What is Phase Angle and Shifting?

Bifwynne, I posted my response in the other thread where you asked the question 1st but I'll post it here again:

>http://forum.audiogon.com/cgi-bin/fr.pl?fcabl&1310053833&openflup&20&4#20

Not just the crossovers. the voice coils and construction of drivers have inductance that affect phase. I was building Bessel filters 30 years ago because of group delay characteristics. Then, there's impulse response ...

Huge, complex topic. Sometimes fairly bleeding edge stuff, especially in digital. Lots of opinion about what we can hear and how we hear it. Even the instruments to detect time domain differences to smaller scales are being developed.

I get a little upset when I read "time and phase aligned" as promotional and restated as dogma. Not that I disagree with the principle, the effort and, sometimes, the results. Narrow viewpoint.

do panel speakers have less problems in phase distortion than cone designs ?

Anybody ready for a trigonometry and vector algebra lesson?

Mrtennis: Not familiar how ESL's compare with their integral transformer but magnetic planars have no voice coils and primarily resistive across their range and have negligible phase "distortion". That, in itself, doesn't make them ideal but I've wondered if that has always been part of the appeal.

Ok thanks. I get the picture. The topic is a can of worms. Let me try to simplify the question a little. In the context of tube versus SS amps, I recall reading comments that certain speakers can be hard to drive for certain amps because impedance in the lower bass frequencies is very low AND the speakers present "hard" phase angles. Anyone care to explain the concept??

Also, as a high level observation, there are a number of OPs that ruminate about accuracy and precision of sound systems. In light of the thoughtful comments made here and elsewhere about so called time and phase coherent speakers, it would appear the macro concept of accuracy and precision is disingenuous. Even if one believes that their electronic gear perfectly amplifies input signal information, i.e., so called gain on a wire, the speakers are at best the culmination of design compromises that include issues pertaining to time and phase conherence.

Notably, there are several comments in various OPs that contend that not all time and phase differences sound that bad. And further, attempts to "correct" such differences create other sonic problems.

In short, if one would compare the complex sound waves comprising music produced by a speaker to the same electronic analogue signal fed into the speaker, there must be considerable distoration, especially around the cross over points of the drivers as well as at the resonant frequencies of the drivers. However, I surmise that the difference between a speaker that sounds good and one that does not is a function in large part of whether the harmonic distortion sounds good or bad.

It's kinda' like tryin' to squeeze jello in the palm of your hand. When you tighten your hand around the jello, some is bound to squeeze out between your fingers. There's no getting around it. So the trick is squeeze, but not too much.

Thanks for the information. This discussion puts a different spin on speakers, at least for me.

"However, I surmise that the difference between a speaker that sounds good and one that does not is a function in large part of whether the harmonic distortion sounds good or bad."

Or an amp, or a concert hall, etc. We all like distortion :).

Mrtennis: Forgot to mention that dipoles have rear dispersion that's out of phase and can react with the room in many ways. For myself, it's most noticeable on vocals.

re: Bifwynne's question:

Without an entire dissertation, consider the analogy of a hose through which water is passing at the end of which is a nozzle. Difficult impedances involve a negative, or capacitive phase angle. That means that the current demand, or flow rate of water, increases before the voltage, or water pressure, is produced that is sufficient to drive the current/water through the load (spkr)/nozzle.

One critical aspect of an amplifier's specification is its ability to deliver sufficient current to capacitivie impedances which most commonly occur at low frequencies.

To all: The following post appears on another OP relating to inductance and capacitance. So I'm posting it here because I think it is more on point with this OP.

"I have a couple of follow up questions re your last comment. You mention in your last post that "[a] ckt that will do this the best is called a first-order x-over ckt. If you do the math, you'll find that the amplitude & phase relationships of the in & out signals are the least altered (compared to 2nd, 3rd, 4th & higher order x-over ckts). That is why many time & phase aligned speakers use 1-st order x-overs."

"So, my question is in cases where a speaker uses higher order X-overs (i.e., 2nd, 3rd order, etc), will the better speaker design attempt to correct the time and phase incoherency electronically or mechanically??

"My other question is a reality check. I own what are probably among the least appreciated speakers on the market, Paradigm Signature 8s v2 (with beryllium tweeters) and a Signature Servo sub-woofer, notwithstanding rave reviewer comments. That's ok, I'm not looking for you or anyone else to ratify or validate that I'm entitled to enjoy my speakers even though I do.

"Here's the question, but first the facts. The S8s use a 2nd order X-over between the tweeter and midrange driver at 2000 Hz and a 3rd order X-over between the midrange driver and woofer at 200Hx. I believe the sub-woofer rolls off at 150 Hz and uses a 3rd order X-over to effect the roll off.

"Based on a review in December 2008, HT magazine reported that the S8's "[i]mpedance reaches a minimum of 4.21 ohms at 98 Hz and a phase angle of –83.18 degrees at 57 Hz." I was not thinking about phase angles when setting up my speakers and sub. I tried to physcially set up the fronts and sub woofer to be on the same physical plane vis a vis my sitting position. However, for some crazy reason, when setting the phase control of the sub, it seemed liked the bass sounded the best at approximately 90 degrees, actually around 85 degrees.

"So my question is does it make sense that my sub woofer's phase control effects, at least to my uneducated ear, the best bass response as I described above?? FWIW, HT magazine reports that the S8s "–3-dB point is at 51 Hz, and the –6-dB point is at 42 Hz." Perhaps coincidentally, I find that the bass sounds its best (e.g., least boomy) in my sound room when I set the sub's frequency rollover control at around 45 Hz.

"Thanks for your impressions.