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Old 16th September 2013, 02:25 PM   #1
Lainus is offline Lainus  Finland
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Default Thodio iBox XC - Hardware Analysis / New boombox concept

Hi, i did just register on this forum, but i've been reading threads around here for a couple of weeks.

I'm planning on making a boombox in the style of a Thodio iBox. I know that there has been many threads about the subject but the amount of hardware analysis hasn't really been done.

Click the image to open in full size.

If you watch this video:
thodio iBox XC audiophile iPod speaker Boombox aptX? Bluetooth - YouTube

The iBox seems to punch a good amount of volume due to it's small size and weight. (9kg or 20lbs)

So what do we know ?

The manufacturer claims that they use a audiophile tripath TK2050 based 2 x 100 watts RMS amplifier.

In my build i would throw that amplifier in the garbage can straight away due to it's high battery consumption compared to a Tripath TA2020 chip based amp like the "41hz AMP6 Basic kit". (I ordered that amp kit last week btw)

Then we got the battery and the speakers.

What do u guys think that would be a fair solution to speakers and battery ?

My demands are low weight and decent volume.

My current boombox is made of 12mm plywood and uses a 12v amp from china (not sure about chipset)
with a 4Ah lead acid battery, the weight is 6kg, and it got 2pcs "Clarion coaxial 5.25" speakers.

I know you boombox veterans will be laughing at my previous build, but i wasn't really in to this back then. Now i have read a whole lot of build, including over half of the legendary Boominator thread by Saturnus.

And guys, i live in Finland so i most likely wont order anything expensive from outside EU due to the VAT and high price shipping.

So feel free to post links and stuff, i really want to make a new kind of "default" boombox design like the Boominator but in a much smaller and lightweight package.

I know you can't brake the laws of physics considering weight and volume do relate to each other in these kind of projects.
But i'm pretty sure we guys can get really close to braking the laws if we all put our competence and experience together.

I don't know if this is the right forum to post but mods feel free to moce the thread if you like.
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Old 16th September 2013, 11:31 PM   #2
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I'm designing my next boom box using PVC pipes

but in the amp stage i'm stuck, the TA2020 can give just 10w with aceptable distortion, but the one Thodio uses is a total overkill, for the first part i will try TDA2040, just to se if the box have a good sound and everything is ok

For the battery i will be using 6 18650 Li-Ion cells, light weight and have a good capacity i think that's good solution, if you need more juice just add more cells
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Old 17th September 2013, 04:39 AM   #3
Lainus is offline Lainus  Finland
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Hmm, interesting idea you got there ..

I still think that the Amp6 could pump that volume lvl than other TA2020 chip based amps like the "Lepai LP-2020A+". The only downside with particularly the Amp6 is the maximum 14.5VDC restriction, but do you guys know if that limit is spot on ?

What will for instance happen if i feed 14,8V DC into the Amp6 (from 4pcs 18650 Li-Ion cells)
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Old 17th September 2013, 06:54 AM   #4
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Quote:
Originally Posted by Lainus View Post
What will for instance happen if i feed 14,8V DC into the Amp6 (from 4pcs 18650 Li-Ion cells)
It will die. A 4-cell li-ion pack is 16.8V when fully charged. Although the amp6 probably can survive 14.8V short term, there's no way it will survive 16.8V.
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Old 17th September 2013, 10:38 AM   #5
Lainus is offline Lainus  Finland
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Well, is there any easy way to regulate the voltage to 14.5v or below ? Or is it easier to go with a amplifier with a wider voltage range .
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Old 17th September 2013, 01:02 PM   #6
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Quote:
Originally Posted by Lainus View Post
Well, is there any easy way to regulate the voltage to 14.5v or below ? Or is it easier to go with a amplifier with a wider voltage range .
If you're willing to accept the losses there's always dc-dc converters or just old fashioned regulators.

I don't see a need though.

Substitute the dangerous li-ion batteries (which are proven to self combust with 100% certainty) for safe LiFePO4 batteries and the problem is solved. LFPs are 3.2V nominal per cell, not 3.7V. Charge voltage is 3.6V per cell, not 4.2V. So a 4 cell LFP is 14.4V max, and maintains above 12.4V for 90% of it's cycle life.
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Old 17th September 2013, 04:40 PM   #7
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But using 3 cells Li-Ion you get 12.6 fully charged and 11.1 almost discharged, you could use that to power the amp6

And yet we could play with the drivers, 2 8ohms driver in parallel you have 4 ohm and 6db more in sensitivity
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Old 17th September 2013, 04:42 PM   #8
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Quote:
Originally Posted by PedroDeMio View Post
But using 3 cells Li-Ion ...
you know it will go up in flames at some point.

Seriously. Forget li-ion batteries for anything you build yourself. When they go up in flames (and they will) you can't even blame the manufacturer or get anything from the insurance.

Last edited by Saturnus; 17th September 2013 at 04:46 PM.
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Old 17th September 2013, 05:14 PM   #9
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Quote:
Originally Posted by Saturnus View Post
you know it will go up in flames at some point.

Seriously. Forget li-ion batteries for anything you build yourself. When they go up in flames (and they will) you can't even blame the manufacturer or get anything from the insurance.
I have to disagree,

Today's Li-Ion cell have multiple levels of protection, a pcb that cut's over voltage, under voltage, over current, short circuit, disable the cell if it's to discharged. A physical valve that prevents the pressure build-up inside the cell

I use the 18650 cell's in flashlight's, everyday on my diy cellphone portable chargers, to power up amp's sometimes, never had problems

I had done in little research about LiFePo, the main problem i see is the low capacity per size, in the 18650 i get 2600ma, a same size LiFePo cell only 1000ma
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Old 17th September 2013, 05:57 PM   #10
Lainus is offline Lainus  Finland
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Okay, so i suggest that LiFePo4 is the battery to go for a lightweight boombox build like this.
How much Ah do you guys think that it will be needed for this kind of project ?, lets think, that small boombox is mostly four one evening use, so let's say we want it to play for 15 hours. I know it's a lot more than just one evening, but let's always be on the safe side.

Let's say that we are listening to music and we are using a total of 10watts from the amplifier at 14.4V.

Ampere is now watts/volts (10/14.4) = 0.69 amps

Ah needed = Hours we want/Ampere (right)? = 15/0.69 = 21,7 Ah battery needed ?

My calculations are really really wrong or my values on the output wattage are not right.
Because we wont need a 22Ah battery to power that boombox for 15 hours do we ?

But okay, the second problem is that if we really need that much Ah from LiFePo4 batteries then isn't it going to cost alot ? I'm not sure what brand i've been looking on but what I have seen i can tell that LFP batteries seems to be really really expensive.

Can you guys link some side that have a EU webshop or Warehouse that sells LFP batteries for a reasonable price ? (if there is any)
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