Fostex TM2: Bluetooth (report for a pro)

About this report

This is a headphone report for professionals.
You can see a simple report for "dummies" with explanations of the main characteristics for Fostex TM2 Bluetooth

One device can have multiple reports in different modes and with different a suite of tests.

Test report - general data of Fostex TM2 Bluetooth headphone

Frequency response

Graphics setting view

Range, dB:

90 50 24

Perception of headphone frequency response curves of equal loudness ISO 226-2009

General results

General results Fostex TM2 Bluetooth

Channel

Center/Summary

Variation in frequency response in band from 100 Hz to 0,01 kHz, dB

-5,58, 7,25

The table shows a most important technical characteristics of Fostex TM2 Bluetooth

*Center channel headphone is received by averaging between left and right channels

*impedance value in the table for channel

Test conditions

Type of headphones: In-Ear or Tablet
Measurements were performed on the stand:

Solid simulator-bushing SIEC (emulation of auditory channel)

Headphone's impedance has not been tested

The model use internal headphone amplifier
Can be used only with special AMP
By other reason

The tags (specifications) for this report are:

Type of device : Headphones Wireless headphones Internal sound cards USB-DAC DACs Combines with USB Smartphones Players Headphones with active amplification External sound cards Headphone Amplifiers with Line In Laptops & Tablets Combines with SPDIF Motherboards Displays Bluetooth-in
Headphones tested in : normal frequency range wide frequency range (HD)
Headphones tested on : stands of the old generation modern stands
Type of headphones : In-Ear or Tablet On-ear Over-ear
The type of acoustic design : Closed Open Semi-open

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Detailed measurements report of technical characteristics

Report content

Frequency response

Perception of headphone frequency response curves of equal loudness ISO 226-2009
Impulse response
Step response
Impulse Response Envelope (ETC - Energy Time Curve)
QSD / Watterfall
Delta QSD / Delta Watterfall

Frequency response of Fostex TM2 Bluetooth headphone

Graphics setting view

Range, dB:

90 50 24

Channel:

Center Left Right Left Right

Brief information

Graph of frequency response ^F.A.Q. the shows the balance of the frequency of the headphones (reproduced frequency spectrum) in dB. 0 dB is the average of the amplitude.

The frequency response of the headphones can be represented as the selected equalizer setting in the player, applicable to headphones with a flat sound. Subjective "flatness" is perceived differently from external conditions: the volume level ^F.A.Q. of the external noise and noise isolation headphones. When connected to an amplifier, the frequency response can change ^F.A.Q..

The frequency response in RAA is obtained through the reproduction and analysis of a special noise signal with the subsequent generation of an impulse response. The frequency response plot is constructed from the spectrum of the impulse response.

According to the frequency response curve, it is possible to calculate the width of the frequency range ^F.A.Q..

The difference in amplitudes of 6 dB is equivalent to a twofold ratio of signal levels.

Original text in Russian report. You can help with translation via the forum or feedback.

Table of measured characteristics

Frequency response Fostex TM2 Bluetooth

Channel

Left

Right

Variation in frequency response in band from 100 Hz to 10 kHz, dB

-5,49, 7,65

-5,67, 6,83

The RMS variation between the right and left channels
Fostex TM2 Bluetooth from stand SIEC

Deviation between channels in band 40 Hz to 15 kHz, dB

0,4

Deviation between channels in low-frequency range 40 Hz to 200Гц, дБ

0,5

Deviation between channels in mid-frequency range 200 Hz to 2 kHz, dB

0,2

Deviation between channels in hi-frequency range 2 kHz 15 kHz, dB

0,4

Comparison of the parameters by on-line services

Comparison the frequency response of
How much frequency response of the Fostex TM2 Bluetooth different from other models?

Device Group Comparison HP Portative (Default): Ambient Acoustics MAD4 Universal, Apple EarPods, Creative In-Ear 3, Kennerton Laguz, Sennheiser CX 5.00.
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Perception of headphone frequency response curves of equal loudness ISO 226-2009 of Fostex TM2 Bluetooth headphone

Graphics setting view

Channel:

Center Left Right Left Right

Brief information

The graph shows the change in the perception of the frequency response^F.A.Q. of the headphones when listening to music with a different loudness relative to the natural level. When listening to headphones at a low volume, the perception of recoil in the low frequency range decreases, and when you listen to it at a high volume, it increases.

According to this graph, you can estimate at what volume the headphones will be perceived more flat.

The perception of the number of low frequencies depends on the volume according to the curves of equal loudness. (ISO 226-2009 Acoustics. Normal equal-loudness-level contours). For the base level, 72 dB SPL (live performance of several instruments with vocals without amplifiers with acoustics) is selected.When you select another base level, the dependence varies slightly and is suitable for almost all levels.

Examples of graphics application in practice ^F.A.Q..

Original text in Russian report. You can help with translation via the forum or feedback.

Table of measured characteristics

Perception of headphone frequency response curves of equal loudness ISO 226-2009 from Fostex TM2 Bluetooth

Channel

Center/Summary

From level 48 dB at 72 dB SPL in band 100 Hz to 10 kHz, dB

-9,8, +15,6

From level 36 dB at 72 dB SPL in band 100 Hz to 10 kHz, dB

-8,7, +12,6

From level 24 dB at 72 dB SPL in band 100 Hz to 10 kHz, dB

-7,7, +9,5

From level 12 dB at 72 dB SPL in band 100 Hz to 10 kHz, dB

-6,6, +6,5

From level 0 dB at 72 dB SPL in band 100 Hz to 10 kHz, dB

-5,6, +7,2

From level -12 dB at 72 dB SPL in band 100 Hz to 10 kHz, dB

-4,6, +8,3

From level -24 dB at 72 dB SPL in band 100 Hz to 10 kHz, dB

-3,6, +9,3

From level -36 dB at 72 dB SPL in band 100 Hz to 10 kHz, dB

-5,2, +10,3

*Center channel is received by data averaging between the left and right channels

Impulse response of Fostex TM2 Bluetooth headphone

Graphics setting view

Time, ms:

2ms 5ms 10ms

Channel:

Left Right Left Right

Brief information

Impulse response is a reaction to the pulse of the minimum possible duration. From the impulse response, most of the parameters under study are calculated: frequency response ^F.A.Q., phase-frequency response, group delay, waterfall, step response and square wave. The impulse response is visually not informative and for obtaining the majority of characteristics a fast Fourier transform and other mathematical algorithms with the analysis of the total pulse length are used. The total pulse length is about 5 seconds, while only the beginning of a pulse of 2-4 milliseconds is visually visible. Vertically, the visual detail does not exceed 40-45 dB.

The impulse response is able to show visually only the same or different polarity of the drivers and possible high-frequency resonance.

The waveform of the impulse response of the Fostex TM2 depends on the Fostex TM2 frequency response and the damped resonances and reverberations of the Astrotec AX-60 and the reverberation in the stand chamber. The visual clarity of the parameters on the impulse response is very low. Visual determination of quality by impulse response was actual in "pre-computer" years.

The frequency response in RAA is obtained through the reproduction and analysis of a special noise signal with the subsequent generation of an impulse response. The impulse response is displayed as is, without compensation of the frequency response for the microphone or smoothing. It is RAW data. The reduction in the frequency response of the microphone starts at 20 kHz^F.A.Q.. When reproducing the test signal via the E-MU 1616m , the original impulse response does not contain any pre-ringing ^F.A.Q.. Translation of the description is not yet ready

Original text in Russian report. You can help with translation via the forum or feedback.

Comparison of the parameters by on-line services

Impulse response

Device Group Comparison IMP HP Portative (Default): Ambient Acoustics MAD24 Universal, Creative Aurvana Trio, Tin HiFi P1 Vent Sealed.
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Impulse Response Envelope (ETC - Energy Time Curve) of Fostex TM2 Bluetooth headphone

Graphics setting view

Time, ms:

2ms 5ms 10ms

Range, dB:

120 90

Channel:

Left Right Left Right

Brief information

The envelope of the impulse response is the sum of the half-wave moduli of the impulse response, constructed on a logarithmic scale.

In speaker tests, the envelope of the impulse response tracks the reverberation of the room. For headphones that operate on a small volume, this feature does not carry any useful information. The envelope of the impulse response is given for general educational purposes - to show that the impulse response is not a short burst of 2-4 ms, but a long-term attenuation within a few seconds. The widespread opinion "on the impulse characteristic all at once it is visible" incorrectly.

Original text in Russian report. You can help with translation via the forum or feedback.

Comparison of the parameters by on-line services

Impulse Response Envelope (ETC - Energy Time Curve)

Device Group Comparison IMP HP Portative (Default): Ambient Acoustics MAD24 Universal, Creative Aurvana Trio, Tin HiFi P1 Vent Sealed.
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Step response of Fostex TM2 Bluetooth headphone

Graphics setting view

Time, ms:

2ms 5ms 10ms

Channel:

Left Right Left Right

Brief information

The step response is a playback on a step (front square) signal. It is built on the derivative impulse response .The response to the step represents the beginning of the meander front with zero frequency.

In the audiophile community on the square wave it is customary to determine the "speed" of the headphones, however this characteristic is applicable only to amplifiers having a flat frequency response with no reverberation and completely not applicable to headphones.

The waveform of the response to the step depends on the frequency response and the resonances of the headphones. In ancient times, before the wide spread of digital technologies, in the form of a meander, a rough estimate was made on the frequency response ^F.A.Q. and F.A.Q.. Today, the analysis of acoustic parameters on the meander is hopelessly outdated and the graphs of the final frequency response and waferballs with resonances are looked at separately.

Original text in Russian report. You can help with translation via the forum or feedback.

Comparison of the parameters by on-line services

Step response

Device Group Comparison IMP HP Portative (Default): Ambient Acoustics MAD24 Universal, Creative Aurvana Trio, Tin HiFi P1 Vent Sealed.
Change to another device group >>

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Fostex TM2: Bluetooth (report for a pro)

Test report - general data of Fostex TM2 Bluetooth headphone

Frequency response

Perception of headphone frequency response curves of equal loudness ISO 226-2009

Detailed measurements report of technical characteristics

Report content

Frequency response of Fostex TM2 Bluetooth headphone

Perception of headphone frequency response curves of equal loudness ISO 226-2009 of Fostex TM2 Bluetooth headphone

Impulse response of Fostex TM2 Bluetooth headphone

Impulse Response Envelope (ETC - Energy Time Curve) of Fostex TM2 Bluetooth headphone

Step response of Fostex TM2 Bluetooth headphone

Square wave of Fostex TM2 Bluetooth headphone