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Old 11th July 2010, 02:31 PM   #651
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Hi there,

Im using lithium polymer, 8A batteries, 3 of them to get 12V, the TA2020 takes around 1A at maximal volume ( sound is not a constant load ) so it runs smooth. a battery protection for under voltage is recommended. my MKIII will still function at 8V, but the batteries should not be discharged lower than 3V per cell at best.

a digital volt meter would be a good addition to this set.

if you want to know how to port you should match the size of the tube to the VAS of the speaker. you can easily use a online calculator to calculate its size in liters, and convert that to the length of the tube you need. in practice its always trial and error for this, but if you want the tubes like i put them you can calculate the quarter frequency wave length according to the Fs of your driver, ( resonant frequency) and make sure that the path that the sound has to travel to get back to the cone of the driver is exactly a quarter of the wavelength of Fs.

This trick works most of the time.

Greetings!

Arjen Helder
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Old 11th July 2010, 03:52 PM   #652
gfiandy is offline gfiandy  United Kingdom
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Quote:
Originally Posted by whelibob View Post
Hmm i just recieved my 2 x P. Audio WN-8R-elements and noticed that the speaker cones are different. One is shiny and the other one is matt. Wonder if they have left out some treatment on the matt-coloured speaker? Do you think this might effect the sound? Product serials and other codes on the packets are identical.
Here is a few fotos:

Lasse
Hi, Yes this will most likely affect the sound quality. One of the speakers is doped the other is not. How this happened is anyones guess. If you have contact details for where you got them from I would complain.

The doped speaker will most likly have a smother roll off at the top but it will also be slightly less efficient due to the extra weight and for the same reason probably has a lower Fs.

Having said all of that they will undoubtly still work and make sound so it depends on how fussy you are.


Regards,
Andrew
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Old 12th July 2010, 10:30 PM   #653
nige838 is offline nige838  United States
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Quote:
Originally Posted by ArjenShenzhen View Post
Hi there,

Im using lithium polymer, 8A batteries, 3 of them to get 12V, the TA2020 takes around 1A at maximal volume ( sound is not a constant load ) so it runs smooth. a battery protection for under voltage is recommended. my MKIII will still function at 8V, but the batteries should not be discharged lower than 3V per cell at best.

a digital volt meter would be a good addition to this set.

if you want to know how to port you should match the size of the tube to the VAS of the speaker. you can easily use a online calculator to calculate its size in liters, and convert that to the length of the tube you need. in practice its always trial and error for this, but if you want the tubes like i put them you can calculate the quarter frequency wave length according to the Fs of your driver, ( resonant frequency) and make sure that the path that the sound has to travel to get back to the cone of the driver is exactly a quarter of the wavelength of Fs.


This trick works most of the time.

Greetings!

Arjen Helder

My appologies for bothering you yet again, but where do you get your batteries. I have searched high and low for a cheap option, but am unable to find one. I have bought these batteries

12V 4800mA Rechargeable Li-ion Battery for CCTV Cam F46 - eBay (item 220607758182 end time Jul-17-10 01:12:38 PDT)

but had to bypass the internal protection circuits because the battery would cut off whenever I turned it on. I have since run several cycles through them without any problem what so ever. If you could kindly show a link to where you're finding these elusive batteries, I would be most appreciative...

Thank you for your time,
Nicholas G.
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Old 13th July 2010, 01:45 AM   #654
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hi there Nickolas,

i have bought these locally at the electronics market here in Shenzhen, i don't think many sell them online, because its difficult to ship them, most air freight companies will not allow lithium cells on-board, bad cells and especially bad protection boards have caught fire before causing great damage to the plane and other shipments on the airplane.

i'm not sure if i can ship them to you if needed, but ill ask.

the price i payed for those 8A cells was 250 RMB for 3 pieces, giving me 12V, 8A.

Greetings!

Arjen
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Old 16th July 2010, 09:50 PM   #655
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I've had them air-mailed from HobbyCity to the USA. I think only certain carriers will do this, plus the freight charges were a bit much.

HobbyKing Online R/C Hobby Store :

I also have a bunch of these... DealExtreme: $8.01 TrustFire Protected 18650 Lithium Battery (2500mAh 2-Pack Blue)
free shipping, but it can take up to 3 to 4 weeks to arrive
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Old 19th July 2010, 12:53 PM   #656
euforia is offline euforia  Sweden
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This battery discussion is a good thing! Most of the Swedish festivals has decided to ban the use of acid type batteries. I finished my clone of the boominator so i could bring it to "Arvikafestivalen" this summer but they put the batteries on the ban list just one week before the start of the festival. Hope you guys find the ultimate powersource soon and post the answer here=)
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Old 19th July 2010, 01:56 PM   #657
Havoc08 is offline Havoc08  Denmark
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The sealed gel lead type is not a problem when built into the speaker and is safe regarding charging compared to lithium. This years Roskilde left alot of car batteries lying around which is a pity as this careless handling of batteries will cause a ban eventually.

The LiFePo4 battery type is another safe option.
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Old 19th July 2010, 02:10 PM   #658
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LiFePo4: Safe, good discharge rate/available current, very fast recharge time, much longer service life that other lithium types or lead-acid. Half the weight per amp-hour as lead cells.

--Buckapound
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Old 19th July 2010, 03:19 PM   #659
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Yup. LFP cells is the end all answer to the battery question. Period.
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Old 19th July 2010, 06:37 PM   #660
Havoc08 is offline Havoc08  Denmark
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Agree, but cost vs Ah isn't quite as good as sealed lead gel
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