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 Grado RA-1

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 Grado RA-1 (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	0.5	ohm
Voltage: Linear Mode / Maximum or before clipping level	16.1/16.1	dBV
	6.4/6.4	V_RMS
Current: Linear Mode / Maximum or before clipping level	14.8/35.2	dB(mA)
	5.5/57.8	mA

Brief information

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

Frequency response Grado RA-1 (as headphone amplifier)

Graphics setting view

Channel

Range

Channel:	Left	Right
Variation in frequency response in band from 40 Hz - 15 kHz	-4.1, +3.6	-4.0, +3.6	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

Impedance Grado RA-1 (as headphone amplifier)

Graphics setting view

Channel

Channel:	Left	Right
Impedance average in band from 40 Hz - 15 kHz	0.5	0.5	ohm
The minimum value in band from 40 Hz - 15 kHz	0.4	0.4	ohm
The maximum value in band from 40 Hz - 15 kHz	0.7	0.5	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.

Frequency response Grado RA-1 with resistive load

Graphics setting view

Channel

Range

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

Channel:	Left	Right
TEST 16 ? + Grado RA-1	0.1	0.0	dB
TEST 32 ? + Grado RA-1	0.0	0.0	dB
TEST 64 ? + Grado RA-1	0.0	0.0	dB
TEST 126 ? + Grado RA-1	0.0	0.0	dB
TEST 256 ? + Grado RA-1	0.0	0.0	dB
TEST 512 ? + Grado RA-1	0.0	0.0	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 Grado RA-1 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 ? + Grado RA-1	0.0	0.0	dB
Grado GH4 Limited Edition + Grado RA-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

Frequency response Grado RA-1 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 ? + Grado RA-1	0.0	0.0	dB
Campfire Audio Andromeda + Grado RA-1	0.9	0.9	dB
Fearless Audio S8F Freedom + Grado RA-1	0.8	0.6	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

THD vs load vs output voltage Grado RA-1

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 Grado RA-1

Graphics setting view

Type of chart

RAW coordinates

Power characteristics of the	Voltage		Current
	dBV	V_RMS	dB(mA)	mA
Equivalent class A	16.1	6.4	14.8	5.5
Equivalent class AB	16.1	6.4	23.4	14.7
Equivalent class B	16.1	6.4	30.0	31.8
Maximum mode	16.1	6.4	35.2	57.8

Volume Control Type	Analog
Optimal range of volume control	36.0	dB

Comparison Grado RA-1 and another amplifiers by loudness (Volume Level)

Main characteristics of the Grado RA-1

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 Grado RA-1

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	-20.6	0.1	-14.6	0.1	-8.6	0.1	-0.7	0.1
24.5 ohm	-17.3	0.1	-8.3	0.1	-1.4	0.1	2.6	0.1
30.5 ohm	-16.0	0.2	-7.0	0.2	-1.0	0.2	5.0	0.2
62.4 ohm	-9.4	0.3	-0.4	0.3	6.6	0.3	11.6	0.3
100 ohm	-6.0	0.5	3.0	0.5	12.0	0.5	15.0	0.5
198.9 ohm	1.3	1.2	11.3	1.2	15.3	1.2	16.3	1.2
300 ohm	4.5	1.7	12.5	1.7	15.5	1.7	16.5	1.7
763 ohm	7.8	2.5	15.8	2.5	15.8	2.5	16.8	2.5
Not loaded	16.1	6.4	16.1	6.4	16.1	6.4	16.1	6.4

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	15.4	5.9	21.4	11.7	27.4	23.4	35.3	58.5
24.5 ohm	14.9	5.6	23.9	15.7	30.9	34.9	34.8	55.1
30.5 ohm	14.3	5.2	23.3	14.7	29.3	29.2	35.3	58.5
62.4 ohm	14.7	5.4	23.7	15.2	30.7	34.1	35.6	60.6
100 ohm	14.0	5.0	23.0	14.2	32.0	40.0	35.0	56.4
198.9 ohm	15.3	5.8	25.3	18.4	29.3	29.2	30.3	32.8
300 ohm	15.0	5.6	23.0	14.1	26.0	19.9	27.0	22.3
763 ohm	10.2	3.2	18.2	8.1	18.2	8.1	19.2	9.1

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	-2.6	0.5	3.4	2.2	9.4	8.6	17.3	54.1
24.5 ohm	-1.2	0.8	7.8	6.0	14.8	29.9	18.7	74.4
30.5 ohm	-0.8	0.8	8.2	6.6	14.1	26.0	20.2	104.2
62.4 ohm	2.6	1.8	11.6	14.5	18.6	72.5	23.6	229.2
100 ohm	4.0	2.5	13.0	20.1	22.0	159.7	25.0	318.5
198.9 ohm	8.3	6.8	18.3	67.6	22.3	169.8	23.3	213.7
300 ohm	9.8	9.4	17.8	59.6	20.8	118.9	21.7	149.6
763 ohm	9.0	7.9	17.0	49.8	17.0	49.8	18.0	62.7

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 Grado RA-1 (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 Grado RA-1 were carried out by Roman Kuznetsov on the hardware-software complex RAA.

The Grado RA-1 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.

RA-1 was given for tests by NEW COLISEUM

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.

Grado RA-1 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

report for a pro

Comparison of on-line graphs

Quick jump to the schedule in this report:

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