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Pre-amplifiers and amplifiers for car audio system

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david90

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car audio questions.

1. what is preamp?
2 What are som good 12v car amp schematics?
3. Where would be a good idea to place a digital pot to control the volume? Between radio and amplifier or from amplifier to speaker?
 

FoxyRick

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Re: car audio questions.

Hi David90,

1. A preamp amplifies smaller signals to a common level acceptable by power amps (1Vpp or there abouts). It also applies volume control, tone control, audio source selection (radio, CD inputs etc) and any other processing required before the final power amplification.

2. Try searching these
https://www.epanorama.net/links/audiocircuits.html#caramp
https://www.aaroncake.net/circuits/amp20w.htm
https://www.discovercircuits.com/A/a-audioamp.htm
https://www.knowledgehound.com/topics/audio.htm

3. Place a volume control after the line-level outputs and before the main amplifier - the power coming out of the power amp to the speakers will fry any electronics in their path, or it just won't work.

Some other points to consider:

a. The difficult part about building a car amp compared to one for home use is the power supply. For high power outputs (more than 25W per channel???) you need a much higher voltage than the car's 12V. That means using a switching power supply to boost up to 40 to 50V or so.

b. More powerfull amps might mean you also need a different battery and alternator to power them - depends on your car and how big you want the amp.

c. Bigger does not mean better in audio. Quiet quality is far more pleasurable to listen to than loud distortion.

Cheers,
FoxyRick.
 

david90

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Re: car audio questions.

Nothing big. Just 25W amp per speakers is good enough for me.

Which amplifier circuit do you recomend? There are so many i'm not sure which one to choose.
 

FoxyRick

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Re: car audio questions.

To be honest, I have more ideas when thinking about home amps than car. How much experience do you have and how much work do you want to do?

I would tend to recommend an integrated amplifier module rather than building with discrete components - it's easier and they have built-in protection. They are not as good sound-wise as a well designed discrete amp, but you pobably can't tell in a car anyway - it's not the ideal listening environment.

How about something based around this:

https://home.maine.rr.com/randylinscott/may98.htm

The amplifier chip is available from Farnell here:
https://uk.farnell.com/jsp/endecaSearch/searchPage2.jsp?Ntt=tda2005&Nty=1&N=401&Ntk=gensearch

The datasheet for it is here:
https://www.datasheetcatalog.com/datasheet/TD/TDA2005.shtml

You will need two of these circuits for stereo, four if you want to drive quad speakers. The data sheet gives a PCB layout and lots more example circuits for you to try, some doing stereo with one chip (but only 10W per channel then) or bridged into 20W.

Bridging, by the way, is a way of driving a speaker between two amplifiers to double the output power.

Hope this helps,
FoxyRick.
 

bimbla

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Re: car audio questions.

For Amps go for TDA2030A!
For Pre-amp use low-noise op-amps like NE5532.
Place vol. control after the pre-amp and before the amp.

bimbla.
 

bimbla

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Re: car audio questions.

If you want Digital amp, take a look at AD1991.

bimbla.
 

metal

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Re: car audio questions.

Hi

Try usingTDA1562, it can deliver 50 watt from 12 volt only.
 

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