Why Why did ML abandon 'ForceForward'

[akm3]

That was their silly trademark name for having two woofers in a hybrid electrostat mounted opposite each other, so that the bass frequencies didn't get muddied.

This appear in Odyssey and Prodigy speakers, and then disappeared. The Summits, also having two woofers, went for a forward and down arrangement, and ForceForward disappeared.

Did it just not work well? What compromises did it introduce?

 

[sleepysurf]

Good question! I suspect the Summit woofer arrangement created more sonic challenges than it solved, hence the new & improved crossover in the Summit X. I'm waiting to read a Summit X review that specifically addresses that!

 

[amey01]

I've wondered that too - note though, that they've kept it in their subwoofers - mechanical opposition anyway, even though it uses a three-driver arrangement.

It seems the Summit was designed to be small/high WAF first and foremost. Important? Yes - of course, and clearly successful, but I too have wondered whether there are any sonic compromises that could have been avoided if they had just made that bass cabinet just a tad bigger!

 

[akm3]

I've wondered that too - note though, that they've kept it in their subwoofers - mechanical opposition anyway, even though it uses a three-driver arrangement.

It seems the Summit was designed to be small/high WAF first and foremost. Important? Yes - of course, and clearly successful, but I too have wondered whether there are any sonic compromises that could have been avoided if they had just made that bass cabinet just a tad bigger!

The Subwoofers isn't 'ForceForceward' it is 'BalancedForce' which is another ridiculous trademarked name.

BalancedForce means the vibrations from the subs cancel each other out so the box doesn't shake and introduce distortion, versus ForceForward which sends sounds waves out the back to reduce muddiness of soundwaves out the front

 

[User211]

So Summits can hop around the floor Just like you after a beer or two

"Let's go do the hop (oh babeee)":music:

 

[akm3]

So Summits can hop around the floor Just like you after a beer or two

"Let's go do the hop (oh babeee)":music:

Do the summit's bass move them?

I think you are thinking BalancedForce instead of ForceForward.

 

[User211]

Do the summit's bass move them?

I think you are thinking BalancedForce instead of ForceForward.

Am I?

Maybe the Summit is HoppingForce We've had a few posts from members saying they move around on smooth floors... seems pretty obvious the woofer arrangement causes it.

Logically, ForceForward or BalancedForce won't lend itself to this type of behaviour...

 

[Gordon Gray]

Do the Summits move on a wood floor? Yes.

I have the spikes seated into the indent on the BDR pucks, which sit on a wood floor.

Not much but I have the outside edge of the BDR's marked with tape so I can monitor the "creep" and readjust.

As Justin said, it's got to be the down firing woofer causing the drift. If you put your hand on the woofer when it's woofing, there's alot of energy coming out of that driver and you can understand why.

GG

PS: I respectfully disagree with Sleepy on his Summit woofer observations. Based on all the rave reviews as well as my and other's experience with this speaker, ML got it right for most users. My sense is that the crossover change will be most noticeable if the Summits are placed in close proximity to side / back walls. However, that is only a spefculation, on my part, at this point. This will hopefully be addressed by future reviews / observations assuming a direct comparison between the original and the "X" can be made within the context that I have suggested.

 

[Craig]

I would speculate that a major reason changing over to the down-firing woofer on the Summit was to make all the parts fit into a very compact cabinet. The Summit and Vantage are much smaller than the Odyssey and Prodigy. Also the rear panel houses amplifiers and controls and connections.

This design probably had more to do with manufacturing cost, ease of maintenance and esthetics than sound.

 

[Rich]

That was their silly trademark name for having two woofers in a hybrid electrostat mounted opposite each other, so that the bass frequencies didn't get muddied.

This appear in Odyssey and Prodigy speakers, and then disappeared. The Summits, also having two woofers, went for a forward and down arrangement, and ForceForward disappeared.

Did it just not work well? What compromises did it introduce?

The Summit X continues the tradition, using the trademarked: "Controlled Dispersion PoweredForce woofer technology". Note that ML states that this technology results in an output that matches closely the output of the electrostatic panel near the crossover point (meaning sound traveling front and back of the speaker rather than omnidirectional). This sounds very similar to the Force Forward technology of the Prodigy but in a more updated engineering design. My guess is that they just continue to evolve these technologies. ForceForward was not abandoned so much as it was evolved. Their marketing department is as busy as their engineering department, that's for sure. What's next? "May the Force be with you" woofer technology?

 

[akm3]

I think we are left with two, equally sad, possibilities.

1) ForceForward was a bunch of a marketing BS to rationalize the design they chose, so no point keeping it. - And if that is true what OTHER marketing BS are they spewing at us?

2) ForceForward WAS a good idea, but to cut down on manufacturing costs, size, room placement, etc, they abandoned it as a compromise of the sound, meaning we aren't getting the best we possibly could be because they had to keep the box the size 'of a case of wine' (which they and magazine reviews are so fond of referencing)

-Allen

 

[roberto]

The Summit X continues the tradition, using the trademarked: "Controlled Dispersion PoweredForce woofer technology". Note that ML states that this technology results in an output that matches closely the output of the electrostatic panel near the crossover point (meaning sound traveling front and back of the speaker rather than omnidirectional). This sounds very similar to the Force Forward technology of the Prodigy but in a more updated engineering design. My guess is that they just continue to evolve these technologies. ForceForward was not abandoned so much as it was evolved. Their marketing department is as busy as their engineering department, that's for sure. What's next? "May the Force be with you" woofer technology?

Hola Rich, I am with you...This is what I got from the ML..."Summit X takes everything that was great about the original Summit and makes it better. Vojtko Voiced™ with a redesigned crossover and electronics, Summit X brings the magical electrostatic mid-range clarity of the CLX™ to a smaller package. Controlled Dispersion PoweredForce woofers tailor output to provide a low-frequency dispersion pattern at the crossover point mimicking that of our Controlled Dispersion XStat transducers. This breakthrough design provides dynamic, room filling bass at the lowest frequencies. By subtly shifting woofer phasing as it approaches the crossover frequency we minimize side-wall reflections and reduce problematic room interactions, while achieving seamless integration between the woofer and electrostatic transducer.

A flexible foot configuration allows listeners to easily adjust the controlled vertical dispersion of Summit X from –1° to 11°. The result? A superb sounding speaker that is easier than ever to integrate into every room!

Key to the Summit X's revolutionary performance is our advanced XStat™ electrostatic panel, which covers most of the audible range, from the midrange to beyond the limit of human hearing, with unprecedented accuracy. A perfectly integrated Controlled Dispersion PoweredForce™ woofer section – the most advanced woofer technology available in a full-range speaker – supplies an authoritative bass foundation from its twin 10-inch aluminum-cone drivers, effortlessly extending the Summit X's response to frequencies below where even most subwoofers reach. Yet the Summit X never, ever sounds heavy.

Nor does it look heavy. In fact, it almost seems to float in the air. We believe you'll agree that the Summit X looks nearly as good as it sounds – maybe because, like all designs, form follows function.
MartinLogan hybrid electrostats are a special breed of speaker, and the Summit X is the most special of them all. Hearing is believing...happy listening,
Roberto.

 

[akm3]

I should have mentioned the 3rd, not sad possibility

3) PoweredForce takes everything that is good about ForceForward and puts it into an even smaller and compact package.

 

[Rich]

I should have mentioned the 3rd, not sad possibility

3) PoweredForce takes everything that is good about ForceForward and puts it into an even smaller and compact package.

This one gets my vote. ML, like most quality companies, continuously works to improve on their existing technologies while also developing new ones. I think this is a prime example. I have heard the Prodigies many times in many different systems, and I own the Summits. I do not believe the bass sound quality was compromised to fit into a smaller form factor. The bass on the Summits is much better and more user-configurable than on the Prodigies. It goes lower and sounds cleaner, in my opinion. The fact that it does so with a smaller form factor is a bonus, not a reason to criticize. And it sounds like it may be even better on the Summit X, although I haven't heard them yet.

 

[lhpcope]

As an owner of Prodigy speakers I can assure everyone that Force Forward is not just marketing hype but does reduce low frequency output from the system in all directions but forward.

 

[JonFo]

Marketing names aside, I can offer the following comments on this.

The key problem ML faced is how to improve the integration of the panels to the woofer.

Most models are crossing over in the 250 to 400hz region, where the panels own low-frequency anechoic output begins to fall off plus the double-whammy of the dipole cancelation beginning to have significant impact below 500hz.

So the problem is, here you have some amount of acoustic radiation in the critical crossover region being dipolar (from the panel), trying to mate with a single woofer (in the original series). The problem is that while one can create a smooth crossover for the woofer, the panels acoustic output (due to dipole cancelation) is changing in ways that’s extremely hard to compensate for with passive crossover topologies.

So one approach is to use more than one woofer driver to help create a lobbing pattern in the mid-bass that will help integrate the crossover region better when placed in-room.
By playing around with how much out-of-phase (relative to the ESL rear wave) is fed to the rear (or down) facing driver, one can use the woofers output to help cancel some of the rear wave’s crossover-range interference.

Note that this is all about improving the blend across the crossover range.

Once you get below 80hz, sound is omni-directional, and the distances between the drivers are pretty meaningless in terms of lobbing and cancelation. The electrical phase relationship between the two woofers will have more to say about whether low bass is reinforced or not.

The balanced forward solution seems to be (and this is conjecture on my part) an in-phase electrically configuration, where the rear facing driver is used to help reduce rear-wave cancelation.
Additionally, the in-phase operation of the opposite side of the cabinet drivers do help cancel physical motion of the cabinet.


The ForceForward is more of a blended phase solution (I’d think) as the lack of a rear-facing driver will limit the management of the rear wave cancelation possible at frequencies above 120Hz.
Also, they are clearly working hard to innovate crossover designs that really improve the blend.
One of the advantages they have with Spires and Summits is that the bass crossovers can be done using active crossovers (vs passive), so more complex topologies and EQ can be applied (although I believe it’s all still in the analog domain, no DSP as far as I know)

Again, all the above is semi-educated guesses on my part. For all I know they’re laughing their heads off at the Factory

 

[User211]

Again, all the above is semi-educated guesses on my part. For all I know they’re laughing their heads off at the Factory

It's probably as good a stab as any we'll get around here, Jon!

When we all make statements here, we should all assume a default of "I might be wrong". It's only gracious

 

[Irishtom]

)

Again, all the above is semi-educated guesses on my part. For all I know they’re laughing their heads off at the Factory

I dunno but in any event you have a pretty good handle on how loudspeakers work and your notions are well informed and sensible.

As an old horny (you ES guys might be surprised how many hornys like ESs) I often wondered why hybrid ES makers used direct radiating woofers rather than basshorns. Basshorns allow controlled directivity of bass, have excellent diaphragm damping and much lower distortion than dynamic direct radiators, thus a subjectively "quicker" and cleaner sound that would much better match the ES panels.

Well I guess I know, size and cost. Still, ya gotta wonder.....

 

[JonFo]

Basshorns would be interesting, but talk about large

A large, yet possibly more manageable design is to use transmission line alignments for the mid-bass/bass. TL's are very clean sounding.

It's actually one of Roger Sanders hobby horses, to pair an ESL with a TL, and he wrote an excellent intro on the why's here

But short-of redesigning the speakers, the best current users can do is to mitigate the rear wave cancelation artifacts by placing the right kind of absorption behind the speakers, and treating the room with bass absorption.

 

[fabulousfrankie]

They are not servo controlled but there is a separate amp for each woofer. They are each phased differently from each other so as to integrate and project forward with the ForceFoward design similar to what we developed on the Prodigy.

So what do you guys think of the above quote that came from Jim Power when talking about Summits, service manager at ML(great buy BTW).

Quote was copied from the below post:
http://www.martinloganowners.com/forum/showpost.php?p=89929&postcount=7