Speaker phase observation and question?


Hi everyone,

After months of playing around with positive phase and reverse phase connections to my Monitor Audio Silver 8 speakers, I have made a couple of observations. When connected in positive phase (red - red, black - black), the speakers put out pretty substantial bass, but the mids and treble are somewhat subdued. Upon reversing the phase, the mids and treble open up substantially, and the bass becomes somewhat subdued. To my ears, I actually prefer the reversed phased.

Moving forward to the current day, I purchased an app that tests phase using a generated tone. In testing my speakers, both bass drivers test positive phase, but the mid and treble test negative. I had read somewhere that some manufactures wire the drivers like this intentionally, but am confused as to whether or not this is the case with my speakers, or if it's a manufacturing flaw?

Any thoughts? 
chewie70
Man, I’m sorry I have to jump in here:

In a good many speakers the phase angle is significantly different for the woofers than it is for the midrange and tweeter. If the woofer has a significant negative phase angle while the midrange and tweeter are quite positive, inverting the phase of the woofer will bring them into better coherence.

This is too confusing phase angle with polarity. The polarity is either positive or negative. Applying the (+) of a 1.5V battery to the (+) terminal of a driver will result in the driver moving OUT. Reverse the battery and the driver will go IN.

Because drivers as well as their crossovers result in phase angles that may not add up correctly, matching the drivers so their total output adds correctly across the crossover frequency often results in the need to invert the polarity of drivers.  Something else not thought about is the time. In a flat baffle, a tweeter arrives about 0.1

My guess is that 99% of two-way systems have the tweeter in negative polarity. This is a good thing, because the alternative would be a deep null.

Designers deal with driver polarity consideirng only a pair of drivers at a time. By convention, the woofer is in positive polarity. Then the woofer/midrange is considered. If necessary, the midrange will be inverted. Based on the phase angles of the midrange and tweeter the polarity of the tweeter is considered. This time the tweeter may or may not be inverted.

The size, depth, placement of the drivers, the angle of the baffle, the order of the filters (1st, 2nd, etc.) all play into whether drivers will need to be inverted.

For goodness sakes, no one should be inverting individual drivers, that way lies madness unless you have the right tools or background information.

There are designers like old Thiel and current VanDerSteen who make polarity and phase coherense an absolute priority, and then buy or have drivers made that can work well in these configurations. It is not rocket-science, but neither is it proven to be desirable above all else, and often has risks associated with it.

Best,

E
By the way, if anyone wants to learn about speaker design, and how drivers and crossovers work together I have quite a bit of documentation, including real-time simulation tools you can use to play around and look at some of these concepts.  Please visit my LM-1 design page, here:

https://speakermakersjourney.blogspot.com/2016/02/the-lm-1-bookshelf-version.html

The files and design info are 100% free for music lovers. :) Haters have to pay.
Thanks everyone. This has been extremely informative, and I have learned far more about speaker design than I could have imagined.
@erik_squires My Focal 936's are exactly opposite of what you suggest about woofer polarity. The midrange and tweeter are in positive polarity while all 3 woofers operate in negative. 

The point of my comment was to point out how speakers are reactive and not subject to the superficial presumption that when voltage is applied a driver reacts predictably. A lot of people don't consider that a driver and crossover become more or less capacitive or inductive when driven by a signal and that the current draw that actually drives the speaker can be significantly ahead of or behind the voltage. 
Hi @kosst_amojan,

Well that is unusual, but not the end of the world.

Well, I consider that quite predictable, this is what math and simulations are for.

But your comments seemed to be mixing up phase and polarity.

Best,

E