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Filter Capacitance

Hello Audiogonners! 

Perhaps this should be placed in tech talk - not sure.... 

In my own clumsy way, I'm building more understanding of amplifiers. I have no electrical training, save some very awkward swings of that hot gun that interacts with solder and a PCB, back in High School, about 400 years ago!

So, I see there are two players in the amp game that I do not understand, about which I am studying (more study of other pieces of the system, later): Filter capacitance and transformer size. Until a few days ago, I might have (entirely) mixed the two in my head... now it's only a partial mix... So, I'm interested to see, for example, that the Schiit Aegir has the following hardware, so far as is described on a Schiit-Euro site:

"The power supply is completely linear, with 600VA transformer, over 150,000uF of filter capacitance." 

That seems like A LOT of capacitance, and I'm totally confounded as to why this doesn't translate into higher output. As you know, the Aegir is described as 20 watts per channel into 8 ohms, and maybe 40 into 4 ohms. Seems like low wattage for all that transformer and capacitance weight! 

The Vidar runs the same size transformer but only 40,000uF of filter capacitance - 20K per side! AND it's a 100w into 8ohm amp - 200 into 4ohms. 

I own the STA200 by Nuforce and I cannot find anything describing capacitance, nor transformer size... I'm studying amplifier tech because I'm running into some difficulty when running the STA200 into my Moabs, at high volumes characterized by significant bass extension: think giant BOOM and you get the idea. Most of what I listen to is jazz/acoustic, so it's not a big issue until I move over to something that emphasizes boom, so I'm curious as to how the tech shows up in these applications...
listening99
erik_squires
16,382 posts
 
One thing that is confusing is that what we call power amps are not power amps at all.

They are voltage amps. We rate them at the power they can emit without clipping at 8 Ohms, but this really is a convenience.

Truthfully most amps attempt to multiply the input voltage by 20 (~ 26 dB I believe), and so long as they do not exceed the power supply rail’s limits they will do so with a great deal of accuracy.

Here is a link that probably explains a great deal I’ve left out or misinformed you:

http://www.skillbank.co.uk/psu/

gs5556
1,239 posts
 
The Aegir and the Vidar both share the same transformer and other parts to keep production costs down. Not the ideal amps to make transformer vs power rating comparisons with.


millercarbon's avatar
millercarbon
12,531 posts
 
I'm curious as to how the tech shows up in these applications...

If you figure it out let me know. All the BS above falls apart (and I do mean all of it) the second you listen to a little 34 watt Raven or other good tube amp and realize it sounds way more powerful than you would ever guess based on tech specs. 

At best tech specs like capacitance correlate only vaguely and occasionally to what is actually heard. More often what happens is guys who memorized some talking points regurgitate every chance they get without regard to any actual real-world experience. Then because this happens so often it becomes common wisdom.

Well, it ain't wisdom. But it is common. 
listening99 OP
172 posts
 


 @millercarbon What then is the secret, if it's ALL BS? How does a person know if they are making a high current, high watt amp, or not? Clearly, companies are aware of their end products in some degree, comparing them to other offerings they have engineered and printing specs that correspond with relative differences connected to those specs. There is a relationship between the specs and the workings of these amps, as envisaged and contrasted in the lineup of a single amp manufacturer of numerous models, no?


millercarbon's avatar
millercarbon
12,531 posts
 
Well when you put it that way then yes there may well be "a relationship between the specs and the workings of these amps, as envisaged and contrasted in the lineup of a single amp manufacturer of numerous models". When you put it that way. Which is not the way I put it. Which was "All the BS above falls apart (and I do mean all of it) the second you listen."

Do you see the difference? You're talking measuring. I'm talking listening. That's the secret.
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