AC to DC converters
Printed From: Speakerplans.com
Category: General
Forum Name: 12v Powered Systems
Forum Description: From Mini-rigs to ICE, all your low voltage audio needs here...
URL: https://forum.speakerplans.com/forum_posts.asp?TID=80095
Printed Date: 20 April 2024 at 12:19pm
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Topic: AC to DC converters
Posted By: Alec_Hood
Subject: AC to DC converters
Date Posted: 29 June 2013 at 12:04pm
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Looking to buy a converter so I can run my 800 watt JVC car amplifier off 240V house power. Can someone please link me to one that is cheap and will give me max wattage. FIY, I only need enough power for 250 RMS for the sub, and two 40 RMS for the speakers. |
Replies:
Posted By: lost eden
Date Posted: 29 June 2013 at 1:23pm
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Something like this should do fine. http://www.ebay.co.uk/itm/AC-110-220V-12V-30A-360W-Switching-Power-Supply-Driver-for-LED-Strip-Light-CCTV-/190837140021?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item2c6ec7aa35" rel="nofollow - http://www.ebay.co.uk/itm/AC-110-220V-12V-30A-360W-Switching-Power-Supply-Driver-for-LED-Strip-Light-CCTV-/190837140021?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item2c6ec7aa35
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Posted By: Alec_Hood
Date Posted: 29 June 2013 at 1:46pm
| Alright thanks man |
Posted By: Alec_Hood
Date Posted: 01 July 2013 at 2:23pm
| Isn't it made for LED lights? They would't use near as much power as speakers would? |
Posted By: studio45
Date Posted: 01 July 2013 at 3:28pm
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I reckon that supply might cut out/blow a fuse if you try and turn the amp up; it is quite beefy, but if your amp tries to develop 800 watts into the speakers, assuming 80% efficiency that means it will be trying to take 1000 watts or 83.3 amps from the supply - almost three times its rating, pretty much guaranteed to make it unhappy. In addition, not all SMPS are equal; there is the concept of rise-time to think about. In essence this means that some supplies, like that one, are designed to supply a constant current without sudden large changes in demand. LED lights are a constant load. Audio amplifiers are not. They require a different type of supply designed to cope with large changes in demand from one microsecond to the next. The "steady" type of supply may become unstable if presented with a large transient load, and this may make the amp unhappy too; the worst case scenarios are that the current spike causes a voltage oscillation and temporary over-voltage leading to damage to the amp or blown fuses, or that the amp and supply get into a fight leading to low-frequency oscillation in the speakers, as the supply dips and bounces back continually; this could easily break your speakers. If it were me I'd use a car battery and trickle charger, and let it recharge while I wasn't using the system. It's a lot simpler, and probably cheaper too. ------------- Studio45 - Repairs & Building Commotion Soundsystem -Mobile PA |
Posted By: audiomik
Date Posted: 01 July 2013 at 5:18pm
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Have a look at this link to Ebay for a http://www.ebay.co.uk/itm/Voltcradt-SPS-1525-PFC-15V-25A-bench-power-supply-PSU-/350825641824?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item51aed67760" rel="nofollow - Voltcradt SPS 1525 PFC 15V 25A Switch Mode Bench PSU This does 3 to 15 Volts DC at up to it's current limit of 25 Amps Others are available but this may give you an idea of what to look for; otherwise go for the 'Battery with Charger' also suggested Mik ------------- Warning! May contain Nuts plus springs, washers, screws, etc, etc. |
Posted By: Audio_AL
Date Posted: 01 July 2013 at 6:19pm
I was in this same boat (only with 110v power). I used a large computer power supply to power my car amp. It worked fine until I cranked it up. It played loudly for about 10 minutes then it caught on fire  . In hind-sight I would have just bought a cheap pa amp to power the car subs. It would have been cheaper in the end. The thing to watch for here is the impedance of the speaker. Car subs are often 2ohm (mine had dual 1ohm voice coils). Be sure to wire in a way that the amp wont mind. ------------- Make it loud! |
Alec_Hood wrote:Posted By: slaz
Date Posted: 01 July 2013 at 6:41pm
Never tried it myself, but you could very well be right about the instablilty stuff .... OTOH - if that "800W" is Chinese/marketing watts .... well that'll likely be into 1R or 2R load(s). And then don't forget that power rating will be at 14.4V power rail ... if you use 12V it'll cut down your power yield by 30% or so .... so "800W" could very easily be more like 200 real watts. ------------- REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON |
Posted By: kedwardsleisure
Date Posted: 01 July 2013 at 9:16pm
I wouldn't directly import any mains equipment like that. There's no saying its built to UK standards and might not be safe. Best buy high technology switchmode stuff from a european supplier.  ------------- Kevin North Staffordshire |
Posted By: SMP
Date Posted: 02 July 2013 at 12:48am
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not too sure what all the song'n' dance is about with this...It seems to
me to be fairl simple although would like to know the exact application
for the amp. But simple enough to deal with any power change requirements just get yourself a fairly hefty Car Battery charger add a large 16Volt Capacitor very often find ex-equipment ones from older Computer server PSU do the job nicely as they are often very high values of 56;000 uF this is a very cheap way of power for 12Volt systems to run on 240Volt AC supplies The charger is not a hard find and generally give high enough supply under load but make sure it is not an Automatic type as they do not behave as needed of course failing this a large Transformer a Rectifier and a Capacitor the amp will be a PWM powered type for the DC/DC converter which will have sufficient filtering on board I have used similar setups to power Car Audio on the bench to test after repair with good results |
Posted By: Edd Jordan
Date Posted: 02 July 2013 at 1:12am
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id already suggested something like this. http://www.ebay.co.uk/itm/1000W-0-12V-0-80A-Adjustable-Switching-Power-Supply-LED-Charger-UK2-/321151765484?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item4ac6230bec" rel="nofollow - http://www.ebay.co.uk/itm/1000W-0-12V-0-80A-Adjustable-Switching-Power-Supply-LED-Charger-UK2-/321151765484?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item4ac6230bec ------------- I do a sideline in ply wood wheels. |
Posted By: slaz
Date Posted: 02 July 2013 at 7:32am
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Just realised I have a large-ish transformer here ... chunky thing - designed for LV lighting I think .... 12V rated at (I think) 300 or 350VA or so .... yours for a coupla beers .... but I _ain't_ shipping it .... collect from London E2. ------------- REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON |
Posted By: shagnasty
Date Posted: 02 July 2013 at 9:18am
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Bit a bit careful here, car amps run on 13.8V (not 12V) if you get a 12V tranny and rectify it (which I highly recommend you do!!!) then smooth with some lumpy caps (1Farad car one might do but check voltage rating and ripple current) you will end up with nearer 17V, can a car amp handle this? Don't do anything daft with a car battery and a computer PSU. 1 car batteries give of explosive gas when charged. 2 a computer PSU (12V) will never charge a car battery (13.8V) without a buck converter. |
Posted By: SMP
Date Posted: 02 July 2013 at 10:10am
perfect for what he needs they are fairly cheap anyway less than a tenner at most Elec wholesalers. So problem solved if a nominal 12V is good enough for his needs rather than the usual 13 point 8 volts and incidentally most of the car amps will run at up to 16V having operating range of 10p6 - 16V but not all so best to check your particular device first but 13p8V is usually the upper limit for auto charge on cars with 12V systems |
Posted By: audiomik
Date Posted: 02 July 2013 at 10:45am
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that LV Lighting Transformer should be interesting for November 5th! They have an AC output Mik ------------- Warning! May contain Nuts plus springs, washers, screws, etc, etc. |
Posted By: slaz
Date Posted: 02 July 2013 at 11:34am
Well erm - I WAS assuming he was gonna DIY the rectifier + smoothing  DC would likely be 16-17V with bridge rectifier + caps ..... prob too high. My Vibe (good quality) car amplifier states (I think) tolerates up to 18V .... but I sure as hell wouldn't use it like that (esp into low impedances). 15V or so mebbe .... ------------- REMEMBER....POLITICIANS AND DIAPERS SHOULD BE CHANGED OFTEN AND FOR THE SAME REASON |
Posted By: Baron Greenback
Date Posted: 03 July 2013 at 11:14pm
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You can easily get hold of 230VAC-12VDC from China, if you want to step up to 13.5 try this: http://www.ebay.co.uk/itm/DC-10-60V-to-12-80V-600W-Boost-Converter-Step-up-Voltage-Module-24V-36V-72V-80V-/251271648601?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item3a80f51559
It should work a treat mate just do not exceed the current, just out of curiosity is the amp rated at 800W @ 1 ohm, I ask as I have noticed a trend among car amps to state this alice-in-wonder-land power claim on their gear, and if this is the case, then this solution will definitely work. ------------- The doctor recons I'm paranoid... well he didn't say it exactly, but I just knew the bastard was thinking it! |
Posted By: lost eden
Date Posted: 04 July 2013 at 12:16am
| The switch mode supply I linked on the previous page is exactly the sort of thing that loads of people use with class D amps with no problems (Sure Electronics, hifimediy, etc.). I've happily raped a little 12v 2A one like that running a TA2020 full tilt for 8 hours without it skipping a beat (not that a TA2020 sounds any good when putting out its headlining figures...). Obviously if you get one rated at 200W you shouldn't expect to get 800W out of the amp, but getting the rated performance out of these things on 'peaky' applications like amps isn't an issue. |