Green Mountain Audio Europas

[TLS Guy]

You fail to understand. What each mic hears coming into it is time-coherent.

Of course that is true for any individual mic. However they are mixed together in a mix panel and the end result is anything but time and phase coherent. That is the vast majority of recordings.

In my view it probably accounts for listeners inability to detect time and phase shifts introduced into a pair of Quad ESLs.

 

[Shakeydeal]

I think a few things are pretty obvious here.

Roy has gone above and beyond to be cordial and answer all questions and comments, no matter how ridiculous. But his work here is done.

Jerry has exhausted all his efforts to like the Europas and he doesn't. Audiogon will be his friend.

And to all of those who piled on this thread with speculations about how a speaker they have never heard will sound, Pooh on YOU. I have heard the Europas sound fantastic, and my C3s are all that raised about two levels.

That's why there is more than ONE speaker manufacturer out there. Different strokes. I have heard lots of speakers, loved some, liked some, and hated a few. I guess we all have.

So let's move on. This thing has run it's course and we all like what we like.

Shakey

 

[MinusTheBear]

I've been doing a lot of reading on Revel loudspeakers lately and came across a question that was posed about the importance of Time-Chorence in loudspeaker design from another industry professional. I know this issue has been a big topic in this thread.

Sumit: Do you feel that time-coherence is an important property of a loudspeaker?

Kevin: No. We’ve done a lot of research in the area. In fact when I made my first loudspeakers at Symdex in 1976, I thought that it was important because that was the fad at the time. With some people, it’s still a fad. But if you look at the way the human hearing functions, you’ll see that time-coherence isn’t important. I actually credit Dr. Stanley Lipshitz at the University of Waterloo with bringing this to my attention, to put it mildly, in the 70’s at Mirage. He and Dr. Vanderkooy came up with a box that would let you alter phase response without altering amplitude response, and by using it you could do listening tests to determine the audibility of phase errors, or time-coherence. It was quite evident then that if you are in an anechoic chamber or you are using earphones, you can detect the difference especially with special clicks that are made to hear it. You can’t always say which is right or better, and as soon as you introduce the room it’s 100% inaudible. The importance of phase is in the crossover region because that’s an indicator of the blending of the transducers that are being crossed over. So in and of itself it’s not a significant thing. And in order to try to optimize it you really sell your soul in terms of things we know are really, really important to sound quality. That is a key fact. It’s not like it’s cost free, audibly, to optimize that parameter.


http://www.hometheaterhifi.com/volume_11_2/feature-interview-kevin-voecks-4-2004.html

 

[TLS Guy]

I've been doing a lot of reading on Revel loudspeakers lately and came across a question that was posed about the importance of Time-Chorence in loudspeaker design from another industry professional. I know this issue has been a big topic in this thread.

Sumit: Do you feel that time-coherence is an important property of a loudspeaker?

Kevin: No. We’ve done a lot of research in the area. In fact when I made my first loudspeakers at Symdex in 1976, I thought that it was important because that was the fad at the time. With some people, it’s still a fad. But if you look at the way the human hearing functions, you’ll see that time-coherence isn’t important. I actually credit Dr. Stanley Lipshitz at the University of Waterloo with bringing this to my attention, to put it mildly, in the 70’s at Mirage. He and Dr. Vanderkooy came up with a box that would let you alter phase response without altering amplitude response, and by using it you could do listening tests to determine the audibility of phase errors, or time-coherence. It was quite evident then that if you are in an anechoic chamber or you are using earphones, you can detect the difference especially with special clicks that are made to hear it. You can’t always say which is right or better, and as soon as you introduce the room it’s 100% inaudible. The importance of phase is in the crossover region because that’s an indicator of the blending of the transducers that are being crossed over. So in and of itself it’s not a significant thing. And in order to try to optimize it you really sell your soul in terms of things we know are really, really important to sound quality. That is a key fact. It’s not like it’s cost free, audibly, to optimize that parameter.


http://www.hometheaterhifi.com/volume_11_2/feature-interview-kevin-voecks-4-2004.html

I agree with those remarks 100%. I have also investigated this area, when this was a fad.

Time aligning speakers makes it very very difficult to get a smooth frequency response, which is job one. No matter what Jerry says getting an optimal off axis response is impossible. So yes, the driver spacing required does shoot you in the foot for optimizing more important parameters.

I will say however that evaluation is difficult as most recordings take more trespasses with time and phase than loudspeakers. Jerry's comment about a single microphone being time and phase coherent is disingenuous and shows he dodges significant problems with his design approach. Almost all recordings are multi miked and and the blend is anything but time and phase coherent. You must use a coincident pair for a time and phase coherent recording. Even in the classical realm this technique has fallen out of disfavor to a degree, as a coincident recordings require directional microphones. Omni directional microphones have an inherently smoother frequency response. So spaced omnis have become popular, and by definition is phase difference stereo rather than intensity difference stereo from a coincident pair.

Now I have used both techniques and I will say that speakers with good time and phase response do I think sound marginally better playing back minimalist intensity stereo recordings. The problem is as soon as you bring up a mic to slightly spot a soloist, time and phase coherence is lost and you can see it it on your monitoring phase scope.

So yes, trying to make speakers with spaced drivers time and phase coherent is a dead end and will introduce other aberrations from the attempt. I will stand by that statement. Jerry can deny it all he wants, but there is a mountain of evidence against him.

That is all I really have to say on the topic.

 

[JerryLove]

Time aligning speakers makes it very very difficult to get a smooth frequency response, which is job one. No matter what Jerry says getting an optimal off axis response is impossible. So yes, the driver spacing required does shoot you in the foot for optimizing more important parameters.

I will say however that evaluation is difficult as most recordings take more trespasses with time and phase than loudspeakers. Jerry's comment about a single microphone being time and phase coherent is disingenuous and shows he dodges significant problems with his design approach. Almost all recordings are multi miked and and the blend is anything but time and phase coherent. You must use a coincident pair for a time and phase coherent recording. Even in the classical realm this technique has fallen out of disfavor to a degree, as a coincident recordings require directional microphones. Omni directional microphones have an inherently smoother frequency response. So spaced omnis have become popular, and by definition is phase difference stereo rather than intensity difference stereo from a coincident pair.

Now I have used both techniques and I will say that speakers with good time and phase response do I think sound marginally better playing back minimalist intensity stereo recordings. The problem is as soon as you bring up a mic to slightly spot a soloist, time and phase coherence is lost and you can see it it on your monitoring phase scope.

So yes, trying to make speakers with spaced drivers time and phase coherent is a dead end and will introduce other aberrations from the attempt. I will stand by that statement. Jerry can deny it all he wants, but there is a mountain of evidence against him.

That is all I really have to say on the topic.

Me?!? Did you mean "Roy" when you said "Jerry"?

 

[TLS Guy]

Me?!? Did you mean "Roy" when you said "Jerry"?

Jerry, please forgive a senile old fool. Yes, I meant Roy, not Jerry. Sorry!

 

[highfigh]

Time aligning speakers makes it very very difficult to get a smooth frequency response, which is job one. No matter what Jerry says getting an optimal off axis response is impossible. So yes, the driver spacing required does shoot you in the foot for optimizing more important parameters.

Now I have used both techniques and I will say that speakers with good time and phase response do I think sound marginally better playing back minimalist intensity stereo recordings. The problem is as soon as you bring up a mic to slightly spot a soloist, time and phase coherence is lost and you can see it it on your monitoring phase scope.

So yes, trying to make speakers with spaced drivers time and phase coherent is a dead end and will introduce other aberrations from the attempt. I will stand by that statement. Jerry can deny it all he wants, but there is a mountain of evidence against him.

That is all I really have to say on the topic.

I realize you wrote that you're done with this topic but, are you saying that two drivers that produce some common signal will sound fine when they're at different differences from the listener? How does this NOT produce comb filtering?

Remember the speakers I was building and didn't like the sound very much? I do, now, and I haven't changed the crossovers at all, other than disconnecting the L-pad. The first thing I did to find out what would help blend the tweeter's SPL relative to the woofer is adjust the receiver's equalizer, starting at 2KHz in a way that would approximate an L-Pad circuit. That helped, but what really made a huge difference was tilting them backward. Any negative physical sensations I was having are gone (the feeling that I constantly needed to "pop" my ears). When I look at the small gap between the woofers, I'm at a right angle to the baffle and now, the tweeter is much closer to the same distance as the woofers. I also made many adjustments in the distance setup menu, at .1' resolution. That was really frustrating- I did this without the subwoofer first, then with it. It's painfully obvious when the settings are wrong- either it feels like a phase issue, the imaging suffers, or both. If you get the chance to do this with a Denon receiver, try it- it's an interesting process.

I'm not saying that my hearing is amazing but I am saying that the results are far more important than any personal feelings about the fact that I'm building them. If they sound bad, I'll just keep trying to make them better- it's not a problem for my ego. I'm not going to say they're great when they have flaws, but making these changes has improved them greatly and they do some things extremely well.

Thanks again for your help with the crossovers.

 

[highfigh]

Me?!? Did you mean "Roy" when you said "Jerry"?

IIRC, you posted that you bought these speakers from a previous owner. Is there any chance that they altered something? Maybe they removed a woofer/tweeter out of curiosity and mis-wired it when they reassembled it. Maybe they changed a crossover component. I have seen this happen before and I doubt it will be the last time it happens.

 

[TLS Guy]

I realize you wrote that you're done with this topic but, are you saying that two drivers that produce some common signal will sound fine when they're at different differences from the listener? How does this NOT produce comb filtering?

Remember the speakers I was building and didn't like the sound very much? I do, now, and I haven't changed the crossovers at all, other than disconnecting the L-pad. The first thing I did to find out what would help blend the tweeter's SPL relative to the woofer is adjust the receiver's equalizer, starting at 2KHz in a way that would approximate an L-Pad circuit. That helped, but what really made a huge difference was tilting them backward. Any negative physical sensations I was having are gone (the feeling that I constantly needed to "pop" my ears). When I look at the small gap between the woofers, I'm at a right angle to the baffle and now, the tweeter is much closer to the same distance as the woofers. I also made many adjustments in the distance setup menu, at .1' resolution. That was really frustrating- I did this without the subwoofer first, then with it. It's painfully obvious when the settings are wrong- either it feels like a phase issue, the imaging suffers, or both. If you get the chance to do this with a Denon receiver, try it- it's an interesting process.

I'm not saying that my hearing is amazing but I am saying that the results are far more important than any personal feelings about the fact that I'm building them. If they sound bad, I'll just keep trying to make them better- it's not a problem for my ego. I'm not going to say they're great when they have flaws, but making these changes has improved them greatly and they do some things extremely well.

Thanks again for your help with the crossovers.

There will be comb filtering with a common signal. Now I suspect your speakers have a tilt to the lobing pattern or tweeter output is reduced in the listening area because the tweeter is no off axis. In fact there will be slight tilt as the electrical portion of your crossover is asymetric.

The real issue is that spacing drivers using first order crossover to try and make spaced driver transient perfect is the dead end.

It is a pity we have to use spaced drivers at all. May be one day there will be a practical end to it.

 

[JerryLove]

I realize you wrote that you're done with this topic but, are you saying that two drivers that produce some common signal will sound fine when they're at different differences from the listener? How does this NOT produce comb filtering?

Doesn't comb filtering require that the two sources be at least a minimum distance (a function of the wavelength) from one another; otherwise they act as a common source?

 

[jostenmeat]

It is a pity we have to use spaced drivers at all. May be one day there will be a practical end to it.

Could you kindly describe, at least for 2-way speakers, why coaxial drivers are not so much more prevalent? (I assume that a coaxial driver is not categorized as "spaced drivers".)

What are the compromises of coaxial drivers (is there something about the larger driver acting as a waveguide for the tweeter, and what are the implications with speakers design)?

I am aware that you use a coaxial driver for center speaker. I suppose even beyond the scope of a 2way, perhaps say for a 3way, we could have a coaxial above a woofer. Any spacing issues might be mitigated by having a lower xover between mid and woofer?

 

[TLS Guy]

Could you kindly describe, at least for 2-way speakers, why coaxial drivers are not so much more prevalent? (I assume that a coaxial driver is not categorized as "spaced drivers".)

What are the compromises of coaxial drivers (is there something about the larger driver acting as a waveguide for the tweeter, and what are the implications with speakers design)?

I am aware that you use a coaxial driver for center speaker. I suppose even beyond the scope of a 2way, perhaps say for a 3way, we could have a coaxial above a woofer. Any spacing issues might be mitigated by having a lower xover between mid and woofer?

The big issue is that if the time path to your ear from two sources is identical, and lets exclude reflections for the time being, then the sources will not interfere. However as listening axis and time lengths from the drivers change then some frequencies will reinforce and others cancel. Then if we add reflections, especially first reflections then there are more sound waves to interfere.

As far as coaxial drivers are concerned there is the advantage of a coherent source and yes, the bass cone does act as a waveguide and also cause reflections that not only reinforce and cancel, but these reflections are modulated by cone movement. So there is inter modulation distortion of the tweeter by the bass/mid cone. Therefore there will be a penalty of increased inter modulation distortion. This was first pointed out by Paul Klipsch. There was a recent paper in the AES journal quantifying the effect.

As an aside many members have their mains far too close together and then you add a center and you have mayhem. The mains should be 8 to 12 ft apart.

In my researches before I did my theater here, I found interference between center and mains a big problem. This was one of the reasons I chose a center coaxial design to narrow the cone of dispersion of the center speaker.

Speakers are really frustrating. All too often to solve one problem you make others worse.

A big part of the solution is development of single drivers to cover the portion of the spectrum where the ear is most sensitive. That requires a driver with a bandwidth of 200 Hz to 8 kHz. The only drivers that make that with even a straight face are the B & W mid and even better the ATC dome midrange, especially the modified version used by PMC. Pretty slim pickings.

I firmly identify that as the most productive area of R & D for any speaker company. This has been Billy Woodman's passion all his life. He is the founder of ATC and his drivers are top of the hill for wide band mid range performance.

 

[jostenmeat]

Thank you for your thoughts! I find your explanation about aiming for the narrowing cone of dispersion from the center to be fascinating, as well as your opinion regarding where present R&D should lie.

Since you have high praise for the PMC and BW drivers, do you presently use any of these? Wait, I suppose the BW drivers are simply not available to the general public (or perhaps anyone or company for that matter), but the PMC . . . well I suppose if they were* available, and at the time you even you built your speakers, I could assume you would have used them. Forgive me, I don't know what drivers you have chosen, I want to say Seas for the coaxial, and oh gosh I can't remember what those interesting looking drivers were in the rears. I know you've worked with Dynaudio too.

I believe my mains are a solid 12ft apart. Would you believe that I would truly gain by changing my center to a coaxial type? (For full disclosure, I do have viewers that are decently off-axis, perhaps near the 20 degree mark.)

I do fully intend to build a new front three this year, and hopefully in the rather near future, so I better pick your brain while I have your attention!

 

[highfigh]

Doesn't comb filtering require that the two sources be at least a minimum distance (a function of the wavelength) from one another; otherwise they act as a common source?

Any time common information is sent from two different locations, comb filtering will occur. The distance and offset will determine which frequencies and how strong the cancellations will be. It's not hard to have problems due to reflections from hard surfaces and that's why speakers that exhibit wide dispersion and strong first reflections with multiple drivers that aren't close together don't mix. Rooms with high RT60 are bad listening environments for this reason.

 

[TLS Guy]

Thank you for your thoughts! I find your explanation about aiming for the narrowing cone of dispersion from the center to be fascinating, as well as your opinion regarding where present R&D should lie.

Since you have high praise for the PMC and BW drivers, do you presently use any of these? Wait, I suppose the BW drivers are simply not available to the general public (or perhaps anyone or company for that matter), but the PMC . . . well I suppose if they were* available, and at the time you even you built your speakers, I could assume you would have used them. Forgive me, I don't know what drivers you have chosen, I want to say Seas for the coaxial, and oh gosh I can't remember what those interesting looking drivers were in the rears. I know you've worked with Dynaudio too.

I believe my mains are a solid 12ft apart. Would you believe that I would truly gain by changing my center to a coaxial type? (For full disclosure, I do have viewers that are decently off-axis, perhaps near the 20 degree mark.)

I do fully intend to build a new front three this year, and hopefully in the rather near future, so I better pick your brain while I have your attention!

None of the units I mentioned are available OEM.

The mains use SEAS excel drivers. The center uses the coaxial units from the SEAS prestige line. I should get around to measuring the tweeter distortion when a 100 Hz tone is sent to the woofer cone. This coaxial is widely recognized as the best available and superior to the KEF drivers.

The interesting thing about the driver is that the bass/mid cone is of a very soft pliable clear polypropylene. So it is not a rigid cone by any means and must be a bend driver. I have a feeling the material is so soft it absorbs and does not reflect much of the sound from the tweeter. That may be one of its secrets.

Also I keep cone motion as low as possible as I use a separate driver via an active crossover for diffraction compensation. Obviously the tweeter is not used in that driver.

I really like that center, it is a TL with very very low coloration with natural speech without chestiness or spitting s problems.

I have just watched a Blue Ray of Acis and Galatea from the Royal Opera House Covent Garden. It was just a pure delight with the Orchestra of the Age of enlightenment under Christopher Hogwood. Voices and chorus were just perfect and a lovely dancing lightness in the bass. Although these speakers can shake the floor, they still are very light on their feet, with no hint of a massive bass reserve. I'm really getting to like seeing seventeenth century opera on the screen. The trouble is there is little good stuff available yet.

I'm hoping someone will put Handel's Julius Cesar with David Daniels in the title role on Blue Ray. Handel's operas are quite rightly getting a new look and rightly so. As Beethoven said: - "Only at the tomb of Handel does one remove the hat and bend the knee. No one produced such great effects with so little means but Handel." I could not agree more.

 

[rich121]

I completely read through this whole thread, I am not a regular poster, but after reading this very negative thread, which was "set-up to fail" from the opening post, I had to comment.

I commend Roy for all his time in answering comments that were obviously closed minded and "us against them" attitude.
How many of the mentioned speaker companies owners have posted to you in your threads, yet, Roy has been "questioned" throughout this thread with a very negative under/overtone.

Yes, I may be viewed as prejudice in my speakers, as I have owned a pair of Continuum 3's since the first year they were introduced, and I have found Roy to be the most accessible and approachable person I know of in the industry.

I find this "review" by Jerry to have lost any credibility from the very first post , and even more as I read to the end of the thread.

What stands out the most to me, are the comments made in Jerrys first posts, no consideration of manufacturers guidlines, and the "damage" done to the "used" speakers during shipment(?). Who knows what these speakers have been through during their lifetime, how many times shipped and what impact happened during shipment that caused the crossover to become disconnect? Is there somehow damage to the voicecoils, were the cones/voice coils over exerted? So many things could have caused these speakers to have abnormalities..including age.
And, what stands very clear, is Jerrys refusal to contact Roy, as Roy has asked for such a long period and many times.

I see this as nothing more than someone with an agenda, carried over from the original Green Mountain thread.

Too bad this forum has closed minded individuals who preffer to attack those with different ideas and background. No wonder few manufacturers post to these boards... I again, commend Roy for at least trying to open some minds.

This thread had no value, no purpose other than to allow "regulars" of the site to sling mud about things they knew/know nothing about, as an "outsider" that is how I viewed this thread.


Rick

I don't know if curiosity killed the cat: but it's done no good for my wallet.

Yes, I now am the proud(?) owner of a pair of GMA Europas. Once I figure out which end of the mic plugs in where, and clear out an appropriate room, and figure out where I put my "good camera", and have time, I will write up my opinion of them.

For you, my friends, I have become the first non-fanboy to actually hear something from GMA. The are a model made in the early 2000's but no longer. I've seen list prices from $800 to $1200 as their "when new" price. If I can setup some ABX testing, I'll compare them with my PSB 400i's, Sig S2's, and anything else I can scrounge up (wish I had a Studio 20: that would be perfect).

Stay tuned... but don't hold your breath.

PS. First impression of one speaker plugged in sitting on a chair a couple feet from my head: harsh in upper-human-voice. I think that can also be perceived as "bright" or "forward" if I get out of the near-field. Even more odd: according to the mic there's a strong *dip* there.

I even tried pushing some chants through (figuring no primary harmonics below 350Hz). Didn't really help. I'm really gonna have to move stuff around to eliminate the room.

The foam looks far better on these than in the pictures I've seen. The weight is very substantial. The grills are... perhaps less than I expected.

Ahh well, I need to get them setup properly to listen.

 

[jostenmeat]

I for one never attacked anyone here.

I didn't even read too much of the thread, and didn't even know there was a different one.

Before you bash us all as a whole, thousands of members or whatever, just make sure that one person doesn't give you that impression. (Assuming that there is a person, or even two, or maybe even three).

It doesn't give your accusations much credence at all.

Also, there have been a number of pros and speaker designers that have posted here. In case you didn't know.

 

[sawzalot]

Too bad this forum has closed minded individuals who preffer to attack those with different ideas and background. No wonder few manufacturers post to these boards... I again, commend Roy for at least trying to open some minds.

This thread had no value, no purpose other than to allow "regulars" of the site to sling mud about things they knew/know nothing about, as an "outsider" that is how I viewed this thread.


Rick

I feel that you missed one of the most important aspects of this thread and others like it, At least Jerry and other members here have taken the time and money (own pockets) to put together such a review of this and many other products, these members take the time to help educate the rest of us to the performance and value of various components that I/We would never even know of otherwise, now I ask you, What have you done for us lately?

 

[rich121]

I feel that you missed one of the most important aspects of this thread and others like it, At least Jerry and other members here have taken the time and money (own pockets) to put together such a review of this and many other products, these members take the time to help educate the rest of us to the performance and value of various components that I/We would never even know of otherwise, now I ask you, What have you done for us lately?

What review? From the very 1st post, it was negative before he even 'reviewed" the speakers...


Rick

 

[rich121]

I didn't "bash" you all, and just read the thread, you will see who I'm talking about, it was just a few "regular" posters. If you read the thread, you would see that the Moderator got involved a number of times.

This is exactly the "mentality" I posted about..."us against them"

Rick

I for one never attacked anyone here.

I didn't even read too much of the thread, and didn't even know there was a different one.

Before you bash us all as a whole, thousands of members or whatever, just make sure that one person doesn't give you that impression. (Assuming that there is a person, or even two, or maybe even three).

It doesn't give your accusations much credence at all.

Also, there have been a number of pros and speaker designers that have posted here. In case you didn't know.