AC to DC converters |
Post Reply | Page 12> |
Author | |
Alec_Hood
Registered User Joined: 28 June 2013 Status: Offline Points: 16 |
Post Options
Thanks(0)
Posted: 29 June 2013 at 12:04pm |
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. |
|
lost eden
Young Croc Joined: 04 April 2011 Location: Dundee Status: Offline Points: 942 |
Post Options
Thanks(0)
|
Alec_Hood
Registered User Joined: 28 June 2013 Status: Offline Points: 16 |
Post Options
Thanks(0)
|
Alright thanks man
|
|
Alec_Hood
Registered User Joined: 28 June 2013 Status: Offline Points: 16 |
Post Options
Thanks(0)
|
Isn't it made for LED lights? They would't use near as much power as speakers would?
|
|
studio45
Old Croc Joined: 16 October 2007 Location: United Kingdom Status: Offline Points: 3863 |
Post Options
Thanks(0)
|
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
|
|
audiomik
Old Croc Joined: 06 April 2010 Location: Bath, UK Status: Offline Points: 2962 |
Post Options
Thanks(0)
|
Have a look at this link to Ebay for a 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 Edited by audiomik - 01 July 2013 at 5:19pm |
|
Warning! May contain Nuts
plus springs, washers, screws, etc, etc. |
|
Audio_AL
Registered User Joined: 20 July 2012 Location: United States Status: Offline Points: 244 |
Post Options
Thanks(0)
|
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!
|
|
slaz
Old Croc Joined: 27 November 2009 Location: London E2 Status: Offline Points: 2713 |
Post Options
Thanks(0)
|
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
|
|
kedwardsleisure
Old Croc Joined: 20 January 2009 Location: Staffordshire Status: Offline Points: 4938 |
Post Options
Thanks(0)
|
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 |
|
SMP
Young Croc Joined: 16 March 2013 Location: East London Status: Offline Points: 1226 |
Post Options
Thanks(0)
|
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 |
|
Edd Jordan
Young Croc Joined: 10 January 2008 Location: United Kingdom Status: Offline Points: 1364 |
Post Options
Thanks(0)
|
I do a sideline in ply wood wheels.
|
|
slaz
Old Croc Joined: 27 November 2009 Location: London E2 Status: Offline Points: 2713 |
Post Options
Thanks(0)
|
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
|
|
Post Reply | Page 12> |
Tweet |
Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |