Make a car amplifier

[HeadHunter]

Hello my name is Dimitris and i am from Greece. i am a new member and this forum is very good sorry for my english is not very good
i have a amplifier for home. is a Sansui with power output tranzistors: 2SA1216 & 2SC2922
the drivers is BD139 & BD140. it has very good output power with 8 and 4 ohms loads.
I want put that amplifier in my car, Become does this?
what power supply i need for this stereo amplifier?? thanks

[protos]

Something like this?A little bit oversized but you get the idea.
http://cgi.ebay.co.uk/2000w-power-in...QQcmdZViewItem
Any way for a power inverter you are going to end up paying as much as for a reasonable car amplifier plus the installation will be a mess.
There are small car amp projects based on easy to diy chip car amps which work on 12v.
Or even something like a T-amp which can do up to 20w.

[HeadHunter]

no my friend i mean SMPS something like this: http://sound.westhost.com/project89.htm

[v-bro]

You're on the right track Dimitris, bypass the internal power supply of the amp and connect the smps directly.

to Protos: did you ever notice how much loss there is developed in a converter? Dimitris would need a bigger battery this way....

First measure the voltage on the rectifier bridge in your amp Dimitris, and than build a smps to deliver that with enough current (/enough power in watts).

[HeadHunter]

I have isolated the factory transformer. the voltage on the rectifier bridge is +/-54vDC, i need smps with following characteristics 2x54vAC (or +/-54vDC) 10A 760W. exists certain schematic with DC protection for that smps?

[v-bro]

It's very high voltage and power! Don't know if your car will have enough power left to charge the battery, how much ampere can your alternator deliver? And is the amp running on +54/0/-54 transformer or a +54/0 transformer?

Most amps will run on lower voltage, but you will have to settle for less power....

If the AC voltage on the retifier bridge is 54V the DC voltage on the output of the bridge is even much higher! Must be quite a beast this amp!

[HeadHunter]

amplifier running on +54/0/-54vDC yeah is very high voltage and power.. my brother has an amplifier sony x-plod for 2x axton subwoofer, that amplifier with bridge output can deliver 1.2kW RMS 4 ohms need 80A on full output power and the car charge battery without problems. i don't know how much ampere can deliver the alternator the car is a FIAT Cinquecento Sporting..
It can be placed a smps with less voltage and power or i will face problems with the amplifier?

[v-bro]

The Ac voltage needed for my amp is 18V, the DC voltage on my rectifier bridge is than some 26V. If your amp runs on 54Vdc the Ac voltage of the transformer should be some 30 to 40 V...

No problem with the amplifier, and as long as your smps can deliver enough current (watt) there should be no problem there either..

Question is how little V the amp will still run on, still sounding good enough...

But you can try without damage...( try it on a lab power supply with infinite voltage adjustment).

The fact that the amp needs + and - 54V I'm afraid would mean you need an smps that can deliver the double 54V. Many amps need double supply, a supply delivering 54v and 0V than won't do the job...

[v-bro]

Actually, just looking at the schematic you previously posted in that link, it delivers + and - 35 Vdc. Using an other transformer delivering more Vac on the secondary side and appropriate buffering caps you can "up" the voltage..

[HeadHunter]

i finish with some tests. the amplifier work very good with another transformer 2x30vAC 500w (DC: 30*1.41=42.3) and 4 ohm load.. Therefore smps as what I gave link it will make good work I believe. with lees voltage I don't have many watt to the output but also 2x90 or 2x100 rms in the 4 ohm they will be very good. what you say?