[earlmarc]

My Magnepan MG1.6QR are considerd phase-coherent. I believe Thiel and Meadowlark speakers are considered phase coherent. I found a good thread on this subject. http://www.geocities.com/kreskovs/TimeAligned1.html

What are your opinions about phase aligned speakers vs. other designs?

[Marbles]

It's all in the implementation.

You really need to take the 20 minute drive to listen to the Ridge Street Audio Sason speaker.

[Bob Reynolds]

I had never heard Maggies being considered phase coherent, but I've never looked into them. Vandersteen and Thiel are the only time and phase coherent speakers I'm aware of. I owned the Meadowlark Kestrels pretty much for the theory of coherence. There is a difference between having time aligned drivers and being phase coherent. I believe I read that it has been shown that humans are not very sensitive to phase and that it is not a dominating feature of speaker design. Obviously, Richard and Jim disagree.

[Daryl]

As Bob said we are not aware of phase.

If group delay becomes great enough it could become a problem.

Your ears work like an RTA (real time analyzer).

There are multiple hairs (silia) which are resonant at different frequencies throughout the spectrum like the tank circuits inside an RTA.

Your brain recieves a signal when they are stimulated by energy at their resonant frequency.

Phase is not in the picture.

Also the Q of each of these circuits I would estimate to be in the neighborhood of 10.

I'm not shure if anyone know the actual number but as the number goes higher you gain more frequency resolution in your hearing but less time resolution.

The opposite is true with lower Q's.

The implications of this are that your ears will have considerable ringing of their own and small amounts of ringing and group delay from things like crossover filters (2nd order vs. 4th) and the bass cuttoff of speakers (sealed vs. vented) will not be audible as many like to claim.

Below I have used Excel to simulate how your ears would hear a step and a square wave.

The Q is set at 10.

[ehider]

Just as a sidenote here, sorry to ruin Earlmark's assumption about his Magnepans, but they are definitely not phase coherent. That being said though, I still love the way they sound and compare to other speakers of any design topology regardless if it is labelled "phase coherent" or not

In terms of other phase coherent speakers (other than Thiel, Vandersteen and Meadowlark) are: Ohm, Dunlavy, Green Mountain, Quad, Spica, Reference 3A, Air Foil, JM Lab, Tannoy, Waveform, Meridian, Kharma, Verity Audio, Symphony, Overkill Audio and a few others that I just can't recall at the moment. Years ago, I came to the conclusion that phase coherent designs must be the best approach since I really enjoyed what I heard from all of the above loudspeakers. Unfortunately, years later (and allot more experience with other "non-phase coherent" designs from a plethora of fine loudspeaker companies) I now don't feel that my hypo thosis about phase coherency is NOT warranted as an absolute for great loudspeaker performance   

As of today, many of my top favorite loudspeakers are NOT "phase coherent" yet I have found they do have other things in common with those "phase coherent" designs that I and others have mentioned in this thread - an extreme attention to detail to all aspects of the loudspeaker's design, cabinet design, driver selection and crossover component quality along with smooth on and off axis frequency behaviors. Those are the attributes that I now think will set a "great" loudspeaker apart from a "wannabe" great performing loudspeaker aa

[Rick Craig]

My Magnepan MG1.6QR are considerd phase-coherent. I believe Thiel and Meadowlark speakers are considered phase coherent. I found a good thread on this subject. http://www.geocities.com/kreskovs/TimeAligned1.html

What are your opinions about phase aligned speakers vs. other designs?

Meadowlark speakers often employed first order filters but this won't guarantee phase coherency; in fact, it often introduces other problems. Thiel strives to obtain true first order slopes but at the penalty of poor lobing behavior and other audible issues.

[ted_b]

Daryl,
What do you mean by "we are not aware of phase"?  I certainly am aware when speakers are out of phase from one another (to a great extent), or even when absolute phase is inverted (less so).  Many test discs include phase tests for speakers, and the examples are so obvious to me that I could pick them blindly 100% of the time.

Am I using the term differently than this discussion?  Probably, but wanted to ask.  Thx,

[Soundbitten]

Though they are out of business now Dunlavys were well known as time and phase coherent speakers .

[Daryl]

Hi Ted,

All channels must be in-phase to avoid cancelations in the low frequencies.

There is also an effect known as the "Wood effect" where you can learn to recognize absolute phase.

This is not necessarily part of your hearing but an anomally.

It only makes sense that a person might be able to distinguish whether a pressure wave was positive or negative, possibly even a deaf person.

As far as your hearing is concerned phase is not important and you will enjoy your music just as much either way.

Keep in mind that phase in recordings is all over the place due processing some equipment will invert polarity (there are some audiophile recordings where absolute polarity is paid attention to).

Most speakers have a phase characteristic that fluctuates radically with frequency (phase coherent speakers have phase shift only at their cuttof points).

People often try and show oscilloscope charts showing the transient response of equipment suggesting that you will hear what they are showing.

Truth is your hearing doesn't work like that and charts like those I posted above would give a more accurate indication of what you are likely to hear.

Daryl

[SET Man]

My Magnepan MG1.6QR are considerd phase-coherent. I believe Thiel and Meadowlark speakers are considered phase coherent. I found a good thread on this subject. http://www.geocities.com/kreskovs/TimeAligned1.html

What are your opinions about phase aligned speakers vs. other designs?

Hey!

   I am an x-Maggie user... for 6 years. Now I'm currently using my own DIY xoverless 6" Fostex based TQWT single driver... okay I added the super tweeter on top.

   earlmarc, sorry to burst your bubble but Magnepan are not phase coherent. For example my Maggie 1.5 use 1st order xover on the mid/bass panel and 2nd order xover on the tweeter panel.   I think the new 1.6 also made this way but with lower xover point.  Although they are better than some becasue bass and high are on the same plan but still because of the xover the bass/mid and high are out of phase.

    Anyway, if you want to hear what coherent sound is like do youself a favor and find some xoverless speakers like Lowther, Fostex, or fullrange stat and see it for yourself. Or a simpler way... just put on a good pair of headphone like Grado or Senn. Withour the xover in the critical range 80hz-10khz the sound is just much better especially with human voice.

  Some other companies try to slove this or at least somewhat by using coaxial driver like those from KEF and Tannoy. With tweeter in the center of the woofer this help but I'm not sure if the xover are inphase between the 2 drivers. Last month I went to NY Rave monthly gathering... this time at Hogg and his Tannoy with the "dual concentric" driver sounded very good. I kindna forget that they are really 2 ways speaker.... they were very nice.

Oh! by the way. My single driver started out as a side project just to see what single driver could do and you know what that was 4 years ago and they are still in my system. In my room and listening SPL they are great! As for my old Maggie 1.5? I still have them.... behind my not so pretty TQWT in the corner. They work great as acoustic control panels! Well, seriouly I think I have to let them go someday. Anyone want them? Make me an offer.

Take care,
Buddy


   

[earlmarc]

My interest in phase coherent speakers was piqued by a conversation I had with Micheal Yee about his PA-3 amplifier. He felt that his PA-3 amplifier performed best with phase aligned speakers. I didn't understand why an amplifier would prefer phase alignment over other crossover designs. I still don't.

[JLM]

Irving Fried believed in phase coherency, particularly in midrange frequencies, and so avoided as much as possible any between 100 and 2,000 Hz.  Typically designs flaunted as phase coherent use 1st order crossovers.  IMO this does provide improved coherency.

My current speakers are single driver (no whizzer cone) mass loaded transmission line designs capable of 30 - 20,000 Hz in room.  No speaker design is perfect.  I traded dispersion for purity of a single cone and high spls for a single driver.  I've not heard a single driver (or most multiple driver) design with this kind of bass authority.  Multiple driver designs will always suffer on the coherency account in comparison.

Fried also opined that 1st order crossovers (and transmission line bass) provided easier loads to amps.

[dwk]

The question of the audibility of phase coherence can be tough for a couple reasons. First, isolating the effect is difficult at best (although easier now with good DSP techniques) and second, some folks cling to one side or the other with a passionate fervor.

Although I think Daryl is mostly right in saying that the ear is not sensitive to phase, I am not convinced that this is an absolute truth. I personally have more experimentation to do before I come down with a firm opinion one way or the other, but there are some things that I think I think:
- the effect is not a dominant characteristic, but rather something on the order of the 'last 10%'
- won't be audible on all material or even on all systems due to other confusing factors
- when implemented via conventional 1st order xovers, I think the compromises/constraints outweigh any benefits. Alternate topologies have more promise IMHO (ie filler driver, subtractive/subtractive-delay, DSP (both FIR and tricked-out IIR))
- I think any audible effect would have to be limited to a band of frequencies where the inter-aural spacing represents a meaningful and identifiable phase difference, otherwise there is no solid explanation as to why we'd care.
- anecdotal evidence does seem to suggest that there is something there.  One opinion that carries some weight with me is Tom Danley - his original Unity versions were time aligned but not phase coherent. His later ones (the Synergy stuff) are now phase coherent and he reports a worthwhile audible improvement.

IMHO anyone interested in this question should look at some of the tools available to experiement with it. In particular, Jan Luzcek's new 'Phase  Allocator/Arbitrator' (thuneau.com) allows creation of higher-order multi-way active xovers where you can switch phase correction on/off (he uses the forward/backward time filtering to cancel out the phase impact). This means you can get a pretty decent apples-apples comparison using arbitrary speakers.  There are lots of things you can also do with headphones, but IMHO working with real speakers is more interesting, even if audibility should be much stronger on headphones.

[Russell Dawkins]

Oh! by the way. My single driver started out as a side project just to see what single driver could do and you know what that was 4 years ago and they are still in my system. In my room and listening SPL they are great! As for my old Maggie 1.5? I still have them.... behind my not so pretty TQWT in the corner. They work great as acoustic control panels! :lol
 

Hey, Buddy, if you want your Maggies to really work as acoustic control panels, try shorting the input terminals.

This will create an electrical short circuit across the panel windings which will dampen its movement dramatically.

Same applies to cone speakers which are not being listened to but must be left in the same room as active speakers. Stops them from singing along.

[SET Man]

Oh! by the way. My single driver started out as a side project just to see what single driver could do and you know what that was 4 years ago and they are still in my system. In my room and listening SPL they are great! As for my old Maggie 1.5? I still have them.... behind my not so pretty TQWT in the corner. They work great as acoustic control panels! :lol
 

Hey, Buddy, if you want your Maggies to really work as acoustic control panels, try shorting the input terminals.

This will create an electrical short circuit across the panel windings which will dampen its movement dramatically.

Same applies to cone speakers which are not being listened to but must be left in the same room as active speakers. Stops them from singing along.

Hey!

    Russell, thanks for the tip. I will try that tonight. I'm very curious of how this will improve the sound.

     Hmmmm.... don't want to steal this thread but... if the unused speaker starting singing along the active one, than that range of frequncy get cancled out or get booted up?   So, this mean that when auditioning speakers at the showroom with many speakers in one room those non-active speakers will have some affect on the sound too just like the room and furnitures? But how much?

I will let you know if I like the sound of my system after shorting those Maggie panels.

Man! I guess everyday I learn something new.

Take care,
Buddy

       

[ZooDog]

I remember reading an interview with Kevin Voecks of Revel in which he discussed the importance of phase and time coherency in speaker design.  Revel has a facility where they hold blind listening tests and different speakers are placed on moving floor panels and are moved in and out of position at the press of a button.  This allows test listeners to hear many different types of speaker in the same room easily and quickly.  Mr. Voecks claims that in Revel's tests listeners do not prefer phase/time coherent designs over non-phase/time coherent designs.

Having said that, I use the NHT Xd system employs DEQX technology to perform all crossover functions in the digital domain.  This allows very steep order crossover slopes (110db/octave) along with phase and time coherency.  Off-axis frequency response and power handling is not nearly as compromised as they often are in designs which employ shallow 6db/octave crossovers in order to preserve phase.