Vertical alignment of speakers

[Dr.db]

I have been told it is allways favoured to vertically align the individual woofers and drivers on a baffle.
As I understand this is to avoid lobing and getting the individual sources to match up better and improve imaging.

A speaker like the JBL S9900 follows this aproach, but the JBL Everest DD66000 or DD67000 doesn´t.
The Everest speakers only use one of their 15" woofers to run up high to the horn. So the center of the "midrange-woofer" isn´t vertically aligned with the center of the horn. It is offset by about 8".
I wonder how this affects the overal presentation?
Is this considered to be a major tradeoff in this speaker-layout or is the offset of such small amount that it doesn´t really affect the sound?

Best regards,
Olaf

[Dr.db]

Anyone :confused:

[jmpsmash]

I am guessing it has to do with comb filtering. once we have separated driver, there will be combfiltering. the question is whether it should happens on the horizontal axis or vertical axis. comb filtering will happen at the overlapped crossover region.

if we have ppl sitting on a couch, we have more listeners separating horizontally and not vertically. so drivers are aligned vertically for that.

as for the DD67000, they probably trade off some aesthetics. otherwise the speaker will be L shaped. Now why didn't they put everything vertically, like the K2 9500, that's another question, perhaps for the marketing department. :)

[Mr. Widget]

I have been told it is allways favoured to vertically align the individual woofers and drivers on a baffle...

...I wonder how this affects the overal presentation? I wonder too. I made a smaller but similar trade off with my own speakers. I am sure that a vertical alignment is better, but is it actually audible? If audible how much of an impact does it make? On the DD66000/DD67000 speakers Greg Timbers was able to get JBL to spend a fair amount on making the woofers swappable so the extended range woofer was always inboard, and the manual explains that the extended range woofer should be inboard. Obviously being offset does make a difference.

If I was younger and had more time I'd explore the question, but these days, I'd rather listen to the music. :D

I'll say this, I enjoyed the heck out of the DD66000/DD67000 speakers... warts and all. These days I'm enjoying my own speakers with their own warts etc.


Widget

[RMC]

Hi Olaf,

I think the following may answer why a vertical alignment of drivers:

"The second rule is: put the drivers in a vertical line with little or no horizontal displacement. When speakers are mounted side-by-side, there will be a difference in the path length from each speaker to the listener's ears, producing phase distortion. Sometimes lack of space makes side-by-side mounting inevitable." (David B. Weems, Designing, Building and Testing Your Own Speaker System, 4th ed. p. 26).

I know, some JBL 43 series monitors for example have drivers that are not vertically aligned.

Some companies seem to put more emphasis on phase issues than others (not a judgement about JBL's practices). However, Widget's questions do remain relevant in my view. Best regards,

Richard

[Dr.db]

Thanks a lot for your comments! :)

[Robh3606]

As I understand this is to avoid lobing and getting the individual sources to match up better and improve imaging.

It does and if you have any doubt listen to a 4311/L100 vs. 4410/L80t as examples. The 4311's are not mirror imaged and not aligned and the imaging suffers compared to the mirror imaged and vertical designs. Look at the polar response plots of the non aligned speakers and you see just how different they are left vs right. Take a look at the differences between the left and right at 20 degrees


http://www.jblpro.com/pub/obsolete/4411.pdf

Rob:)

[Dr.db]

I have to come back to the Everest DD66000 or 67000 with it´s dual woofers.
Swapping the extended range woofer to the inside makes sense... But they could have avoided this hassle by simply placing both woofers in a vertical line instead of horizontal.

As Rob pointed out it makes a noticeable difference...

[rusty jefferson]

... But they could have avoided this hassle by simply placing both woofers in a vertical line instead of horizontal.

As Rob pointed out it makes a noticeable difference...
It's not necessary to vertically align the 2 woofers as the wavelengths are so large you'd never hear a difference between vertical/horizontal mounting. However it would have completely changed the design of the speaker from other aspects including aesthetics. Everything is a compromise.

The mid woofer being off center could effect things at crossover to the horn, but I assume dispersion at crossover is still similar and/or time alignment is addressed in the crossover, although we know GT now runs his active.

Some speaker builders offset the driver(s) to reduce cabinet diffraction. Nothing is absolute.:)

[rusty jefferson]

This is probably a better example of offsetting drivers to reduce diffraction.

[Ian Mackenzie]

I have to come back to the Everest DD66000 or 67000 with it´s dual woofers.
Swapping the extended range woofer to the inside makes sense... But they could have avoided this hassle by simply placing both woofers in a vertical line instead of horizontal.

As Rob pointed out it makes a noticeable difference...

I have spend considerable time with an Everest DD67000 user trying the reversal of the woofers and other adjustments.
It really depends on the listening room and how the enclosures are located relative to the side walls and rear wall.

The effect is not a deal breaker but l generally preferred the main woofers on the inside.
There are far less subtle issues that will effect the overall performance of a system of this caliber.
The challenge with a system like the DD67000 is setting it up properly from the get go.

[Mr. Widget]

I have to come back to the Everest DD66000 or 67000 with it´s dual woofers.
Swapping the extended range woofer to the inside makes sense... But they could have avoided this hassle by simply placing both woofers in a vertical line instead of horizontal.Yes, they could have, but did they want to build another M9500? To make the aesthetic statement they wanted to go with, they had no choice but to go with side by side woofers, and due to the size of 15" drivers, they had to be offset.

In my project, I could have perched the ET-703 up top on a mast or other appendage or extended the cabinet top above the horn and vertically align all of the drivers... during my development phase I did test these various physical layouts prior to construction. I found the sonic trade off to be minimal and wanted a particular aesthetic direction.

As many of us have said numerous times on this forum, loudspeaker design is all about compromises.


Widget

[Dr.db]

It's not necessary to vertically align the 2 woofers as the wavelengths are so large you'd never hear a difference between vertical/horizontal mounting.


That´s a very interesting approach!
Do you have any idea of where about the threshold is? Like more than half a wavelength at crossover of vertically missalignment is noticeable...!?



I have spend considerable time with an Everest DD67000 user trying the reversal of the woofers and other adjustments.
It really depends on the listening room and how the enclosures are located relative to the side walls and rear wall.


Swapping the left and right woofers probably affects the room-reflections in particular. I guess it wouldn´t have any effect on the vertically missallignment, since both woofers are off center by the same amount...



Yes, they could have, but did they want to build another M9500? To make the aesthetic statement they wanted to go with, they had no choice but to go with side by side woofers, and due to the size of 15" drivers, they had to be offset.


I have to admit the horizontally mounted dual 15´s look very formidable! With a speaker being this size you can´t ignore the aesthetics, I get that.

[Robh3606]

Hello Rusty


It's not necessary to vertically align the 2 woofers as the wavelengths are so large you'd never hear a difference between vertical/horizontal mounting. However it would have completely changed the design of the speaker from other aspects including aesthetics. Everything is a compromise.

Well that is a conditional statement that depends on how the woofers are set-up. The Everest only uses the second woofer up to 150Hz so no issues. Now if you ran both woofers over the same range up to the horn then you would have significant issues off axis. All you need to do is look at one of the dual 15 cinema boxes and you can clearly see some real issues in the Vertical axis. If you lay the box on it’s side like the Everest woofers are set up its going to make it very hard to get them to sound right. After about 20degrees or so it quickly starts to degrade the off axis response.

If you compare the polars in the 4638 you can see how much better the horizontal polars are with a vertical alignment A good argument for setting up the woofers in a vertical vs side by side if running full range.

Rob

[rusty jefferson]

Hey Rob,

Agree completely. It's because the 2nd woofer is playing so low I made the comment.

The helper isn't technically doing subwoofer duty, but it's similar enough. No need to vertically align our subs. In some cases they are many feet away from a midwoofer.

I am curious about the midwoofer/horn alignment. I've never heard these speakers.

[Dr.db]

To simplify the discussion let´s narrow our attention to the extended-woofer only.
Above 150hz this woofer operates alone and it´s the transition between this extended-woofer and the midhorn at 850hz that´s of interest ;)

Another extreme example would be the old 4355.
The 12" midwoofer is mounted right beside the midhorn. The midwoofer is roughly 13" off center compared to the midhorn.
Several people reported this baffle-layout messed up the dispersion and imaging characteristics of this speaker...

Compared to the Everest the woofer is much more off center compared to the horn and the crossover is at 1200hz (4355) rather than at 850hz (67000). Both would have a negative influence I guess. But where about is the threshold of what is noticeable or not?

[Mr. Widget]

Another extreme example would be the old 4355.
The 12" midwoofer is mounted right beside the midhorn. The midwoofer is roughly 13" off center compared to the midhorn.
Several people reported this baffle-layout messed up the dispersion and imaging characteristics of this speaker...
I don't think we need to consider the original 43XX series in this discussion, as GT and JBL have learned a lot since that era. Those speakers were big badass designs, but compared to modern designs, they are not the last word in high fidelity.



Compared to the Everest the woofer is much more off center compared to the horn and the crossover is at 1200hz (4355) rather than at 850hz (67000). Both would have a negative influence I guess. But where about is the threshold of what is noticeable or not?As to the degree of a compromise for the DD66000/DD67000, I imagine only GT could really answer that question. It would be great if he were to respond, but I don't think he visits this site often these days.


Widget

[Ian Mackenzie]

Part of the issue is people’s brains visualise via the optic nerve and that influences the perception of localisation.

They listen with their ��.

The Everest woofers are angled slightly outward. Maybe that has an impact. Maybe it doesn’t. Something for Olaf to ponder over.

[Mr. Widget]

Part of the issue is people’s brains visualise via the optic nerve and that influences the perception of localisation.

They listen with their ��.I think this plays a much larger role than most of us care to admit.

I always listened to my Everests with their grilles on, so the imaging was pretty good. :D


Widget

[Ian Mackenzie]

I was listening to a live Jazz quartet last night at a local venue. Only the vocals and the Hammond organ were amplified and as you might expect was the only thing coming from the centre.

There was no point source.

The enjoyment was the tone of the sax, the snap of the drums, the fine metallic overtones of the cymbals.

Getting a loudspeaker to do all of that well is the priority.

There are plenty of loudspeakers that image well but they don’t do anything else well. That might be what an audiophile craves for but what they are listening for is a lot of tiny unrealistic detail because the loudspeaker can’t do anything else.

But where’s the tone, the realism at almost live levels and the micro dynamics that help a listener visualise the sound of individual musical instruments?

[jmpsmash]

Last year I was visiting a high school open house with my prospective son. they had a ~20 person jazz band playing outdoor in their main yard. I couldn't help but stood there and listened for 20 mins. Wondering about the same thing. There are so much details that comes out with natural timbre and so much texture from each instrument that paints a uniform acoustic image.

I guess that's why we still go to concerts.

having said that, compression horn seem to do much better than dome tweeters in terms of dynamics and details. But seems to be a bit to aggressive sometimes and spoils the natural part of it.

[Dr.db]

I was listening to a live Jazz quartet last night at a local venue. Only the vocals and the Hammond organ were amplified and as you might expect was the only thing coming from the centre.

There was no point source.

The enjoyment was the tone of the sax, the snap of the drums, the fine metallic overtones of the cymbals.

Getting a loudspeaker to do all of that well is the priority.

There are plenty of loudspeakers that image well but they don’t do anything else well. That might be what an audiophile craves for but what they are listening for is a lot of tiny unrealistic detail because the loudspeaker can’t do anything else.

But where’s the tone, the realism at almost live levels and the micro dynamics that help a listener visualise the sound of individual musical instruments?


I couldn´t aggree more on that!

That´s actually what I love JBL for, the live-like and very dynamic sound. Actually imaging isn´t that important to me at all. But I worry about good driver integration.



https://de.wikipedia.org/wiki/Elbphilharmonie#/media/Datei:Elbphilharmonie,_Hamburg.jpg

Unfortunatelly everything was amplified... :blink:

[rusty jefferson]

....That´s actually what I love JBL for, the live-like and very dynamic sound. Actually imaging isn´t that important to me at all. But I worry about good driver integration.....


Live, life-like sound can only come from speakers with good driver integration. Speakers with good driver integration will image well. It goes hand in hand. Any horn speaker can be dynamic, but to have natural reproduction of instruments, voices, and venues, time alignment, phase, matched dispersion at crossover, etc.(integration) are critical.

Here's a good example. A recent review of a Klipsch horn speaker from Stereophile. These were great speakers when first implemented, but not so much today. I've linked just the measurements page. Look at the impedance plots and most importantly, the step response. Between 1.5ms-6ms delay between drivers. That's approaching 1st reflections delay. That speaker will never sound right, but will be dynamic. Many will like it for that reason alone, and that's fine. Note JAs comments at the end.

https://www.stereophile.com/content/klipsch-klipschorn-ak6-loudspeaker-measurements

[rusty jefferson]

Compare to the review of the 1400 Array measurements from (yikes) almost a decade ago. Good driver integration, great FR, good time alignment (especially for horns on a passive network), and (because of those things) excellent imaging. Plus, good dynamics.
https://www.stereophile.com/content/jbl-synthesis-1400-array-bg-loudspeaker-measurements

From the review:
"Conclusions
JBL's Synthesis 1400 Array BG impressed me with its three-dimensional imaging, impressive transparency, ambience retrieval, capacity to "disappear," and fine timbral detail. It gave my similarly priced reference speakers, the electrostatic Quad ESL-989s, a run for their money for its excellent balance across the audioband, its good timbral retrieval, and its three-dimensional imaging—and it exceeded the bass-shy Quad in its reproduction of pipe organ and percussion and its ability to play much louder.. . "

[SEAWOLF97]

Live, life-like sound can only come from speakers with good driver integration. Speakers with good driver integration will image well. It goes hand in hand. Any horn speaker can be dynamic, but to have natural reproduction of instruments, voices, and venues, time alignment, phase, matched dispersion at crossover, etc.(integration) are critical.


Some of the most coherent, lifelike speakers that I've ever owned have been KEF Uni-Q coaxials (and 1 way Walsh's) ... I seem to recall that JBL made a coax (LE14C ?).

question is: why haven't coaxials been more successful ? (except in car audio)

they seem to fulfill most of the requirements that Rusty enumerates.

[toddalin]

Vertical alignment vs offset certainly shows up on the RTA as peaks and dips.

[Dr.db]

@Rusty: You´re absolutly right, these parameters cannot be seen isolated. Thanks for the informative articles.

@Tod: The question still remains: where about is the threshold for this being audible for the human ear?? Maybe 8" off center at 850hz is unaudible, but 8" at 1200hz is audible?

[Ian Mackenzie]

You can easily determine this with a modular loudspeaker project.

That said the sensitivity to a variation in the distance between left and right drivers is going to increase where the listening position forms an equilateral triangle. Other factors include the symmetry of the loudspeaker locations in the room. You can validate this by moving your own system enclosures closer or further apart. Relatively small distances are audible. You can then estimate the threshold of variation by careful listening to midrange sounds and then higher frequency sounds. You might call this a linear distortion of the image. Where the drivers are not symmetrical it would be non linear.

Toe in of the loudspeaker also has an impact on the image. In the case of the DD67000 the is already done with the angle of the woofer baffle to some extent. Was that done by design or anaesthetic is unknown. Given the width of the enclosures off the cuff l would say it was done to account for any fall off in the polar response of the inner woofer near crossover point. Toe in of a wide enclosure is never going to please the WAF factor. I would point out a wide enclosure like the DD67000 imposes limitations on adjustments to the distance between the horns in all but very wide rooms.

In my own experience bringing the mid range closer below 1000 hertz leads to the perception of centrally coherent vocals. On the other hand moving the horn and high frequency drivers closer can shut down the image beyond a certain point producing a less open soundscape. So it’s a balancing act.

Back to Olaf’s point l think Olaf is concerned with localisation of the source (the drivers). My feedback on that is the impact is on the sound stage or sound cape. Once the drivers blend and you have the equilateral listening position what your hearing is the soundstage not the point of localisation of the woofer/mid woofer.

This is my analysis at this point and may serve to more discussion on this topic.

No doubt you all have your own thoughts on this.

[Ruediger]

The slit is a simplification here, it shows the problem in one plane instead of two. There is also an article in Wikipedia about "Acoustic Lobing".


Consider two drivers, each sending soundwaves. At some points in space the sound waves arrive with equal phase, they will add. This is constructive interference.

At some other points in space the sound waves arrive with a phase difference of 180 degrees, they will subtract, null each other. Tis is destructive interference.

There is plenty of articles about this.

Ruediger

[Dr.db]

Very useful input, thanks :)

[toddalin]

@Tod: The question still remains: where about is the threshold for this being audible for the human ear??

If you saw the spectra for two speakers and one was obviously smoother than the other, wouldn't you want to go with the visibly smoother pair even if you didn't think you could hear a difference? I know that I would, and do.

Remember that there is no way to A/B/X something like this unless you created a speaker that could instantly shift to two different drivers mounted in the two positions. So sometimes I have to trust my eyes, rather than my ears, to optimize what's there.

You can optimize a car for the 1/4 mile, but unless you have timing equipment to make the most of it, your butt isn't going to feel a couple 10ths of a second difference. Same thing.

[jmpsmash]

Remember that there is no way to A/B/X something like this unless you created a speaker that could instantly shift to two different drivers mounted in the two positions. So sometimes I have to trust my eyes, rather than my ears, to optimize what's there.


what would that experiment involve?

ie. if there is a way to shift 2 drivers horizontally with respect to each other, what do we measure?

I have 2 2123H (which covers around 300Hz to 3kHz) that are mounted on separate open baffle that I can move around. They are driven by DSP crossovers and identical amps. They can act as tweeter/midbass with the appropriate curves. I also have a couple of minidsp measurement mics.

If we can come up with the right experiment, I can try to make some measurements.

[toddalin]

Actually, I was thinking that there is a way to at least A/B it with the current set up as the 10" and Heils are separate from the 18"s and a simple double throw switch could be used to select which 10"/Heil plays, either the one vertically aligned, or the one next to it.

http://www.audioheritage.org/photopost/data//500/medium/DSC_000413.JPG


But to me, with the ability to vertically align things and from what I've seen on the RTA, there is no reason to change things here.

[ditusa]

it is call mutual coupling effect same as the 4435 studio monitor both woofers side by side 2" spacing.

[DavidF]

I have been told it is allways favoured to vertically align the individual woofers and drivers on a baffle.
As I understand this is to avoid lobing and getting the individual sources to match up better and improve imaging.

A speaker like the JBL S9900 follows this aproach, but the JBL Everest DD66000 or DD67000 doesn´t.
The Everest speakers only use one of their 15" woofers to run up high to the horn. So the center of the "midrange-woofer" isn´t vertically aligned with the center of the horn. It is offset by about 8".
I wonder how this affects the overal presentation?
Is this considered to be a major tradeoff in this speaker-layout or is the offset of such small amount that it doesn´t really affect the sound?

Best regards,
Olaf

You will get interference with drivers separated in distance that manifests in lobing and radiation tilt. The acoustic response will vary depending upon things like crossover alignment, the number of drivers, driver phase characteristic and the bandpass range involved. I suspect is just easier to deal with the response deviations having the drivers on, or nearly on, the same vertical plane. Especially in a multi-way system.

So the woofer does not have line up on-center to the mid range as long as you know what is happening to the response around the crossover frequency.

[Ian Mackenzie]

Hi Olaf,

If you have a look at the DD67000 user manual and specifications JBL specify the mid woofer should be placed on the inside for correct imaging.
JBL also mention the system can be used with the enclosures far part such as room corners with the enclosures aimed towards the centre of the room.

Perhaps an over looked virtue of the midrange horn is the wide 100 degree horizontal dispersion and the physical width of the midrange horn. This wide horizontal directivity means horn dispersion will closely match the dispersion of the woofer and load the compression driver correctly at the lower end of its operation range. These properties make the transition from the woofer to the horn subjectively less sensitive than a horn with a narrower dispersion.

[Dr.db]

Thanks a lot all of you.

The reason for my initial question came up with an idea for a diy-speaker a year ago:
85136

It would use the following parts:
JBL 2405
JBL 2441 on 2397 horn
JBL 2123
TAD 1603

If all compontents would be lined up vertically, the 15" woofer would be right at the bottom of the enclosure. A woofer that close to the floor would interacts badly with the room-acoustics and the bass gets boomy... To avoid this I thought I could mount it much higher on the baffle, but therefor I would have to offset the 2123 off center. This can be seen in the illustrated drawing...

[Ian Mackenzie]

Have you trialed that woofer in your listening environment?

You are making too many assumptions in an attempt to settle on a design before you cut timber.
It doesn’t work that way. You can’t avoid doing some real work yourself before finalising a design. A Yabba fest on a forum is not an alternative approach to refining a loudspeaker project. It’s opinions and insights but that’s all.
If you can do that simply build a Jbl clone. The work has been done.

Try the woofer out in several positions and at several baffle heights. The same with the 2123 under the horn.

I would not compromise or complicate the baffle layout without doing some fact finding practical trials.
Do a test and learn trial with that baffle. Have you considered mounting the 2123 above the horn and placing the tweeter lower at ear height. Try a few different driver layouts and see what works best for you.

You can move the enclosure, raise the enclosure slightly or if a real problem exist use some for of EQ. You can also tune the enclosure to account for room boundary proximity. Connect it you with a cheap Minidsp crossover to see how well it all works.

[Mr. Widget]

If all compontents would be lined up vertically, the 15" woofer would be right at the bottom of the enclosure. A woofer that close to the floor would interacts badly with the room-acoustics and the bass gets boomy... To avoid this I thought I could mount it much higher on the baffle, but therefor I would have to offset the 2123 off center. This can be seen in the illustrated drawing...I’m not sure you have to worry about the woofer becoming boomy just because of the proximity to the floor. If you were making a three-way, getting the woofer up a bit will help with the mids, but in your case that isn’t as important.

As Ian suggests, there really is nothing like building test mules when creating a new speaker from the ground up. You can follow all the rules and do everything right and still end up with a stinker, or you can make a number of compromises and hit it out of the park. (American baseball reference)


Widget

[Dr.db]

Both of you are absolutly correct, in the end I have to try it.

Currently my listening room is very small and the speakers are very close to the sidewalls and the listening position. I can´t really judge anything under these bad room acoustics to be honest. Right now I´m using another much smaller speaker for dailly listening (1,3" Audax softdome, 6" Audax mids, 12" PHL) as the big speakers won´t work in this room.
But I´ll be moving in a bigger place next year, so I started plans on the big speakers ;)