What's The Deal With Phase Angle? - diyAudio
Go Back   Home > Forums > Loudspeakers > Multi-Way

Multi-Way Conventional loudspeakers with crossovers

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th October 2012, 10:15 PM   #1
Einric is offline Einric  United States
diyAudio Member
 
Einric's Avatar
 
Join Date: Feb 2011
Location: Bozeman, MT
Default What's The Deal With Phase Angle?

Well Fellas (and Ladies)?
What IS the deal with phase angle & why is it so important?
  Reply With Quote
Old 15th October 2012, 10:20 PM   #2
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

The real acoustic phase angles or the very different impedance phase angles ?

rgds, sreten.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow
  Reply With Quote
Old 15th October 2012, 10:29 PM   #3
Einric is offline Einric  United States
diyAudio Member
 
Einric's Avatar
 
Join Date: Feb 2011
Location: Bozeman, MT
I don't know the difference soooooo both.
In relation to the "Difficulty" of an amplifier to drive.
  Reply With Quote
Old 15th October 2012, 10:50 PM   #4
benb is offline benb  United States
diyAudio Member
 
Join Date: Apr 2010
Oh, that's what the speaker looks like to the amplifier - that's definitely the electrical or impedance phase angle. Speakers almost never look purely resistive to an amplifier - the impedance, boththe "8 ohms" approximation of the absolute value and the phase angle between the voltage and the current, change with frequency, and can be either inductive or capacitive in different frequency ranges (though I think most of the range is inductive). Resistive is the easiest for the amplifier to drive. The more reactive (inductive or capacitive) the speaker is, the more current the amplifier must provide to get the same output as a frequency where the speaker's impedances is more (nearly) resistive .

Expect Smith-chart-type graphs to be posted...
  Reply With Quote
Old 15th October 2012, 10:54 PM   #5
Einric is offline Einric  United States
diyAudio Member
 
Einric's Avatar
 
Join Date: Feb 2011
Location: Bozeman, MT
SO......The steeper the phase the harder it is for the amp to drive?
Attached Images
File Type: png DA175-RS100-DC28F.png (115.6 KB, 118 views)
  Reply With Quote
Old 15th October 2012, 10:59 PM   #6
Einric is offline Einric  United States
diyAudio Member
 
Einric's Avatar
 
Join Date: Feb 2011
Location: Bozeman, MT
So, how do amplifiers handle phase reversals in 3rd order crossovers?
Are they "Hard" to handle?
Attached Images
File Type: png DA175MTM.png (135.9 KB, 109 views)
  Reply With Quote
Old 15th October 2012, 11:20 PM   #7
sreten is offline sreten  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: Brighton UK
Hi,

Difficulty to drive is related to the impedance phase angle,
and nothing to do with high order x/o acoustic phase changes.

Simply put you want to avoid large phase angles at the same time
as low impedance, large phase angles at high impedance don't matter.

For a purely resistive 8 ohm load power is dissipated in the load.
For a purely reactive 8 ohm load at the same current no power is
dissipated in the load and this power is dissipated by the amplifer.

The more reactive a given load impedance, the more it thermally
stresses the amplifier compare to a purely resistive load. As the
thermal stress on amplifier into resistive loads depends on
current there are some simple rules of thumb :

An amplifier for 8 ohm speakers must be able to drive 4R.
An amplifier for 6 ohm speakers must be able to drive 3R.
An amplifier for 4 ohm speakers must be able to drive 2R.

In all cases for the latter not necessarily continuously. This
covers the phase / reactance issues of nearly all speakers.

With proper amplifier design and sensible speaker design its no
big deal most of the time. However with chip-amps and their
aggressive protection and in particular current limiting, and
their specification chasing, supply design is a big issue.

rgds, sreten.
__________________
There is nothing so practical as a really good theory - Ludwig Boltzmann
When your only tool is a hammer, every problem looks like a nail - Abraham Maslow

Last edited by sreten; 15th October 2012 at 11:24 PM.
  Reply With Quote
Old 15th October 2012, 11:32 PM   #8
benb is offline benb  United States
diyAudio Member
 
Join Date: Apr 2010
No, those diagram show the phases generated by the crossover, or more accurately, the difference between the phase of the input voltage (of the crossover) and the phases of the output voltages at the driver terminals. These determine whether each driver should be connected with "+" polarity or "-" polarity to get the proper acoustic phase from the speaker. These have little to do with the phase between the input's voltage and current. That phase also varies with frequency, whether it's a single full-range driver or a multi-way system with a crossover. One design isn't necessarily harder than another for an amplifier to drive, but specific models of speakers are harder than others.

The whole thing is basically AC circuits analysis (one of the fundamental courses in Electrical Engineering), which needs (the mathematical concept of) complex numbers as a prerequisite.
  Reply With Quote
Old 15th October 2012, 11:46 PM   #9
Einric is offline Einric  United States
diyAudio Member
 
Einric's Avatar
 
Join Date: Feb 2011
Location: Bozeman, MT
OK, that being said, how can you predict the Impedance and Acoustic "Phase" of a given loudspeaker in simulation?
I take it Crossover Pro 3 cannot show these aspects of design?
  Reply With Quote
Old 16th October 2012, 07:56 AM   #10
diyAudio Member
 
wolf_teeth's Avatar
 
Join Date: Mar 2006
Location: Indiana
Blog Entries: 1
Quote:
Originally Posted by Einric View Post
OK, that being said, how can you predict the Impedance and Acoustic "Phase" of a given loudspeaker in simulation?
I take it Crossover Pro 3 cannot show these aspects of design?
You answered your own question there...

Basically, the phase plot is the derivative (calculus) of the FR plot. You can extract phase with a Hibert-Bode transform applet, but that doesn't mean you can use it in a certain program to your advantage. Some simple calculators or simulators assume perfect resistive loads and flat-FR drivers; and offsets, phase, and such are not factored into the box of tools to produce good results.

Later,
Wolf
__________________
Photobucket picture pages: http://photobucket.com/Wolf-Speakers_and_more
Writeups/thoughts/blogs: http://techtalk.parts-express.com/blog.php?u=4102
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
LM1875 & phase angle, is it enough? Shike Chip Amps 1 28th October 2010 10:58 AM
Calculations for 2ohm into 1200w @ a 60 degree load phase angle. ? Fanuc Solid State 0 26th December 2007 12:25 AM
motor control by phase angle mitwrong Everything Else 6 5th November 2006 11:39 PM


New To Site? Need Help?

All times are GMT. The time now is 07:41 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2