Power supply for amplifier

[francoissteyn]

Hi Everyone!

This is my first time posting in this forum! I would like to know if anyone can please help me determine a few things about two power supplies that I want to build for two amplifiers.

The first amplifier is this one:
http://www.kemo-electronic.de/en/bausaetze/b086/index.htm

I was thinking of using a toroidal transformer, a bridge rectifier and two electrolytic caps. But I have no idea what the specs must be. On the site it sats this amp needs 24 to 40V. But what must the VA rating of the transformer be and is it possible to power two of these amps from one psu? Lastly, for this amp, how many RMS watts does it put out? Cause I need to power a 40W rms speaker off one of them.

The second amp:
**broken link removed**

They recommend a 2 x 25VAC output toroidal transformer. But they say this reduces power by 15% (15W rms)! I want to know which transformer would you guys recommend I use to get the full 100wrms? I would also, like the first amp, power two amps from one psu.

If anyone can point me in the right direction, or even give me a design or anything I would really appreciate it, cause I don't want to build an amp that is underpowered, and I'm on a really tight budget, but am willing to buy the right components for the jobs, just not unneccasary ones .

Thanks all!

Francois.

Added after 1 minutes:

I just noticed that the forum removed the double t's in the address, but i know that is obvois to all!

 

[rkodaira]

Hi !

For the first amplifier, check the PDF file available (in the page) with more detailed description in several languages (french, english, spanish, deustch, portuguese, greek). There is written that the power supply for best results is 40Vdc x 3A = 120W (not VA, VA is for AC). The maximum power that can be obtained is with a 4 ohms speaker. considering 40Vpp (at class A configuration) you could have: 20Vp / 1.41 = 14.1 Vrms what turns to: Power = 14.1 ^ 2 / 4 = 50 W
I think you can reach the desired 40W with 4 ohms loud speaker, but i don´t think sound quality will be good (very simple and poor design).

I could not check for the second amp.