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410 HD-150 speaker impedence

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Peter Maziar (mosfet)
Username: mosfet

Registered: 11-2006
Posted on Tuesday, December 19, 2006 - 04:54 pm:   

Hi, I have the original 10" ceramic magnet eminence speakers in my Music Man 410-HD150 combo amp. Does anyone know what their impedence and power handling is? markings: C10GHD 67 8115
Peter Maziar (mosfet)
Username: mosfet

Registered: 11-2006
Posted on Tuesday, December 19, 2006 - 08:05 pm:   

They read 5.5 ohms each on my multi-meter. And the total wired in series-parallel is 5.5 ohms. What impedance should the amp be set to? 8 ohms or 4 ohms??? Anyone know the correct answer????
Rob Brotherston (bamboo633)
Username: bamboo633

Registered: 11-2006
Posted on Wednesday, December 20, 2006 - 02:20 pm:   

What a multi-meter measures is resistance, or the DC opposition of the speaker coil to current, the impedance is frequency dependant and somewhat harder to measure.

The speakers probably have an impedance of 8 ohms each, with the overall cab impedance also being 8 ohms. An 8 ohm speaker usually measures about 6 ohms of resistance with a 4 ohm speaker measuring about 3 ohms of resistance.

I hope this helps...
Peter Maziar (mosfet)
Username: mosfet

Registered: 11-2006
Posted on Friday, December 22, 2006 - 08:34 am:   

Yes, and that's why I'm unsure... Most 8 ohm speakers I have measured read at around 7.5 ohms, most 4 measured 3.5 to 4. These measured 5.5 ohms, so I though they may be 6 ohm... Did Music Man ever use 6 ohm eminence speakers?
Mike Kaus (mm210)
Username: mm210

Registered: 05-2006
Posted on Thursday, December 28, 2006 - 04:51 am:   

I assume by the numbers that you are using some form of a Digital meter. Most of the good ones that I see(and it's a shame) DON'T have a zero balance. Even my flukes and Snap Ons don't. When you touch the probes together at low ohms, what do you get. I think you're seeing the mis-match with the leads too. You need a meter that will zero, for sure. Either Low tech analog or a zero'ing DMM. One of my shack meters zero's, believe it or not. Other than that, I use my simpson 260.
Peter Maziar (mosfet)
Username: mosfet

Registered: 11-2006
Posted on Saturday, January 20, 2007 - 09:26 am:   

One of my digital meters reads 0.3 ohms shorted, and 5,4 ohms across the speaker load (original speakers and wiring, 200 ohm range). The other digital meter reads 0.2 shorted, and 5.4 across the load, 200 ohm range.
Steve Kennedy (admin)
Username: admin

Registered: 03-2002
Posted on Saturday, January 20, 2007 - 04:21 pm:   

The must be 8-ohm drivers. They measure close enough to the expected 6-ohms AND it is too high to be 4-ohms AND Music Man factory speakers have ALL been 8-ohms from the very beginning!

Modern digital meters are not optimized for accurate low-ohm readings and we aren't looking for accuracy anyway, just a ballpark clue.

I have never seen a Music Man factory speaker that WASN'T an 8-ohm driver.

Steve
Peter Maziar (mosfet)
Username: mosfet

Registered: 11-2006
Posted on Tuesday, January 30, 2007 - 08:33 pm:   

Thanks, Steve. I have set my impedence switch back to 8 ohms. Your input certainly is appreciated!