@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?
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...
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...
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- 12 posts total
@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? |
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. |
How does a person know if they are making a high current, high watt amp, or not?The first thing to understand here is that power, current and voltage have a direct relationship; 1 watt = 1 Amp x 1 Volt That's called the Power formula, and like Ohm's Law, cannot be violated, unlike a speed limit :) So right away, if you work the math, you can see that a 'high current' amplifier is a misnomer. You can read more about that here: http://www.atma-sphere.com/Resources/Common_Amplifier_Myths.php One thing about filter capacitance: the amp circuit has timing constants in it, usually a coupling capacitor somewhere, which rolls off at some low frequency that can be calculated. The power supply has timing constants too (it takes a certain amount of time to discharge the filter caps based on how much current can be drawn from them); for best results the power supply should always have a timing constant considerably lower than that of the amplifier, otherwise low frequency instability and/or intermodulations can result. You might be thinking 'what about amps that are direct-coupled input to output?' and its a good question. They will always have the ability to modulate their power supplies! This is why you tend to see excessive amounts of filter capacitance in solid state amplifiers. Now its a pretty good bet that the amp won't see really low frequencies that will get it in trouble, due to the fact of timing constants rolling off in the sub-bass octaves upstream. But if there gets to be any noise or sag in the power supply, in a solid state amp that can be pretty audible as transistors tend to be more sensitive to voltage variations in the supply than tubes (generally speaking of course). So large filter banks are common in such amps. |
OP said: 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.. I mock this stuff because it is so eminently mockable. But the fact of the matter is it is also nice stuff to know. You just need to keep straight that its nice stuff to know, and not drink the Kool aid and start thinking you can actually build a music system with it. You can't. You can only build a music system by listening and evaluating by ear. Look, some of these tech stories are really well crafted. For sure. Heck I start to believe them myself sometimes! Over the years though I noticed some things. Several tube amps would drive speakers just as loud as I wanted, and feel more powerful doing so, and have greater bass slam and extension, than some other amps that were on paper much more powerful. Smaller power supplies, less capacitance, more powerful sounding. Now listening99 I hope you are listening because I want you to listen to this. Someone gonna attack me for this on the basis of some technical reason or other. They will in doing so glide right past the fact it sounded better, more powerful, with greater extension. A lot of them know this to be true. Heck a lot of them have heard it, actually experienced it themselves. So they know, on some level, the pointlessness of the tech talk. Nevertheless they persist. Nevertheless they try and explain away reality. Just watch. The technical reason for this, at least the one we are given, is bandwidth. The claim is made that transformers with greater bandwidth sound more open, dynamic, and powerful. So there is a technical explanation. Might be right. Then again, might not. |
- 12 posts total