car amp

Hey everybody! I'm new around.

Ok, now my question: I'm about to build amp. for car and I could use some help First of all, does anybody happen to know where to find some circuit diagrams? And I mean real amps - something like 4x75W[rms] and higher.

thanx

Short-circuit said:

Hey everybody! I'm new around.

Ok, now my question: I'm about to build amp. for car and I could use some help First of all, does anybody happen to know where to find some circuit diagrams? And I mean real amps - something like 4x75W[rms] and higher.

thanx

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I'm sure you could buy one for far less than the components would cost you - just be careful over the specifications, most don't give RMS values. I've got all the Sony in-car amplifier manuals on DVD at work (as password protected PDF's) - but it would cost a fortune to build one, assuming you could get the special parts used.

BTW, a Sony 200W in-car amplifier is only 2x35W, and I'm sure Sony are probably more honest than most manufacturers!.

I agree, buying one would be cheaper!
Secondly, try to get a look beyond the more 'known' makes (like sony, pioneer,...) when buying one. Car-audio is a world on its own. Many specialized makes like Rockford fosgate, DLS, ... offer systems that regular makes can't even get close to in sound quality

Make sure to check for a shop wich sells Beyma. Kickass material!

Worth noting - you will only get so much current to flow in a 2 or 4 ohm speaker at 12 volts. As power goes up it would seem that power supply voltage must increase as well.

You are absolutelly correct. Higher power systems are worth
only when coupled with DC/DC converters. Using only 12V,
even standard car stereo is pretty much on the limits.

stevez said:

Worth noting - you will only get so much current to flow in a 2 or 4 ohm speaker at 12 volts. As power goes up it would seem that power supply voltage must increase as well.

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'Honest' power from a car battery is only 4 watts single ended, or 16 watts bridged (into 4 ohms) - but the manufacturers specs usually hype that considerably.

Higher power amps have inverters inside to give a higher HT rail, some older ones even used speaker coupling transformers to give higher power into a 4 ohm load while maintaining a 12 volt supply.

Circuit Schematics

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schematics

Thnx everybody for being honest - I already know some things about acoustics and electrotechnics. Hehehe and thnx for believing in my capabilities of building something that will work (booom)

Now, let me reform my question - I know what rms and peak power are! And I know that from car's 12V supply you can get nothing more than 12-18W. I already have some schematics of poweramps and their supplies, but I wanted to check here if anybody had anything better. Maybe even some schematics of original amps - like Lanzar Vibe Series or similar... 8)

But if not, never mind. Thnx anyway :wink:
BTW: It would cost me cca 50-60€ to build an amp of 4x75W[rms] - under condition that nothing gives nice light effects :roll: :lol:

Re: schematics

Short-circuit said:

But if not, never mind. Thnx anyway :wink:
BTW: It would cost me cca 50-60€ to build an amp of 4x75W[rms] - under condition that nothing gives nice light effects :roll: :lol:

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And assuming that you are infact stepping up the voltage, because most normal amp circuits don't do that on their own, but rather rely on their power supply to provide the higher potential rails.

Edit: Just realized that if you were driving a 2ohm load, you might get close.

P = V^2/R ==> P = (12*12)/(2) = 144/2 = 72W

Re: schematics

fat-tony said:

Short-circuit said:

Edit: Just realized that if you were driving a 2ohm load, you might get close.

P = V^2/R ==> P = (12*12)/(2) = 144/2 = 72W

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Major boo boo! - you used 12, that's peak to peak, you need to divide it by 2.828 to get RMS - which works out at 9 watts. In reality you're not likely to get 12 volts PP from a car amplifier, so 8 watts is more likely.

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Hi!
You can build a power amp using tda7294 (93) ICs (circuit from data sheet) and switch mode dc-dc converter using sg3525, tl494 etc ( for example, **broken link removed** )

thanx everybody