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Replacing a midrange driver - different impedance

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Posted on February 4, 2021 at 07:55:45
Byrd69
Audiophile

Posts: 2481
Location: East Syracuse, New York
Joined: August 23, 2004
A friend has a pair of Glenspeak (may be mispelled) speakers with blown 5" mids. They are 6 ohm.

I have a pair of Peerless 5" mids, but they are 16 ohm.

Is there a mod at the back of the driver or on the crossover that can be made so this 16 ohm driver can be used satisfactorily?


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The short answer is "no.", posted on February 4, 2021 at 16:27:21
Brian H P
Audiophile

Posts: 779
Location: Oregon
Joined: December 18, 2012
A speaker driver does not present a flat impedance like a resistor. If you wanted to bring a 16 Ohm resistor down to 6 Ohms, you would parallel it with a 9.6 Ohm and that would be that. But a nominal "6 Ohm" driver will havie a variable impedance vs frequency, from a large peak at free air resonance, to a minimum of 4 or 5 ohms toward the bottom of its useful range, then rising steadily with frequency. The crossover filter is designed to work into this complex impedance, which you can not simulate accurately with a shunt resistor.

Plus, the two drivers may differ in broadband efficiency and frequency response. Making the substitution, even with a shunt resistor to bring the impedance "into range," will "kind of" work but will never sound right. Your friend would be much better off asking Madisound to recommend a closer replacement or substitute.

 

RE: Replacing a midrange driver - different impedance, posted on February 4, 2021 at 18:26:59
hahax@verizon.net
Audiophile

Posts: 3753
Location: New Jersey
Joined: March 22, 2006
It's not just impedance. It's impedance as frequency changes. It's the response of the driver itself. It's any changes in the dispersion. It's the new relationship to the driver characteristics of the driver it's being crossed to. It may ask for changes in the crossover points. A good crossover takes all this into account. It means a brand new crossover literally from scratch to do the job right.

 

you'd have to redo the crossover and adjust the sensitivity of the driver..., posted on February 5, 2021 at 05:46:30
mhardy6647
Audiophile

Posts: 14052
Location: New England
Joined: October 12, 1999
Contributor
  Since:
October 23, 2016
if the "new" MR is more sensitive than the old. If it is less sensitive, not much you can do about it.

Bottom line: look for a better (more approriate) replacement -- if you/your friend wish, go with a cheap generic replacement that's "close" in nominal parameters and physically fits (check PartsExpress, e.g.). Install and listen. If you/your friend can live with the result (e.g., until a proper replacement can be sourced), then do so. ;)

I've done the redneck, willy-nilly driver replacement thing before... a time or two. ;)
I am not proud of it, but sometimes "good enough" is good enough. "


all the best,
mrh

 

RE: Replacing a midrange driver - different impedance, posted on February 22, 2021 at 21:32:55
Presto
Audiophile

Posts: 5925
Location: Canada
Joined: November 10, 2004
It's a complete waste of time.

He may as well listen with the original mids removed. Stuffing a random replacement in there will probably be more offensive. Plus, it's the wrong impedance so frequency rolloff points will not just miss but be off completely.

I'd recommend you and your friend go on a journey of discovery and mystery and try to find that driver. They are probably out there - sitting on a shelf somewhere.

Get the proper name of the speaker and take the time to photograph the dead mids. I used to 'read' speaker driver catalogues at night to help me sleep (not on my online dating profile mind you) and I can often identify drivers on site. If you get enough speaker nerds seeing these mids, someone is bound to recognize them. Speakers sometimes have distinctive frames, hole patterns, cone markings, surround shapes and sizes, colors, textures...

So either put those wrong speakers in and risk taking down the entire electrical grid (kidding - probably bad sound at worst) or get your hands dirty and try to solve the actual puzzle.

Using those mids you have is a good, eco friendly idea.

But it's also a horrific and bad idea.

Get the right parts. Fix the speakers properly.

I rest my case.

Cheers,
Presto

 

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