Transformer voltage for chip amp?

[Tony D.]

Hi All,

I'm building four channels of amplification for a two way active stereo set up, I'm using the Peter Daniels 3875 kits. I have a 22volt-300VA toroid for the woofer amp. channels and I want to use a 20volt-100VA toroid for the tweeter amp. channels because I have it laying around.

I only need 10 or 15 watts RMS output from the tweeter amps and my question is will my chip amp make that much power with the 20volt transformer into the LM3875 chip amp?

Thanks for an information.

 

[nigelwright7557]

20vac gives 28VDC.
So power vv/r = 98watts into 8 ohms.
I usually go for 1.5 times wattage for transformer VA.
So 150VA transformer.
If your not going to be pushing the amp hard al the time the 100VA transformer will do.

 

[Tony D.]

Thanks Nigel, I'll be using the amp. for tweeters in an active system and it won't be being played overly loud.

 

[seanny]

Transformer 20 Vrms - 2V diodes drop = 18 Vrms
P=18*18/8 = 40.5W

Your amp would put out a little less than 40.5 W

Your 22V transformer handles around 50 W but your amp put out less