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A quick cheap 12v system...

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wentalong View Drop Down
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    Posted: 05 October 2012 at 12:49am
Hey guys, 

Been doing a little research for a 12v system which shall be used quietly when i am fishing next weekend, it will be used at maybe half volume of the TA-2020 and half volume on my phone (Blackberry) so power draw/use will be minimal.

I plan to use a TA 2020, x2 40w car speakers I have in my garage (i know their inefficient however this build is trying to be the cheapest, smallest possible) and am currently stuck on finding a battery...
I may use some PA speakers if i can find anything small in the loft... Tongue

I have done some sums but am unsure on the 'Ah' of the 12v battery I should get...

I worked out that x2 20w RMS from the 2020 gives 40w/12v= 3.3a (roughly?)

a car battery for £35 on eBay at 44Ah=  44Ah/3.3a=13.3Hours of use?!? Confused 

I have a feeling i have worked this out wrong, can anyone help and suggest a battery please? Smile

Many Thanks,
Curtis Smile
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RAGING PROMOTIONS View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RAGING PROMOTIONS Quote  Post ReplyReply Direct Link To This Post Posted: 05 October 2012 at 4:26am
someone will correct me if i'm wrong but i remember people saying that with that amp and a 12Ah SLA battery they were getting 20+ hours
8X Turbosound TSW-721's and 4X TFL-760Ht's
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 05 October 2012 at 8:41am
Originally posted by wentalong wentalong wrote:

I worked out that x2 20w RMS from the 2020 gives 40w/12v= 3.3a (roughly?)


That would be about right .... if you were playing sine waves Wink

You haven't factored in crest factor in music. Typically about 8 to 1 .... typical mean current consumption of a 2020 amp flat out (its really about 15W/channel into 4R) is less than 0.5A.
REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wentalong Quote  Post ReplyReply Direct Link To This Post Posted: 05 October 2012 at 9:33am
Surely dubstep can cound as sine waves? :D but that helps a lot guys thanks :) I wasn't sure I did it right but its looking good now, Only going for a small 'sound bar type design like a gold brick :)

This is really back to basics, but it is simple as splicing a wire and hook it straight to the car battery? Or am I to use some kind of car invertor for a ciggarett lighter and a fuse etc?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote markie Quote  Post ReplyReply Direct Link To This Post Posted: 05 October 2012 at 10:15am
I just hope the fish don't Carp about the noise, that'll really knock you off your Perch. By the way don't have the Bass to high or it will affect your Herring. Keep a lookout for the water bailiff, Eel be along in a minute.
If it's got wheels or tits it's gonna cost a fortune
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 05 October 2012 at 10:44am
Originally posted by wentalong wentalong wrote:


This is really back to basics, but it is simple as splicing a wire and hook it straight to the car battery? Or am I to use some kind of car invertor for a ciggarett lighter and a fuse etc?


Well an in-line fuse (something like 3-5A) is always a good idea, but other than that - yes.
The 2020 amps will happily work across the voltage range of a normal charge/discharge cycle
(which I regard as nearly 14V down to about 11V) of 12V lead-acid batteries.

I dare say you _could_ get a regulated 12V DC o/p cigar-lighter blob, but I can't really see the benefit, unless you're hell-bent on maintaining a consistent o/p power within ±0.1 dB for some reason ....

I just use cables from ubiquitous 5.5mm barrel connector-equipped wall-warts - chopped off near the wall-wart end - so you have a moulded barrel connector at the amplifier end.
REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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Post Options Post Options   Thanks (0) Thanks(0)   Quote login4 Quote  Post ReplyReply Direct Link To This Post Posted: 05 October 2012 at 10:49am
ye a 14ah battery would last ages and ages, i run mine off bits of old laptop batteries and li-po RC batteries and thats only around 2ah and lasts a whole weekend of music with peeps saying turn it down a bit mate. Tongue
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Post Options Post Options   Thanks (0) Thanks(0)   Quote login4 Quote  Post ReplyReply Direct Link To This Post Posted: 05 October 2012 at 10:49am
p.s. efficient drivers though
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slaz View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 05 October 2012 at 10:51am
Originally posted by markie markie wrote:

I just hope the fish don't Carp about the noise, that'll really knock you off your Perch. By the way don't have the Bass to high or it will affect your Herring. Keep a lookout for the water bailiff, Eel be along in a minute.


GET OUT OF HERE !!! LOLLOL

Wonder if you could get an underwater speaker and play something like (in fish language with dream-like hypnotic sound FX) "You're hungry aren't you ? Veeerrrrry hungry ... and don't worry about that bit of metal attached to those maggots"
REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wentalong Quote  Post ReplyReply Direct Link To This Post Posted: 05 October 2012 at 11:16am
Originally posted by markie markie wrote:

I just hope the fish don't Carp about the noise, that'll really knock you off your Perch. By the way don't have the Bass to high or it will affect your Herring. Keep a lookout for the water bailiff, Eel be along in a minute.

Ohh dear... LOL Clap

On a serious note.... i've been given 3 batteries... x2 Bike batteries 12v @6ah and one smaller electric scooter battery at 12v and 7ah...

What do we think on the running time of these batteries? as the Ah is a lot lower? Confused
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Post Options Post Options   Thanks (0) Thanks(0)   Quote slaz Quote  Post ReplyReply Direct Link To This Post Posted: 05 October 2012 at 11:46am
Originally posted by wentalong wentalong wrote:

Originally posted by markie markie wrote:

I just hope the fish don't Carp about the noise, that'll really knock you off your Perch. By the way don't have the Bass to high or it will affect your Herring. Keep a lookout for the water bailiff, Eel be along in a minute.

Ohh dear... LOL Clap

On a serious note.... i've been given 3 batteries... x2 Bike batteries 12v @6ah and one smaller electric scooter battery at 12v and 7ah...

What do we think on the running time of these batteries? as the Ah is a lot lower? Confused


6Ah should get at least 12 hours or so .... (but less if you run flat out with bass eq'd up). A good deal more if you keep volume low-ish. ..... but thats assuming the batteries are in close-to-new condition.
The 2020 amps are very efficient and have very low idle consumption.
REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wentalong Quote  Post ReplyReply Direct Link To This Post Posted: 05 October 2012 at 6:30pm
This is okay then, my battery should be aright (Hopefully...) Big smile

Currently screwing with which drivers to use... I've got 2 old pioneer Hifi Speakers that are 3 way and pan to use the peizo and 2"paper cone thing from them for my Highs, however i need a bass driver, want to spend no more that £30 and will need the drivers by next Saturday, i've found these:


or


With the crossover from the Pioneer speakers, They must be 6" though.

What do we think? Any recommendations? 
Thank you, you beautiful people Smile
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