Axiom Home Page Forums General Discussion Home Theater Need help deciding on receiver

>>There's also no need to think about a lower impedance speaker "pulling" more power from the receiver; if the 4 ohm speaker isn't less sensitive it doesn't use more power.

One more point which will either fill in the blanks or confuse everything...

For a given volume control setting the 4 ohm speakers actually *will* pull more power from the amp, but as JohnK says as long as the efficiency is the same that just means you won't turn the volume control up quite as high...

But before you get too excited, no you normally can't turn the volume control up as high with 4 ohm speakers as with 8 ohm speakers. If you could you would get twice as much power, in practice you get 20-50% more from a receiver that handles 4 ohms well.... and thermal or overcurrent shutdown on a receiver that doesn't handle 4 ohms well

Another way to think about all this is by using the garden hose analogy. Current would be the amount of water flowing through the hose. Voltage would be the pressure of fluid in the hose. Wattage would be a mathematical sum of the two (power). Resistance would be your thumb (ohms).

Put your thumb over the end of the hose, resistance is high and you get restricted flow (current) but higher pressure (voltage). Wattage remains constant because the voltage dropped, even though current increased. Remove your thumb, resistance drops and flow increases, but voltage drops. Again, wattage stays constant. Now, open the spicket and pressure will increase. By opening the spicket, you just increased flow (current). But if the spicket was already fully open, then the voltage will not recover.

With low impedance speakers, there is very little resistance to current flow, so in order to maintain wattage, voltage must increase by supplying more current. But with the inability to supply adequate current, voltage and wattage will ultimately drop, and stay below the speaker’s design parameters. This is where high current amps shine over amps with low current capacities. Without the capability to maintain a steady supply of electrons (current), voltage drops, hence the drop in wattage. So, in a sense, low impedance speakers do “suck” power from an amp more so than high impedance speakers. This occurs at one watt, or 100 watts. One watt at 4 ohms requires more electrons than one watt at 8 ohms. Can’t remember the formula, but it’s a substantial amount in %.

ok, i think i understand now, thnx.. however i have decided against the m80's as i have read in several other posts that in order to sound right they must be 4' from the wall, and my room is only 12x12 so that is like impossible, im sure ill be fine with the m60's

I think you will be very happy with the 60's.

for your reference, and others who may be reading, the 80's do not need to be away from the wall 4'. 12" is enough, although some folks have them up to 18".

You will be happy. Listening now to Kenny G in pure direct mode. Awesome.

Couple of questions to the board:

I've been to the ubid website and noticed a 4000 series Denon. The U.S. Denon website does not show that one. I went to the Canadian Denon and it is there. Without going through a lot of detail, what are the differences between it and the 3805 and 5305?

Second, I took a couple of pictures and tried to post them. Couldn't get it to work. Son says that I can't just go from my picture file and import it to this thread. Anyone have the magic to post pictures?

The Rat.

You need to have the photos hosted on a website. Many of us here use Photobucket.com. It's free, but there are limitations on image size, disc space, etc.. If you find you need more, you can pay for it. You'll want to keep your photos small anyway so they don't take up too much space here on the forum, and cause those who are using a dial-up connection to wait forever for the doggone thing to load.

Just go to the website, sign up, upload your photos, copy the info in the "Img" box beneath your photo, paste that info into the post form here on the forum, and VIOLA!

Thanks Ajax.

I printed the instructions and I'll give it a try.

Looks like my son was right when he said that I couldn't just import the pictures!

The Rat.

Test.

The rumors on the net says the 4805 will be out late this year. Basically the same features as 3805 with dvi inputs/ouputs. Don't know the wpc. Price estimates 3600-3800.