Impedance????

First question: impedance of what ? There are lots of impedances through the chain of a hifi.

Second question: Why ? What problem are you trying to solve ?

Well, impedance is different at each input and output of each component of your system so there is no "system" impedance. To measure impedance of your speakers or input/output of a component, the only accurate way is to use an oscilloscope and sweep the frequencies from DC to 50kHz while in Bode plot mode.

An ohm meter will only give you the resistance and not the impedance - thus it will do this only for DC and not for any other frequency so its informational value is very limited.

Arthur

I am biamping 2 nad2200 amps to a set of Paradigm monitor 11's V.3.

I want to make sure I am at 8 ohm coming to the speaker.

"I want to make sure I am at 8 ohm coming to the speaker." You can't because no normal amp is. Typically, the amp has a much lower output impedance than the rated load. Usually by a couple of orders of magnitude.

Now, if you meant to determine the load that the biamped speakers represent, you can estimate the LF load with a DC ohm-meter since it will measure a bit less than the AC impedance. For the HF load, however, there's undoubtedbly a DC block and you would have to get an AF signal and an AC meter, at the very least.

Kal

ok, I have the amp set to 8 ohm and the speakers are rated at 8 ohm, but does the fact that I have the Amp/speaker set up vertical(v/s active) biamping change the impedence v/s 1 amp run to both speakers?

I started this when Diewallen inquired about vertically biamping. My rhetorical question was basically "If you use one preamp output through a double terminated (split?) interconnect into multiple amp inputs duplicating the signal into both channels, does it change the impedance the preamp sees enough to affect the outcome?" I didn't know the answer, but thought it might.

David (Diewallen) is this correct, or are you asking something else?

Jim S.

I do not understand the question but I doubt if bi-amping changes any loads.

Kal

Yes, that is correct jim, that is what I am asking.

DLEWALLEN

Jim,

If you split a preamp output into two poweramp inputs then the preamp sees the poweramp load in parallel.

When two equal impedances are put in parallel the resulting impedance is halved.

So running a "Y" type splitter from a preamp to two poweramps will reduce the input impedance seen by the preamp to one half of the input impedance of a single poweramp.

For example if you have two identical poweramps with an input impedance of 40k Ohms, and you connect both of them via a Y type split interconnect to a single preamp output then that preamp output will effectively see a poweramp input impedance of 20k ohms.

Seandtaylor99,

In your opinion, what is the consequence of halving the impedance with a Y interconnect in a vertical biamp configuration. Will it change the sound characteristics, or could it even endanger the amplifiers?

Thanks for your advice?

Jim S.

ok, I have not received the pre-amp i purchased yet(should be here next week) but it is a NAD 1600, I do not know if it has enough out-puts for bi-amping, if I use a "Y" I am changing impedance, So what do I do to biamp?

I think you're worrying too much.

You don't have to match the preamp and amp impedance, in fact quite the opposite.

The output impedance of the preamp has to be low (few hundred ohms or less), and the input impedance of the amp has to be high (10k ohms or more).

It's really only a big factor if you have long interconnects with high resistance or high capacitance, so that cable losses are significant. Under 1 meter it will make little difference.

And, in any case I expect the preamp will have multiple outputs: they usually do.

Post back here if it doesn't sound right. If the input impedance of the two power amps is too low it will likely sound lacking in dynamics, and a bit rolled off in the high frequencies. If it sounds dynamic and sparkly all is well.

Jim, I highly, highly doubt it could ever damage the amps: there's just not enough power coming out of a preamp to do damage. Perhaps a really terribly designed preamp might fail.

To comment on whether the sound might change I'd have to know the output impedance of the pre, the input impedance of a single power amp, and the capacitance and resistance of the interconnect.

In most cases, with an active preamp, I highly doubt it would affect the sound. With a passive preamp, and/or power amps with input impedances under 10k ohms it might lose dynamics and roll off the high frequencies, but really you'd have to try it.

Thanks for your advice and the education!

Jim S.

Thanks so much for the advice and help Seandtaylor99 , sounds like you have some experience in this. I will post back after the holidays when all is hooked up and let you guys know how it does.

Thanks again

David