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Need a little advice before I over commit

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Pigeonkid666 View Drop Down
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    Posted: 16 January 2020 at 1:52am
Hey guys I'm try to making a couple portable speakers from some spare PA speakers I have... 

I have a pair of skytec 500w 8ohm speakers ideally I'd like to make 2 separate systems from them but I'm open for ideas, each rms at 250w and peak 500w
I'm also a bit of a cheapskate and cornercutter.... 
As the speakers already have passive crossovers i figured to leave that part alone. Unless I can use equalizer knobs to play with it.

I wondered if a 1000w car amplifer would do. I was thinking of the pa-80d P.M.P.O 1000w will do it (currently quiet cheap) and then to build a easily re-chargeable battery array for the 12v supply, also id need to be able to turn it off and allow it to charge. 

If I was to get a similar amp which being only 4ohm be much of a problem? From what I'm gathered as long as the wattage is doubled it's okay right?

Also would like some advice on making the battery serial and/or parralel. (I know this will cost the most...)

Sorry if I seem a bit thick this is my first proper project outside hooking up home hifi, I think I understand it but I know you'll all be able to my straight Any wiring schematics would be much appreciated if you have any around



 


Edited by Pigeonkid666 - 16 January 2020 at 1:57am
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studio45 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 16 January 2020 at 4:09pm
I don't think that amp is 1000 watts!
Looking at the pictures, I would be surprised if it can do more than 150 watts into 8 ohms - so that'd be 300 into 4 ohm - 600 into 2 ohms BUT.....That power supply on the front of it probably can't do more than 300 watts continuous, given the size of the coil in it. It's also class AB as evidenced by the large white emitter resistors, whereas the state of the art is class D, being much more efficient (won't waste power heating up the output transistors).

Try the Pioneer GM-D8604. I think it's the best bang for buck available on the 12v market right now.

One decent 50-100AH lead acid battery will be good enough to get you started. Later, you might wish to experiment with lithium batteries to save on weight. However, they're different voltages to lead-acid so it is not as straightforward as you might think. You run up against problems with the maximum voltage the amp can take, not being the fully-charged voltage of your pack. So lead-acid is the place to start until you know more about batteries.
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studio45 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 16 January 2020 at 4:15pm
Other things you should buy are some heavy power wire (minimum 4mm2, 6 or 8mm2 better, pure copper is better than CCA) some heavy duty ring crimp ends and a crimp tool, a good distribution/ fuse box, and a good high current switch or two. Anderson (Powerpole) connectors are the ones to use for high current low voltage stuff like this, either the small PP30's or the larger grey PP60's. You'll also find a permanently mounted current/voltage meter very useful. And if you don't already have one, an electronic multimeter is essential for setting up and working with 12v soundsystem. Even a £10 sh1tter will tell you what you need to know. 

Good luck! ;)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pigeonkid666 Quote  Post ReplyReply Direct Link To This Post Posted: 17 January 2020 at 11:53am
Hiya I've taken on your advice but my biggest issue is the money 🤦‍♂️🤦‍♂️ I'm trying to do it as cheap as possible and the £200 amp is a little out of my price range.... that being said I have been looking into the simpler class d board amps...  I've been researching and thought I could maybe use a irs2092s 1000w, but my biggest fear was power consumption so I got to some digging... on aliexpress they'll sell you batteries straight from China... I've opted to combine 100 32650 6000mah 5c batteries to try create a 12.8v 150ah battery.... 
I've also choosen a 

KKmoon 1200W High Power DC-DC Converter Boost Step-up Power Supply Module 20A IN 8-60V OUT 12-80V Adjustable

I also understand that the power supply to the amplifier board needs to be about 20% higher in order to negate the ripple effect I'll have using dc to dc step up, I also intend to use a pre amp on top... my only fear is that it won't be powered for long enough 3/4 hours on max? I figured that the usage can only be as high as the speaker plus  bit of board resitence but that would be equalizer by the preamp..... please tell me of I'm stupid before I spend £120 on batteries 😂 I so have some very heavy duty cable around atm not sure how thick but it's the thinnest I've ever had and it's pure copper.. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 17 January 2020 at 2:20pm
Hmmmm I would not buy those batteries right now. If they are that cheap they are probably not really 6000mAH. Also you won't be able to make a 12.8v nominal pack out of 3.7v cells (closest would be 4s at 14.8v nominal, but that charges to 16.8v when full, which will make a lot of car amps unhappy)
The IRS2092 boards need a BIPOLAR power supply (Ie, +60v and -60v) which is very difficult to get out of a boost converter especially with significant current
Seriously just buy the Pioneer amp and a decent leisure battery and you will have a lot of fun....
Run time will be longer than you think. A battery that in theory would last for only 2 hours on "full tilt" usually gets you at least 4 to 6 hours of actual music at a sensible level.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote imageoven Quote  Post ReplyReply Direct Link To This Post Posted: 17 January 2020 at 4:36pm
Start off with an old car starter battery. One that wont start a car will still play you some music for a bit and it won't cost you a penny (ask around, someone you know will have one they want rid of). Put the money towards a decent amp and then save up for a better battery.

I have run 4 x 15" drivers for 8hrs + from a 7Ah lead acid battery that came from an old emergency light fitting. This was on a  25W per ch chip amp board and was plenty loud.

Sure electronics amps are worth a look.
Keep pushing on, things are gonna get better.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pigeonkid666 Quote  Post ReplyReply Direct Link To This Post Posted: 17 January 2020 at 7:55pm
Hey lemme start with studio, I've done some more digging into it and they may not be a who 6ah but the lowest I've seen then is 5Ah they are ifr32650 rated at 3.2v for scooters apparently, I really don't wanna really be paying £200 for a amplifier. I wanted to keep the whole build to a worth of about 150... i have considered underpowering the speakers have also considered using a 2channel amp for the woofer to be separate from the tweeters more. Honestly I don't mind the idea of building a amp from scratch it just where to start!? 
Image! Hey man I've heard of a few people doing that, ive already nabbed a old battery but it's a bit of weight to drag across the mud even with wheels. I think I'll defo stick with it for now tho, I've heard that when you underpower speakers that there's some not so good distortion... considering there 500w max across 1 8" woofer and 2 piezo (one square, one horn) a easy 250+250 should do it considering the ohms will be different? It's at 8 so I assume it'll drop to about 4 a channel which is piss easy to power right? And if I'm gonna underpower them would be best to stick about 150+150? Thanks guys this is helping I know I'm slow asf
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JonB67 Quote  Post ReplyReply Direct Link To This Post Posted: 17 January 2020 at 11:47pm
+1 on the pioneer 12v amps

D8704 only £115 new online.  Still in your budget 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote studio45 Quote  Post ReplyReply Direct Link To This Post Posted: 18 January 2020 at 5:20pm
Originally posted by Pigeonkid666 Pigeonkid666 wrote:

Hey lemme start with studio, I've done some more digging into it and they may not be a who 6ah but the lowest I've seen then is 5Ah they are ifr32650 rated at 3.2v for scooters apparently
Ah right on, so those must be lithium iron phosphate cells (LiFePO4) rather than lithium ion cells (LiIon, LiPo)  - the LiFePO4 chemistry works at slightly lower voltages so a 4s pack is indeed 12.8v nominal and will power car audio gear no problem. They're also a lot safer than LiIon in terms of fire risks when charging, they have no potential thermal runaway problems.
But I'd still consider them an unwise investment for a newbie, especially if you're having to really compromise your amp budget to afford them! 
My own system uses Sure Electronics 500 watt boost regulators (+12v > +48v converters) and 2x300 watt TAS5630 amp boards. It was complicated to build and took a lot of time to get right. The Pioneer amps weren't available at the time, if they had been, I would almost certainly have bought them!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Pigeonkid666 Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2020 at 9:46am
Okay dudes spent days going out my head trying to figure this all out must of gone round in circles God knows how man times!! But sure I can can stick with a similar idea to my first... but I'll use this amp 
So if I run my skytecs (250rms 500max 8ohm) in a series ill need
https://gb-jbtools.glopalstore.com/lanzar-htg257-heritage-amplifier-2000w-2ch/
 a mono amplifer capable of 500rms 1000 peak 4ohm? Right.... this amp is 500rms 1000 capable of 4 ohms? That way I can go straight boominator and put in a car stereo right? Or will it just blow up both speakers? Or because the ideal amp does exist is this a good idea at half the price of the pioneer?
Thanks again for all the advice
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bitSmasher Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2020 at 10:06am
You don't need to run everything at max power all the time Wink

See what a clean 50-100w amp sounds like first.
I am inclined to take the "brute force" option with quality parts, and would suggest seeing if you can find a Pioneer amp cheap on 2nd hand market
"Battery Acid Sound System" blog hopefully happening in 2017
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Post Options Post Options   Thanks (0) Thanks(0)   Quote imageoven Quote  Post ReplyReply Direct Link To This Post Posted: 20 January 2020 at 10:17am
Originally posted by Pigeonkid666 Pigeonkid666 wrote:

So if I run my skytecs (250rms 500max 8ohm) in a series

You will want to run them in parrallel to create a 4 ohm load.

Originally posted by Pigeonkid666 Pigeonkid666 wrote:

 a mono amplifer capable of 500rms 1000 peak 4ohm? Right.... this amp is 500rms 1000 capable of 4 ohms?

So you plan to bridge it? I can't see the spec where it says 500W RMS when bridged into 4ohms but if its there then ...

Originally posted by Pigeonkid666 Pigeonkid666 wrote:

That way I can go straight boominator and put in a car stereo right?

No idea what you mean here.


Originally posted by Pigeonkid666 Pigeonkid666 wrote:

will it just blow up both speakers?
No.

Originally posted by Pigeonkid666 Pigeonkid666 wrote:

is this a good idea at half the price of the pioneer?


I doubt it.
Keep pushing on, things are gonna get better.
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