The technical characteristics of the Dayton Audio AMT2-4 and the VCD-Type VCD-DT63 are analyzed based on their Impulse Response waveforms, shown in the upper plot (overall view up to 1.00 ms) and the lower plot (expanded view up to 200 µs).
In addition, the relationship between these characteristics and the resulting sound quality is discussed in conjunction with listening impressions. 

■ Main Peak (Impulse 1st Peak)
　(Energy Concentration and High-Frequency Extension )
The main peak is an important indicator of initial transient reproduction capability.
Although both drivers exhibit extremely fast initial responses, the AMT2-4 shows a lower main peak, with its energy distributed over a slightly wider time interval.
As shown in the expanded view (0–40 µs) in the lower plot, the VCD-DT63 forms a sharp peak at around 30 µs, whereas the AMT2-4 exhibits a broader peak width and a relatively lower degree of energy concentration.
This is thought to be due to the distribution of energy over time caused by multiple vibration modes and non-uniform in-plane velocity distribution associated with the pleated diaphragm structure unique to the AMT-Type.

[Impact on Listening Impressions]
Although both drivers exhibit excellent transient performance, the VCD-DT63 delivers a sharper attack, providing a clearer sense of speed and realism in the initial rise of the sound.
In contrast, the AMT2-4 presents a slightly smoother attack, resulting in a more gentle overall impression.

■1st Valley（First Negative Peak）
Both drivers reach approximately −100%, indicating excellent high-speed transient response performance. However, the AMT2-4 exhibits a larger reversal component afterward, indicating that the energy does not settle in a single event.
In contrast, the VCD-DT63 settles more rapidly after the reversal, with significantly less residual energy remaining.

[Impact on Listening Impressions]
With the VCD-DT63, sound image contours are clearly defined, and the sound remains well focused after the attack. In contrast, the AMT2-4 tends to produce slightly broader sound images and slightly softer sound contours. 

■ Second Peak (Approximately 70–120 µs) (Most Important)  
The Second Peak is the region where the differences between the two drivers are most pronounced.
In the AMT2-4, a very large Second Peak appears at around 80 µs, indicating that energy not released during the Main Peak is emitted again with a time delay.
In AMT-Type drivers, the energy in this region tends to increase due to multiple vibration modes associated with the pleated diaphragm structure and non-uniform in-plane velocity distribution.
In contrast, the Second Peak is significantly suppressed in the VCD-DT63, indicating that the energy is more highly concentrated in the Main Peak.

[Impact on Listening Impressions]
The VCD-DT63 provides clear image localization, excellent separation between individual sounds, and a well-defined core to each sound.
In contrast, the AMT2-4 delivers a slightly wider soundstage and richer resonance, but the sound images also tend to become slightly broader. 

■ 100–300 µs Region (Initial Residual Vibration)  
This is the time interval that has the strongest correlation with perceived sound quality.
In the VCD-DT63, the amplitudes in this region are small and decay rapidly, allowing the response to settle quickly. In contrast, the AMT2-4 continues to exhibit relatively large vibration components beyond 100 µs, and multiple peaks and valleys can still be observed around 150–250 µs.
This indicates that the energy is being distributed and released as multiple time-domain components.

[Impact on Listening Impressions]
With the AMT2-4, rich resonance and a spacious sense of air can be perceived. However, the sound images tend to become slightly broader, and fine details may overlap, giving a slightly blurred impression.
In contrast, the VCD-DT63 delivers clearly defined sound image contours, excellent separation between individual sounds, and a clearer sense of spatial transparency.

■ Settling Process (300–800 µs)  
In the AMT2-4, periodic vibration components continue to be observed even around 400–700 µs. Looking at the overall Impulse Response, intermittent energy components remain up to approximately 800–900 µs.
This may be attributed to factors commonly observed in AMT-Type drivers, such as multiple vibration modes, in-plane vibrations, and reflections within the back chamber.
In contrast, the VCD-DT63 has almost completely settled by around 400–500 µs, confirming that delayed components are extremely well suppressed.

[Impact on Listening Impressions]
The AMT2-4 delivers rich resonance and a strong sense of air, giving the impression of a slightly wider soundstage.
In contrast, the VCD-DT63 offers a quieter background, along with a clearer view into the soundstage and more precise image localization. 

■ Overall Evaluation (Impulse Response)
The Dayton Audio AMT2-4 exhibits excellent initial response performance characteristic of AMT-Type drivers. However, its very large Second Peak and relatively large residual components in the 100–300 µs region indicate that energy is distributed and released as multiple time-domain components.
In addition, intermittent vibration components continue beyond 400 µs, confirming the presence of relatively large re-radiated energy following the main response.
In contrast, the VCD-DT63 exhibits a high degree of energy concentration in the Main Peak, a small Second Peak, rapid decay in the 100–300 µs region, and extremely low residual components beyond 400 µs.
This difference is thought to result from the VCD-Type design philosophy, which does not forcibly suppress vibrations through high rigidity, but instead suppresses the propagation of unwanted vibrations themselves.

[Impact on Listening Impressions]
With the AMT2-4, a rich sense of air, smoothness, and a spacious soundstage can be perceived.
In contrast, the VCD-DT63 delivers high transparency, precise image localization, excellent separation between individual sounds, and superior reproduction of fine transients. In particular, because it leaves very little residual resonance when a sound should stop, the quietness of the background and the clarity of the soundstage become more apparent, allowing the information contained in the original source to be reproduced more faithfully.

The technical characteristics of the Dayton Audio AMT2-4 and the VCD-Type VCD-DT63 are analyzed based on their ETC (Energy Time Curve) plots, shown in the upper plot (overall view up to 2.0 ms) and the lower plot (expanded view up to 250 µs, ETC smoothing: 0 ms).

In addition, listening impressions are used to examine how these characteristics are reflected in actual sound quality.

In this ETC analysis, the differences observed in the Impulse Response become even more apparent as differences in time-domain energy behavior.

■ Initial Decay (0–150 µs)
This is an important time interval that represents the energy settling characteristics immediately after the direct sound.
Although both drivers exhibit nearly identical direct sound peaks (0 dB), the VCD-DT63 (red) maintains lower overall energy levels in the 70–150 µs range.
In contrast, the AMT2-4 (blue) retains relatively large energy components around −15 to −20 dB, indicating that a portion of the main energy is distributed and released over time.

[Impact on Listening Impressions]
The VCD-DT63 provides a more clearly defined onset of sounds and a stronger sense of coherence after the attack. In contrast, the AMT2-4 presents a slightly smoother attack, along with a moderate sense of body and airiness.  

■ 100–400 µs Region (Most Important)
This is the region where the differences between the two drivers are most clearly observed and where the correlation with perceived sound quality is the strongest.
In the VCD-DT63, the energy decays rapidly to around −45 dB, and energy re-concentration is significantly suppressed. In contrast, the AMT2-4 exhibits a relatively large re-emergent energy component of approximately −15 dB around 100 µs, followed by multiple peaks and valleys that continue thereafter.
This indicates that the VCD-DT63 maintains a high degree of energy concentration along the time axis, whereas in the AMT2-4, energy is distributed and released as multiple time-domain components.

[Impact on Listening Impressions]
With the VCD-DT63, clearly defined sound image contours, excellent separation between individual sounds, and a clear sense of spatial transparency can be perceived.
In contrast, the AMT2-4 delivers rich resonance and a spacious soundstage, but the sound images tend to become slightly broader, and fine details may overlap, resulting in a slightly less focused presentation. 

■ Intermittent Energy Components (Approximately 300–800 µs)
In the VCD-DT63, the energy has already decayed to around −60 dB by approximately 700 µs, indicating that unwanted delayed components are significantly suppressed. In contrast, the AMT2-4 continues to exhibit relatively large energy components beyond 300 µs, with periodic peaks and valleys remaining visible.
In particular, relatively large re-emergent energy components of around −30 dB can still be observed in the 300–600 µs range. This may be attributed to a combination of factors commonly observed in AMT-Type drivers, such as multiple vibration modes, non-uniform in-plane velocity distribution, and reflections within the back chamber.

[Impact on Listening Impressions]
The VCD-DT63 stands out for its quiet background, providing a clearer sense of spatial transparency and more precise image localization. In contrast, the AMT2-4 delivers a rich sense of air and greater resonance, giving the impression of a slightly wider soundstage. 

■ Late Residual Energy (After 800 µs)  
This region does not represent the direct sound, but rather late residual energy components that appear with a time delay after the main response.
In the VCD-DT63, the response reaches almost the noise floor at around 700 µs, indicating that late residual components are extremely well suppressed. In contrast, the AMT2-4 continues to exhibit periodic peaks and valleys up to approximately 1.5–2.0 ms, indicating that energy is distributed and released over an extended period along the time axis.

[Impact on Listening Impressions]
The VCD-DT63 provides an exceptionally quiet background, allowing even subtle reverberation and spatial information to be reproduced clearly. In contrast, the AMT2-4 delivers rich reverberation and smoothness, although very low-level sounds tend to be slightly masked.  
■ Overall Evaluation (ETC)
The Dayton Audio AMT2-4 exhibits excellent initial response performance characteristic of AMT-Type drivers. However, relatively large re-emergent energy components are present in the 100–400 µs region, followed by intermittent energy components that continue throughout the 400–700 µs range. In addition, late residual energy can be observed up to approximately 2.0 ms, indicating that energy is distributed and released as multiple time-domain components.
In contrast, the VCD-DT63 exhibits extremely fast initial decay, small re-emergent energy components in the 100–400 µs region, and extremely low residual energy beyond 400 µs. This difference is thought to stem from the VCD-Type design philosophy, which does not forcibly damp vibrations through high rigidity, but instead suppresses the propagation of unwanted vibrations themselves.

[Impact on Listening Impressions]
With the VCD-DT63, high transparency, precise image localization, clearly defined sound images, and excellent reproduction of low-level signals can be perceived. In particular, because the background remains exceptionally quiet after a sound has faded away, hall reverberation, spatial depth, and even subtle nuances can be reproduced without being masked, resulting in a soundstage with greater resolution and transparency.
In contrast, the AMT2-4 delivers a rich sense of air, smoothness, and a spacious soundstage.

The technical characteristics of the STEP Responses of the Dayton Audio AMT2-4 and the VCD-type VCD-DT63 are analyzed based on both the upper graph (overall response up to 2.0 ms) and the lower graph (an enlarged view of the initial rise up to 220 µs). Their implications for actual sound quality are then discussed in conjunction with the listening test results.
The STEP Responses reveal clear differences in the energy convergence process. The VCD-DT63 (red) releases its energy in a highly concentrated manner within a very short period and converges rapidly, whereas the AMT2-4 (blue) tends to distribute its energy over multiple temporal components, resulting in a more time-dispersed response.

■ Initial Rise (0–50 µs)
Both drivers exhibit an extremely steep initial rise, indicating excellent transient response performance.

However, while the main peak of the VCD-DT63 reaches approximately 100%, that of the AMT2-4 reaches only about 75%, revealing a difference in the degree of energy concentration at the main peak.

In addition, the VCD-DT63 exhibits a slightly sharper rise, indicating that its energy is released in a more concentrated manner over a shorter period of time.

[Impact on Listening Impressions]
Both drivers exhibit excellent high-frequency attack and transient reproduction.

However, the VCD-DT63 conveys a greater sense of speed and realism in the onset of sound, whereas the AMT2-4 produces a slightly softer attack, resulting in a smoother overall impression. 

■1st Valley (First Negative Peak) (50–100 µs)

In the VCD-DT63, the first negative peak is limited to approximately −50%, whereas the AMT2-4 drops to nearly −100%, forming a much deeper valley.

This indicates that the VCD-DT63 experiences significantly less energy cancellation and therefore exhibits more stable convergence behavior.

[Impact on Listening Impressions]
With the VCD-DT63, the sound image is reproduced with well-defined contours, and the sound remains well controlled after the initial attack, resulting in a tight and focused presentation.
In contrast, the AMT2-4 tends to produce a slightly broader sound image, with somewhat softer image contours. 

■Initial Residual Vibration (100–300 µs) (Most Important)
This is the region where the difference between the two drivers is most pronounced and where the strongest correlation with perceived sound quality is observed.
In the AMT2-4, a relatively large secondary rise of approximately 20–25% is observed around 150–180 µs. In addition, multiple peaks and valleys continue throughout the 100–300 µs interval, indicating repeated reconcentration of energy.
In contrast, the VCD-DT63 exhibits significantly lower amplitude beyond 100 µs, with much less residual vibration and energy reconcentration, allowing the response to converge rapidly.
This behavior is in excellent agreement with the tendencies observed in both the Impulse Response and the ETC.

[Impact on Listening Impressions]
With the VCD-DT63, sound images are precisely localized, individual sounds are well separated, and each sound is reproduced with a clearly defined core.
In contrast, the AMT2-4 conveys a rich sense of resonance and spaciousness; however, the sound image tends to become slightly broader, and fine details are more likely to overlap. 

■Settling Process (300～800µs)
The VCD-DT63 has almost completely converged by approximately 400 µs, indicating that delayed components are extremely small. In contrast, the AMT2-4 continues to exhibit relatively large vibration components beyond 300 µs, with additional secondary rises observed around 500–600 µs.
This indicates that, in the AMT2-4, energy is re-radiated intermittently and distributed over multiple temporal components. This behavior is consistent with the presence of multiple vibration modes characteristic of the AMT structure, non-uniform in-plane velocity distribution, and reflections within the back chamber.

[Impact on Listening Impressions]
With the VCD-DT63, the soundstage is presented with excellent clarity, a remarkably quiet background, and precise localization of sound sources.
In contrast, the AMT2-4 conveys a rich sense of resonance and lingering decay, giving the impression of a slightly more expansive soundstage.  

■Late Residual Energy (After 800 µs)
This region represents the late residual energy that appears after the main response with a temporal delay, rather than the direct sound itself.
The VCD-DT63 has almost completely converged by this stage, leaving very little late residual energy. In contrast, the AMT2-4 continues to exhibit periodic vibration components up to approximately 1.5–2.0 ms, indicating that energy is released over an extended period and distributed along the time axis.

[Impact on Listening Impressions]
With the VCD-DT63, a high level of background silence is achieved, allowing even subtle reverberation and spatial information to be reproduced with remarkable clarity.
In contrast, the AMT2-4 provides a rich sense of lingering decay and smoothness; however, very low-level details tend to be slightly masked. 

■ Overall Evaluation (STEP Response)
The VCD-type VCD-DT63 is characterized by a high degree of energy concentration at the main peak, a shallow 1st Valley, small secondary rise components, rapid response convergence, and extremely low levels of late residual energy.
In contrast, the Dayton Audio AMT2-4 exhibits the excellent initial transient performance characteristic of AMT-type drivers; however, it also shows a deep 1st Valley, large secondary rise components, long-lasting residual vibration, and energy distributed over multiple oscillation cycles.