Power Supply, Filters
published: Mar-11-2013
This section is divided into several pages. Klik on the links below to visit that page
1: Description of different types of power supplies and their properties
2: Why SMPS often fail after a few years, tips and background info on how to fix SMPS
3: Mains filters why they are there and are they really needed
4: Basic information about mains transformers
5: Information about rectifiers and how they actually work
6: Snubbering of rectifiers, what is snubbering (aside from being a weird word), do I need it ?
7: Regulated power supplies, the basics of regulators
8: common mode currents explained and what to do about it
9: ground what does it do, what is it for
Comments
DIY-Audio-Heaven 
Another informative and clearly explained post. Thanks, Solderdude.
There’s a tendency among audio enthusiasts to recommend high-watt transformers to power amps, for added “headroom.” (For instance, using a 100W PSU to power a 20W amp.) Is there any science behind this thinking?
Also, if an amp can handle, say, 8 to 20 VDC, is there any valid reason that one should choose the higher voltage PSU?
There is some science behind that thinking. If an amplifier can supply 20W (lets assume 4 Ohms) it will deliver 9Vrms = 13V peak. There is always some voltage drop so the power supply rails will be at least +/-15V in this case. Peak current is 3.25A (13V/4Ohm). To deliver 20W you will thus need a power supply that can deliver 15V x 3.25A = 50W peak and 35W continuous… for a stereo 20W amp 100W is needed if you do not want the power supply voltage to drop too much.
As the transformer itself also has some losses add 10% so a 110W trafo is needed to deliver 2x 20W into 4 Ohm.
Whether an amp will perform better on 8 or 20V completely depends on the design of the power supply and amp. If it has a switched mode power supply for instance the supplied voltage will always be transformed to the same operating voltage of the amp. If it has an internal regulator that makes an internal 5V from any voltage between 8V and 20V it also does not matter (on 20V the regulator will get hotter). If the voltage is used directly it will produce more output power on 20V.
Hmm is anyone else experiencing problems with the pictures on this blog loading?
I’m trying to determine if its a problem on my end or
if it’s the blog. Any feed-back would be greatly appreciated.
This sometimes seems to happen.
I think it is a host/browser issue.
Clicking on weird (pancaked) pictures seems to help just like the refresh button (F5).
Can’t do anything about it though.
Thank you for this information. I hope I will read everything one day 🙂
great article, thanks so much