How do I explain speed?

One term reviews talk about is how fast a headphone is. Is there an objective A/B test to hear the difference between a sound that is fast, vs that same sound being slow? Like when someone describes the bass being good because is fast, vs it being bad because it’s slow.

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I think impulse response should be an objective test for this metric.

The real question is, do reviewers even know what that is? I mean, I see reviewers talking about it, but from a subjective point of view.

As always, blame the game not player. :wink:

Cheers. :beers:

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Square waves?

Seriously I notice speed when percussive sounds like snare rims are struck or a string is plucked and it sounds real.

This presupposes that the listener knows what real sounds like by having heard an unamplified banjo in the same room (for example).

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This is something I have tried to explain for years. You run into this in loud speakers. I am a gigantic fan of vintage, by vintage I mean no newer than about 1972, British Wharfedale speakers. If you listen you can hear the difference between digital, and analog sound. The difference is the speed of the dynamics. An analog recording will almost always have, what I call a rounded sound. Digital sound is faster and tends to be edgy. The most obvious example is the difference between the sound of a tube amplifier and a solid state amp. This isn’t the whole story. There is the quality of the original recording. Compression crappola etc.

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I listen for two things:

  1. Bass texture: Slow headphone setups tend to combine rapidly changing low notes into rounded-off fuzzy blobs. It helps to listen to the same content back-to-back on different headphones. The faster ones can present 2 versus 1 note for the same passage. The slow ones can also lag behind the rest of the music (slightly delayed), as the driver can’t respond to changes quickly enough.

  2. Treble edginess: Headphones can be bright for many reasons, but fast setups tend to fracture transitions into discrete steps. No smooth flow. Don’t confuse speed with random noise and treble spray (i.e., artifacts from imprecise headphones or amps). Randomness comes across as general whining, hiss, or white noise rather than discrete steps and edginess. The Koss Porta Pro is prone to frequency-related whines rather than speed issues.

Fast isn’t always good. I hated the pairing of the Focal Clear with THX AAA 789 – both are quite fast and when added together they are faster than natural music. Plus, the 789 is excessively lean and highlights every edge.

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I always go back to Steroephiles long time descriptions;

fast Giving an impression of extremely rapid reaction time, which allows a reproducing system to “keep up with” the signal fed to it. (A “fast woofer” would seem to be an oxymoron, but this usage refers to a woofer tuning that does not boom, make the music sound “slow,” obscure musical phrasing, or lead to “one-note bass.”) Similar to “taut,” but referring to the entire audio-frequency range instead of just the bass.

speed The apparent rapidity with which a reproducing system responds to steep wavefronts and overall musical pace. See “fast,” “slow.”

slow Sound reproduction which gives the impression that the system is lagging behind the electrical signals being fed to it. See “fast,” “speed,” "tracking.

tracking The degree to which a component responds to the dictates of the audio signal, without lag or overshoot.

I got to the point I just listen to what I feel sounds good to my ears, based on the music playing.

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I always likened speed in the bass to decay.

When I first began measuring the in-room bass response of my living room, I used waterfall plots to find the problematic decay areas and subsequently treated the room to improve those areas. The bass “speed” vastly improved after doing so. With headphones, I just figured it had to do with the driver material, phase and step response. I don’t know if PEQ can necessarily change “speed,” but I’d be interested in learning more about the topic.

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Speed as mentioned by those above has to do with decay and the perception of a clean attack and decay.

One of the main factors for this happening is related to damping - a critically damped system will have a perceptual speed which is appropriate to the program material. Underdamped may sound faster but come at the expense of too much decay, blurring and homogenizing textures and smearing complex basslines, or result in other artifacts (Abberations in frequency response, boominess, or ability to handle dense dynamic material) while overdamping will tend to lead to a sense of things being ‘slow’ or having too short a decay time, which tends to also homogenize texture and dynamics by making everything sound dry.
Essentially you want high contrast but consistent tone between the transient event and the sustain, and underdamping will tend to let sustain be perceptually exaggerated, while overdamping will bring transients down - both decrease the contrast between transient and sustain, but with differing perceptual results.

In amplifiers feedback is directly related to damping factor, while in mechanical/acoustical alignments such as transducers in headphones or speakers, there is both electrical damping of the voice coil and also acoustical damping of the transducer and enclosure.

An easy way to hear this is to pay attention the tail ends of notes in classical or other acoustic music (bluegrass for example, or percussion-heavy jazz) as well as the transient attacks in percussive material. How basslines groove in funk or soul music can be an easy test of relative bass alignment ‘speed’ or decay. For the pro savvy, a simple reverb plugin and a copy of reaper is an easy way to begin identifying the sound of decay or ‘speed.’

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For those slightly confused by the varying terms, I do believe this is what Andrew is referring to when he uses the phrase “trailing ends of tones.”

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Perhaps also useful to understand the basic anatomy of a note played on an instrument.

The Envelope of a sound contains the attack, sustain, and decay of a sound. These correlate to what you might think of as the beginning middle and end of a individual note played on a trumpet (or any instrument, but for simplicity, let’s stick with a trumpet.)

Attack consist of the creation of the sound and includes changes occurring before the sound reaches a steady state. - think initial lip movement, breath or even the mechanical noise from a valve being depressed or released. In amateur players it is often not at the volume they want, as they have to overcome initial resistance and then modulate volume

Sustain refers to the steady state of a sound at its maximum intensity, - this part is where the trumpet player is still actively blowing to make a note.

And finally, decay is the rate at which it fades to silence. this would be resonance such as the ringing of the brass after the note is released, concert hall ambiance and reverb.

A poorly damped driver will struggle to return to “off” after a sound has gone through attack, sustain and delay. In fast music, you may get a lot of attacks, little sustain and a lot of overlapping decays from the released notes stacking up in the acoustic space. How well a driver deals with the end of each sound is pretty important.

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