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Discussion Starter · #1 ·
Dear friends,

The Magic Bus embodies a number of superlative attributes with regard to design, fabrication, and sonic performance. Among these, highly regarded audiophiles have raved about its revelatory rendering of bass:

The bass was fabulous in many respects: pitch definition, extension, dynamics, and the ability to play loudly without strain. Kick drum was taut, punchy, and tight, with no sense of slowness or overhang. Moreover, the bottom end, reproduced by enormous bass cabinets in the van’s cargo area, blended seamlessly with the midrange and treble drivers located in front of the listener.
-- Robert Harley, Editor-in-Chief, the abso!ute sound®, Issue 188, Dec '08.

The lower bass was superlative. It was as deep and tight as one could hope for, never calling attention to itself, simply blending in with the rest of the spectrum.
-- Bob Smith / respected DIYMA.com forum member

At CES I heard Whitledge's Magic Bus, and it's by far the best bass I've ever heard in a car. I've run my TH-Mini in my car, and the Magic Bus was deeper and more authoritative, without any kind of 'ringing' or overhang. More importantly, the magic bus didn't sound like the sealed or bandpass subs that I've heard.
-- Patrick Bateman / respected DIYMA.com forum member

There are numerous factors that contribute to the bass performance in the Magic Bus, including the use of
  1. 3 (three) Dynaudio Esotar2 1200 subwoofer loudspeaker transducers with Thiele-Small parameters optimized for sealed enclosure performance. Each of the 3 (three) transducers was meticulously matched to achieve an Fb of 42.4 ± 0.7 Hz, and a Qtc of 0.687 ± 0.006.
  2. 3 (three) Genesis Dual Mono Xtreme amplifiers (bridged for mono) delivering up to 1104 W to each loudspeaker transducer, for a total output power of 3312 W. The amplifiers were carefully level matched to within 0.8%.
  3. a 290-pound Baltic birch enclosure featuring a wall thickness of 3 inches (76 mm) on all sides, thereby limiting enclosure wall deflections to the micrometer level.
  4. 3 (three) separate chambers for each of the loudspeaker transducers, distributing each subwoofer within the spatial confines of the Magic Bus for improved acoustical performance (reference: Dr. Earl Geddes). Consequently, the loudspeaker transducers avoid exciting fundamental resonances.
  5. a centerline subwoofer system placement within the vehicle where the fundamental resonance mode for the width (102 Hz) is null, therefore reducing a major resonance at a frequency best handled by the midbass loudspeaker transducers located at the front sound stage.
  6. 4 (four) military-grade, fail-safe, generator mounts specifically selected and tuned to a resonant frequency of 11 Hz, effectively decoupling the entire subwoofer enclosure from the chassis of the vehicle, thereby reducing its localizability through conduction.
  7. 34 (thirty-four) Helmholtz absorbers, each strategically tuned and placed for maximum effectiveness. The tuning frequencies of bass absorbers were 102, 93, and 36 Hz, which corresponded to fundamental resonant modes in the length, width, and height of the vehicle.
  8. Kimber Kable 12TC loudspeaker cables (8-gauge), routed to minimize their lengths and avoid interference (EMI, RFI, for example), for maximum instantaneous current delivery.

Here’s an entertaining movie of an unthinkable act, which demonstrates the extraordinary rigidity and damping of the Magic Bus’ subwoofer enclosure:

An amazing Feat Performed by the Subwoofer in the Magic Bus

I hope you found this information insightful and this movie entertaining. It has always been my goal to apply state-of-the-art scientific and engineering principles to achieve the most accurate reproduction of music (permitted by the recording), which hopefully, also sounds lifelike. I cordially invite you to experience not only the revelatory bass performance in the Magic Bus but also its other extraordinary balance of playback attributes. Please visit my website frequently to stay abreast with news and upcoming shows.

Warmest regards,
Jon Whitledge
Aug 3, 2013
 

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Jon,

That's amazing! Just last week I was looking at silicone vibration damping methods. I saw vibration mounts and silicone mats and whatnot.

I keep hearing "stories" about the magic bus and have been curious. Perhaps I'll be able to take a trip out to San Diego from Phoenix to give it a listen someday.

Thanks for posting!
Kevin
 

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Weren't the drivers originally in an iso-baric configuration? What happened to that?
...one of the less common, more interesting parts of the build. I also would like to know why the shelving of the additional three subs. Did the theory not ultimately pan out in practice?
 

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im sorry but i wouldnt expect anything to happen to the glass at that volume on any box..

do it at full tilt
 

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im sorry but i wouldnt expect anything to happen to the glass at that volume on any box..

do it at full tilt
Twenty hertz is over fifty six feet long.
To generate twenty hertz without spilling that glass is quite a feat.

SPL cars might get louder, but they generate all their energy in a very narrow set of frequencies, frequently as little as one or two hertz of bandwidth.

On top of that, I've seen SPL cars generate so much energy that the walls of the vehicle flex.

 

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It's funny, this lack of vibration would be considered a fail by most of the YouTube idiots posting videos of "flex" lol. I had no idea the enclosure was 3" thick!:eek: I have uploaded a few videos of my 182s and 430s "flexing" lol but it's just for a reference for myself for different crossover points and slopes, not to impress anyone. Unfortunately that glass on my car would spill and I'm not proud of it. I've run into some dead ends, areas that will never be vibration or flex free.

Jon, your bus is completely free of vibrations inside but I remember the outside mirrors going crazy when you had it cranked up a bit, specifically the cannon blasts. It was an awesome experience for sure.
 

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Lol, very true buickgn i've seen videos of guys proud of their entire vehicle flexing haha all you hear and see if flex and very little bass sound ??? Not my style for sure, in another note from what understand part of jon's magic bus clean bass is no 3 on the list:

-a 290-pound Baltic birch enclosure featuring a wall thickness of 3 inches (76 mm) on all sides, thereby limiting enclosure wall deflections to the micrometer level.

It's ok if you don't daily drive the car but not so good if it's your commuter and have to haul around 300+ lbs inside your trunk/cargo area as gas mileage and overall performance of the vehicle will be affected in a negative way I suppose.
 

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Discussion Starter · #14 ·
SkizeR: please keep your uninformed, negative comments out of my threads. i don't pollute your threads, please don't pollute mine. professional courtesy please.

quality_sound: don't be stuck on the past. but if you must know, they were MW190s in an isobaric configuration. some of the best bass i ever had, but a bit excursion limited. the esotar 1200s play low bass with IMPUNITY! solid frequency response down to 10 Hz. contrary to common belief, one CAN hear a 20 Hz note.

ecobass: the magic bus is my only car and daily driver. it just surpassed the 100k mile mark yesterday. it got 19 mi/gal before the subwoofer, and it still gets 19 on the highway. in the city, about 17. i gladly accept this fuel mileage in exchange for the tunes :)

thanks everyone for your support and wonderful comments. i'm planning to exhibit with Larry Mitchell at T.H.E. Show Las Vegas. please come check out our exhibit. if you play guitar, larry will give you a private lesson on his limited edition Ibanez with Fractal Audio processor through Dynaudio loudspeakers (of course).
 

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SSorry it just didnt translate to me before. But can u try it at full volume to see if it still has no vibration?
 

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Also do u have pics of the mounts? I'm curious as to what they are
 
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