Sendy Audio Audio Apollo (report for a pro)

After testing in the benchmark mode in the Reference Audio Analyzer software, the data is added to the online database of the RAA website.

You can view the test results on the comparison pages and summary reports for beginners and professionals. You can go to the desired report or comparison/selection service through the menu on this page. Additionally, you can go to the comparison pages from any graph in this report and add other tested products for direct comparison.

This is a summary report of headphones for professionals.

You can additionally look for Sendy Audio Audio Apollo

Sensitivity average in band from 100 Hz - 10 kHz	100.2	dB/V SPL
	82.6	dB/mW SPL
Impedance average in band from 40 Hz - 15 kHz	17.4	ohm
For 90 dB SPL, a voltage is required	-10.2	dBV
	0.309	V_RMS
Taking into account the peak factor of 9 dB for the music signal	-1.2	dBV
	0.870	V_RMS
Measurements were performed on the stands:	HDM-X, Human: romanrex

С 2024 года измерения полноразмерных наушников в RAA проводятся не только на инструментальных стендах, но и вживую с помощью разработанной системы в RAA - Live Measurement System. Это позволяет увидеть реальное поведение наушников и их вариативность звучания относительно стандартных стендов. Результаты таких измерений в отчетах обозначаются как со стендов Human. В этом отчете - это: Human: romanrex

Т.к. АЧХ зависит от посадки наушников и их прогрева/износа, то в RAA была разработан универсальный комплект Live Measurement System для контроля своих наушников на собственной голове. Типовые комплекты доступны для приобретения.

Frequency response Sendy Audio Audio Apollo headphone

АЧХ - Стенд: HDM-X

Graphics setting view

Channel

Range

Frequency band

Smoothing

АЧХ - Стенд: Human: romanrex

Graphics setting view

Channel

Range

Frequency band

Smoothing

Brief information

The graphs show the frequency response of the headphones without compensation to the target curves. Additionally, the basic target curves are shown. The frequency response depends on the measurement stands used. Since all artificial stands are simplified or averaged models of people, the results are always approximate.

The HDM-X stand uses the concept of a binaural microphone with microphone caps positioned at the entrance to the ear canal. The unevenness in the high frequency range above 2~3 kHz is formed from the shape of the auricle, the fit of the headphones on the stand and the relative internal volume between the ear and the driver. There is no resonance from the ear canal in this type of stand.

The combined frequency response of the Sendy Audio Audio Apollo with various amplifier sources is shown in an additional summary report.

The export of the frequency response graph is available on the comparison pages, which can be accessed using any graph from the report below. A separate summary report shows the recommended Sendy Audio Audio Apollo equalization settings and a comparison with various target curves.

Clicking on the graph will take you to the comparison page of different models with advanced graph display settings.

Impedance / Electric phase Sendy Audio Apollo headphone

Graphics setting view

Channel

Frequency band

Channel:	Left	Right
Impedance average in band from 40 Hz - 15 kHz	18.2	16.6	ohm
Resistance at 1 kHz	18.2	16.7	ohm
Resistance at 500 Hz	18.2	16.7	ohm
The minimum value in band from 40 Hz - 15 kHz	17.9	16.4	ohm
The maximum value in band from 40 Hz - 15 kHz	18.5	17.1	ohm

Graphics setting view

Channel

Range

Frequency band

Channel:	Left	Right
Phase deviation is the average in the range 40 Hz - 15 kHz	0.3	0.4	°
Phase at 1 kHz	-0.1	-0.1	°
Phase at 500 Hz	0.1	0.0	°
The minimum value in band from 40 Hz - 15 kHz	-1.1	-0.9	°
The maximum value in band from 40 Hz - 15 kHz	1.9	2.1	°

Brief information

Clicking on the graph will take you to the comparison page of different models with advanced graph display settings.

Frequency response and sensitivity Sendy Audio Apollo headphone

Graphics setting view

Channel

Frequency band

Smoothing

Channel:	Left	Right
Sensitivity average in band from 100 Hz - 10 kHz	99.6	100.7	dB/V SPL
Sensitivity average in band from 100 Hz - 10 kHz	82.2	82.9	dB/mW SPL
Sensitivity at 1 kHz	101.9	102.2	dB/V SPL
Sensitivity at 500 Hz	104.7	104.2	dB/V SPL

Graphics setting view

Type of chart

SPL

SPL	Voltage		Current		Power
dB SPL	dBV	V_RMS	dB(mA)	mA	dBm	mW
60	-40.2	0.010	-5.0	0.56	-22.6	0.005
70	-30.2	0.031	5.0	1.8	-12.6	0.055
80	-20.2	0.098	15.0	5.6	-2.6	0.55
90	-10.2	0.31	25.0	17.8	7.4	5.5
100	-0.21	0.98	35.0	56.1	17.4	54.8
110	9.8	3.1	45.0	178	27.4	548
120	19.8	9.8	55.0	561	37.4	5482
130	29.8	30.9	65.0	1775	47.4	54819

Brief information

Clicking on the graph will take you to the comparison page of different models with advanced graph display settings.

Impulse response Sendy Audio Audio Apollo headphone

Graphics setting view

Channel

Stand

Duration for impulse

Waveforms

Graphics setting view

Channel

Stand

Frequency of square wave

Brief information

The impulse response is a reaction to a single pulse of the shortest possible duration

The step response is a playback on a step (front square) signal. It is built on the derivative impulse response. According to the transition characteristic, the correct polarity of the inclusion of radiators in the speaker is usually determined.Most of the studied parameters are calculated from the impulse response: frequency response, phase-frequency response, group delay, Watterfalls, step response and square wave.

Since the waveform of the impulse response primarily depends on the frequency response and attenuated resonances and reverberation of the headphones themselves and the camera of the stand, the visual visibility of the parameters directly on the impulse response is extremely low. To obtain most of the characteristics, the fast Fourier transform and other mathematical algorithms with analysis of the total impulse length are used. The total pulse length is about 5 seconds, while visually the pulse is displayed with a duration of 2-4 milliseconds. Vertically, the visual detail does not exceed 40-45 dB. Thus, for a visual view, an alternative view is used from the sum of the half-wave modules of the impulse response shown on a logarithmic scale.

The visual definition of frequency response and resonances by impulse response was relevant only in "pre-computer" times. Today, according to the impulse response, only the same or different polarity of the emitters and the possible high-frequency resonance are looked at, if there is no graph of attenuated resonances. There is an opinion that the impulse response "immediately shows everything", and its absence is a concealment of the truth. Here the impulse response is given to dispel this misconception. Additionally, you can see the dependence of the shape of the impulse response on the stand.

When testing the speakers, the reverberation of the room is determined by the impulse response. The headphones work on a small volume and there is no reverberation from late reflections and this characteristic does not show useful data. The impulse response on a logarithmic scale is given for general educational purposes - to show that the usual type of impulse response is not a short burst of 2-4 ms, but a long-term attenuation for several seconds.

RAA measurements are made in 192 kHz / 24 bit mode.

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. The lower limit is from 2~4 Hz.

Clicking on the graph will take you to the comparison page of different models with advanced graph display settings.

Динамический спектр Sendy Audio Audio Apollo headphone

Ваттерфол

Graphics setting view

Channel

Stand

Frequency band

Graph Display Type

Затухание

Graphics setting view

Channel

Stand

Frequency band

Graph Display Type

Brief information

Thecumulative spectrum of the signal attenuation shows resonances and reverberations after the headphones cease to reproduce the signal.

The change in the cumulative spectrum of the signal attenuation is a cumulative spectrum of the signal attenuation, where the original frequency response is represented by a straight line.

The cumulative spectrum of signal attenuation is constructed by impulse response . The graph does not use three-wave smoothing. Time zones with an interval of 1 ms are painted in a certain color. For convenience of perception, the graph does not have vertical displacement, limited only to horizontal displacement. From the position of 3D - this is a view with a small turn in the horizontal plane. You can accurately assess the level on a vertical scale. To obtain good resolution in the time domain, a small window of 2048 samples is used, which directly affects the low resolution of the low frequency region and the graph in the region below 200-300 Hz does not show useful information.

Variants of "good" and "bad" cumulative spectra

Clicking on the graph will take you to the comparison page of different models with advanced graph display settings.

Other summary reports for Sendy Audio Apollo headphone

report for a newbie

A simple report for beginners with explanations of the main characteristics.

Compatibility with amplifier sources

A report evaluating the compatibility of Sendy Audio Apollo with various amplifier sources.

Target curves and equalization

A report with an assessment of compliance with target curves and recommended settings for Sendy Audio Apollo equalization

More detailed

Measurements of Sendy Audio Audio Apollo were carried out by Roman Kuznetsov on the hardware-software complex RAA.

The Sendy Audio Audio Apollo test was conducted as a black box test, without regard to cost and prestige. This is the basic principle for making measurements, measurement reports and developing tests in RAA.

I believe that it is important to do not make an absolute assessment of the device, but an aggregate assessment when working together with a source amplifier and taking into account external factors. This allows you to effectively reveal the potential of the entire set of devices or to make a more optimal choice of components.

Kuznetsov Roman
Founder of RAA

Known by the nickname romanrex
Аuthor of articles iXBT.com

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