I have to agree with Zkzpb8. Overall I thought the sound at the show was pretty bad. I can only think of one or two rooms where I was really enjoying what was going on and the Vandy room by Audio Connection was, IMHO, clearly the best. Most of what I heard elsewhere was crappy audiophile stuff--you know, "great" recordings of bad music and sound effects. Far too many "demonstrations" and far too few folks who actually seemed to like music. In the Audio Connection suite they played all kind of stuff and, to my ear, it all sounded great. It's funny, I've been looking and listening to speakers for about a year now and have boiled my search down to 4 models--three of which are phase coherent designs. I may be one of those who is also sensitive to phase and time relationships. I donno. |
I've tried to like the sound of Joseph speakers, but I don't think I ever will. It seems a lot of other listeners think they're great, so yes, it's possible to design a time in-coherent speaker and still have an audience. Personally I stand behind time coherent design. A lot of the (expensive) speakers that I heard at the show in New York last week struck me as designs that were made by music lovers who never actually go out and listen to live music. I've always found time coherent designs to be all about music, and not hi-fi. |
I have no doubt Jeff Joseph is a good designer based on his beliefs and having never met the man, I'll take your word that he is a good fellow(which I'm sure he is.) However, I'm of the camp that there is only one way to skin a cat. These two designs are too far apart for even a sorta right pick between them. Sorry, this falls into a more right or wrong area. Otherwise, it forms a who cares theory (which is probably a good one since most will pick what sounds best to them no matter what the design.)
My opinion certainly doesn't invalidate anyone else's choice. I'm sure these speakers have a loyal following just as most other brands. They just weren't for me.
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Jeff Joseph seems like a very good guy, he gave a nice presentation in New York last week. Yes, with his speakers' performance he finds himself in good company, but only through a time coherent speaker can one accomplish the acoustic output as a duplicate of its electrical input. The infinite slope cannot maintain the acoustic waveform.
Richard Vandersteen though that I'm more sensitive to time domain shifts than most people. Not that I have golden ears, but it's just where my sensitivies lie. For other listeners, higher order cross-overs may be perfect for them - so yes, there is more than one way to skin a cat. |
Though my own sensibilities lie with Roy, and the very cogent points he put forth, I want to make it clear that as Jeff Joseph basically said, there's more than one way to skin a cat. Jeff's speakers have established themselves as fine a loudspeaker as one can find in this hobby. I admire and respect both he and his products. |
Roy, I played sax for over 30 years and I became sold on time and phase speakers when listening to this instrument as well as other woodwinds (and other various instruments.) Other speakers with high slopes just destroyed a lot of what should have been there. For some years (in the past), I blamed it on electronics and/or the recordings. With time, I discovered what you already knew. I have found very few speakers that get the attack, decay and harmonics correct for me. It was extremely interesting to read your explanation and examples. It definitely follows what I personally hear.
I have noticed the positive recommendations you are receiving here and other places on your speakers. With the apparent unfortunate situation with Meadowlark, it looks like you, Richard V. and Thiel must carry the load.
It is good to see Green Mountain Audio being successful. I'm certainly going to have to give your product a whirl at some point.
Curently, I am investigating no negative feedback equipment. With time and phase coherent speakers, it has proven to be extremely interesting. There is something to it for sure. It seems to open up the presentation even more and further enhance that "You are there sensation." It is also interesting that time and phase coherent speakers, for all the critcisms they get for being laid back and not transparent, sure show this difference. |
Thanks Roy,
indeed these difficulties can be minimized with careful design!
Thats why I use Tannoy LittleReds. It uses a combination of
first and second order filters. The phase response curve shows it to shift the entire audio spectrum uniformly by 30deg compared to amp output with a slight dip and a bump around the crossover frequency (+8deg,-10deg). So it acts as a time delay
(unavoidable) with a maximum phase shift of 18deg but this is limited to about 200hz either side of the x-over frequency ie the shift starts at 1k,
goes through zero (that is the 30deg total shift) at 1.2k rises again and is back at zero (30deg) at 1.4k.
Also, being point sources, they stay in phase no matter where you are in the room, unlike common multi-driver systems.
Personally, I have NEVER heard a speaker to be 'too analytical' or 'too revealing' although I heard speakers being 'too forward' or 'fatiguing' these usually featured metal-dome tweeters. I would have thought that 'analytical' and 'revealing' are essential attributes of any accurate speaker.
Without being 'analytical','revealing' and accurate any critical listening is
obviously impossible. People having problems with these attributes should probably by a Bose waveradio and just be happy with all the money they saved. They are the reason that high quality audio is in the dire state its in.
(Sorry, didn't mean to be ranting but statements like 'too analytical' just get me going. I am also aware that it wasn't you who said it, so don't take it personal.)
In my own experience, based on spending time in recording studios and listening to every speaker I can since I was 15 I have to say that Tannoys are closest to the real thing followed by decent studio monitors. Than come a variety of planars ( fantastic at low volume but lacking in macro dynamics),
full-range drivers ( great dynamics and imaging, bad at low volume, dodgy treble and (if in a horn) lumpy bass response.
After that the majority of dynamic speakers who do everything somewhere between average and badly.
This, of course, is a grotesque over-generalization as there are really bad studio monitors and really good HiFi speakers. I have not come across any
green mountain gear here in Europe so I cannot say anything to your product.
Overall you still have to look at the whole speaker-system and not just the xover, my Tannoys have loworder filters and sound fantastic, most studio monitors use fourth order and sound very good and back in the 80' I came across some 5way, first order filtered Dynaudios which also were excellent!
Cheers Golix
(haven't founded anything but...
can explain gravity without
bending space) |
Dear Golix,
You are right in several ways. First-order filters shift the phase of each driver by 45 degrees, one driver's output is "leading", the other's is "lagging". Thus, the Phase Difference between them is 90 degrees, as I think you implied. But your concerns about the impossibility of achieving "phase coherency" for "odd-order" crossovers are not warranted:
For a second order filter, the phase shift is 90 degrees per driver at the crossover point. This is where your 180 degrees comes from- as the Phase Difference between them, at the crossover point. That Phase-Difference analysis extends, with your numbers, for the third-, and fourth-, and higher-order filters, at their crossover point.
Higher-order circuits, from 2nd on up, cannot be made time-coherent, because that Phase Difference each one exhibits at the crossover point does not remain a Constant Phase Difference when the tones move away from the crossover point. In other words, the drivers' Relative Phase Difference is always changing- which can be heard in many ways:
- As an image always shifting (depending on the note).
- Complex timbres which are not realistic.
- Dynamic attacks that are slurred.
- Truncation of the depth of the image in that crossover region.
- An audible "disconnect" in the depth of the image heard from the tweeter, compared to depth of the image revealed by the woofer. When an instrument demands some output from each of those two drivers, the same instrument apparently exists in two different rooms.
- There is "height" in many recordings.
- The speakers "don't measure like they sound."
Listen to a tambourine on a high-order speaker (an instrument that requires output from woofer AND tweeter), then listen to it on a decent pair of headphones, which are most always time coherent across that tambourine's tone range. You'll hear most all of the effects listed above from the speakers. Then compare using applause, acoustic guitar, piano, voice, using any wideband signal with transient complexity.
The audible effects of a constantly-changing phase relationship depend entirely on your choice of music- on what frequency range your music occupies, and also on the "frequency content" of each transient.
Different listeners use different music, some that easily reveal phase shift around the crossover point. Most crossovers to tweeters occur around 2 to 3kHz. A constantly-changing phase relationship between the two drivers above and below that crossover frequency has specific audible consequences we have all heard. In my experience, it is the leading cause for someone to say a speaker is "too analytical" or "too revealing", "too forward", or even "too exciting". One often remarks that a recording is "too harsh, too hard to listen to." It is why the preferred audiophile recordings are rather bland.
If the speaker designer physically steps that out-of-synch tweeter back from the woofer, and/or "pulls" the crossover point apart between the two drivers, you often hear "laid back", often with "a little less energy around the crossover point."
So, why use a first-order filter?
That Phase Difference remains Constant for a first-order filter: The output from the two halves of a first-order filter are always 90 degrees apart, on every frequency, not just at their crossover frequency. So their Relative Change in Phase Difference, at every frequency, is zero.
With a first-order circuit, the image does not wander on different notes, transients are preserved right down to knowing when the tip of the tongue left the roof of the mouth, and existing distortions in the recording or in your gear are not re-distorted, by being smeared out in time.
So, after passing through a first-order circuit, when the high- and low-passed signals are recombined, then the original, transient perfect, signal is recreated. Of course for a speaker, those high- and low-passed signals can emerge from drivers that have their own severe, mechanically-caused phase shifts. Perhaps the high and low sounds start off at unequal distances from your ears, or arrive at different times from "duplicate" drivers (like multiple tweeters). They could be time-warped from improperly-designed Zobel networks in the crossover circuit. Then there is a good chance that the high-passed signals will be "hazed-over" by cabinet reflections.
Fortunately, all of these difficulties can be minimized.
I hope this clarifies things. Thank you for your participation in an interesting thread.
Best regards,
Roy Johnson
Founder and Designer
Green Mountain Audio |
How is it possible to build a phase-coherent speaker using 1st order filters?
I learned in electronics that a 1st order filter (ie 6dB slope) shifts the phase between woofer and tweeter by 90deg;a second order (12dB slope) by 180deg; third order (18dB) by 270 and a 4th order (24dB) one by 360deg.
This should mean that it is impossible to create phase-coherent first order systems, in a system using second order filters you'd have only to invert one driver to achieve coherence, a third order system again is impossible whilst a fourth order system is always in phase as it has been shifted by a full 360degrees.
Now, when it comes to to transient response and xover "ringing" ( electric resonance) a first order filter is unbeatable as the transient response is helped by having fewer passive components and the filters total inability to resonate. But for phase-coherency they are, together with 3rd order, the worst possible solution. You can fix 180 and 360 degree shifts, but theres nothing fixes 90 deg shifts, other than active electronics like in better bass-management systems for HT. |
I have no doubt you build a quality product but so do a lot of others who believe in them as much as you. It's good that consumers have choices. If everyone liked the samething then we wouldn't need but one manufacturer! I'm all for driving the economy. But, who is to say what is right and what is wrong when it comes to listening on a personal basis? Nobody can sure decide which slope to use. Seems the best is whoever is doing the talking.
All I can do is relate my experiences in these threads for better or worse. I have been at this over 35 years. Based on that experience, it is wise that people go out and listen for themselves just as I have done(and the fellow who started this thread.) Does this mean I'm an "Authority?" No, it doesn't, but I do know what sounds good to ME and the point of these threads, I thought, was to share our personal experiences, not those who scream loudest get heard.
Most of the population has no clue to what crossover design is all about. I'm not so sure they need to know. Most don't know how a car is designed. They base their choice on looks and performance just as most do with speakers. I think here in the US, we boarder on false advertising way too much. It then makes everyone suspicious of every claim.
All I'm saying is you must satisfy oneself. It's your money and your satisfaction at stake.
Go out at listen for yourself and make a decision based on ones personal wants and needs (ie; does it look pretty or whatever.)
This "Best of the show" stuff is a little free advertising in these threads don't you think? Is that why these threads are here? Or is it for you to justify a point?
Your participation is always welcomed as any manufacturer would be but don't use it as a free format for advertisement. It just proves my point---your design based on your opinion is the one to go with. Hell, it may be but buying based on a show, review or especially advertisement is risky business at best. Tell people to compare your speakers side by side in the same room with the same electronics. Be confident enough to say comparison is welcome and recommended. That's all I'm saying. |
Bigtee,
I went into the speaker business because I believe we have something special to offer. I think if you look at our track record, "best sound at show" year after, "speaker of the year"
excellent reviews, and a loyal group of Joseph Audio speaker owners who wouldn't give them up for anything else.
I care deeply about musical enjoyment, enough to want to share it with others - enough to bet the farm on others being able to hear it for themselves. |
I just wouldn't focus so much on design. I would focus on what I thought would satisfy me over the long haul or you will be one of those with speakers for sell every few months. This debate about time and phase coherent speakers vs steep slope will go on forever with nothing being accomplished. Everyone is in a camp and will probably stay there until they gain enough experience listening (and becoming a critical listener)to understand what they are hearing and why.
I am in the time and phase camp and got there after many different speakers and years of analysis and listening.
Technically, ALL speakers are a trade off of one sort or another. However, phase and time aligned speakers come closer to reproducing the input signal than other designs. Steep slope speakers may swoon the listener but they have scrambled the output signal compared to the signal coming in. Would you buy an amp that screws up phase and time domain (actually high global feedback amps do this)?
Time and phase speakers are not perfect and there is lots to understand but for me, they simply sound more musical. Are they right for you? Only you can answer that.
Now, with all that said, one has to decide on what it is that they are after, wether it be dynamics, transparency or whatever. It is not arrived at easily. As your experience grows (and I actually think age plays a factor here)things will change and you may appreciate other designs.
So just don't get so caught up in all the design BS. It confuses the issue and will ultimately lead you to disappointment. Find something you like and go with it.
Also, no disrespect to Joseph Audio, but do you think he would recommend something he doesn't build? It would be like a Ford dealer telling you to buy a Toyota! If someone really cares about your musical enjoyment, they would tell you to satisfy yourself. It is you that has to be happy not them! |
I don't believe you can demonstrate that having a time and phase coherent speaker is more important than having a just a phase coherent speaker. The problem in being definitive is not merely that it's largely a matter of preference - which it is, just like I prefer Patti Smith to Norah Jones - there are unresolved matters of psychoacoustics in testing something like this, as well as a particular design method's suitability to a particular use. For example, a time aligned speaker might not be appropriate for extreme near field listening; it objectively wouldn't be the best for that situation. But it might be the best in another situation.
Of course, Jeff J. thinks each kind is less appropriate for virtually every situation. |
The speakers in our room were not the Pearls but a new model called the RM55LE. I am glad to hear that you noticed the excellent image focus of our design - something that low order fans often cite as a benefit of that approach!
The sense of musicality is hard to define - it is by and large a subjective topic. I think for some it means a softer tonality or euphonic balance.
What it means to me is to experience the full expression that is part of the musician's interpretation. Dynamics and subtle details that rivet your attention not on the mechanical aspects of reproduced sound, but on the human heart beating within the performer(s). Another poster mentioned that when he listened to an LP on our system that the system itself seemed to "go away" - and that is the highest compliment one can hope for.
A euphonic system will sound more pleasant on poor recordings, but it can never sound real enough to bring the performance back to life. |
Jeff, I totally accept your position. Having initiated the thread on crossover design (on which you were a gracious participant) I just thought it interesting to go back and forth between the rooms and listen to the two top models of reputable brands' that approach the crossover differently. I realize that other factors contributed to the differences I heard. I'm just wondering to what degree those differences are attributable to the diametrically opposed crossover designs. One thing I did notice was that the Joseph Audio Pearls seemed to image with greater precision than the Vandersteen 5A's. Localization of individual instruments was much easier. The images on the Vandy's seemed to float around. They weren't anchored in position as they would be live. On the other hand, the soundstage depth and width of the Vandy's was, to my ear, far superior to the Pearls. I wonder if others have had similar experience listening to either of these models and whether, again, the crossover design is in part to blame. |
There are far too many variables from one system to another for you to conclude that the crossover method is the root cause of the difference. Our speakers are used by many discerning professionals who know what live music sounds like, since they are exposed to it every day. |
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Thanks to you both. Let me see if I understand this correctly. Phase irregularities caused by steep slope crossovers can be compounded by an alignment of the drivers which further distorts the arrival of sound waves at your ear. What I am wondering is which tends to have a greater impact on phase coherence--a steep slope crossover which delays the sound eminating from certain drivers or a poorly conceived alignment of the drivers? Let's take the new Fried Studio 7 for example (photos are on the website). It has a flat baffle with the tweeter flanked on top and bottom by a 6" midrange (top) and an 8" woofer (below). Is this a time aligned (or as Richard Hardesty would say "temporally aligned") arrangement? If so, great. If not, how much of an impact does this have on phase coherence? In other words, if the drivers are not temporally aligned then are the supposed benefits of 1st order crossovers lost due to improper driver alignment? Or is the phase coherent crossover 90% of the battle and the lack of temporal alignment only a small piece of the sonic picture?
Also, can we really hear these phase irregularities or what? Some say we can and others say impossible. All I know is that the phase coherent designs I've heard sound more like live music than designs using steep slope crossovers. I was at the NY Hi End Show last weekend and it was very interesting for me, after reading through the dispute between the "steep slopers" and the "first order crowd" in the previous thread, to walk back and forth between the Joseph Audio room (a steep sloper) and the Vandersteen Room (a first orderer). They were right next door to each other so I could drift back and forth. The rooms were identical. Both used (different) but high quality upstream components. Here is what I observed. The Joseph Audio room sounded like hifi and the Vandersteen room sounded like music. I could point out other specific differences that I heard but this pretty much captures the essence of my experience. I'm not prepared to say the this essential difference was due purely to the crossover designs of the two speakers but it may have SOMETHING to do with what I heard. |
Partially true. In a hurry today so I'll be brief and general.
Time alignment generally refers to the alignment of the theoretical point sources of all drivers in a cabinet, such that the signals emanating from them at one moment in time all reach your ear at the same time. The sloped or stepped baffle tries to accomplish this - but of course, if you're not at EXACTLY the right seating height for that particular geometry, and EXACTLY the same distance from both speakers, and have no near field room reflections, much of the benefit is lost.
Phase Coherence problems are mostly created by crossovers as they split the frequency bands. So a time aligned speaker is no more likely to be phase coherent than any 2 or 3 way speaker, unless much care, measurement and testing and re-testing and re-testing goes into the crossover design. Without that - even though what's leaving the tweeter and the woofer may arrive at your ear at the same time, the signals from each have probably lost their phase "alignment" while travelling through the crossover and drivers.
There is some dispute over whether you could actually hear this if a crossover had a true infinite slope. But since the reality is that there is large overlap in the midrange where the woofer and tweeter are producing the SAME frequencies, if they're out of phase with each other it's bad news. In a worst case scenario, in an anechoic environment, they could perfectly cancel each other.
Not a thorough explanation but I have to run. I'll bet Roy frm GMA has expounded on this somewhere already. |
"Phase coherence" and "time alignment" are related concepts.
I think what you're thinking of as time alignment is aligning the acoustic centers of the drivers with either a stepped or slanted baffle. This "phase aligns" them, so to speak. (Differences in phase are differences in time. Don't forget that a typical plot of a sine wave has two axis - amplitude and _time_.)
It's possible to have alignment without a slanted or stepped baffle. You have to look at what the listening axis is, and see if the extra distance between your ear and other drivers spaced farther away will make up the alignment.
Let's take a 2-way (TM, not MT) as an example. The woofer's acoustic center is 5 feet away from your ear. The tweeter's acoustic center will be farther forward. Step the baffle to put the tweeter farther back and you get alignment. Or tilt the front baffle back and you also get alignment of the acoustic centers.
Now lets assume that the woofer is at your ear level. So it's 5 feet away. The tweeter is 10" above the woofer on the front baffle. You now have a triangle with 3 sides, 60, 10, and 60.8. Just by the increased distance to your ear, you've done the equivalent of moving the tweeter back.
I'm sure that the designers of the Studio 7 took this and other factors into account, and that they're a minimum-phase design. |
