Scratch Build – In Progress Megablaster 2010 work log (diy ghettoblaster)

This is a work log of my fourth ghettoblaster project. Here's the two first models I've built (2007) to give you the idea of my work:



For the year 2010 my goal is to make lighter yet louder model. First dark grey model weights 11kg. I plan to cut the weight 25% using LiPo battery. Here is the 3d plan for my 4th design.



I will build it using plywood which will be covered with 1mm black acryl. I searched for speaker part for a month. I was after high efficiency drivers to get out as many db per watt as possible. I found a DIY kit of a PA speaker which converts one watt of amplifier power to 94db of sound. This PA kit has horn tweeter so I had to alter the 3d plan a bit. Here's the final plan with horn tweeter in place:



My plan consists of 2x100w class-d amp, 5,8Ah LiPo battery and Visaton MB 208/H speaker kit. Here's some parts as they arrived to me:



First test of the amplifier:



Cardboard model to see that the drivers fit:



Time to start building. I chose 9mm plywood. My first blaster had 12mm plywood walls and it was overly sturdy and added unnecessary weight.



Battery compartment:



Bracing:



Starts to look like a ghettoblaster:



And first sound test:



So this is where I am at the moment. Next I will build the plywood base for the carrying handle. After that the next step is to measure everything and draw the acryl cover parts in cad.

Here's my modding gallery: http://allthemods.com/userinfo.php?userid=25

Thanks for reading!

 

Welcome to the forum, and nice job on that so far! But this is in the wrong forum, you want "project logs" under "modding".

I'm sure a mod can move this.

 

Thanks! Project log rules said project logs can be only about pc mods. Im confused :]

 

Oops, that should be modding then. Sorry!

 

Apparently drakmin was too lazy to post his earlier work here, so I'll fill in
Original Ghettoblaster
Midi keyboard
Logiwood speakers
Embryo Zero case
Teh worldfamous FIRST trans-TFT

And looking good as always, can't wait for the summer and to hear that thing in action. Also I reckon this is the right place for the thread? In a sense it's like the Gooster thread..

 

Thanks Jouni. Here's fancy links to my previous projects, thanks for watching!

 

impressive

I especially like the logiwood project

 

Thank you! Here's a quick plan I made for the carrying leash:

 

I think I'll go with the polished look:

 

This seriously tasty project is moved to the exalted heights of the Project Logs, where it belongs.

 

Nexxo has spoken! Welcome to Bit-Tech, and remember to fill in all the juicy details on the electronics.

 

nice work....will there be an LCD screen in the middle?

 

Thanks a lot Nexxo and Cheapskate!

Here's the electronics simplified:


I chose litium polymer battery since it's light and small. LiPo batteries are more expensive and dangerous than "normal" acid batteries. My 5,8Ah model cost about 80 dollars. Blaster need battery monitor since lipo batteries cant be drained too empty, they will be damaged. I bough 2 dollar lipo monitor from Hobbyking. It gives alarm sound when battery voltage drops too low.

When building portable audio devices it's important to choose amplifier with high efficiency. Class-d amps are good choice, I found my model over ebay. It gives 2x100w into 4ohm load when fed with 36V voltage. My battery has 18,5V voltage so I will get "only" 2x40W power from the amp.

Even more importand aspect is the sensitivity of the speakers connected to the amp. Sensivity tells how much sound speakers produces with 1 watt power. I chose Visaton diy kit which has 2x 8" bass drivers and a horn tweeter. These speakers will produce 94db of sound with 1 watt power. (pretty loud) I calculated with 40W power I will get about 120db of sound!

 

HandMadeAndroid: Nope, no lcd's.

My design philosophy is to keep the electronics as simple as possible. The K.I.T.T scanner is great exception here Atleast on my scale. Led scanner has no other function that to look cool! It's more like a pseudo cool addition.

The center hole is reserved for the horn tweeter. Here's a pic of the drivers while I tested the crossover:



And here's a bonus photo of me in my fancy working environment. Modders spring fashion 2010:

 

I almost forgot. Here's first soundtest. Shot with my cellphone but I'll do better videos later. Not sure how to forward the 110db sound to video's watcher. In real life it plays really really loud!

 

Ah... good to see Drakmin has wandered way over here onto the Bit-Tech forums The blaster better be finished before the next LAN...

 

This is seriously awesome.

Please forgive my ignorance but is there a reason to build the frame out of wood? I ask because you mentioned weight as a concern and I would think a fiberglass base would solve that issue nicely.

Does it have to do with tonal quality?

 

This is excellent. Mod on.

 

Tonal Quality, yes. Same reason acoustic guitars are made with wood and not metal/fiberglass

 

shomann:

First of all plywood is cheap and really easy to work with. Also thin plywood is pretty light. I think my whole box weights 3kg since I routed unnecessary areas thinner. Sound _quality_ isn't first priority in ghettoblaster so glassfiber would be fine but harder to work with. Glassfiber box with some plywood braces inside would be pretty optimal in my opinion. Weight and sound pressure come before sound quality for me with blasters Wall thickness in this box vary from 6mm to 12mm. My first model was thicker and it turned out to be unnecessary. As I've already tested this box it doesn't rattle or do anything unwanted