Planar Speaker Asylum

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Is fast bass...... overly "tight" and "dry" bass?

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In Reply to: RE: best recording to show off Maggie lightning fast bass ? posted by trioderob on November 10, 2021 at 21:15:38

Could never understand the term "fast" or "tight" bass!
Natural "acoustic" bass is not "fast or tight" IMO.

Edits: 11/11/21 11/11/21

Follow Ups:

What is a 'fast' or 'slow' speaker? - SteveJewels 05:08:44 11/13/21 (2)
The ability or inability of the transducer to respond accurately to the input voltage from the amplifier is what is referred to when describing a speaker as 'fast or 'slow'.

Audio voltages have a 'rise time' and fall time'. Rise time is the amount of time it takes for the voltage to increase from zero to its maximum although people working with these measurements usually measure and refer to the 10 to 90% rise or fall time.

Cone woofers have significant mass and take more time (if only milliseconds or fractions of a millisecond more) to respond to the input voltage so the movement of the transducer cannot faithfully follow the input voltage.

Additionally, the inertia of the additional mass causes the cone to be more difficult to stop at the peaks (positive and negative) therefore the 'slowness' is exacerbated at the peaks. Servo speakers are an attempt to ameliorate this effect and why, I believe, they are regarded as a better match to planars. They have better control of change of direction of the transducer and of overshoot.

Because cone speakers have mass and woofers have more mass they are less able to respond instantaneously. If you make them lighter they are usually less stiff and physically deform (15" and 18" Altecs and Klipsch's) from the shape in which they are made. If you make them stiffer to hold their shape better they are usually heavier. If they are heavier you need a stronger motor as in a heavier voice coil and pole piece and stronger magnets although I don't think magnets contribute to a speaker being 'slow'.

To reproduce lower frequencies larger cones are needed. The larger the cone, 8", 10", 12", 15", 18" the more serious the detrimental effects of the mass. Some speaker manufacturers use advanced materials and/or methods to increase stiffness, sometimes without increasing mass but this has it's own problems. Stiffer materials such as metals, tend to ring or have their characteristic voicing, think titanium vs aluminum, vs silk vs beryllium vs paper, carbon fiber or perfectium unobtanium but voicing is a different topic. JBL uses aquaplas on paper cone speaker for damping and rigidity. "Aquaplas is a sound damping elastic used to provide greater bass control and more accurate woofer movement."

Another phenomenon that affects transducer performance is that a it can apply more force to the air when it pushes than when it pulls. When the transducer pushes the air in front of it becomes (however slightly) compressed and more force can be imparted into it. When the transducer pulls, the air becomes less dense and less force can be imparted to it. This includes the mass of the entire column of air through which the sound is conducted from the transducer to your ears. This is why the speed of sound is faster (I knew I could get that word in somehow. :)) through liquids and ever faster through solids than in air, the molecules are closer together.

I'm not sure I can identify the characteristics that result in perceiving planars as 'faster' than cone speakers but I can hear it.
- RE: What is a 'fast' or 'slow' speaker? - DrChaos 10:55:26 11/16/21 (0)
  > Cone woofers have significant mass and take more time (if only milliseconds or fractions of a millisecond more) to respond to the input voltage so the movement of the transducer cannot faithfully follow the input voltage.
  
  It's more complicated than this. Traditional electrodynamical speakers also have wire wound dozens to hundreds of times around in the coil vs once or twice in a planar.
  
  That means the force applied, at least in that location, can be much larger and well makes up for the significantly increased mass.
  
  > Another phenomenon that affects transducer performance is that a it can apply more force to the air when it pushes than when it pulls.
  
  atmospheric pressure is plenty to push back, normal audio is well in the highly linear regime. We're not getting supersonic shocks.
  
  Simple mechanical analogies aren't so helpful--it's compressible fluid mechanics described by partial differential equations.
  
  The impedance of the air matters more for a planar with a large area, light membrane and lower local force applied. Being in the linear regime the frequency (spatial and time) model analysis is more appropriate.
  
  I think the psychoacoustic advantages of planars aren't found in simple mechanical ideas.
- RE: What is a 'fast' or 'slow' speaker? - trioderob 09:47:13 11/13/21 (0)
  I guess that's why most cone speakers sound mussy to me - in the bass
  
  I did hear a field coil speaker at T.H.E. IN los angeles that blew my mind tho
A 42 Hz bass note - M3 lover 09:18:52 11/12/21 (2)
If that is "fast", does it mean it is reproduced as 45 Hz or 50 hz?

I agree. While fast is a term frequently associated with bass reproduction, isn't really rise time what is critical for accurate reproduction? That is, no or minimal overhang. Which Maggies and some electrostatics can do.

"The only cats worth anything are the cats who take chances. Sometimes I play things I never heard myself." Thelonious Monk
- RE: "isn't it really rise time which is critical for accurate bass reproduction?" ... - andyr 14:23:49 11/12/21 (0)
  My thoughts exactly! :-))
  
  But also "fall time", as DrC posted. IE. the driver can stop quickly ... with no overhang.
  
  For these, you need drivers with little inertia.
  
  Andy
- probably not rise time, but fall time - DrChaos 13:35:31 11/12/21 (0)
  I take 'fast bass' as one which stops quickly when it is supposed to.
  
  Good 'rise time' means a good midrange & tweeter integration with the woofer.
RE: Is fast bass...... overly "tight" and "dry" bass? - trioderob 17:40:40 11/11/21 (1)
well it sure aint " loose and flubby "
- RE: Is fast bass...... overly "tight" and "dry" bass? - Sondek 07:34:09 11/12/21 (0)
  and much less likely to be out of phase

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