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Old 10th May 2006, 10:03 PM   #11
space is offline space  Norway
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I've seen equipment (the more expensive ones) than can take 17V but I do think they are the minority. Something tells me 15.6V (or was it 15.2) usually is the highest allowable voltage.

The biggest problem with raising the supply voltage I believe is the supply voltage to the amp section created by the SMPS. It will rise with the same proportion as the +12V line when the SMPS aren't regulated, which often is the case.

space
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Old 10th May 2006, 11:58 PM   #12
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SPL competition amps can typically be run up to 16-17v without a problem, but most amps are limited to ~15v. Even a bad alternator that's spitting out 15-15.5v can throw most car amps into protection.
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Old 11th May 2006, 07:06 AM   #13
beppe61 is offline beppe61  Italy
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Quote:
Originally posted by msharpe
Well, I'm certainly no expert, but I do know that most car amplifiers should be able to handle at least 14.4 volts DC, as this is the fully-charged voltage of a 12 volt car battery.
I would image that running one off of 17 volts would present no danger.
If anyone else has anything to say on this matter then please do. I'm just making an educated guess here essentially.
So, unless someone says that I'm totally wrong, then I would say at least experiment with it.
Dear Sir,

thank you so much for your very kind and extremely valuable reply.
Actually after having read of the high quality of some car audio and also of their ability to source good amount of current to drive demanding loads I had this idea.
Presently I am learning and gathering technical info.
Another datum that I have to establish is the needed amount of capacitance after the diodes bridge.
After that I can start testing some nice car audio amps I can obtain from friends.

Thank you so much again for your very precious advice.
Kind regards,

beppe
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Old 20th May 2006, 06:23 AM   #14
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Why not disconnect the SMPS in the amp and run a 120V (240v) to whatever your rails are transformer (to the rectifier)? This would skip a couple conversion steps that you are needlessly making using 12V supplies.

Here is what you are planning to do:
120vac - transformed - rectified - filtered to 12-14Vdc - SMPS back to AC (square wave) - transformed to Rail voltage - rectified filtered.

Using a Mains toroid its:
120vac - transformed - rectified - filtered to rail voltage.

To step voltage up or down you need to have AC, you are starting with AC, no need to convert it to DC and back.

It would be easiest with an unregulated PS car amp.

-Ken
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Old 20th May 2006, 05:50 PM   #15
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Quote:
Originally posted by Vodkatonics
Why not disconnect the SMPS in the amp and run a 120V (240v) to whatever your rails are transformer (to the rectifier)? This would skip a couple conversion steps that you are needlessly making using 12V supplies.

Here is what you are planning to do:
120vac - transformed - rectified - filtered to 12-14Vdc - SMPS back to AC (square wave) - transformed to Rail voltage - rectified filtered.

Using a Mains toroid its:
120vac - transformed - rectified - filtered to rail voltage.

To step voltage up or down you need to have AC, you are starting with AC, no need to convert it to DC and back.

It would be easiest with an unregulated PS car amp.

-Ken
That is a good idea in some ways but in others for example the protection circuit of the amp will be usless.

Most amps protect them selfs (and speakers) by turning off the psu. If you power it from mains with out building into the protection part, any problem that arrises will or can destory the amp or speakers.
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Old 21st May 2006, 03:49 AM   #16
Eva is offline Eva  Spain
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The SMPS solution made real:

0-15V 0-120A adjustable PSU attempt with average current control.

This project is on hold, as I'm currently working on other stuff, but I would still like to finish that power supply and turn it into a nice commercial product in the future. It will include a "stacking" feature to obtain up to 1000A through active paralleling techniques. I might even get it distributed in USA if there is enough demand.
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Old 21st May 2006, 05:11 AM   #17
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I powered a car amp from the mains,with a regular transformer once while I was waiting for the SMPS FET's to come in..I actually left it that way for a few months running my subwoofer,but eventually replaced the SMPS FET's,and then built a 12Vdc supply with a microwave oven transformer to test the complete amp.
Easy to experiment with different power supplies and stuff too..
(with a 50/60hz mains transformer,you'll need to add more filtering than stock.)
BUT-Do beware that when bypassing the internal SMPS most/all of the protection circuitry will be disabled! (already mentioned,but a good point to repeat!) Don't wanna fry any amps/speakers.
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Old 21st May 2006, 08:35 PM   #18
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Quote:
Most amps protect them selfs (and speakers) by turning off the psu. If you power it from mains with out building into the protection part, any problem that arrises will or can destory the amp or speakers.
Piece of cake.. Connect the protect ckt to a relay or SSR that supplies the mains. I use Sharp solid state relays in a lot of pic designs. They have 4 pin SIP and smd packages that can handle 16A at 480V with a 5V or 1.2V input for less than $5.

I will admit, that it would be more "work" to connect the amp to mains via a transformer. It would require some skill too. However, it would be the most efficient and least "clunky". My 30A 13.8V supply at the shop is the size of 2 shoeboxes and thats a small power supply. A 100A regulated supply is bigger than an ATX size computer. Conversely a 1.5KVA Toroid transformer is the size of a large coconut.

On the cheap and easy but VERY clunky.. A car battery charger and battery is probably the lowest cost solution. A Battery charger is horribly dirty but so is an alternator (3-phase ripple DC).

-Ken
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