What makes a headphone "fast"

[crimsonadam]

From an engineering standpoint, what makes a headphone's driver response "fast?"

 

[robzy]

A big v8?

I have never heard the term "fast".

Rob.

 

[crimsonadam]

It seems like i've seen headphones described as having a fast driver response, or quick driver response.

 

[UAndy]

A quick response, i.e. fast rise-time in all frquency areas that allows a lifelike presentation of cymbals, kick-drums etc. Good example AKG-K1000, UE10Pro with proper amplification. The opposite would be a dynamic compression with slow response resulting in a rather tired performance.

 

[NightStalker]

could it be the speed at which the driver can physically moves (eg. its hardness) combined with the speed/strength of the magnet (eg. its force or impulse). Thats always what I believed it to be... but I'm no engineer, will be interested to see what it really is

Cheers
-jake

 

[crimsonadam]

Quote:

Originally Posted by NightStalker could it be the speed at which the driver can physically moves (eg. its hardness) combined with the speed/strength of the magnet (eg. its force or impulse).

That does sound like what it would be.

It's nice to know that i'm not the only one that doesn't have the definitive answer.

 

[ReDVsion]

It is a very hard thing to describe; I noticed it when I first got the MS2s... it was as if the sound was being rushed to my ears faster than with my other headphones. But even that description doesn't sound entirely accurate to me. I think you'd just have to hear it to understand.

 

[crimsonadam]

What do you think it is about their construction and design that contributes to them reacting with "more attack" and "faster response."

 

[NightStalker]

Another thing that I just thought of that would influence the 'speed' of the headphones would be the sound stage/presentation. I noticed that for example grado v. senn headphones seem to have much different 'speeds' to them which I think is only different due to the presentation of them (which I'd be buggered to know what causes it), the the 'in your face' presentation of the grados makes them seem like a faster and more agressive can.

Hope that made some sence

Cheers
-jake

 

[crimsonadam]

Is that a result of the Grados being traditionally an open headphone wheras a lot of the Senns are closed?

 

[NightStalker]

Never really thought of that, but the air pressure in which the diaphram moves would also influence the speed at which it can move. Good spotting

 

[gsferrari]

NOTE : All theories below are mine and I dont guarantee that they are correct. I have made assumptions from my experience and from an engineering point of view.


[size=medium]SPEED of response:[/size]

[size=small]Analogy :[/size]

An automobile engine responds to throttle input by raising or lowering RPM. There is a small lag between the change in input level (movement of throttle pedal) and the change in output level (change in rpm according to throttle movement).

This delay is either small or large and is usually VERY small in sports car engines.

Similarly in audio transducers (drivers/mics etc.) the speed of the transducer is defined as the time delay between the change in stimulus to a corresponding change in output.

For a headphone driver - a change in current will result in the displacement of the driver therefore changing the sound. If the response is fast then the driver is a FAST driver. if the response is slow then the driver is a SLOW driver.

[size=medium]ATTACK Speed and DECAY Speed :[/size]

[size=small]Analogy :[/size]

Push down on the throttle and the rpm increases : Attack
Release the throttle and the rpm decreases : Decay

Similarly in drivers : The response to an increasing input is not always the same as the response to a decreasing input. Therefore we are able to classify drivers as FAST ATTACK and FAST DECAY or any nuber of combinations of FAST/SLOW and ATTACK/DECAY.

For example : The Etymotics ER4 P/S has a very fast attack and decay.



These terms are usually relative and classification will depend on what the listener has heard or has experienced prior to listening to the headphone under consideration.

For example - moving from a Senn HD-650 to a Senn HD-497 - the attack and decay are slow by a fair margin. Moving from a Senn HD-497 to a Grado RS-1 the attack and decay will be incredibly fast in comparison. Moving from RS-1 to HD-650 you will be hard pressed to tell any difference.

[size=medium]More Theory :[/size]

[size=small]What does attack/decay speed depend on :[/size]

* Amplifier Power Headroom
* Coil Design
* Baffle Design
* Enclosure Design
* Operating Temperature
* Operating Humidity
* Nominal Air Pressure

1] Amplifier :

If the amplifier has a sizeable "headroom" in terms of voltage swing and current capacity to handle sudden changes in the input (music signal) then it is able to deliver the rapid increase/decrease in current MUCh faster than an amplifier with less headroom.

Example : A Headroom MAX has more headroom than a MINT amp. Therefore it will be able to respond faster to changes in the input signal and deliver the required current to the driver without delay.

2] Coil Design :

A coil is a current carrying conductor that is placed in the magnetic field. Tha magnet is included when we talk about coil design.
- A larger and more powerful magnet will allow the driver to respond faster
to changes in input.
- A high resistance coil will be slower than a low resistance coil
- A heavier coil will respond slower than a lighter coil

All these are assuming that other conditions remain the same.

3] Baffle Design :

The baffle is the "cone" and includes the suspension as well. If this is a high inertia membrane then the response will be slower than a low inertia membrane. suspension stiffness also plays a part here.

4] Enclosure design :

Theoretically a closed enclosure will be slower than an open enclosure but not necessarily because it all depends on the damping. A well damped driver will be faster than one that is over damped or underdamped. Damping could well be the most significant variable in this discussion.

5] Temperature/Pressure/Humidity :

Higher temperature = less air density = easier to move drivers = faster response. But again - if damping is insufficient then overshoot becomes a problem and it may well have reverse effects.

Temperature and pressure are inversely related to driver speed...again keeping damping in mind.

Humidity - higher the humidity, slower the driver response and vice versa.



Hope this helps

 

[GlowWorm]

I would think that your source, and amp have more to do with it than the 'phones themself?

 

[saint.panda]

I like those analogies, especially the differentiation between attack/decay and speed.

 

[gsferrari]

Speed is actually a combination of attack and decay.

Speed = Delta A + Delta D

A and D depend on Inertia Factor(v) and Environment Factor(t)

t - time
v - driver membrane velocity
A - Attack
D - Decay

Delta A = rate of change of input / rate of change of output | Rising input

Delta D = rate of change of input / rate of change of output | Falling input

Inertia Factor = I know this should be considered but I cannot think of a formula

Environment factor = includes driver enclosure, operating conditions (anything extraneous to the driver)