Impedance - The most ignored and useful measurement tool


I’m constantly reading about audiophiles diagnosing their speakers or attempting to mod their crossovers with expensive new parts. The one tool I wish they’d all get and rarely do is an impedance graphing tool. These are either nearly free or affordable.

They let you produce impedance charts like Stereophile does, as well as measure capacitors and inductors with ESR/DCR respectively.

In the nearly free variety you can build one and use Room EQ Wizard. In the affordable is the Dayton Audio V3. Either one does an excellent job of measuring a driver, crossover parts and the entire speaker as well. Completely irreplaceable tools.

Diagnosing your speakers with the help of others on the internet is made so much easier when you have one of these. Even if your speakers are fine, measure them and keep the charts handy for when they do go bad, it will make it much easier to understand what is and is not working. Replacing a cap/coil? Measure them and the speaker before and after when you are done to make sure everything came back together properly.

You’d be surprised how many speakers have a woofer or tweeter that has stopped working but the listeners don’t even realize it.  These are immediately visible problems in the impedance plot.

Of course, it's just a tool, but when a driver goes bad, or a solder joint fails the impedance charts will go wildly off track.  It's up to you to dig in and diagnose further.

erik_squires

Not long ago I went down that rabbit hole.  Replaced a set of Focal 807Ws as I wanted to downsize.  It's impedance curve if I remeber correctly show two humps in the bass regions and a rising impedance in the mids to relatively high ohms although it's sensitivity was measured an avg of 88.2 or thereabouts.

What I replaced them with were Audel Magika II as a smaller option that has worked well for me.  It also shares a similar impedance curve.

Some notable brands/reviewers have stated (without assessing phase) that these kinds of impedance were an old design designed to be more tube friendly and modern designs should be more level after bass and closer to 4 ohms to maximize the power output and ability to play the speakers louder.  Wont mention who but many should know. Probably right for some, not for all.

Whether it's better SQ, specs, whatever is the question I suppose. 

My Dali Opticon 1s have a relatively flatter impedance, also decent measured sensitivity at around 88 dB.  My main amp plays both well although my smaller amp  could not bring the Audel to perform as well while it did with all others so current might be a factor also. 

If I went tubes, then impedance may be more critical. 

Also, the Audels hit a low of 7 ohms in the mids whereas many speakers can dip below 4.   In the higherst frequencies it dips to 5 ohms but there it is inconsequential regarding power output of the amp.  essentially it acts like a 9 ohm or higher speaker which relies on current output. Perhaps the high ohms prevent my 40 watt amp form delivering enough current?  

My CA-1 performs great and the combo is very transparent but just avoids being too much in being described as analytical as well as being overbearing in the upper mids like many speakers can be. 

Ideally I suppose tolerances and curves would be tighter but those are how things measure versus sounds to an individual. 

Learned alot from Erin's Corner but never bought based soley on his recommendations.  I live with what I buy and like.  Not perfect but good.  If it works well, I'm good.  Getting a better something here typically meant giving up something there all too often.  If a speaker, amp, dac, etc. performs well enough, then enjoy.

 

I haven’t read this entire thread, but so far, I’m finding it to be a very smart conversation, just the kind of thing that I wish was posted more often on platforms like Audiogon.

The only thing I want to add is that anybody seriously interested in this topic should try to search out a copy of Joe D’Appolito’s long-out-of-print book "Testing Loudspeakers," published in a 1988 small-print run by Audio Amateur Press (which at the time was publishing Audio Amateur and Speaker Builder magazines).  Yes, this book was writtten by THAT D'Appolito.

It’s an outstanding reference, a bit technical for some, but written from an audiophile / speaker-designer’s perspective.

It took me several years to find a copy in the early 90s, and it cost me over $150 from a rare-book seller.  But it was worth the cost & effort to me b/c at the time, I was testing speakers for mainstream magazines. Today, though, even Amazon has copies of a 2018 reprint in the $40-50 range and I believe it's also on Google Books.

Highly recommended.

 

I wonder if Joe is still alive.  Last I heard, he was at Snell, but that was 15 or 20 years ago...

Honestly, if anyone is interested, head over to DIYaudio were a lot over talented and helpful builders hang out.

I didn't mean to start a whole conversation on impedance, just on how having basic diagnostic tools like this one can be really helpful..