Transformer required for an Amplifier

[DonJose]

Hey guys,

It's been a while since I got a 250W woofer speaker (for $10) and buying a suitable amplifier will cost so much more than $300. So I decided to build one.

I researched about amplifiers a little but I still don't know how to select a transformer with suitable power rating.

I have this doubt because of this https/www.dropbox.com/s/y1dk5xfp7dj1fu7/Capture.PNG?dl=0
It says Total RMS power is 1000w but it also says power consumption is 70w and this is a home theater system from sony http/www.sony.co.in/product/dav-dz350

and the speakers are all passive and the dvdplayer+amplifier thing is so small to fit a 1000w transformer inside it.

Anyone know about it, please do reply

 

[kanewolf]

You are creating a class AB or similar amplifier -- https/en.wikipedia.org/wiki/Amplifier#Class_AB . Systems like the sony use a class D amplifier -- https/en.wikipedia.org/wiki/Class-D_amplifier

 

[DonJose]

You are creating a class AB or similar amplifier -- https/en.wikipedia.org/wiki/Amplifier#Class_AB . Systems like the sony use a class D amplifier -- https/en.wikipedia.org/wiki/Class-D_amplifier

@kanewolf

I don't know if this doubt of mine is valid for this case. So, I read that class D power amplifiers are the most efficient one, so we can only increase the efficiency of a system right? like we can make it near to 100% but we can never get full 100% right?. So to produce 1000W, apart from the amplifier type we use, shouldn't we give a power input equivalent to 1000W? i.e. we need a bigger transformer for any type of amplifier we use right?

 

[kanewolf]

You are creating a class AB or similar amplifier -- https/en.wikipedia.org/wiki/Amplifier#Class_AB . Systems like the sony use a class D amplifier -- https/en.wikipedia.org/wiki/Class-D_amplifier

@kanewolf

I don't know if this doubt of mine is valid for this case. So, I read that class D power amplifiers are the most efficient one, so we can only increase the efficiency of a system right? like we can make it near to 100% but we can never get full 100% right?. So to produce 1000W, apart from the amplifier type we use, shouldn't we give a power input equivalent to 1000W? i.e. we need a bigger transformer for any type of amplifier we use right?

That 1000W is probably for VERY short transient periods. The energy can be stored in capacitors to provide very high amperage for a short time period.

 

[americanaudiophile]

There are no standards for how power is measured in a many types of equipment so the manufacturers basically can make up any number they want. You are exactly right that there is no way that the power output is even remotely in that range. Most of the time it would melt the power cord if the unit drew that much power even for a short time and blow the cones off the speakers.
Pro amps are usually capable of their power rating but don't produce the same kind of current that an audiophile amp can.
http/www.amazon.com/Pyle-PTA1000-1000W-Professional-Amplifier/dp/B0010K6TXQ
http/bryston.com/products/power_amps/28BSST-2.html