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The following page was printed from RemoteCentral.com:
| Topic: | How to measure speaker impedance? This thread has 49 replies. Displaying posts 16 through 30. |
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| Post 16 made on Tuesday October 29, 2019 at 22:42 |
tomciara Loyal Member |
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Posts: | May 2002
7,969 |
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On October 29, 2019 at 19:58, tweeterguy said...
Here’s what I use: Tenma 72-6948 Audio Impedance Meter Tenma [Link: amazon.com]Tenma has been making test gear for many years. There’s one of those on eBay for $80.
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There is no truth anymore. Only assertions. The internet world has no interest in truth, only vindication for preconceived assumptions. |
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| Post 17 made on Wednesday October 30, 2019 at 00:32 |
highfigh Loyal Member |
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On October 29, 2019 at 13:27, rguy1 said...
Grab a multimeter and check the resistance of a whole bunch of different speakers. That will give you a feeling of whats going on and go from there.
The measurements will vary but, will give you an idea of what to expect in the real world.
If you were wiring a series/parallel setup, use the manufacturers spec and calculate from there. When finished wiring them up, read the resistance across the final load to see if you are in an accepatble range. If your close to the expected resistance, then you should be alright given your amplifier can handle that load.
Impedance is dynamic in loudspeakers. Can, and does, vary across the frequency spectrum.
You can understand alot by using a multimeter for everything you do electrically.
I too came from the car audio industry. Attended Rockford Fosgate's 3 day course they offered back in the late '80's in Tempe AZ. Still have the 3 ring binder somewhere in my shop.
It seems that car audio guys,many times, have a better understanding of system design from experience. (Breaking shit) If these were single drivers, a series/parallel setup might work but even then, ignoring the current seen by each driver is a good way to end up with a bad system and blown drivers. These, being two way (at least) would end up being two woofers in series with their own passive crossovers plus two tweeters parallel to the woofers. That's a whole lot of screwed up impedance for the amp to deal with. I never made it to Rockford Fosgate's boot camp, but I still have my binder with the Power Cube specs. I also went to Alpine's GAIT training- we calculated box dimensions using worksheets and calculators. That was(n't) fun, but it was good to learn how everything ties together. Impedance is an indication of the reactance of the speaker. Many amps have serious problems dealing with capacitive reactance, some have problems with inductive reactance and some just don't care. If the amp cares, smooth the impedance with Zobel networks.
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My mechanic told me, "I couldn't repair your brakes, so I made your horn louder." |
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| Post 18 made on Friday November 1, 2019 at 15:20 |
wildulmer Long Time Member |
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Posts: | June 2007
273 |
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I will second the Gold Line. Great tool for anyone who deals with speakers. The only place that meter falls down is when testing subwoofers, the results are all over the map because it does not have the power to really drive a sub.
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| Post 19 made on Sunday November 3, 2019 at 00:12 |
lowvoltguy Long Time Member |
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Posts: | September 2002
176 |
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On October 29, 2019 at 18:36, Trunk-Slammer -Supreme said...
I used the Gold Line ZM-1P for years, and it came in handy many times.
Seriously overkill, but none of the cheap Chinese meters were around back in the day. We still use them.
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| Post 20 made on Sunday November 3, 2019 at 16:53 |
tomciara Loyal Member |
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On October 30, 2019 at 00:32, highfigh said...
Impedance is an indication of the reactance of the speaker. It is way more than a simple indication. It is actually the sum of the DC resistance plus any inductive or capacitive reactance factors. And it varies depending on the frequency it is measured at.
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There is no truth anymore. Only assertions. The internet world has no interest in truth, only vindication for preconceived assumptions. |
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| Post 21 made on Sunday November 3, 2019 at 22:13 |
buzz Super Member |
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| Post 22 made on Monday November 4, 2019 at 09:07 |
highfigh Loyal Member |
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On November 3, 2019 at 16:53, tomciara said...
It is way more than a simple indication. It is actually the sum of the DC resistance plus any inductive or capacitive reactance factors. And it varies depending on the frequency it is measured at. Never said it's a simple indication and the fact that a graph of a driver's impedance is often called an 'impedance curve' implies that it's not the same for all frequencies.
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My mechanic told me, "I couldn't repair your brakes, so I made your horn louder." |
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| Post 23 made on Monday November 4, 2019 at 12:16 |
Ernie Gilman Yes, That Ernie! |
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Tom,
highfigh's exactly right. He never said it was simple and "curve" blatantly says "different frequencies" to the experienced person.
If you want to be picky, then add to your description that impedance is not the sum, but the vector sum, of resistance plus capacitive and inductive reactance. (In fact, one could go so far as to use the term resistive reactance, but since reactance implies a phase angle and the phase angle of pure resistance is zero, we never call it resistive reactance.)
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A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw |
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| Post 24 made on Wednesday November 6, 2019 at 11:22 |
Ernie Gilman Yes, That Ernie! |
Joined:
Posts: | December 2001
30,104 |
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Hey, Fins, it just occurred to me: why do you want to measure speaker impedance?
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A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw |
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| Post 25 made on Wednesday November 6, 2019 at 17:19 |
HiFiRobbie Select Member |
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Posts: | June 2006
1,565 |
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I've had one of these for years. Could probably count the amount of times I've used it on my fingers and toes, but it's relatively cheap, and great to have. 
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Problems worthy of attack, prove their worth, by hitting back. -Piet Hein. |
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| Post 26 made on Thursday November 7, 2019 at 02:15 |
buzz Super Member |
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Measuring speaker impedance only at 1KHz can be misleading. In this case one would walk away rating the speaker at 8 Ohms, but the low points will fluster some amplifiers. If one would parallel connect two pairs of these "8 Ohm" speakers to an amplifier that is rated at 4 Ohms, the amplifier would probably freak out. 
Last edited by buzz on November 7, 2019 02:40.
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| Post 27 made on Thursday November 7, 2019 at 11:06 |
tomciara Loyal Member |
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What Buzz said.
In our service days, Good Guys sold Infinity speakers. They sold a lot of a certain model called a Kappa 7, and it had an impedance dip that caused the middle of the road Kenwood amplifiers to go into protect at high volumes. It was due to an impedance dip in the upper bass range. They learned to sell higher powered Denon receivers when they were selling the Kappa speakers.
The run of the mill Japanese speakers were no problem. But everybody knew that if you wanted better sound, you would not go that way, instead would put a nice American, British, or Canadian speaker system in, and the better speakers tended to need more power and more current capability.
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There is no truth anymore. Only assertions. The internet world has no interest in truth, only vindication for preconceived assumptions. |
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| Post 28 made on Saturday November 9, 2019 at 10:43 |
TimmyS Long Time Member |
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Posts: | March 2011
235 |
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On November 3, 2019 at 22:13, buzz said...
The Dayton Audio DATA V3 is a cost effective speaker measurement instrument. I do not think the V3 is shipping yet and the older V2 is sold out, maybe you can buy the V2 used if you need this in a pinch right now.
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| Post 29 made on Saturday November 9, 2019 at 21:55 |
Ernie Gilman Yes, That Ernie! |
Joined:
Posts: | December 2001
30,104 |
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Okay, but wait a minute. When do you ever connect a woofer to a piece of test equipment without the woofer being in an enclosure?
Wired as it appears to be on the site's home page, you can measure, what? DC resistance? Impedance above its useful range? Every other important aspect of woofer performance requires an enclosure.
Sorry, but this kind of makes me wonder if this company knows what they're doing.
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A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw |
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| Post 30 made on Saturday November 9, 2019 at 23:41 |
buzz Super Member |
Joined:
Posts: | May 2003
4,387 |
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I’ve talked with them at trade shows. They know what they are doing.
In many respects, this instrument is over kill for our simple application, but it is cost effective.
Any variable frequency oscillator with a constant output voltage, coupled with a VOM having adequate frequency response, will work for our purposes.
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