Lightest, most efficient solution for a Sound Sys On a Bike

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timcarouge · #16 Post by **timcarouge** » Wed Mar 19, 2014 4:22 am

escapemcp wrote: One (obvious) thing I have found whilst building is that some plywood is lighter than others. I got some really bad ply that had the veneer on - it was a proper PITA to make the sub BUT once all the swearing at the wood had subsided I realized that my creation was so light!!

I wonder how I could "weigh" it before buying. Maybe bring a kitchen scale to the shop and weigh some of the scraps, and calculate Xm2.

escapemcp · #17 Post by **escapemcp** » Wed Mar 19, 2014 6:28 am

timcarouge wrote:
escapemcp wrote: One (obvious) thing I have found whilst building is that some plywood is lighter than others. I got some really bad ply that had the veneer on - it was a proper PITA to make the sub BUT once all the swearing at the wood had subsided I realized that my creation was so light!!
I wonder how I could "weigh" it before buying. Maybe bring a kitchen scale to the shop and weigh some of the scraps, and calculate Xm2.

I have found that the decent wood shops have specs for the wood... one of which is density. Use that if it has it... if not... err... guesstimate. Heavy BB feels like heavy BB however it is cut or whatever size it is. The cheap stuff that I used felt like it would fly away if I blew on it too hard.

Gauss · #18 Post by **Gauss** » Thu Mar 20, 2014 8:06 pm

Don't plan on rolling a T39 behind the bike unless you put shock absorbers on it. Mine bounce like crazy when I pull them quickly on anything uneven. Maybe pneumatic tires would work.

timcarouge · #19 Post by **timcarouge** » Fri Mar 21, 2014 7:06 am

Gauss wrote:Don't plan on rolling a T39 behind the bike unless you put shock absorbers on it. Mine bounce like crazy when I pull them quickly on anything uneven. Maybe pneumatic tires would work.

Yeah, I'd probably use 16" (kids bikes) or 20" (BMX) wheels, which are cheap and easy to add

SoundInMotionDJ · #20 Post by **SoundInMotionDJ** » Fri Mar 21, 2014 8:49 am

Something like this might be easily modified. The cargo area is 16.5" wide....so that will still hold a T39 downfiring. You might even be able to add some "rack space" to the "back" of the T39 and host all the electronics in there.

http://www.amazon.com/Aosom-Traveler-Fl ... B00AJQVVMQ

timcarouge · #21 Post by **timcarouge** » Sat Mar 22, 2014 10:02 am

SoundInMotionDJ wrote:Something like this might be easily modified. The cargo area is 16.5" wide....so that will still hold a T39 downfiring. You might even be able to add some "rack space" to the "back" of the T39 and host all the electronics in there.

http://www.amazon.com/Aosom-Traveler-Fl ... B00AJQVVMQ

One of my guiding principles of design is a saying from Saint Exupéry "A designer knows he has achieved perfection not when there is nothing left to add, but when there is nothing left to take away." http://www.brainyquote.com/quotes/quote ... 21910.html
So my question is, what does the trailer add, that the speaker alone, with wheels added, cannot provide?

DJPhatman · #22 Post by **DJPhatman** » Sat Mar 22, 2014 12:33 pm

timcarouge wrote:So my question is, what does the trailer add, that the speaker alone, with wheels added, cannot provide?

Stability and balance. Unless you are very comfortable engineering a stable wheel assembly and a safe, secure attachment point, the trailer has that built in. You do not want to use the smaller wheels recommended in the plans as they are not strong or stable enough to be safely pulled behind a bicycle. You will want some sort of "shock resistance" so the "trailer", whatever it may be, doesn't pull the bicycle, and rider, to the ground at the most inopportune time, like crossing a busy street. Pulling anything of significant weight behind a bicycle is a challenge.

SoundInMotionDJ · #23 Post by **SoundInMotionDJ** » Sat Mar 22, 2014 4:24 pm

DJPhatman wrote:
timcarouge wrote:So my question is, what does the trailer add, that the speaker alone, with wheels added, cannot provide?
Stability and balance. Unless you are very comfortable engineering a stable wheel assembly and a safe, secure attachment point, the trailer has that built in.

This. The attachment mechanism is not trivial to design correctly. The trailer will be designed so that the wheels will track correctly to keep the trailer running straight. That can be DIY'd without a lot of effort, but it is nice to just "trust" the trailer out of the box.

Having a trailer will allow many "trial and error" attempts to find the best orientation and placement (forward and aft) of the sub for overall balance and pulling comfort. A movable axle is not as trivial to build into the sub...being able to move the sub around a little as you practice pulling it is a big advantage.

Adding up the cost of wheels, some bar stock, and so on, and the $100-ish price tag seems reasonable.

Also, if you decide that pulling a trailer on the bike is something that you want to do with other things (picnic, bike camping, etc) then removing the sub should be straightforward, leaving you with a perfectly serviceable trailer.

David Raehn · #24 Post by **David Raehn** » Sat Mar 22, 2014 4:49 pm

This may provide some insight for you.....

http://www.atomiczombie.com/CycleBully% ... ailer.aspx

timcarouge · #25 Post by **timcarouge** » Sun Mar 23, 2014 3:44 am

draehn wrote:This may provide some insight for you.....

http://www.atomiczombie.com/CycleBully% ... ailer.aspx

Those designs are well done, thanks. I've made trailers before, and it is quite easy.
I'll use this coupling system, which is lockable and easy to install on the rack (or you can even get a rack with it built-in from several manufacturers)

: andersenCoupler.jpg (10.16 KiB) Viewed 1691 times

http://www.andersen-shopper.de/en/produ ... ing-extras

Rickisan · #26 Post by **Rickisan** » Sat Apr 26, 2014 4:49 pm

I am quite surprised an AutoTuba/SLA combo has gone unmentioned. Maybe I missed it...?

AutoTuba: lowest cost, dimensions/form factor lending to externally attachable wheels and coupling mechanism. Width adjustable to preference. Designed with 12V amp in mind.

SLA: low cost, efficient, attachable to the AT with a piano hinge for a fold out/removeable configuration.

Interesting thread.

Grant Bunter · #27 Post by **Grant Bunter** » Sat Apr 26, 2014 5:11 pm

Rickisan wrote:I am quite surprised an AutoTuba/SLA combo has gone unmentioned. Maybe I missed it...?

AutoTuba: lowest cost, dimensions/form factor lending to externally attachable wheels and coupling mechanism. Width adjustable to preference. Designed with 12V amp in mind.

SLA: low cost, efficient, attachable to the AT with a piano hinge for a fold out/removeable configuration.

Interesting thread.

The autotuba SPL chart shows an average SPL in the low 90's, and there is no cabin to gain from in this application, whereas the T39 averages 100dB ish. The SLA's average about 95dB, also down from the Otop12.
Given the application, you want the most sensitivity you can get...

Rickisan · #28 Post by **Rickisan** » Sat Apr 26, 2014 5:31 pm

Ahh... ok.... my omission.... on both counts... upper and lower. Makes perfect sense Grant.

Rick Lee · #29 Post by **Rick Lee** » Thu May 01, 2014 5:40 pm

If you go T39 build it out of 1/4" BB. Make the baffle and spacer 1/2".

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