Re: Phase Arbitrator DSP: significant improvement without drawbacks
- Thanks, Robert. It was careless of me to use the term "multi-way" instead of describing the issue with more precision.
That said, in my system, the results of phase correction are hard to miss. Careful listeners, tested using a "single blind" design, can tell when it's "on" or "off." Those who can hear the difference consistently prefer the quality of sound with the Phase Arbitrator "on," describing it as more lifelike. (I'll refrain from inundating you with descriptive prose.)
I wonder whether it's possible that the effect is relatively easy to detect in my system because all first-order and second-order reflections (including floor and ceiling reflections) are absorbed, speakers are on high stands well away from all reflecting surfaces, listeners are well away from reflecting surfaces, speakers are positioned to minimize room resonances, and remaining resonances (as well as the M40's few colorations) are reduced through careful equalization.
As you've stated, the effects of phase correction are subtle -- less striking than those associated with careful speaker and listener placement, acoustical treatment of the listening room, or judicious equalization. However, my experience and that of my music-loving friends suggests that it may enhance the accuracy of sound systems (like mine) in which less subtle problems have been mitigated.
And, as you wrote, the effects are more evident on some instruments than others. For example, percussion (including piano) and brass instruments benefit more than do flutes.
My point, of course, is precisely that it's a significant (albeit subtle) improvement that, for those who appreciate it, may be worth its relatively small cost.
--- In email@example.com, "Robert" <regtas43@...> wrote:
> This is interesting but it is not
> really the full explanation of
> why speakers are phase nonlinear(when
> they are) and --no offense--is not
> really the correct explanation at all.
> If it were, then any multiway speaker
> would have problems since all have
> tweeters midrange/bass drivers
> or tweeter midrange and woofer
> But in fact such speakers can easily
> be phase linear--if one uses first order
> crossovers and lines up the acoustic centers,
> Bobs your uncle.
> Go look at a Dunlavy on Sphile.
> What makes speakers like the M40.1 not
> phase linear is the use of higher order
> crossovers. These cause phase nonlinearities.
> Does this matter? Some but not very much.
> There have been many many tests of this.
> I have been able to do them myself
> on occasion. There are some effects.
> The timbre of things with broad continuous spectrum
> like woodblocks changes. A certain types
> of massed ensemble material(choral music) changes
> But slightly is the operative word. It is a
> fairly small effect, so small that in
> a lot of blind tests people could not detect
> it realibly(these are the same kinds of tests where
> they can reliably detect response shifts of
> 0.2 dB. Still, if it is easy
> to come by....
> More on this later--it is bed time.
> --- In firstname.lastname@example.org, "barnet.feingold" <barnet.feingold@> wrote:
> > Hi All,
> > My apologies for presuming to start a conversation without having participated previously; I usually keep my mouth shut unless I'm certain I have something worthwhile to say.
> > Inspired by this forum's discussions of the potential of digital signal processing, I decided to try Phase Arbitrator DSP from Thuneau.com. The program and its associated hardware are inexpensive; the improvement was impressive. Unlike many alleged improvements, it appears to have no drawbacks.
> > The Phase Arbitrator program allows users to the correct phase errors of multi-way systems by entering information about their speakers (i.e., enclosure design, -6 db. frequency, and acoustical crossover frequencies and orders) into the program's graphical user interface. Further improvements can be made through the use of software allowing visualization of impulse and/or phase response.
> > With testing, my system (Harbeth M40s supplemented at very low frequencies by a subwoofer) reduced phase shift from 1230 degrees to less than 120 degrees from about 30 Hz. to over 16,000 Hz. The corrected phase shift is within +/- 30 degrees across most of the speaker's operating range, with one narrow deviation from that window in the area of the midrange-tweeter crossover. Note, however, that even when set using loudspeaker specifications and adjusted by ear, the Phase Arbitrator made dramatic improvements.
> > Making the speakers phase-accurate does not alter their frequency response. It merely allows sonic events that occurred together to be reproduced together. As most participants in this forum know, the tweeters in multi-way systems respond more quickly than midrange drivers, which respond more quickly than woofers. This results in "temporal smearing" of sonic events, which reduces the dynamic impact, artificially emphasizes high-end detail while obscuring midrange detail, reduces the depth of the silences between musical events, and obscures musical events taking place after the slower drivers "should" have stopped speaking. When this "temporal smearing" is eliminated, sound much more closely approximates that of live music. The effect in my system is unmistakable.
> > The Phase Arbitrator program costs $89. It requires an ASIO-compliant sound card. While it requires a computer, it is compatible with hardware and operating systems that are old enough to be found in computers many of us are no longer using. (I use my wife's obsolete laptop.)
> > I'd be glad to share my (testing-determined) settings with those of you who have Harbeth M40s. I suspect that those of you who own systems popular in this forum could split the cost of testing a representative speaker. (Corrections are room-independent.)
> > If anyone wants details of the evaluation procedure or would like to see graphs of the corrected and uncorrected phase responses and associated confidence curves, let me know.
> > Barney