTH: 17.5 inches (444.5 mm)
DEPTH: 17.5 inches (444.5 mm) 
HEIGHT [With spikes]: 6.8 inches ( 172.72 mm) no feet - [8.5" (215.9 mm)]
WEIGHT:26 lbs.  (12kg)
SRP:$1200
 
TBI 200 SU SUBWOOFER POWER AMPLIFIER
SPECIFICATIONS:

FREQUENCY RESPONSE:10 Hz –150 Hz (-3db x-over @ 150 Hz)
POWER OUTPUT: 200W 4? (150W 8?)
CONTROLS: Level—Phase--Crossover 50 Hz-150 Hz (18db/oct)
CONNECTION: 5-way Binding Posts
ACCESSORIES:IEC Power Cord
DIMENSIONS:
WIDTH: 6.25 inches (158.75mm)
DEPTH: 8 inches (203.2mm)
HEIGHT: 6.75 inches (171.45mm)
WEIGHT: 6 lbs. (2.72kg)
AC INPUT REQUIREMENT:120V- 240V 50-60-Hz (Internal Jumper Selectable) 355 VA max
SRP: $450

Intro

This review should be read in conjunction with my review of the Magellan VI SU in the July –Aug. issue. These subs are the big brothers of the VI subwoofers. These subs are 3 inches bigger in width and depth, 1.5 inches higher and 11 pounds heavier than the VI’s. They are rated to go 8 Hz lower in frequency. The same basic theory is used in both subwoofers. Both subs have the same high build quality with a very pleasing look to the units.

You do not see many subwoofers in high-end audio systems. There is a very good reason for this. Most subs are gloried boom boxes, even very expensive ones. In a system they usually do not sound like they are integrated with the main speakers. They usually sound slow and undefined. They also produce bass that is too large in the soundstage. This in turn mucks up the soundstage at all frequencies. Manufactures tend to use large drivers to move lots of air. But large drivers are slow. Most subwoofers run at several percent distortion. This is because a high mass driver traveling at high speeds over several inches of throw length, have a lot of overshoot and response slowness. Many subwoofers like very high power to try to control the overshoot. There is a fallacy that bass is non-directional, and a sub can be put any place in the room. Most manufactures want you to put the subs near walls or corners to boost their output of bass. Most subs do not have enough deep bass response without the walls reinforcing them, however. This is only acceptable if you do not want to have a defined soundstage. Bass notes and their harmonics must line up properly to have natural sound. To do this the subs should be as close as possible to the main speakers.

There is a crossover in most subwoofer systems. The upper end of the subs and the lower end of the main speakers will both try to play the same note. If they are very far apart, the notes will not match up and create image smear. The phase control can be used but can only be set optimally for one or two frequencies. Most subwoofers also pressurize a listening room with high bass output. When a room is pressurized the sound quality of a system totally falls apart. The use of multiple bass drivers in a speaker or subwoofer, enhance this pressurization. It also has a tendency to create an overly big image that is not well defined. When you add the room acoustic problems created by low bass, most audiophiles don’t bother. They would rather have better sound with less or no low bass response than unnatural sound with the deepest bass output.

I received two of the Magellan VIII SU passive subwoofers and two TBI 200 SU Subwoofer Amplifier/ Crossover. I noted the high quality finish and build quality of the subwoofers and amp. The subs came with both rubber and spike feet. I used the spiked feet. As you can see from the dimensions above, that both amp and subs are fairly small in size. Their instructions were minimal and could use some work. The amp came with a removable power chord, which was nice. I used a Kimber power cable on the unit. The speaker wire connectors on the subs were quiet good. The speaker-cable binding posts on the amp were not so good. You need to wrap the wire around the center post or modify a smaller than normal ring connector. The amp allowed for Phase adjustment, 0 or 180 degrees. It would be nice to have continuous phase adjustment. Output volume and crossover frequency controls (50 to 150 Hz with 18 dB per octave crossover) are also included. Unfortunately the amplifier sums the right and left line inputs to mono. The amp will however power two subs in mono.

Setup

I used 16 gauge Monster cable for speaker cable. I ran an 8-foot pair of Jena Labs interconnects between Preamp and amp. I ran a Y connector out of my Preamp sub-out output. I was using a Paradigm 8-inch subwoofer before. It mated well with my electrostatic array, but had little response below 40 Hz. My electrostatic arrays have 5 - 9X22 inch bass panels on each side, which give strong bass response to 50 Hz. Crossing my panels at about 80 Hz made them sound clearer however. I first tried to place the subs in the same position as I had finally decided on for the VI’s. My big screen TV was about 2 feet behind the main speakers. My room is 20 by 21 feet, with the speakers and TV at the left end of the wall and the equipment shelves at the right end of the wall. Pictures of my system can be seen on the www.positive-feedback.com site “Met the Staff” section. The pictures do not include the TBI woofers as yet. The extra size of the VIIIs did not allow me to angle them in between the speakers and the TV. I had to angle them at 90 degrees to the TV. Once I can afford one of the new thinner DLP rear projection TVs, probably a year or two off, I will have more room to play with. I used 25 pounds of lead on top of each sub.

How They Sounded

I used a bass sweep cut on a test CD to determine the frequency response. I got good strong response down to 24 Hz and audible response at 20 Hz. The sound pressure meter showed strong response down to fifteen cycles. At this type of frequency you feel the music more than hear it. The VIIIs did not go too much lower in frequency, but did go down with more ease and slightly stronger output. The real key to these subwoofers is that they are highly tonal in the deep bass. Low notes have character and convey feeling with the music. There is also bass detail in the music that is covered up by the slowness and distortion of most subs. You can hear a bass note travel through the back of the soundstage, which adds a lot of sense of space to the music. On the Gorecki Symphony #3, the underlying bass foundation in the first movement, give you an insight into the true nature of the piece. On New Age music such as Michael Stearns The Lost World the subs added the low octave bass that makes the music more interesting. Without the low bass it is like Musak. On soundtracks such as Angels in America the low bass formed a needed foundation for many of the pieces on the disc. On rock it gave the music a needed sense of power. On organ such as the Dorian Records recording of Pictures at an Exhibition transcribed for organ it allowed you to hear more of the room acoustics of the performance. The best of all was on classical orchestral performances that the bass did not get overly big and dominate the soundstage. The bass came from a certain point and radiated out. Another high point of these subs is how well they mate up with even very fast speakers. The realistic production of very low bass can greatly enhance the music listening experience.

Magellan VI Further Thoughts

Since I have the VIIIs in the main system, I decided to try the VI’s in a completely different sort of a system. The system was a high quality passive preamp, custom built mono amps, a $150 Pioneer uni player and two small Cambridge Audio speakers on stands. The room is about 10-foot wide 22 feet deep with standard ceiling height. This is far from an audiophile system, but a very high achiever of a system. It is a system that is in the process of being developed as part of a video room. The room contained a LCD front projection system that had been highly tweaked. The subs and amps cost more than the whole audio system. I was a little afraid that the subs might over power the room. I also questioned how the subs would match up with speakers that were much slower than my electrostatics. To my surprise and elation, they seamlessly integrated into the system and created some of the best bass that I had heard in a system. We found that 50 pounds of lead bricks helped the sound. Most subs take much more than this. One friend of mine with two conventional subs has 200 pounds of lead on each woofer. Through experimentation we found the subs sounded the best behind the main speakers with the ports pointed into the corners. The subs had even more sense of power in this room than they did in my main room. They produced lots of deep powerful bass without overloading the room. The bass did occasionally rattle things in the listening area, which is to be expected with this low bass. We tried using stereo bass by using two TBI amps to drive the two subwoofers. This added even more sense of power, greater dynamics, more control and better bass imaging.

The subs substantially opened up the sound of the system. With the subs in the system, the sound became audiophile listenable, which it was not before. The subs also added a great deal to the video watching experience. At a listening session at a local speaker builder’s house, we played the DVD-Audio of Koyaanisquatsi. I told them that they were missing a whole octave of bass. They had a large conventional subwoofer that was bigger than six of the VIIIs and placed in the middle of the right side of the room. When their subs got loud the bass sound came from a large nebulas area to the right side of the soundstage. They did not believe it until they heard the piece on the TBIs. The VI’s have found a permanent home in this system. The eventual plan is to add surround sound, upgrade the main speakers and to use a third sub for the surround sub output and leave the two subs in stereo. I don’t ever see having to upgrade the subs.


Summary

Let me start out by saying that this are the only subs that I would own or recommend. The subs mate perfectly into a system with no sense that the sound is not coming from a spacious front soundstage. The subs provided the final step in building my system. Low bass with realistic sound is the hardest thing for a stereo system to do. Most subs sound like they are an addition just tacked onto the system. The bass is detailed, deep, fast and musical. You hear much more of the bass reacting with the acoustical space of the recording. The subs give more texture to the bass, which adds emotion to the sound. I feel that the use of low mass with low movement drivers is the key to the success of these subs. Which subs between the VIs and VIIIs would I suggest depends on your budget and situation. I feel that the VIs would do for most rooms. I feel that there is a need to use two of either of the woofers in any system, because of their lower output per unit. If you have a larger room or want more output, the VIIIs are probably for you. The use of two amps or a stereo amp for stereo bass will add to the sound of your system. One problem with current surround sound based systems is that they have a mono sub output. Most main speakers sound better if the lowest bass is eliminated from them, which can be done using the processor’s bass crossover. This however gives you mono bass. It would be nice to have a stereo output without the bass crossover in addition to main outputs with bass crossover, to be able to use stereo bass into two subwoofers. Also, many recordings are recorded with mono bass. Even using two amps from a mono signal gave some advantages in dynamics and solidity. I feel that using outboard amps is the way to go. Strapping an amp to a heavily vibrating box is not a good idea, especially after you take a lot of care to eliminate vibration from your components. Thorough Bass does offer their subs with amps attached if you should want them. There is also a new version of the VIIIs called the Magellan VIII XU. This version was built to give more above 80 Hz output for speakers than need it. I mentioned in the previous review that I did not care for the speaker cable connectors on the amps; they e-mailed me that they will be improving them. For more information on the speakers you should go to their web site www.thoroughbassinc.com or www.musicalsubwoofers.com. These are great bass music producers and I highly recommend them.

- Clay Swartz








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