60's, 150, 8's and a 350 are on their way (I had to tell FedEx to delay; won't be home this weekend...arggh!)

The 60's are 8 ohm, the 150 and 8's are 6 ohm.

I'm running these from a Harman Kardon 325. Specs (sorry don't know how to title the link):

http://www.harmankardon.com/specifications.aspx?cat=REC&ser=&prod=AVR%20325&sType=H

Here's all the 325 info: http://www.harmankardon.com/product_supp...jump=qs&#active

Will the amps (7x50) automatically drive 6 ohm speakers? Can you guys explain a little ohmage to me?

I'm also thinking of running pre/pro and amp (Emotiva MMC1) OR a new receiver with hdmi (no hdmi on the 325).
Any comments on that decision are greatly appreciated (probably new thread worthy).

Thanks all
Chaitanya

The H/K will handle the 6 ohm load no problem. If it has an impedance switch leave it set to 8 ohm and you'll be fine.

What wid said.

Once you have it all set up, and if you feel like you are still wanting more(upgradeitis) then by all means look for a new amp and pre/pro.

You can run 4, 6, or 8 ohm all in combination with your HK receiver, no problem.

I have the 525 and I run M80s, a VP100, and QS4s on it. You're just fine. The x25 series is generally pretty solid, even if they do run hot.

Chaitanya, the listed number of ohms for a speaker represents how much the wire in the speaker drivers resists the flow of power through them. The lower the ohms, the lower the resistance(or impedance, which is the more specific term), and more current can flow through the wires for a given amount of voltage "pushing" it through. Amplifiers, including those in receivers, don't know what the impedance of speakers they're connected to is, just that they have to supply a certain amount of voltage and current at a given instant in time. So yes, the receiver can be said to "automatically" adjust to the impedance of the speakers as long as it isn't called upon to supply more voltage and current than it's been designed for.

The lower impedance switch or menu setting that many receivers have just limits the maximum amount of voltage that the receiver can supply, and when the maximum voltage is limited so is the maximum current and power, because of Ohm's Law. This is a safety-related measure to help prevent overheating, but because it reduces the maximum power available by as much as half, it should never be used.

Your 325 will drive your Axioms very well and the 50 watt rating is quite conservative, so the sound level can be quite high. If you want to change to a new receiver because of HDMI or other features, that's a topic that can be considered later.

John,

That was a very lucid treatment on amps and ohms, the only addition I'd make is that some modern amps 'do' account for speaker impedance dynamically. For instance, NAD's Powerdrive circuitry. Instead of me explaining, I'll clip some text from the data sheet:

NAD's PowerDrive™ technology measures load impedance continuously on each channel and adjusts the power supply voltage for maximum undistorted dynamic power into the connected speaker at all times and under all operating conditions. The signal processor also continuously measures temperature and average long term power and, based on this information, chooses the optimum voltage.

Hi ClayB,

What NAD is doing with their fancy "PowerDrive" description is essentially admitting that the protection circuitry is always operating and will current-limit the NAD's output (hence reduce the power output) if it senses too low an impedance, or excessive current flow. When protection circuitry is too over-protective, as it is in some brands (Onkyo, for one), it may severely limit the receiver's power output into lower impedances.

As JohnK points out, one way of "tricking" the protection circuitry on some units is to always leave the impedance switch on the receiver (if there is one) set to 8 ohms.

On the other hand, NAD amps and receivers in the past have not had any problems driving lower impedances.

Regards,

Alan

The HK will have no problems driving those speakers, I also have m60's, vp150, and two qs8's being ran by a HK247 and it drives those speakers very well! Congrats on your purchase, you will love it!