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Selecting Power Supply for Car Amplifiers

Selecting Power Supply for Car Amplifiers

The following discussion informs us regarding how to select the right power supply for a car amplifier which needs to be operated at home. The questions were raised by Mr. Gyaneshwar Singh.

Questions and Answers Regarding Selecting Car Amplifier Correctly

Question: Thanks for creating awareness on your own concept and resolving problems of others.

I am music lover requiring high bass with soft treble. .

Considering my requirement, I had initially planned to get an amplifier assembled, which would be getting inputs through USB kit having features of FM, Pendrive and Micro-card reader.

But due to feeling lacking a technical person to meet my requirement, I opted and got a Sony Car Music Player (Model No. XR-CA360X) to be used at home (not in car). It can run 4 speakers each of 45 Watts. ( 45 W x 4). On the backside of it, cc 12 volt 10 amp is written while on fuse, 10 is mentioned.

 One electronic shop runner has advised to 12 volt and 5 ampere of quality transformer while sony service engineer has apprised to that the system will use ampere ranging from 5 ampere to 20 ampere on 4 speakers.

I am very much confused. This is why, I am approaching you to extend me your help in term of suggesting me volts and ampere of a transformer or alternate viable option to run the above music system to its optimum. It would be a great help.

Answer: The Sony technician is obviously right and you must strictly follow his instructions, because while selecting a power supply for a car amplifier one must make sure that it has a range higher than the maximum possible consumption from the connected load...in your amplifier the peak power of the music could demand as high as 20 amps, therefore the power supply should be at least 20 amp rated.

A 10amp power supply might also work but that will restrict you to hear the music at lower volumes or you might experience occasional distortions in the music.

Question: :You mean I should opt for 12 Volt and 20 ampere Transformer ? Is it a safe suggestion given by sony person??

One electronic person, who does repairing of car music system, has advised me not exceed above 12 volt and 5 amp otherwise music system would be damaged.

Please make me further clear about above.

Answer: The voltage should NEVER be exceeded above the maximum specified rating of the gadget, that can be fatal!....but increasing current rating will only help to enable the gadget to run at the most optimal level, so in your case current should be 20 amps or as I mentioned earlier it could be 10amp with a compromised listening experience.

So if your amp is rated at 12V/10amp then as prescribed by the Sony technician the power supply should be a 12V/20amps preferably.

Question: You mean high level of ampere is not fatal to gadget.

If it is so (12v and 20 amp), then why fuse of 10 amp is installed. Also, please make it clear.

Answer: yes that's right you can use a 12V 100amp or 1000amp power supply without any fear.

The 10amp fuse is for ultimate protection against a catastrophic situation, in case the power supply malfunctions and its voltage rises or if any of the part inside the amp fails.

Question: For your kind perusal, I have attached manual of Sony music system. You may once again be sure for your recommendation ( 12 v and 20 amp) and suggesting me for:

1- speaker and woofer ( size, watt and ohm and company) for above music system ( 45 W x 4) or I should opt speaker meant by Sony for car.

2 Whether, can I link this music system with 2.1 home theater ( around 30 watt) ?

2- an amplifier for music purpose ( around 200 watt ) wanting two speakers and 1 woofer ( 2.1 home theater) for all purposes. I want high bass but soft high treble.

Answer: My suggestion is technically correct regarding selecting power supply for car amplifiers, and there's no doubt about it.

The manual specifies 12V as the operating voltage for the amplifier, so the power supply should be rated at a fixed 12V (regulated) and the current is immaterial and could be anything higher than 10amps upto infinity.

The speaker power should be preferably rated higher than the max wattage rating of the amplifier.

you can use it with a 2.1 home theater, there's nothing critical about it.

Sorry, telephonic conversation will not be possible due to my busy schedule.

Question: Behind my several questions, there reasons were different recommendations, contradicting to each other. Hope, you will understand my position.

In the light of below mentioned guidance, will you like to add anything related to my case? Your reply will support me.

Please note that Sony Music Company always claim that car music system will not work properly in non-car environment (at home) if I use transformer.

Is it true or only it is stunt to create fear in customer to go for purchasing otter set. Please share your views? Accordingly, I will do so.

Answer: Car amplifiers are extremely efficient units, of course I am referring to the good quality ones.

These may be emitting more heat because these are designed for high bass music, heat and power dissipation are directly proportional to the bass level, and therefore car amplifiers could be notorious for their heat dissipation rate, it's not their fault.

power supply could be a transformer based or SMPS but of a good quality to ensure perfect output.....lower quality could pose problems.

V and I specs will be as specified by me earlier.

A car amp can be operated at home as effectively as in car using a high quality SMPS power supply with specifications as explained by me earlier, however nothing can match the quality using a car battery since these are ideal DC producing devices.

The "stunt" to is to make sure that the amp is strictly used with a 12V source (car batt) and not with non-standard power supplies which could damage the amp and result in higher replacements.

Question: A lot of thanks for sharing your technical opinions. It has been very enlightening for me. After three days of discussion, I have been enabled by you to say below mentioned points seeking conclusive clarification:

1.Car Battery is the most suitable option but very costly (In this situation, Can I use my inverter battery of Exide 150 amp connected with Micro-tek inverter 1025 E Square)

2.SMPS is second preferred option (Can I use SMPS of computer to be purchased from market? If no, which SMPS I need to purchase. Please recommend name of company, which make SMPS)

3.Electric Transformer is third option (Sony Technician has recommended it over SMPS).

4.Can I use 12 V and 5-amp transformer for running only one speaker (instead of all 4 speakers) in low volume for connecting to 2.1 home theater? ( Is it a safe method for both music system and home theater)

Solving the Queries:

1) Car battery can be the ideal choice for all electronic equipment right from a home theater, computer, DVD player, TV set etc. but since we have mains operated equivalent converters at home in the form of SMPS and transformers, a battery is never preferred.

2) It can be an SMPS or a transformer, doesn't make any difference, but it must be a regulated voltage type (fixed voltage DC).

12V 5amp power supply will do if you are using just one speaker instead of the stipulated 4. Assuming your 2.1 has a separate power supply, still there's no harm in feeding the music from it to your amplifier.


About the Author

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials. If you have any circuit related query, you may interact through comments, I'll be most happy to help!

23 thoughts on “Selecting Power Supply for Car Amplifiers”

  1. Hi, Swagatam.

    This is Divyarajsinh Rathod from Ahmedabad (Gujarat).
    I have JBLE250P powered sub woofer that I was using at my home.
    But before few days the back plate AMP burnt, also when i approached the JBL service station for the replacement amp for it, they told me that the model is out dated and no replacement plate for this model availabe now.
    So if you can suggest me what should i do. One of my friend told me to use the car audio amp with computer smps, but i doubt that it wont give enough current(amps) for the sub and car amp.

    The help which I want is, Is there any proper ready made plate amps for this sub indian made available, or is there anyone who can make on demand.
    If not than shall i go with the car amp, please suggest me the proper power supply for it.


    • Hi Divyarajsinh, I don’t know much about plate amps so I won’t be able to suggest much, but you can surely use a car amp instead. For the power supply you can easily buy a 12V/20 amp SMPS from amazon at less than Rs.1500/-

  2. There are several yellow and black wires in SMPS. whether I should use all or particular one plug which has two yellow wires and one black wire.

  3. Yellow wire of SMPS is 12 volt therefore yellow ( as mentioned on PCB) and black wires, need to be used.

    a black cable with 3 pin plus comes for SMPS and green wire is not visible inside the black cable.

    • It's important to check from where these wires are terminating…look for the (+) and (-) symbols around the SMPS connectors and integrated the wires accordingly…or you can also use a multi meter for verifying the same.

      if green wire is not provided at the input side of the SMPS then simply don't use it, and anyway since your amp does not have a green (earthing) wire so you can just forget about it

    • I think it won't be there since there would be just a (+) and a (-) to connect…so ignore the green wire, use only the red and black outputs from the SMPS.
      at the AC input side make sure to use the green wire, with a 3-pin plug

  4. Thanks

    What about green wire of SMPS. whether it is to be liked with any material like speaker or other material.

    I have arranged two computer SMPS of Hipro and Zerbanoics companies. Is their any comment on these two SMPSs.

    Today, I had seen two sony car speakes each of 150 watts and 4 ohms. Will these speakers will work properly with sony car music syste of 45watts x 4.

    • green wire is the earthing wire, use it only if your amp has a compatible earthing wire with its cord, otherwise just leave it.

      all reputed companies are reliable, you can use any of those.

      150 watt speakers will work, but according to me the speaker wattage should be on par with the amp wattage rating, hence a 70 watt speaker will perhaps work better with a 45 watt amp rather than a 150 watt speaker.

  5. I am finally recommended to use a transformer of 12 v and 20 amp with output of 240 watt.
    Now, I need to connect this transformer with music system of 180 watt (45 watts x 4 speakers).
    If I want to use one pair speaker wires (45 watt) with home theatre, what would be effect on both music system and home theatre, as music system would be bearing an input of 240 watt through the transformer.
    In other words, whether one pair speaker wires (having flow of 240 watt ???) would damage both the music system and home theatre as the power (240 watts) of music system would not be full exploited through this arrangement.

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