Mains adaptor for 200w car amp??

ward91

:mad: :cool: :rolleyes:

I have bought a 200w car amp of eBay it hasn’t arrived just yet but I am planning on using it to power my custom home cinema sub
what would you suggest to power it???

hellohello

depending on the amp itswelf, ud need something that puts out more like 20 AMPS or more, car audio stuff runs on a lower volatge with higher amps

neomagus00

agreed, you'd need to draw 15 amps or more off a 12-volt adaptor, which is fairly significant (in home audio terms)... look around here if you're technically savvy, you can find a schematic to build your own adaptor...

PoweredByDodge

way to waste money bud...

www.partsexpress.com sells plate amplifiers that bolt to the back of subwoofer boxes -- they put out 300 watts at 4 ohms... they're about 100 bucks and plug right into the wall.

ward91

could a pc power supply be moded to do the job ???

PoweredByDodge

nope... you'll get 12 to 12.1 volts out of a computer power supply - but even a 500 watt supply will only give you at most 6 or 7 amps through any given 12 v line -- AC power supplies output 3.3, 5, and 12 volts... total "output power" is a combination of all 3 of those... and each 12 v line is not intended to be jumped together. you would have to disassemble the power supply casing and then, with a thorough understading of how it works, modify it... if you're asking if it can be done, then you do not have said thorough understanding. it's not a "blue print" thing either - it's going to vary from supply to supply.

besides - a good AC supply that you could possible modify to do the job will run you between 60 and 100 bucks from a discount store like newegg.com --- it is SAFER and easier to get get a 100 dollar plate amp such as this one -- http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-804

hellohello

ive heard of people basically daisy chaining pc supplies to work, but ud need 2 or 3 of the same amperage, otherwise u risk destroying all of them, and even then, like pbd said, its work and a half

ward91

wont this do

http://www.dabs.com/productview.aspx?Quicklinx=39N9&SearchType=1&CategorySelectedId=11023&SearchTerms=power+supply&PageMode=3&SearchKey=All&SearchMode=All&NavigationKey=11023

it will give 24A at 12v that is what my amp runs at but is 24a enougth?? and could you get a 24a peak rarther than continuas output???

ward91

the amp has just arived its a maystar mx2200 mosfet amp it has a 20a fuse in the back . i think a good price was paid about $20 inc p&p

http://cgi.ebay.co.uk/A-Mosfet-power-amplifier_W0QQitemZ5821043199QQcategoryZ3280QQrdZ1QQcmdZViewItem#ShippingPayment

ward91

just tried to power it up to a pc power supply (13a)whilst its powering the pc although the amp had no load the output of the power suplly dropped so lo the pc turned off. at lest we know it proberly works as the red power light goes on.

PoweredByDodge

eh - if its got a 20 amp fuse, then a 20 amp supply should work.

ward91

does anyone have any info on the maystar mx2200 power amp it doesnt say aneything about it on it other than it gives out 200w it doesnt ewen say wether its total or 200w into both channels.

PoweredByDodge

looks to be flea market stuff... probably 200w peak, both channels driven... so more like 100w rms bridged into 4 ohms... or 25 to 35 watts per channel into 4 ohms rms.

which makes sense... 20 amp fuse... * 0.75 efficiency = 15 amps * 14.4 volts = 216 watts measured Vpeak @ rated load.

yup - that's at 25 to 35 x 2 at 4 ohm amp. you're going to have a hell of a lot of trouble trying to drive any worth while sub with that.

ward91

i am going to make a power supply with my dad rated at 20.8amp that will cost about £30? (the transformer cost £20, and got a huge capacitor and a box for it.) i got the amp for £16 and sold my old sub for £60 i have already got a box and acoustic dampening for my sub box , all it needs is a sub to go in it and and amp to power it . the sub i may use is a infinity 1240w at £50 (half price)



the rest of my system is 80wpc so idont need a hugely powerfull sub do i?


I dont want to spend too much over £80
(my old sub was a bit naf it cost £80 new and was 70w at huge distortion)



do you think its worth it? if not what else should i use for a amp?

hellohello

well, lower frequencies require more power to be made audible, u have to move the cone farther in and out in order to get the lower frequencies. thats a 35x2 ch roughly 70-100wx1 at 4ohm MAYBE... Im not sure it thats gonna be enough for a large room, maybe a tiny bedroom... depends on the subwoofer.

neomagus00

agreed... at least in a car, the rule of thumb is you need twice as much sub wattage as you have mids and highs wattage, so if you have 4 channels at 80 wpc, a car would like 80*4*2 = 640 watts or so for the subs...

PoweredByDodge

i have 100 wpc in my home system -- it's nothing spectacular -- but i find that my 300 watt plate amp and 250 watt rated mtx 6000 series sub do quite well... they could be louder, but it's fine for my application in roughly a 40 x 50 living room. it shakes the walls pretty damn good.

i had a 100w rated sub/amp premade deal from Onkyo many years ago - sounded like **** - performed like **** - total junk. cost me like 300 bucks... i spent about 150-175 on my home-made one and it blows everything else i've heard out of the water.

ward91

i think i will try to grab a better amp then. i got a pioneer 306dvc sub (dual voice coil)
it has 400w rms per coil.

ward91

neomagus00
Polkologist

---

agreed... at least in a car, the rule of thumb is you need twice as much sub wattage as you have mids and highs wattage, so if you have 4 channels at 80 wpc, a car would like 80*4*2 = 640 watts or so for the subs...

6 channels at 80wpc

PoweredByDodge

he can get away with a 250 - 350 watt sub in the home environment.

neomagus00

really, even with 480 other watts? i'd have guessed at least equal wattage for the sub in-home...

ward91

could i blow up my 400wrms sub with the small amp??

hellohello

no, itll distort if u set the gain on the amp too high, probably wont blow it up tho

ward91

cheers all

PoweredByDodge

ward, you said it was 400 per coil, thats an 800 watt rms sub... good luck trying to amp that with 100 watts rms into 4 ohms bridged. -- by the way, if its dual 4 ohm coil, then its 2 ohms in parallel... that'll cook the amp, but you could run it stereo - which would give you 25 wpc rms into 4 ohms / coil - which yields 50 watts to your sub out of that amp.

... and this is why we use PLATE AMPS that are MEANT FOR HOME USE.


neo - far as the power thing goes... personal experience tells me that a 250 to 350 watt sub is plenty good for home use... a little bass goes a LONG way in a house... you can feel the floor pound upstairs and the china and **** all rattles. i'm not sure why - but it works wonders.

ward91

for "christmas" i may get one of these as i am on a Budget, these are always on ebay.
but if i see anything better for around that price i will go for it. i dont think i realy need too mutch power in that sub ? do i ? all my other speakers are set to large with the mains at 40hz same surrounds center 60hz and rear surround 35hz (the rear surround isnt shealded and are wired in parralel as only take 70w each

http://cgi.ebay.co.uk/SKYTRONIC-2X250-DISCO-AMPLIFIER_W0QQitemZ5825252215QQcategoryZ69962QQrdZ1QQcmdZViewItem

PoweredByDodge

i'm done with this kid.

anybody else wanna bother ? feel free... me, i'm frickin done...

you can work wonders on a budget - but that doesn't mean you have to buy scrap - "skytronic" - ... no comment.

*hands over keys and walks out door*

ward91

ive had the amp hooked the amp up to a 25amp 12v power supply, sounds good, ive hooked it up to my surround center speaker's. it is loud enought compared to my main amp, it just seemed to be needed to warm up slower before louder volumes, it seems quite alot more than 45wrms per chanel.

ward91

PoweredByDodge thanks for input but chill.
£16 is the price of a cd...
and with a 400wrms per coil sub dont you think that i was maby planing on upgrading my amp? otherlwise i could have got away with spending half the money on a subwoofer

neomagus00

that's a lot for a CD, jeepers... and he's just frustrated... you can work with a budget, like he says, and still get good equipment... if you're looking for home stuff, pop over to the home section of the forum - give them a budget and your requirements and they can find stuff that would take you (or me) a hundred years to think up... just make sure to type with proper grammar and such, they're a little pickier over there

ward91

:rolleyes: cheers