What does the term "Speed" mean in a speaker?


I often hear people say "That speaker has great speed". What do they mean? I know the music isn't playing at a different pitch. Could it possibly be related to efficiency?
koestner
From my time in the audio hobby and profession,  I feel speaker "speed" has much to do with the response time in moving with the very first note/electrical impulse.  The trailing edge of a note is easier for a transducer as it is already in motion.  However the leading edge begins with the speaker/transducer at "rest", and the possibility of the transducer being slower than the electrical impulse being sent to the transducer.  (sorry for the "transducer" word, but I do not put electrostatic and planer speakers in the same category as push-pull standard types of speakers).  

Interesting question and answers. 


When a speaker has "speed" it's approaching the sound of real, life like, sound

Designing speaker is a compromise - some are optimized for speed (dynamic), or soundstage, or musicality.  Some $80K speakers can have a huge soundstage but lack musicality.  Some are optimized for speed but soundstage may lack bloom.  And so on ...
I do not put electrostatic and planer speakers in the same category as push-pull standard types of speakers
That may be true, but conventional drivers are transducers nevertheless - they convert electrical energy to mechanical energy hence by definition they are transducers. And fundamentally there’s not much difference between electrostatic panels and conventional drivers.  They might be different but not fundamentally.
The issue of loudspeaker speed (like almost everything else about loudspeakers) seems to be endlessly complex.

Here's an interesting interview with Allan Hendry of Monopulse loudspeakers.

https://www.monopulse.co.uk/quest.htm

If what he's saying is correct, and I don't have enough knowledge to know any better, then many (if not all!) two way designs could be seriously flawed when it comes to speed, phase and integration issues.
Transient response, certainly, as has been pointed out by others, sonically perceived as a lack of smear/crispness, unforced clarity and liquidity. Usually, not least through quality all-horns, I find it linked to uninhibited dynamics as well (or: ease of "explosivity," felt as a startling experience), coupled to (at least as a partially responsible aspect) a pronounced degree of low volume level "ignition," whereby music comes alive quite easily at lower SPL's. 
Hold on Andy. That is a mistake. Yes they are all transducers but their ability to function in air is quite different. ESLs and horns are a better impedance match to air and transmit sound waves more efficiently. Dynamic drivers have to work harder to get the same results. ESLs work entirely differently than conventional speakers. First, there are no magnets. ESLs are capacitors conventional drivers are not and represent an entirely different load to the amplifier. Designed correctly their transient response is superior to conventional drivers because the moving system has far less inertia and is a better impedance match to air.
Planar speakers are somewhere in between. IMHO in spite of the compromises you have to make ESLs rule as long as you can make them. I have personally not heard a conventional speaker sound as convincing. Some say well designed horns can do it. But I am still waiting to hear one that does. 
cd318, quite a long marketing dissertation for a easily solved problem. All he says about our hearing is correct. Our ears are primarily location detection devices. They evolved to locate danger. His analysis of speakers is correct. This is the major problem for horn speakers like the K horn. The drivers are at significantly different distances from you ears.
The "easy" solution is to use one driver and no cross over. Not so easy.
The only transducer type that has been able to do this successfully is the full range ESL. Trying to do this in the analog domain with conventional drivers is difficult and only really effective at one location. At higher frequencies say the midrange to tweeter crossover it is more difficult to match things up then at much lower frequencies with longer "slower" wave lengths like a sub woofer crossover. 
All speakers have mass and inertia, because they are mechanical devices pushing air. This means the "thing" in the speaker that moves the air will never respond instantaneously to what the amplifier throws at it (i.e. be fast).

Electrostatics is one technology that is 'faster' than most.

Large cone speakers (woofers) driven by electromagnetic coils are slow because the cones are heavy and electromagnets have electrical inertia. Electromagnets resist any signal feed to them from an amplifier and they return a signal back to the amplifier (back-EMF).

Low impedance output stages on amplifiers are important because they help 'dampen' the back-EMF, effectively stiffening the cone speaker. 

Tweeters and electrostatic panels tend to have light mass - they respond faster than woofers (bass speakers). Hence why Martin Logans can sound like the bass is slower than the panel.

Some speaker designers used to put the tweeters physically behind the plane of the woofer to try and accomodate the slower response of the woofer. Perhaps the B&W 800's do this?

Any two or three way speaker will struggle with phasing. Two way speakers often sound cleaner because of less speaker phase issues and the cross-over networks are simpler. Cross-over networks that use inductors and capacitors can potentially introduce phasing issues.

Quad electrostatics always sounded great because they were basically a single cone speaker. Bass was not great though. It was interesting playing Telarc's 1812 CD through Quad ESL 2905's.
 


 
There are many different factors that can make a speaker sound “faster,” but in my opinion, the biggest factor is the class bias of the amp.  I’ve made this analogy before.  A class B bias amp is like a dragster sitting on the starting line with the engine at idle.  When they get the green light, they floor the throttle and are off toward the finish line.  A class A bias amp is a like a top fuel dragster.  The throttle is wide open and they pop the clutch getting off the line SOOO much quicker.  Class A bias amps are always wide open, just waiting to reproduce the musical note, hence a faster response time.
I believe it is all things that come together to have a fast set of speakers. Well designed paper drivers in a well design enclosure . With as high end crossovers as you can afford , with an amplifier with the appropriate taps , bi amplified . I think fast is what we are all trying to achieve . A speaker doing precisely what it is told . 
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@obelisk- "Some speaker designers used to put the tweeters physically behind the plane of the woofer to try and accomodate the slower response of the woofer." No- The physical time alignment, in multi-driver systems, has nothing to do with the relative speed of the drivers. Rather: to get the acoustic centers(actual sound source/voice coil) of the drivers, in the same plane/in phase. https://en.wikipedia.org/wiki/Loudspeaker_time_alignment
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Great discussion and lots of good info to consider. At the end of the day, it’s what one hears. I have experienced speakers that are fast but didn’t sound it because of bass overhang attributable to room acoustics. Fix the room and you’ll extract everything the speakers can offer. And also be confident when evaluating new speakers. I have a really good room acoustically and whe I compared new Raidho speakers to my existing Burmesters (both ribbon tweeters) I could really feel the impact of the transients. Not sure I would have before getting my room right. Just my opinion. 
Boy some really odd analogies flying around here. Audiokinesis are you out there somewhere? Your help would be appreciated:)
Obelisk, rodman is correct. The drivers have to be phase/time aligned. Sound from each individual driver has to reach your ears at exactly the same time. The Dalquist DQ-10 was the first speaker to try and deal with this. 
It is all about transient response, the ability to start and stop fast without ringing.
Hold on Andy. That is a mistake. Yes they are all transducers but their ability to function in air is quite different. ESLs and horns are a better impedance match to air and transmit sound waves more efficiently. Dynamic drivers have to work harder to get the same results. ESLs work entirely differently than conventional speakers. First, there are no magnets. ESLs are capacitors conventional drivers are not and represent an entirely different load to the amplifier. Designed correctly their transient response is superior to conventional drivers because the moving system has far less inertia and is a better impedance match to air.
Planar speakers are somewhere in between. IMHO in spite of the compromises you have to make ESLs rule as long as you can make them. I have personally not heard a conventional speaker sound as convincing. Some say well designed horns can do it. But I am still waiting to hear one that does.
OK, you're right.  Opposite attracts :-)

By the way, horns use conventional drivers so they are probably the same.
Time cohesion has never been proven. Most speakers are not time cohesive and nobody seems to care or notice. 
Most speakers are not time cohesive and nobody seems to care or notice.
Just because nobody seems to care does not mean it does not matter.  Just because if something has not been proven, it does not mean that it's not true.  
I agree with most of the theories above for sure.  I also agree that the room acoustics have a lot to do with frequency dispersion and speed. To much absorption and or diffusion will have a profound effect on the fastest speaker production.
It is unfortunate fact for all of this as it really difficult to find the perfect combination without serious experimentation and or expense. I am fortunate to own full ribbon driver speakers and have had all types before them......they are easily the fastest I have experienced because of driver mass and height of the panel allowing driver radiation accuracy. In addition, I have experimented with acoustic treatments extensively (both absorption and diffusion) and feel they do pretty well with minimal treatment accept for my room's obvious modes. Nothing will be perfect so you have to choose the combination that pleases you most in the overall selection of components, speakers, and room acoustics. Everyone has different thoughts in perceived musical reproduction.

Best of luck,
gwalt
Speed = Rise and Decay

I enjoy a fast midrange/woofer/subwoofer and cabinet design, as it sounds crisp and accurate. 

Tweeters are generally fast. I enjoyed the Focal Tc120/90 series tdxt with the vented pole piece, as you could build a rear enclosure and affect the sound/speed of the tweeter like other drivers in the system. 
Listen to the Bass Line in Glad Tidings by Van Morrison.....

Does the whole song sound in sync or can you sense some lag ...
Speed as a function...

Small floorstander, Castle Conway III, intel Nuc, Benchmark Dac pre, Mystere PA, you want ‘speed’, transient attack, dynamics with decay, openness?  Try Captains Audio Envy cables.  I’ve a pr. of the Studio Prestige rca, a usb, & a balanced cable.  Remarkable spacious detailed resolution, the fastest cable I’ve heard.  Lightweight, easy to handle, affordable, speed.   

Example... the Castles r bottom ported adjustable thru spacers to various room sizes.  With AE interconnects, ports wide open, they sound like sealed boxes, absolutely no overhang, spacious, neutral, dynamic, textured speed unleashed thru the speakers carbon fiber drivers.

Addictive.

Same thru a pr. of 1SC’s.  AE interconnects r FAST, and one can easily appreciate such thru the additional frequency range moving beyond the monitors.  Fun too.  Refined, cohesive, spacious, they convey a distinct ‘house sound’ that reminds of a good modern tube amp, or a great set of headphones, the small Castles sound like lovely dark electrostatics with better dynamics.  
Speed indeed...



regismc, a fast cable? Please don't make me choke on my dinner. Electricity travels at the speed of light. All wires have exactly the same speed. Resistance and capacitance are separate issues. Personally, I would rather be addicted to sex. (Big smiles from the wife)
 As much as I have enjoyed reading through this thread, I couldn't help but remember when Velodyne made subs that used an accelerometer on the woofer cone, allowing it to be 'corrected' by the sub amp 3,500 times per second (maybe that is the way they still operate, dunno). It has been a very long time since I have owned such an animal, but I still remember the speed that I heard in the bass. To me, it came across not only in impact, but pitch definition as well. 
 Years earlier, when I owned a pair of corner horns, the bass had much of this kind of quality too, IIRC. 
 The sub that I am using presently (10" driver with a 12" passive radiator) with a velodyne SMS-1, doesn't have these effects, even though the bass is enhanced (increased).
By the way, horns use conventional drivers so they are probably the same.
surroundings which hold cone and magnets(alcinico,neodium) usually is different


The TS parameters for bass driver being used in a horn is very different from the same sized driver used elsewhere. For example, the surround of the driver is much stiffer (typically a cloth material), since the cone moves very little. +/- 1/16 was amount stated in the horns that I made.