Is There a Measurement for “Dynamics”

[morricab]

For loudspeakers, the perception of dynamics has a lot to do with impulse response (time coherence) but also thermal compression. The later one is main reason I think high sensitivity speakers generally sound more dynamic and alive than lower sensitivity speakers. The onset of thermal compression starts as soon as you apply current to a voice coil. The lower the sensitivity, the lower the volume of onset. Also, a lower sensitivity driver will be more resistant to motion in the first place, retarding micro dynamics.
Keep in mind also that SPL is a function of driver membrane acceleration and not excursion. A light cone or dome with a very powerful magnet can have a high SPL and you never see the driver move. Bass must move more for the frequency but long excursions are not seen on Classic high sensitivity drivers like ALTECs or JBLs…or if horn loaded excursion are further reduced and SPL boosted with virtually zero excursion.
That said, some horns don’t sound terribly dynamic and this might have to do with the relatively large timing delays between sounds of individual drivers reaching the listeners ears.
My experience with electronics is generally, amps that are very complex and/or have a lot of negative feedback tend to sound lacking in dynamics. Not sure the mechanism for this but it is something I consistently hear. They tend to sound more compressed, over damped or, for lack of a better term, constipated. Low/zero feedback amps breath more freely and sound more dynamic, IME.

 

[hopkins]

.
My experience with electronics is generally, amps that are very complex and/or have a lot of negative feedback tend to sound lacking in dynamics. Not sure the mechanism for this but it is something I consistently hear. They tend to sound more compressed, over damped or, for lack of a better term, constipated. Low/zero feedback amps breath more freely and sound more dynamic, IME.

Agreed with all your explanations. I suspect that crossover complexity (and parts quality) may also have detrimental effects.

The sense of dynamics has very little to do with the dynamic range of the recording, and the ability to play loud.

 

[DasguteOhr]

Does power really equate to dynamics?

Yes, actually. The dynamic depends heavily on how quickly an amplifier can process an impulse in the music. The size of the impulse (dynamic e.g. 20db means providing 100 times the power in the short term) is not a problem at low listening volumes, but becomes difficult at high volumes. Then the efficiency of the loudspeaker comes into play. The more efficient the speaker, the less power is required to achieve 20dB of dynamics. although 20db is almost the limit.

I thought power was a reaction to low efficiency speakers. If one were to place mids and highs on one amp and integrate bass on another, you could conceivably have excellent dynamics with 1 to 3 watts. Isn't it the bass that eats up the power. Then the ugly crossover sucking up power itself from the single amp trying to drive too much. Yes, the bass end may enjoy 1 3kw . But the mid and high don't.

You are probably familiar with pink noise, which you can use to measure frequency response. The amplitude decreases the higher the frequency, according to the hearing curve of the ear, from -3 dB/octave. That corresponds pretty much to music. For example, the bass driver needs 10 watts at 100 Hz. How much power does the tweeter get at 3 kHz? For every octave minus -3 dB (halving the power, so -15 dB at 3 kHz, that's a tenth of the power, 1 watt). There are other factors too: when does the tweeter have to transmit? Which filter is used? If the tweeter is louder than the bass driver (sensitivity), energy has to be destroyed in the voltage divider(l-pad). As you can see, it gets more complex.

 

[morricab]

Yes, actually. The dynamic depends heavily on how quickly an amplifier can process an impulse in the music. The size of the impulse (dynamic e.g. 20db means providing 100 times the power in the short term) is not a problem at low listening volumes, but becomes difficult at high volumes. Then the efficiency of the loudspeaker comes into play. The more efficient the speaker, the less power is required to achieve 20dB of dynamics. although 20db is almost the limit.

You are probably familiar with pink noise, which you can use to measure frequency response. The amplitude decreases the higher the frequency, according to the hearing curve of the ear, from -3 dB/octave. That corresponds pretty much to music. For example, the bass driver needs 10 watts at 100 Hz. How much power does the tweeter get at 3 kHz? For every octave minus -3 dB (halving the power, so -15 dB at 3 kHz, that's a tenth of the power, 1 watt). There are other factors too: when does the tweeter have to transmit? Which filter is used? If the tweeter is louder than the bass driver (sensitivity), energy has to be destroyed in the voltage divider(l-pad). As you can see, it gets more complex.

The problem with your explanation about power is that a sense of dynamics is not only evident at high SPL, where power draw is high. It is also evident low and normal SPL, where nearly all amps should be operating well within their limits.

 

[DasguteOhr]

The problem with your explanation about power is that a sense of dynamics is not only evident at high SPL, where power draw is high. It is also evident low and normal SPL, where nearly all amps should be operating well within their limits.

Then there is the question of how much membrane mass do I need to move and how strong is the drive of the driver (magnet). Example: for openbaffle you need a weak drive (magnet high qts 0.8-1.0) to reproduce low tones. A weak drive ensures that the sound pressure is the same up to the fs (cut-off frequency), not -6db like with qts 0.5. That's why strong drives are completely unsuitable for openbaffle unless you use DSP to increase the volume in the lower range close to fs.You need a lot of power for open baffle in the bass. A lot of energy is wasted through dipole cancellation (180 degree phase at the back).

P.s
but it sounds really good if you do it right

 

[Al M.]

The sense of dynamics has very little to do with the dynamic range of the recording, and the ability to play loud.

Not quite. I know what you mean, but

a) If the dynamic range of the recording is excessively compressed, there is no breathing room for proper dynamics.

b) If the system can't play reasonably loud, it can't reproduce natural dynamics. Real music can be loud, including unamplified music.

I do agree, however, that a sense of dynamics needs to be present even at background or late night listening levels. There should not be a threshold below which the system doesn't "wake up".

 

[exupgh12]

When the word “dynamic” is used by audiophiles I assume this is shorthand for “dynamic range”, which to me is the difference (in decibels) between the quietest and loudest music passages. Like many of you I prize dynamics in an audio system, so much so that without “good dynamics” it’s difficult for me to emotionally connect with music.

Dynamics were in mind then when I was researching my next pair of speakers. But there is no “dynamics” measurement I could point to which would help me find a more dynamic speaker than what I already had. Sure, I looked at sensitivity and impedance curves, made sure my amp was a good match and so on. I ended up purchasing a similar style of speakers which were 8 ohm, 94 db sensitivity, to replace my 4 ohm, 91 db sensitivity speakers (both are open baffle). Long story short - the old speakers are more “dynamic” than the new ones. They’re still good, but instead of a step forward, they’re a step back.

To keep this conversation on track please, horn lovers, don’t just say “buy horns”. And this isn’t a thread about amp/speaker synergy, or which tube is the “most dynamic”.

Question: Is there a way to measure, using industry standards, the “dynamics” of a speaker, that could be published alongside standard speaker specifications?

I asked Claude AI, and this is what it came with.

Speaker dynamics can be measured through several methods:

1. Maximum SPL (Sound Pressure Level) Testing
- Measuring the maximum clean output before compression or distortion
- Using burst signals at different frequencies
- This shows how well the speaker handles sudden peaks

2. Dynamic Compression Testing
- Using tone bursts of varying amplitudes
- Measuring how the speaker maintains linearity as power increases
- Looking for signs of compression or power compression

3. Power Testing
- Short-term and long-term power handling measurements
- Testing with dynamic music signals (not just continuous tones)
- Measuring thermal and mechanical limits

4. Impedance Testing Under Dynamic Conditions
- Measuring how impedance changes under different power levels
- This can reveal mechanical limiting and voice coil behavior

Professional measurement tools used include:
- Audio Precision analyzers
- MLSSA (Maximum Length Sequence System Analyzer)
- High-quality measurement microphones
- Real-time analyzers with burst testing capabilities

 

[Tangram]

I asked Claude AI, and this is what it came with.

Speaker dynamics can be measured through several methods:

1. Maximum SPL (Sound Pressure Level) Testing
- Measuring the maximum clean output before compression or distortion
- Using burst signals at different frequencies
- This shows how well the speaker handles sudden peaks

2. Dynamic Compression Testing
- Using tone bursts of varying amplitudes
- Measuring how the speaker maintains linearity as power increases
- Looking for signs of compression or power compression

3. Power Testing
- Short-term and long-term power handling measurements
- Testing with dynamic music signals (not just continuous tones)
- Measuring thermal and mechanical limits

4. Impedance Testing Under Dynamic Conditions
- Measuring how impedance changes under different power levels
- This can reveal mechanical limiting and voice coil behavior

Professional measurement tools used include:
- Audio Precision analyzers
- MLSSA (Maximum Length Sequence System Analyzer)
- High-quality measurement microphones
- Real-time analyzers with burst testing capabilities

Gulp.

That’s awesome and scary at the same time.

 

[exupgh12]

Gulp.

That’s awesome and scary at the same time.

Exactly my thought when I saw the answer it came with.

 

[Tangram]

Then there is the question of how much membrane mass do I need to move and how strong is the drive of the driver (magnet). Example: for openbaffle you need a weak drive (magnet high qts 0.8-1.0) to reproduce low tones. A weak drive ensures that the sound pressure is the same up to the fs (cut-off frequency), not -6db like with qts 0.5. That's why strong drives are completely unsuitable for openbaffle unless you use DSP to increase the volume in the lower range close to fs.You need a lot of power for open baffle in the bass. A lot of energy is wasted through dipole cancellation (180 degree phase at the back).

P.s
but it sounds really good if you do it right

Thanks for specifically addressing open baffles! The designer who made my OB speakers caters to SET lovers but I’m using a 25W Class A SS amp with a high damping factor (subject of another thread) that is producing really satisfying bass. That said, I just hooked up my subs (but still running the OBs full range) to see which I enjoy more.

 

[Tangram]

To those who’ve contributed to this thread thus far I want to say THANK YOU because I am learning a lot on this topic. The quality of information imparted is top notch, including Claude’s .

 

[DasguteOhr]

Thanks for specifically addressing open baffles! The designer who made my OB speakers caters to SET lovers but I’m using a 25W Class A SS amp with a high damping factor (subject of another thread) that is producing really satisfying bass. That said, I just hooked up my subs (but still running the OBs full range) to see which I enjoy more.

open baffle friends must hold together.
Here is a graphic of the different qualities of bass drivers and what happens to the sound level at the cut-off frequency fs. If the quality is less than 0.8, it gives a noticeable lost in level. My coax driver has a qtc of 0.92. My active bass has a qtc of 1.2. In my experience with various amps, the damping factor should be in the range of 150 - 300. This gives the bass a richer tone and liveliness, but still enough control.

 

[morricab]

I asked Claude AI, and this is what it came with.

Speaker dynamics can be measured through several methods:

1. Maximum SPL (Sound Pressure Level) Testing
- Measuring the maximum clean output before compression or distortion
- Using burst signals at different frequencies
- This shows how well the speaker handles sudden peaks

2. Dynamic Compression Testing
- Using tone bursts of varying amplitudes
- Measuring how the speaker maintains linearity as power increases
- Looking for signs of compression or power compression

3. Power Testing
- Short-term and long-term power handling measurements
- Testing with dynamic music signals (not just continuous tones)
- Measuring thermal and mechanical limits

4. Impedance Testing Under Dynamic Conditions
- Measuring how impedance changes under different power levels
- This can reveal mechanical limiting and voice coil behavior

Professional measurement tools used include:
- Audio Precision analyzers
- MLSSA (Maximum Length Sequence System Analyzer)
- High-quality measurement microphones
- Real-time analyzers with burst testing capabilities

Part of the story but not all of it. The effects of thermal compression on micro dynamics is probably not easilY measured and most would say insignificant…and yet, dynamics differences can still be easily heard at levels well below what most would consider relevant. The heating of a voice coil is nearly instantaneous and the cooling off quite slow by comparison. Looking at average temp far from where the actual heating takes place (as most papers on the subject) won’t tell you much about very short term effects that subtle dynamic shifts rely upon to sound realistic.
This is also only the speaker part of the puzzle.

 

[exupgh12]

Part of the story but not all of it. The effects of thermal compression on micro dynamics is probably not easilY measured and most would say insignificant…and yet, dynamics differences can still be easily heard at levels well below what most would consider relevant. The heating of a voice coil is nearly instantaneous and the cooling off quite slow by comparison. Looking at average temp far from where the actual heating takes place (as most papers on the subject) won’t tell you much about very short term effects that subtle dynamic shifts rely upon to sound realistic.
This is also only the speaker part of the puzzle.

Thanks for filling on this more knowledge.

 

[microstrip]

Part of the story but not all of it. The effects of thermal compression on micro dynamics is probably not easilY measured and most would say insignificant…

No, they can be easily measured if they exist. A childish affair to someone used to differential instrumentation.

and yet, dynamics differences can still be easily heard at levels well below what most would consider relevant.

Surely. Can you put numbers is your sentence?

The heating of a voice coil is nearly instantaneous and the cooling off quite slow by comparison. Looking at average temp far from where the actual heating takes place (as most papers on the subject) won’t tell you much about very short term effects that subtle dynamic shifts rely upon to sound realistic.

Yes, resistance is a function of the instantaneous temperature. All else is verbiage.

This is also only the speaker part of the puzzle.

Ok. Are you addressing the thermal compression in the crossover components? It can happen in cheap or poorly designed crossovers.

Thermal compression can be a real problem. But I never found data proving its existence at typical audiophile levels in decent speakers, just suppositions. But I am always eager to learn.

 

[mtemur]

IMHO, there is no single test method or technique to determine a speaker’s dynamic capability. However, a few key factors play a major role in dynamics:

- Speed of drivers is crucial. They should be capable of reaching high SPLs very quickly and stopping just as fast. This is extremely difficult to achieve, but the key is using lightweight, robust, and fast drivers -preferably modern ones. Impulse response measurements may be helpful in assessing this characteristic.

- Very low distortion drivers are also necessary. Among all audio components, speakers typically exhibit the highest distortion. To prevent distortion from clouding very quiet passages, it must be kept to a minimum. Otherwise, lowering the volume results in a loss of dynamism.

- High sensitivity and high SPL capability are essential for dynamics. High-sensitivity speakers require less power at normal listening levels, allowing a large power reserve for loud passages. More importantly, a speaker’s maximum SPL determines how loud it can play without compression or distortion.

All of these qualities are necessary for a truly dynamic speaker, and it should achieve them without causing listener fatigue.

 

[Robh3606]

Thermal compression can be a real problem. But I never found data proving its existence at typical audiophile levels in decent speakers, just suppositions. But I am always eager to learn.

To answer the OP's question you can measure for dynamic compression give these a look. They can do long term compression testing as well. So there is data that you can use to compare between loudspeakers if the manufacturer makes it available or they simply may not measure it.

Rob