Axiom Home Page Forums General Discussion Home Theater VP160 Concept Discussion

The speakers are wired in parallel and the amp achieves that much power, even more, IIRC.

You also have to consider how Axiom produces their lineup and to add another box design might be more costly than to simply router out a second hole in the already large cabinet of the 600 turning that cabinet design into a sealed unit.

We seem to have a different approach on this forum, straight talk and no myths.

I believe it was Ian that mentioned using the 600 box and amp due to the factors I previously mentioned way back when it was first introduced.

Whoa... FINALLY!!! That's what I'm talking about. I believe I can form a pretty solid foundation of education about sealed vs ported design characteristics based on that explanation alone! Why has it taken me so long for to find that tid bit of information? I'm not saying everyone's been hiding it away from me or anything of that nature, I've just never been able to find that sort of description anywhere!

Thanks for that. Ok so now on to my next real weakness in audio knowledge... It was said that the twin woofers in the EP800 are hooked up in 'parallel'... So does that mean that they each receive the roughly 800 watts put out by the amp? That's another thing that I've never truely understood, the laws of division and multiplication when it comes to electricity.

Say for instance an amp puts out 1000 watts and you hook one 8 ohm woofer up to it, now its driving that woofer at 1000 watts. So when you hook up another 8 ohm woofer up in 'parallel', they both get 1000 watts, at a 4 ohm load? Is that right? So in other words the two woofers in the EP800 are actually being driven harder than the one woofer in the EP600... Yes? I had been thinking that with the amp being an 800 watt amp, and there being two woofers to drive, that they both only got 400 watts a piece.

Hmmm... I may just grasp these concepts after all, provided I'm right in both of those assumptions. If not, then perhaps I'm a hopeless case!

Well, unless the amp is turned up to maximum gain, with a signal at maximum gain, no driver is getting 1000W or 800W, regardless of how many drivers are hooked up.

Yes Micah, you continue to discuss amplification as if the maximum output capability of an amplifier had something to do with how much power is actually used, despite much info to the contrary having appeared here. At a typical comfortably loud average listening level in the mid-80s of dBs, more like 1 watt, rather than 1000, is used.

If two drivers are driven in parallel, each uses the same amount of power and since they would put out at least 3dB more sound level than a single driver(of the same sensitivity)using the same amount of power, in order to keep the same sound level the power to the parallel drivers could be reduced and they would be driven a little less hard.

One of these days it will sink in John.

Take a gander at some of these sub drivers (scroll down).

http://www.tcsounds.com/index.htm

Stop right there! Just because an amp is rated for 1000W doesn't mean it is actually putting out 1000W the moment it is powered on. Maybe that's where your confusion lies. A 1000W amp paired up with a woofer does NOT mean that the woofer is being driven at 1000W. The amp does not "drive" the woofer in that sense, instead the woofer draws on the amp.

Here is a loose analogy. Think of an amp like a big magical well (of water). Let's say the well is capable of supplying 1000L of water. If one day you're thirsty and you go to the well for some water, you don't get hit with 1000L of water do you? No, instead you simply pull up and/or drink up as much water as you need in order to quench your thirst.

Likewise, a woofer (you) will only draw as much power (water) from an amp (the well) as needed in order to acheive the desired volume (quench your thirst).

I was using a 'max gain' scenario in my example, just for shits & giggles.

Good people understand that was not an attempt to say that the EP800 is ALWAYS pumping out 800 watts to each woofer 24/7. I was merely using the 'maximum output' scenario to understand the way power works. My previous understanding was that at maximum output of a 1000 watt amp with two drivers hooked up,each driver would consume 500 watts a piece.

So in that example I gave, I was showng off how wickedly knowledgeable I've become as I'd finally come to understand that they would both draw the full 1000 watts (at maximum output) that was available. Not divide that available power between them.

To add to the humor portion, I'll throw in this hardly related story.

I once tried using the water analogy on a coworker in trying to explain the difference between what our company describes a "access speed" vs. "service speed" on fiber circuits.

My explanation:
If you were building a house and needed some pipes to get water from your well to your sink, there would be different size pipes.
Lets say instead of MB per second, we are talking water so lets call it "liters per second." You know you need to be able to pump through 5 liters per second at your sink ((yes I know that's a crazy number.)) That would be your desired "Service Speed".

When you go to the hardware store, the pipes come rated for only two sizes, the small one is 10 liters per second but the bigger one is rated for 100 liters per second. These pipe sizes are the "access speeds."

Either one would support your smaller service requirement of 5 LpS but the bigger one is going to cost you more. However, the smaller one will be limited to a max of 10 LpS, should you ever find a need for much more water flow later on.

Her Response:
"Ohhh, I get it. So the Access speed is the size of the pipe and I'd only need a 100MB pipe if I needed more Service speed than what the 10MB pipe can hold." (Yeah, I think shes got it!!!)
"But what is the water for, to keep the fiber cool?"

(DOH!!!, slaps forehead and gives up.)

The water analogy works well for describing electricity, but the way you've presented it here paints the wrong picture. Speakers do not draw anything, they are more of a flow restriction than anything else.

I've been meaning to write this up for a while. Consider this my first draft.

As I said the water analogy works well. So lets assign some common water works parts to an amplification/speaker system.

The electric grid is like a reservoir feeding a large area.
The power supply in an amp is like the a water tower covering a community.
The capacitors would be like a pump in a house.
The output transistors are a valve.
The speaker is plumbing after the valve.

We'll ignore the voltage/current thing for now, and I'll say power. But if you want to think about them, in terms of water, voltage is how much water there is, and current is how much pressure is behind it. You can have a lot of water at low pressure, and it'll just flow calmly, like a sewer pipe. Or you can have a little water at very high pressure, and it can be used for cutting, like a water saw.

The electric grid has a pretty much unlimited supply of power from the point of view of the amp. But only part of that is being made available by the power supply. You can't draw any more than power supply makes available at any given time. But if you need a little extra push for a short period of time, you can rely on the capacitors.

Most multi-channel amps have one power supply, and one bank of capacitors for all the output transistors. Think of the output transistors as a number of push-button valves. They're all fed from the same source, if you open all of them at once you'll come closer to exhausting the supply. But even wide open they can only flow so much. The reason I said push-button valves is because of what they're doing. Think of a valve that automatically springs shut when you stop pressing on it. But the harder you press the more water that flows at the time. The pre-amp stage is what's pressing that valve open. It's taking a little action, the desired output waveform, and causing it to be amplified by opening and closing the valve in the same pattern.

Finally after the valves there are a series of pipes. If a speaker has high resistance those pipes are narrow. If it's of lower resistance then the pipes are bigger. If you connect two pipes in parallel they'll have half the resistance of a single pipe.

Here's where the analogy breaks down. Water vales don't suffer the same was transistors do when they're turned wide open, and have big fat pipes behind them. But if you can imagine the water being damaging to the valve, and the valve itself not being designed to flow into an open space, but only being spec'd to use a specific diameter of pipe or smaller you can get a better idea of what happens with a too low of resistance speaker.



As I said, first draft, just off the top of my head.