Floyd Toole's Presentation at CIRMMT

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JoshK

Re: Floyd Toole's Presentation at CIRMMT
« Reply #20 on: 3 Jun 2015, 01:30 pm »
I would disagree on that. A few years ago I was at an Axpona show in Atlanta and they had  saxophone groups play in one of the large conference rooms. Obviously poor acoustics but the sound was amazing, especially when the largest ensemble perform (20+ players I believe). Some sounds were  spacious / wide with others very specific depending on how the horn projected. In my experience very directional speakers fall short when reproducing this kind of music. The room has to be energized to a degree in order to give you a sense of space and envelopment. With speakers that have a more narrow horizontal coverage I find the sound to be what I call "formatted" in that it's just not as realistic or engaging. Vertical coverage affects this as well but not as much as the horizontal plane.

I think you are right.  There is meant to be an appropriate reverb time in a room, so it isn't dead nor too alive.  Narrow dispersion can sound a bit dead space wise, like my headphone analogy.  That is why acousticians tell you not to cover all walls with treatment, only the first reflections, so the other parts can scatter sound and add to spaciousness.

I think for HT where you are employing surround speakers the narrow dispersion is a major asset, taking the room out of the picture to a large degree and allowing the surround matrix to produce the directionality and spaciousness of the audio mix.   For stereo, I think wider dispersion has some merit.  But then narrow dispersion speaker with rearward facing radiation like Linkwitz and Duke LeJeune have done tackled that another way.   The narrow dispersion just helps a great deal on early and first reflections.

poseidonsvoice

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Re: Floyd Toole's Presentation at CIRMMT
« Reply #21 on: 3 Jun 2015, 01:50 pm »
I would disagree on that. A few years ago I was at an Axpona show in Atlanta and they had  saxophone groups play in one of the large conference rooms. Obviously poor acoustics but the sound was amazing, especially when the largest ensemble perform (20+ players I believe). Some sounds were  spacious / wide with others very specific depending on how the horn projected. In my experience very directional speakers fall short when reproducing this kind of music. The room has to be energized to a degree in order to give you a sense of space and envelopment. With speakers that have a more narrow horizontal coverage I find the sound to be what I call "formatted" in that it's just not as realistic or engaging. Vertical coverage affects this as well but not as much as the horizontal plane.

Honestly Rick you can have your cake and eat it too. What I ended up doing was adding diffusion to my rear side walls and rear wall. That completely provided the 'envelopment and spaciousness' while the narrow controlled directivity design provided my 'image lock.' The reverb contributes to spaciousness and envelopment. Treating the 1st reflections with absorption with narrow controlled directivity speakers made an improvement in the space between instruments (i.e. blackness), although, the improvement was small (This is most likely due to the design of the loudspeaker itself). For my front wall ,behind the loudspeaker,  I have diffusers as well, which I interchange with absorbers. The diffusers are used for 2 channel and the absorbers are used for HT.

To each their own I guess. But after having listened to numerous designs that are wider dispersion and some degree of directivity control, I only became convinced and satisfied when I started listening to speakers with narrowing and constant directivity. So my choices became limited, basically well designed waveguide based loudspeakers, or well designed OB speakers like Linkwitz latest LX series.

Best,
Anand.

Tyson

Re: Floyd Toole's Presentation at CIRMMT
« Reply #22 on: 3 Jun 2015, 04:19 pm »
I think Duke here on AC at Audiokinesis has done some very interesting work regarding CD/swarm based speaker systems, very much in the Geddes mold.  But even MORE interesting has been his development of the LCS (Late Ceiling Splash) technology - basically it's a CD speaker firing forward, and a 2nd CD speaker firing upward.  This gives the laser like focus of a traditional CD speaker, but also gives the air and soundstage width/depth/spaciousness of an OB speaker.  It's really a remarkable design.

Rick Craig

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Re: Floyd Toole's Presentation at CIRMMT
« Reply #23 on: 3 Jun 2015, 04:52 pm »
A good friend of mine told me that audiophiles tend to "hear with their eyes". I'm wondering how the other formats (dipole, waveguides, etc) would fare under a blind test. Last year I attended an event where most of the listening was blind except for a few guys and myself who were switching out the speakers. It was interesting to see the owners try to guess if it was their speakers.

Tyson

Re: Floyd Toole's Presentation at CIRMMT
« Reply #24 on: 3 Jun 2015, 04:57 pm »
A good friend of mine told me that audiophiles tend to "hear with their eyes". I'm wondering how the other formats (dipole, waveguides, etc) would fare under a blind test. Last year I attended an event where most of the listening was blind except for a few guys and myself who were switching out the speakers. It was interesting to see the owners try to guess if it was their speakers.

I think a lot of it depends on the room - if it's fairly large and acoustically decent, then the OB and CD stuff becomes less important.  I think the CD and OB approach are useful in situations where that's not the case.  Also, if you sit near field, then the room matters less.  But if you sit far field and in an acoustically challenging room, then these other approaches become very useful.

For myself, I love blind testing - it really does separate what's truly audible from what is not.

Russell Dawkins

Re: Floyd Toole's Presentation at CIRMMT
« Reply #25 on: 3 Jun 2015, 05:10 pm »
I would disagree on that. A few years ago I was at an Axpona show in Atlanta and they had  saxophone groups play in one of the large conference rooms. Obviously poor acoustics but the sound was amazing, especially when the largest ensemble perform (20+ players I believe). Some sounds were  spacious / wide with others very specific depending on how the horn projected. In my experience very directional speakers fall short when reproducing this kind of music. The room has to be energized to a degree in order to give you a sense of space and envelopment. With speakers that have a more narrow horizontal coverage I find the sound to be what I call "formatted" in that it's just not as realistic or engaging. Vertical coverage affects this as well but not as much as the horizontal plane.

I can see we fundamentally disagree on this. In my experience, the most convincing re-creations of the recording space, if there is one, have been from listening in a nearly anechoic environment, i.e., outdoors over an acoustically absorbent surface (a lawn).

Finally, in my books the ultimate test for effective speaker configuration/acoustic environment arrangement is a simple as playing a true mono signal. If the result is a sharply defined, very narrow central image then all is probably well in the spatial department. In my experience, again, almost no set up I've heard does at all well on this test. If your set up in mono cannot produce a sharp phantom image, how can you expect it to reproduce an accurate "sound stage" in stereo? Another complication is the very poor quality of most "stereo" recordings - most even orchestral recordings are the result of somewhat arbitrarily positioned spaced omni mics, even for the primary array; in more correct terms 'A-B stereo' as opposed to X-Y (coincident). Accurate image placement in this type of recording - and for many this is their only experience of 'stereo' - is just plain not there, so people do not know what they are missing.
A seasoned listener and talented amplifier designer, a former member of this group now dead (Dan Banquer, RIP) told me up until he positioned his speakers as I suggested and played my orchestral recording he had never heard stereo before. He thanked me profoundly for 'enlightening' him. He said his engineer friends went 'bonkers' when they heard it. Yes, there is life beyond what is sold as 'stereo'.
What everyone is experiencing is a wash of sound with some sort of spatial differentiation and that's enough (and perhaps it should be) but that is not what serious engineers and listeners call "Real Stereo".
http://www.tnt-audio.com/topics/realstereo_list_e.html

Rick Craig

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Re: Floyd Toole's Presentation at CIRMMT
« Reply #26 on: 3 Jun 2015, 05:34 pm »
Honestly Rick you can have your cake and eat it too. What I ended up doing was adding diffusion to my rear side walls and rear wall. That completely provided the 'envelopment and spaciousness' while the narrow controlled directivity design provided my 'image lock.' The reverb contributes to spaciousness and envelopment. Treating the 1st reflections with absorption with narrow controlled directivity speakers made an improvement in the space between instruments (i.e. blackness), although, the improvement was small (This is most likely due to the design of the loudspeaker itself). For my front wall ,behind the loudspeaker,  I have diffusers as well, which I interchange with absorbers. The diffusers are used for 2 channel and the absorbers are used for HT.

To each their own I guess. But after having listened to numerous designs that are wider dispersion and some degree of directivity control, I only became convinced and satisfied when I started listening to speakers with narrowing and constant directivity. So my choices became limited, basically well designed waveguide based loudspeakers, or well designed OB speakers like Linkwitz latest LX series.

Best,
Anand.

I would love to visit sometime and hear your system.

JoshK

Re: Floyd Toole's Presentation at CIRMMT
« Reply #27 on: 3 Jun 2015, 07:31 pm »
A good friend of mine told me that audiophiles tend to "hear with their eyes".

I think there is a lot of truth to that statement.  I am still in my 30's (at least for a couple months) but I feel like I am getting old and jaded with this hobby.  Certainly I've become much more of an objectivist, or at the very least put things into what I think are the priorities (acoustics/speakers >>> cables and tweaks) and spend effort and money accordingly.   

I mean the hobby seems to focus and pride itself on being able to hear the subtlest minutia, presumably with the hopes that numerous small changes add up to some grand nirvana of sound.   But I think many/most of these differences counteract the others, except for the ones we can objectively measure and analyse so we can shape the system as a whole. 

I'd trust my ears if something measures better but sounds really off (can't say that has ever really happened in my experience) but I'd want to know what was going on, so I wouldn't just give up on the measurements.   I also recognize that biases are hugely impactful on our perception.  To deny such or to think you are impervious to biases is foolhardy.  This is where at least some controlled blind testing of sorts helps a lot.   At least you know where you are susceptible.   

poseidonsvoice

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Re: Floyd Toole's Presentation at CIRMMT
« Reply #28 on: 3 Jun 2015, 08:07 pm »
I think there is a lot of truth to that statement.  I am still in my 30's (at least for a couple months) but I feel like I am getting old and jaded with this hobby.  Certainly I've become much more of an objectivist, or at the very least put things into what I think are the priorities (acoustics/speakers >>> cables and tweaks) and spend effort and money accordingly.   

I mean the hobby seems to focus and pride itself on being able to hear the subtlest minutia, presumably with the hopes that numerous small changes add up to some grand nirvana of sound.   But I think many/most of these differences counteract the others, except for the ones we can objectively measure and analyse so we can shape the system as a whole. 

I'd trust my ears if something measures better but sounds really off (can't say that has ever really happened in my experience) but I'd want to know what was going on, so I wouldn't just give up on the measurements.   I also recognize that biases are hugely impactful on our perception.  To deny such or to think you are impervious to biases is foolhardy.  This is where at least some controlled blind testing of sorts helps a lot.   At least you know where you are susceptible.

I agree with both you and Rick regarding 'hearing with our eyes.' In Floyd's presentation which the OP so kindly posted, he showed how drastically different listeners rated speakers based on 'looks' versus being truly blind. FWIW, I think waveguide based speakers look very, very, very boring. Nothing amazing. Just a box with a circle on top. No fancy veneering, and no fancy talk about how the cabinet is made of an unobtanium plutonium product from planet krypton. I also listen in the dark and all my equipment is in a separate room. I find equipment to be extremely distracting to my aural experience. And yet I spend so much in my DIY builds! Why? Resale value. That's why.

Best,
Anand.

Tyson

Re: Floyd Toole's Presentation at CIRMMT
« Reply #29 on: 3 Jun 2015, 08:42 pm »
I think there is a lot of truth to that statement.  I am still in my 30's (at least for a couple months) but I feel like I am getting old and jaded with this hobby.  Certainly I've become much more of an objectivist, or at the very least put things into what I think are the priorities (acoustics/speakers >>> cables and tweaks) and spend effort and money accordingly.   

I mean the hobby seems to focus and pride itself on being able to hear the subtlest minutia, presumably with the hopes that numerous small changes add up to some grand nirvana of sound.   But I think many/most of these differences counteract the others, except for the ones we can objectively measure and analyse so we can shape the system as a whole. 

I'd trust my ears if something measures better but sounds really off (can't say that has ever really happened in my experience) but I'd want to know what was going on, so I wouldn't just give up on the measurements.   I also recognize that biases are hugely impactful on our perception.  To deny such or to think you are impervious to biases is foolhardy.  This is where at least some controlled blind testing of sorts helps a lot.   At least you know where you are susceptible.   

One reason I really liked going "active" for several years is I was able to spin up substantial changes to my speakers with the click of a button and do real time listening comparisons between different crossover choices and different EQ choices, and it's pretty interesting what was audible and what really wasn't.  The DCX was my first box, then the DEQX I ran for a few years till moving on to the miniDSP stuff.  Each one I used with a couple different boxes and a whole lot of different drivers.  Being able to swap things around and adjust them to your environment and tastes was really enlightening.

A few things it taught me -

1. phase matters
2.  Shallower crossover slopes sound better than steeper crossover slopes. 
3. Crossover points matter a whole lot. 
4. Driver size plays a large role in off-axis power response
5. EQ can help but only if used in small/limited doses
6. Some room problems, such as unevenly loaded bass, cannot be solved with an EQ with box speakers
7. Etc...

Because you could load up different presets/configurations in the active crossover unit, you could very quickly cycle between different settings for your speakers and hear very clearly what they sounded like with different choices. 

JoshK

Re: Floyd Toole's Presentation at CIRMMT
« Reply #30 on: 3 Jun 2015, 08:58 pm »
Without getting too far off-topic, I highly recommend you have a read on diyaudio, a thread about quasi-optimal crossover designs.  It was probably one of the most enlightening things I have read on the subject (I haven't done a lot of xo work).   Active/digital/brickwall filters still don't cheat the physics, so understanding all the variables in play helps a lot.   I think this might shed a lot of light on the why your conclusions are what they are, also how to deviate from that while still obtaining as good of results.

http://www.diyaudio.com/forums/multi-way/231594-quasi-optimal-crossover-high-efficiency-loudspeaker-system.html

Quote
It has been demonstrated that it is impossible to obtain: (A) perfect acoustic summing (flat frequency response), (B) perfect phase match AND (C) flat Group Delay using a simple analogue passive crossover [Vanderkooy, J. and Lipshitz, S. P., “Is Phase Linearization of Loudspeaker Crossover Networks Possible by Time Offset and Equalization?”, J. Audio Eng. Soc., vol. 32 (Dec. 1984)].

(5)
Given (3) and (4) above, a number of efforts have been made to design "quasi-optimal" crossovers that strike the best possible balance between the three goals (A),(B) and (C) (rather than only considering (A) - e.g. conventional 3rd order Butterworth, or (A)+(B) - e.g. even-order Linkwitz-Riley).


Tyson

Re: Floyd Toole's Presentation at CIRMMT
« Reply #31 on: 3 Jun 2015, 11:16 pm »
Nice link!  They have a bit of added complexity due to focusing mainly on horns.

For a non horn speaker, something like the miniDSP is nice because you can simply dial up different crossover points and slopes and actually measure the results from a phase standpoint, and do it iteratively to see if the theory matches practice.  Also you can deal with group delay separately from phase because the miniDSP has a separate digital delay function tied to each individual driver.

What I've noticed is that phase is reasonably easy to deal with when using a lower order filter, but goes all to hell when using higher order filters.  Now, a steep filter is nice because it allows you to have a clean frequency response transition so it's ideal for people that feel phase is not audible.  For myself, I like the idea of steep filters, but they always sound lifeless and sterile when I actually use them. 
« Last Edit: 4 Jun 2015, 01:06 am by Tyson »

poseidonsvoice

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Re: Floyd Toole's Presentation at CIRMMT
« Reply #32 on: 4 Jun 2015, 01:16 am »
SL has picked up Dr. Toole's recent talk and provides his input: http://www.linkwitzlab.com/links.htm#Toole

Best,
Anand.

JoshK

Re: Floyd Toole's Presentation at CIRMMT
« Reply #33 on: 4 Jun 2015, 01:04 pm »
Nice link!  They have a bit of added complexity due to focusing mainly on horns.

For a non horn speaker, something like the miniDSP is nice because you can simply dial up different crossover points and slopes and actually measure the results from a phase standpoint, and do it iteratively to see if the theory matches practice.  Also you can deal with group delay separately from phase because the miniDSP has a separate digital delay function tied to each individual driver.

What I've noticed is that phase is reasonably easy to deal with when using a lower order filter, but goes all to hell when using higher order filters.  Now, a steep filter is nice because it allows you to have a clean frequency response transition so it's ideal for people that feel phase is not audible.  For myself, I like the idea of steep filters, but they always sound lifeless and sterile when I actually use them. 

I am not an expert on the matter, but to my understanding the problem with steeper filters and phase has to do with the rolloff of the actual driver with the filter in place doesn't match the textbook roll off, usually because drivers don't have perfect response.  Their impedance plots aren't perfectly smooth.  They have breakups, notches, etc that need to be accounted for in the steeper filter to match the textbook.  Then and only then is the phase more idealized.   This is why off the shelf xo filters don't work well. 

The link does use horns and is focused on passive, but the freedom provided by the horns is the physical offset flexibility.  But in a box world, you could build a non-standard box to offset the drivers or with the aide of digital xos, delay the needed driver to compensate for the offset.   That is why I pointed out the thread.  It is a seriously useful thread regardless of whether you are using horns or not.


JoshK

Re: Floyd Toole's Presentation at CIRMMT
« Reply #34 on: 4 Jun 2015, 01:16 pm »
SL has picked up Dr. Toole's recent talk and provides his input: http://www.linkwitzlab.com/links.htm#Toole

Best,
Anand.

I somehow always forget to go back to Linkwitz's page for updates.  There are some really good links on that page! 

ACHiPo

Re: Floyd Toole's Presentation at CIRMMT
« Reply #35 on: 5 Jun 2015, 01:55 pm »
I somehow always forget to go back to Linkwitz's page for updates.  There are some really good links on that page!
I hadn't visited before it was referenced on this link, but I agree.  Lots of good stuff there.  I'd like to hear his designs one of these days--they seem to incorporate the backsplash idea that Duke's getting raves about.

DaveC113

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Re: Floyd Toole's Presentation at CIRMMT
« Reply #36 on: 5 Jun 2015, 04:34 pm »
Honestly Rick you can have your cake and eat it too. What I ended up doing was adding diffusion to my rear side walls and rear wall. That completely provided the 'envelopment and spaciousness' while the narrow controlled directivity design provided my 'image lock.' The reverb contributes to spaciousness and envelopment. Treating the 1st reflections with absorption with narrow controlled directivity speakers made an improvement in the space between instruments (i.e. blackness), although, the improvement was small (This is most likely due to the design of the loudspeaker itself). For my front wall ,behind the loudspeaker,  I have diffusers as well, which I interchange with absorbers. The diffusers are used for 2 channel and the absorbers are used for HT.

To each their own I guess. But after having listened to numerous designs that are wider dispersion and some degree of directivity control, I only became convinced and satisfied when I started listening to speakers with narrowing and constant directivity. So my choices became limited, basically well designed waveguide based loudspeakers, or well designed OB speakers like Linkwitz latest LX series.

Best,
Anand.

I agree.

One system I got to hear recently was big Focals in Boulder Amplifier's listening room at their factory. It's a VERY damp room and the result was sound similar to what you'd hear from a speaker with controlled directivity. And, they sounded amazing... better than I've ever heard Focal speakers sound at a show, by a long shot.

Like most things, either wide or narrow dispersion speakers can be setup to sound excellent, it's all in the implementation. However, it's pretty common to see wide dispersion speakers used in rooms that would work much better with narrow dispersion speakers, there is something to be said for the lesser quantity of room treatments required.

Nate Hansen

Re: Floyd Toole's Presentation at CIRMMT
« Reply #37 on: 23 Jun 2015, 09:50 am »
Hey guys, I don't post much here but thought I'd throw in my 2c anyways....

I am not an expert on the matter, but to my understanding the problem with steeper filters and phase has to do with the rolloff of the actual driver with the filter in place doesn't match the textbook roll off, usually because drivers don't have perfect response.  Their impedance plots aren't perfectly smooth.  They have breakups, notches, etc that need to be accounted for in the steeper filter to match the textbook.  Then and only then is the phase more idealized.   This is why off the shelf xo filters don't work well.

Exactly! I use active myself. When done correctly I can get good phase tracking on both sides of the xo for nearly an octave with 6th and 8th order acoustic slopes. Phase can be dealt with in brick wall filters using FIR dsp. Whatever slope provides the best blend at all off axis angles is what "sounds best" to me.

I'd also like to point out that there's been talk about dipoles being narrow directivity.....IMO they really aren't. If they are working perfectly as a dipole then you have a 120 deg front and rear pattern which can be wider than a typical cone and dome type speaker in the top octaves. The M2 is also about a 120deg pattern. If you do a drawing of a speaker like a dipole or the M2 in a small room and start laying out the angles you will see what I mean about 120deg being wide wrt to the energy being directed at the side walls, and potentially the front wall depending on toe in.

To me narrow directivity (90deg or less) speakers excel in a typical small, untreated, or minimally treated, room. A constant directivity type speaker can be toed in so that the contralateral reflection occurs late enough to help with spaciousness without coloring the first arrival. My speakers are about 110deg in the lower midrange transitioning to a large wg which is around 80deg average. I get precise imaging and good spaciousness. IMO too much spaciousness due to my narrow room so I'm working on some narrower pattern speakers.......

Duke

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Re: Floyd Toole's Presentation at CIRMMT
« Reply #38 on: 7 Sep 2015, 06:33 am »
I think Duke here on AC at Audiokinesis has done some very interesting work regarding CD/swarm based speaker systems, very much in the Geddes mold.  But even MORE interesting has been his development of the LCS (Late Ceiling Splash) technology - basically it's a CD speaker firing forward, and a 2nd CD speaker firing upward.  This gives the laser like focus of a traditional CD speaker, but also gives the air and soundstage width/depth/spaciousness of an OB speaker.  It's really a remarkable design.

Thank you very much!

I've learned from Toole and Geddes both, and also Roger West of SoundLab.   His big electrostats seemed to me to be doing more right than could be explained without really taking their radiation pattern into account, which was a 90 degree pattern front and back.   So my first foray into polydirectional speakers was a bipolar that borrowed from Dr. West's design in spirit at least.

Toole seems to advocate wide dispersion, with good response across maybe a 180 degree frontal arc.  Conceptually Roger West was taking that 180 degrees and dividing it in two, aiming half forward and half backwards, and I emulated that. 

My next step was to incorporate Toole's findings on the ideal direction for the additional reverberant energy to arrive from, which turns out to be about 60 degrees off the centerline to either side ("10 o'clock and "2 o'clock").   That was an improvement in rooms that allowed the placement needed, but such rooms were rare. 

My friend Jim Romeyn was experimenting with various bipolar configurations, having heard some merit in my designs.  He was using multiple mini-monitors, and at one point tried the upfiring configuration that became the Late Ceiling Splash we now use.   While not giving us the ideal direction for the additional reverberant energy, the path length was longer in most rooms, and apparently the greater path length made more of a difference than getting the direction just right.   Of course this is based on far less rigorous testing than what Toole would have done!

If one has free reign to place speakers as he sees fit, and a nice big room, a bipolar may make the most sense (well, to me and those drinking the Kool-Aid that I serve).  But in most rooms, I think the LCS is the preferred configuration.

Swing by our room at RMAF, we plan to show the Swarm with dedicated satellites, along with a more adaptable LCS module.