Oh Impedance gurus....Question?

[jgcable]

Re: Oh Impedance gurus....Question?

You would think that Altec Lansing's would measure dead nutz. After all, these 300w Whiteframes were $180.00 each.
They must weigh 25lbs each.
Siggy, I trust your opinion. Since one measures 6.12 and the other 6.14 should I assume they are 8 ohm speakers? It certainly makes more sense then 4 ohms.

[OnlineStageGear]

Re: Oh Impedance gurus....Question?

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Resistance has a phase angle of 0 degrees, and Reactance has a phase angle of +/- 90 degrees. Therefore, when R and X are cominged, the phase angle of the ac circuit is between 0 and + 90 degrees. Futher, the ohms of resistance, and reactance must be combined by phasor addition, because of the 90 degree phade angle between the two. The sultant sum is called Impedance, with the symbol Z, which is the total opposition of resistance, and reactance to a sine-wave alternating current.


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You had to break out the long defination didn't ya ?? [img]/images/graemlins/laugh.gif[/img]
In a nutshell an Ohm meter will just get you close to the Impedance of a speaker. They will almost always tend to read under the rated OHms on an Ohm meter, plus 99% of all speakers aren't actually rated at 8 or 4 to begin with. Most are just close to 8 or 4 or 16. An 8 ohm speaker can have an Impedance of 6.9 ohms and still be called an 8 ohm speaker.

Matt

[siggy14]

Re: Oh Impedance gurus....Question?

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Resistance has a phase angle of 0 degrees, and Reactance has a phase angle of +/- 90 degrees. Therefore, when R and X are cominged, the phase angle of the ac circuit is between 0 and + 90 degrees. Futher, the ohms of resistance, and reactance must be combined by phasor addition, because of the 90 degree phade angle between the two. The sultant sum is called Impedance, with the symbol Z, which is the total opposition of resistance, and reactance to a sine-wave alternating current.


[/ QUOTE ]

You had to break out the long defination didn't ya ?? [img]/images/graemlins/laugh.gif[/img]
In a nutshell an Ohm meter will just get you close to the Impedance of a speaker. They will almost always tend to read under the rated OHms on an Ohm meter, plus 99% of all speakers aren't actually rated at 8 or 4 to begin with. Most are just close to 8 or 4 or 16. An 8 ohm speaker can have an Impedance of 6.9 ohms and still be called an 8 ohm speaker.

Matt

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Exactly what he said, mesa's and the other speakers just might be closer to spec's then normal, Mesa is good for being consistant.

[Deneb]

Re: Oh Impedance gurus....Question?

Yeah, that's about the next thing, Altec isn't consistant, well if they are metering in the 6s, they are, but maybe that's what they are supposed to read for that company

6>=4 ohm, 12>=8 12<=16 ohm.

[siggy14]

Re: Oh Impedance gurus....Question?

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Technically those speakers are probaly both 8 Ohm Speakers, being that your meter could be slightly off and not to mention speakers are not always what they read on a meter, for example most marshall cabinets actually read 15 Ohms.

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They are 8 ohm. Your meter is measuring resistance and speakers are rated in Impedence which is both reactance and resistance.

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If I assume the speakers are 8 ohms then I can take your suggestion and plug them into the two 4 ohm outputs which is basically a series box built into the amp. I'll try it tonight. Thanks..


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Plugging the 2 speakers into the 2 4 ohm labeled outputs should be fine. The back of an amp usualy is not series if it has 2 speaker outs, it is probably parallel.

Matt

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Like he said here, speakers arent really read in resistance like you are using with a meter, it is close but should not be right on, if you are reading 8ohms on a 8 ohms cab that means the actual speaker is higher then 8 ohm impendence.

The guitar world seems back assed, you have the ohm thing as well as watts, Sound level is not really measured in watts, a 100 watt amp is not twice as loud as a 50 watt amp. If you have a 50 watt amp you would actually need a 500 watt amp in order for it to be twice as loud.

[mulder1966]

Re: Oh Impedance gurus....Question?

I thought that 4 ohm speakers (or loads)metered at about 3.4 ohms, and 8 ohm speakers are close to 7. (from what I remember back in the day) [img]/images/graemlins/popcorn.gif[/img]