Author Topic: giant "back to the future" subwoofer for real  (Read 5943 times)

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Offline FrankBuss

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giant "back to the future" subwoofer for real
« on: June 14, 2014, 03:42:16 pm »
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Offline Noise Floor

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Re: giant "back to the future" subwoofer for real
« Reply #1 on: June 14, 2014, 04:46:14 pm »
I'm glad they summarized it fairly. :)
 

Offline FrankBuss

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Re: giant "back to the future" subwoofer for real
« Reply #2 on: June 14, 2014, 05:38:14 pm »
I'm glad they summarized it fairly. :)
Right, I wonder why it doesn't appear louder in the video with that much power. Must have a terrible efficiency factor. Or they need to connect an additional guitar amplifier and use it with a guitar :)
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Offline SeanB

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Re: giant "back to the future" subwoofer for real
« Reply #3 on: June 14, 2014, 05:46:29 pm »
Probably the AGC of the camera used, along with the built in microphone having almost zero response at the 34Hz used. Most camcorder microphones have a very steep filtering below 150Hz to reduce both mains hum, handling noise and wind noise. They are in no way going to be good at recording bass notes. Most of the recording seems to be the regular speakers used as mid range ( if you can call using a 10 inch woofer as midrange, but with that big sub it is so) and tweeters.
 

Offline BennyBoy

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Re: giant "back to the future" subwoofer for real
« Reply #4 on: June 14, 2014, 11:33:50 pm »
Doc's was full range! :scared:
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Offline AmmoJammo

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Re: giant "back to the future" subwoofer for real
« Reply #5 on: June 15, 2014, 01:24:21 am »
Doesn't seem very loud... when you overload the microphone in a camera, it stops recording the mids and highs as well ;)
 

Offline Flump

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Re: giant "back to the future" subwoofer for real
« Reply #6 on: June 15, 2014, 01:28:53 am »
yeah a mate of mine recorded my home audio setup
and the bass from the sub turned the audio to shit
couldn't even hear anything he was saying when the sub
was hitting the lows and rattling me door knocker
 

Offline zapta

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Re: giant "back to the future" subwoofer for real
« Reply #7 on: June 17, 2014, 01:26:08 am »
WMD

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Offline Stonent

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Re: giant "back to the future" subwoofer for real
« Reply #8 on: June 17, 2014, 04:33:40 am »
*Slight* chance of overload
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Offline TerraHertz

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Re: giant "back to the future" subwoofer for real
« Reply #9 on: June 17, 2014, 12:24:55 pm »
WMD

Weapon of Mass Distortion?

The room windows didn't break. Nobody bleeding from the ears. Not good enough.
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Offline Legit-Design

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Re: giant "back to the future" subwoofer for real
« Reply #10 on: June 17, 2014, 01:03:13 pm »
I think it needs bigger magnet and speaker coil. In proportion that's not very big when compared to some bigass subwoofers.
 

Offline rob77

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Re: giant "back to the future" subwoofer for real
« Reply #11 on: June 17, 2014, 01:18:36 pm »
i think the cone is way too heavy to be any good ;) compare it to the regular woofers - few grams of cone, few grams of voice coil and few hundred of watts, while the woofer in the video has many kilograms of cone and 7kW of power... i wouldn't be surprised if a low-end cheap (but high power)  sub-woofer would outperform it :D
 

Offline M4trix

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Re: giant "back to the future" subwoofer for real
« Reply #12 on: June 17, 2014, 01:34:17 pm »
I would like to see what's inside that '8kW' amplifier.   :-/O
 

Offline TMM

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Re: giant "back to the future" subwoofer for real
« Reply #13 on: June 17, 2014, 01:39:31 pm »
i think the cone is way too heavy to be any good ;) compare it to the regular woofers - few grams of cone, few grams of voice coil and few hundred of watts, while the woofer in the video has many kilograms of cone and 7kW of power... i wouldn't be surprised if a low-end cheap (but high power)  sub-woofer would outperform it :D
Yep, this. Also the cone seemed to be supported by a rather small bush bearing on the metal pole in the center rather than being properly suspended.
 

Offline rob77

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Re: giant "back to the future" subwoofer for real
« Reply #14 on: June 17, 2014, 01:49:56 pm »
I would like to see what's inside that '8kW' amplifier.   :-/O

not too much ;) i assume it's a D-class power amp. so what you would find there (very simplified description) is a bridge rectifier, filer caps, a mosfet H bridge and a big ass low pass filter. the audio signal is converted to PWM and the H bridge is driven by that signal - the low-pass at the output is smoothing it out back to analog.
 

Offline TerraHertz

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Re: giant "back to the future" subwoofer for real
« Reply #15 on: June 17, 2014, 02:47:33 pm »
About that cone. I noticed that when it's supposed to be driving in and out, if you look at the reflections of the ceiling lights in the cone, there's a difference in how the reflections behave nearer the (lower) rim of the cone.
If the cone as a whole was traveling back and forth without distorting, the light reflections should do the same everywhere on the cone.
Collecting old scopes, logic analyzers, and unfinished projects. http://everist.org
 

Offline rob77

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Re: giant "back to the future" subwoofer for real
« Reply #16 on: June 17, 2014, 03:39:03 pm »
About that cone. I noticed that when it's supposed to be driving in and out, if you look at the reflections of the ceiling lights in the cone, there's a difference in how the reflections behave nearer the (lower) rim of the cone.
If the cone as a whole was traveling back and forth without distorting, the light reflections should do the same everywhere on the cone.

yes, noticed that as well.. that cone is way to heavy and lacks stiffness , so instead of traveling forth and back it's just flexing. (and most of the energy is absorbed by that flexing instead of moving the air and generating sound waves )

i would say those guys could have spend the many in a better way :D or they should have doing more research before building it ;)
 

Offline jlmoon

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Re: giant "back to the future" subwoofer for real
« Reply #17 on: June 17, 2014, 03:53:25 pm »
I would like to see what's inside that '8kW' amplifier.   :-/O

lots of smoke waiting to get out!.. er.. I mean released..

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Offline rob77

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Re: giant "back to the future" subwoofer for real
« Reply #18 on: June 18, 2014, 02:10:18 am »
i just noticed the rivets in the cone  :-DD LOVELY !  :-DD

at least they should have made the cone out of carbon - less weight and much more stiffness (but the cost would go rocket high :D )
 

Offline SL4P

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Re: giant "back to the future" subwoofer for real
« Reply #19 on: June 18, 2014, 02:29:20 am »
You can see the light reflections on the cone - suggest the cone is not rigid, hence all sports of intermodulation distortion on the audio projection (let alone anything in the driver stages).
Fix the cone, larger voice coil & magnet, than look at the driver.

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