This is a report for professionals with a suite of test of headphone amplifier.
You can see a simple report for "dummies" with explanations of the main characteristics for IBM ThinkPad X31

A suite of tests for a headphone amplifier can be applied to just a universal output without a formal presence of an amplifier, if in this mode you can connect headphones to this output. Based on the results of the tests, you can understand the real picture, is the output powerful enough or not, with the initial data on the circuitry as a "black box".

Line-out, differences from the output for headphones and speakers

Advantages and disadvantages of balanced amplifiers

Test report - general data IBM ThinkPad X31 (as headphone amplifier)

Frequency response, Impedance and Frequency response with standard headphones

Voltage levels from the load at the output of the amplifier

Average value of impedance band in 40 Hz - 15 kHz	70.0	ohm
Voltage: Linear Mode / Maximum or before clipping level	-12.1/-12.1	dBV
	0.2/0.2	V_RMS
Current: Linear Mode / Maximum or before clipping level	-15.4/9.2	dB(mA)
	0.2/2.9	mA

Brief information

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

Frequency response IBM ThinkPad X31 (as headphone amplifier)

Graphics setting view

Channel

Range

Channel:	Left	Right
Variation in frequency response in band from 40 Hz - 15 kHz	-0.1, +0.1	-0.1, +0.1	dB

Brief information

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

On the frequency response comparison page, there is an export option and additional tools for adjusting the frequency response

Impedance IBM ThinkPad X31 (as headphone amplifier)

Graphics setting view

Channel

Channel:	Left	Right
Impedance average in band from 40 Hz - 15 kHz	71.8	68.2	ohm
The minimum value in band from 40 Hz - 15 kHz	70.7	67.2	ohm
The maximum value in band from 40 Hz - 15 kHz	80.1	75.7	ohm

Comparison of basic characteristics AMPs

Brief information

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

Crosstalk IBM ThinkPad X31 (as headphone amplifier)

Graphics setting view

Channel

Range

Load

Channel:	Left	Right
Crosstalk @ 1 kHz @ 15.8 ohm	-46.8	-47.2	dB
Crosstalk @ 1 kHz @ 24.5 ohm	-46.9	-47.3	dB
Crosstalk @ 1 kHz @ 30.5 ohm	-49.0	-49.5	dB
Crosstalk @ 1 kHz @ 62.4 ohm	-53.0	-53.3	dB
Crosstalk @ 1 kHz @ 100.0 ohm	-51.8	-51.8	dB
Crosstalk @ 1 kHz @ 198.9 ohm	-57.4	-57.1	dB
Crosstalk @ 1 kHz @ 300.0 ohm	-66.3	-67.3	dB
Crosstalk @ 1 kHz @ 763.0 ohm	-66.2	-64.8	dB
Crosstalk @ 1 kHz @ Not loaded	-81.0	-80.7	dB

Brief information

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

Crosstalk Phase IBM ThinkPad X31 (as headphone amplifier)

Graphics setting view

Channel

Load

Brief information

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

Frequency response IBM ThinkPad X31 with resistive load

Graphics setting view

Channel

Range

Frequency response of amplifier with resistive load @ 40 Hz - 15 kHz

Channel:	Left	Right
TEST 16 ? + IBM ThinkPad X31	1.1	1.1	dB
TEST 32 ? + IBM ThinkPad X31	0.9	0.9	dB
TEST 64 ? + IBM ThinkPad X31	0.7	0.7	dB
TEST 126 ? + IBM ThinkPad X31	0.5	0.5	dB
TEST 256 ? + IBM ThinkPad X31	0.3	0.3	dB
TEST 512 ? + IBM ThinkPad X31	0.2	0.2	dB

Brief information

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

On the frequency response comparison page, there is an export option and additional tools for adjusting the frequency response

Frequency response IBM ThinkPad X31 loaded dynamic headphone type

Graphics setting view

Channel

Range

Frequency response of amplifier loaded dynamic headphone type @ 40 Hz - 15 kHz

Channel:	Left	Right
TEST 10000 ? + IBM ThinkPad X31	0.0	0.0	dB
Grado GH4 Limited Edition + IBM ThinkPad X31	6.1	5.6	dB

Brief information

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

On the frequency response comparison page, there is an export option and additional tools for adjusting the frequency response

Frequency response IBM ThinkPad X31 loaded type balance armature headphone type

Graphics setting view

Channel

Range

Frequency response of amplifier loaded type balance armature headphone type @ 40 Hz - 15 kHz

Channel:	Left	Right
TEST 10000 ? + IBM ThinkPad X31	0.0	0.0	dB
Campfire Audio Andromeda + IBM ThinkPad X31	15.9	15.9	dB
Fearless Audio S8F Freedom + IBM ThinkPad X31	11.2	10.3	dB

Brief information

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

On the frequency response comparison page, there is an export option and additional tools for adjusting the frequency response

THD vs load vs output voltage IBM ThinkPad X31

Graphics setting view

Channel

Load

Harmonic, number

Graphics setting view

Channel

Load

Harmonic, number

Graphics setting view

Channel

Load

Brief information

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

Maximum voltage output level vs load IBM ThinkPad X31

Graphics setting view

Type of chart

RAW coordinates

Power characteristics of the	Voltage		Current
	dBV	V_RMS	dB(mA)	mA
Equivalent class A	-12.1	0.2	-15.4	0.2
Equivalent class AB	-12.1	0.2	-6.3	0.5
Equivalent class B	-12.1	0.2	-1.2	0.9
Maximum mode	-12.1	0.2	9.2	2.9

Volume Control Type	Digital
Optimal range of volume control	36.0	dB
Signal/Noise / Maximum	106.0/-12.1	dB/dBV
Signal/Noise @ -14.9 dBV 32 ohm (1 mW)	Low	dB
Signal/Noise @ -5.2 dBV 300 ohm (1 mW)	Low	dB

Comparison IBM ThinkPad X31 and another amplifiers by loudness (Volume Level)

Main characteristics of the IBM ThinkPad X31

Brief information

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

Maximum voltage output level vs load IBM ThinkPad X31

Graphics setting view

Type of chart

RAW coordinates

Maximum Amplifier Voltage Level

Load	Pure or equal class A		Optimal or equal class AB		Hard or equal class B		Max, before clipping
	dBV	V_RMS	dBV	V_RMS	dBV	V_RMS	dBV	V_RMS
15.8 ohm	-51.7	0.0	-41.7	0.0	-38.7	0.0	-26.7	0.0
24.5 ohm	-48.9	0.0	-38.9	0.0	-32.9	0.0	-23.9	0.0
30.5 ohm	-43.6	0.0	-37.6	0.0	-31.6	0.0	-22.6	0.0
62.4 ohm	-39.6	0.0	-30.6	0.0	-24.6	0.0	-18.6	0.0
100 ohm	-34.6	0.0	-25.6	0.0	-20.7	0.0	-16.7	0.0
198.9 ohm	-29.7	0.0	-19.7	0.0	-14.7	0.0	-14.7	0.0
300 ohm	-25.8	0.1	-15.9	0.1	-13.9	0.1	-13.9	0.1
763 ohm	-21.8	0.1	-12.9	0.1	-12.9	0.1	-12.9	0.1
Not loaded	-12.1	0.2	-12.1	0.2	-12.1	0.2	-12.1	0.2

Maximum level of amplifier current

Load	Pure or equal class A		Optimal or equal class AB		Hard or equal class B		Max, before clipping
	dB(mA)	mA	dB(mA)	mA	dB(mA)	mA	dB(mA)	mA
15.8 ohm	-15.7	0.2	-5.7	0.5	-2.7	0.7	9.3	2.9
24.5 ohm	-16.6	0.1	-6.6	0.5	-0.6	0.9	8.3	2.6
30.5 ohm	-13.3	0.2	-7.3	0.4	-1.3	0.9	7.7	2.4
62.4 ohm	-15.5	0.2	-6.5	0.5	-0.5	0.9	5.5	1.9
100 ohm	-14.6	0.2	-5.6	0.5	-0.7	0.9	3.3	1.5
198.9 ohm	-15.7	0.2	-5.7	0.5	-0.7	0.9	-0.7	0.9
300 ohm	-15.4	0.2	-5.4	0.5	-3.4	0.7	-3.4	0.7
763 ohm	-19.5	0.1	-10.5	0.3	-10.5	0.3	-10.5	0.3

Power

Load	Pure or equal class A		Optimal or equal class AB		Hard or equal class B		Max, before clipping
	dBm	mW	dBm	mW	dBm	mW	dBm	mW
15.8 ohm	-33.7	0.0	-23.7	0.0	-20.7	0.0	-8.7	0.1
24.5 ohm	-32.7	0.0	-22.7	0.0	-16.7	0.0	-7.8	0.2
30.5 ohm	-28.4	0.0	-22.4	0.0	-16.4	0.0	-7.4	0.2
62.4 ohm	-27.5	0.0	-18.5	0.0	-12.5	0.1	-6.5	0.2
100 ohm	-24.6	0.0	-15.6	0.0	-10.7	0.1	-6.7	0.2
198.9 ohm	-22.7	0.0	-12.7	0.1	-7.7	0.2	-7.7	0.2
300 ohm	-20.6	0.0	-10.6	0.1	-8.6	0.1	-8.6	0.1
763 ohm	-20.7	0.0	-11.7	0.1	-11.7	0.1	-11.7	0.1

Brief information

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

Spectrum of Total Harmonic Distortion vs Level IBM ThinkPad X31 (as headphone amplifier)

Graphics setting view

Channel

Level

Range

Graphics setting view

Channel

Level

Range

Graphics setting view

Channel

Shift

dBm

Range

Graphics setting view

Channel

Shift

dBV

Range

Brief information

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

Spectrum of Multitone Distortion vs Level vs Load IBM ThinkPad X31 (as headphone amplifier)

Graphics setting view

Channel

Level

Range

Graphics setting view

Channel

Level

Range

Graphics setting view

Channel

Shift

dBm

Range

Graphics setting view

Channel

Shift

dBV

Range

Brief information

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

Spectrum of IMD SMPTE vs Level IBM ThinkPad X31 (as headphone amplifier)

Graphics setting view

Channel

Level

Range

Range

Graphics setting view

Channel

Level

Range

Range

Graphics setting view

Channel

Shift

Range

dBm

Range

Graphics setting view

Channel

Shift

Range

dBV

Range

Brief information

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

Spectrum of IMD CCIF vs Level IBM ThinkPad X31 (as headphone amplifier)

Graphics setting view

Channel

Level

Range

Graphics setting view

Channel

Level

Range

Graphics setting view

Channel

Shift

dBm

Range

Graphics setting view

Channel

Shift

dBV

Range

Brief information

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

More detailed

Measurements of IBM ThinkPad X31 were carried out by Roman Kuznetsov on the hardware-software complex RAA.

The IBM ThinkPad X31 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 headphones 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

Information for Authors. You can freely use the graphics in your articles with a link to us.

IBM ThinkPad X31 is available in reports and services. You are in a professional report.

Information for entry level users

report for a newbie

The automatic selection of the optimal AMP models

Information for all

Versus of characteristics

Information for professionals

reports for a pro (Headphone amplifier)

Headphone amplifier

reports for a pro (DAC Line Out)

DAC Line Out

Comparison of on-line graphs

Quick jump to the schedule in this report:

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