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WHF headphone amplifier reviews

shafesk

New member
Sep 18, 2010
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Dear What Hi-fi staff and readers,

Reading this month's arcam r-pac review I was left wanting to know more about the headphone amplifier. I didn't feel that I got enough information about the headphone amplifier section. I would like to know more about how powerful it is, can I use them to power the likes of the Sen HD-800 or AKG-k702s? The drive ability of headphone amps vary wildy and most serious headphone enthusiasts have very power hungry headphones so it is a crucial piece of information for most of us, especially some people like me who often have to buy based on reviews. Would love to see this incorporated in all future headphone amplifier reviews.
 

shafesk

New member
Sep 18, 2010
136
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Thank you so much Andy. Is there any chance that future headphone amplifier reviews will contain a brief description of their power? (I know I'm getting greedy here :pray:)

Sincerely,

Shafin
 
A

Anonymous

Guest
Andy - I hope you don't mind me giving a technical reply.

Whilst I leave subjective comments to the WHF team I can comment on the typical measured power outputs of the rPAC.

The headphones amplifier has no output capacitors (i.e. it is direct coupled to the phones) and its output impedance is less than 1 ohm per channel, so there is very little effect on the frequency response of those headphones whose impedance varies a lot with frequencies (this is often true of balanced armature types).

The rPAC amplifier is rated to drive loads of 16 ohms or greater (actually it will work into even lower impedances than that). Maximum output power is typically in the order of 140mW per channel into 16 ohms and 80mW per channel into 32 ohms. Into higher impedance loads, say above about 100 ohms, the maximum undistorted voltage swing approaches 1.8V rms per channel. For most headphones this is very loud indeed (and not recommended for long term listening).

The distortion at normal listening levels is very low (<0.01%) and is benign in terms of high order crossover distortion artefacts - not all headphones amplifiers are! Signal to noise ratio into 16 ohms is about 98dB ref 35mW (104dB ref full power output), well below the noise floor of even the best CDs.

So whilst it is not a huge high voltage class A amplifier it is (in my opinion) pretty darned good as part of a 150UKP package which includes an asynchronous transfer protocol USB DAC :)

Hope this helps,

John Dawson (Arcam)
 

Andy Clough

New member
Apr 27, 2004
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shafesk said:
Thank you so much Andy. Is there any chance that future headphone amplifier reviews will contain a brief description of their power? (I know I'm getting greedy here :pray:)

Sincerely,

Shafin
I'll raise the issue in my next meeting with the test team. In the meantime, hopefully John Dawson's reply from Arcam is suffcient.
 

shafesk

New member
Sep 18, 2010
136
0
0
John Arcam Dawson said:
Andy - I hope you don't mind me giving a technical reply.

Whilst I leave subjective comments to the WHF team I can comment on the typical measured power outputs of the rPAC.

The headphones amplifier has no output capacitors (i.e. it is direct coupled to the phones) and its output impedance is less than 1 ohm per channel, so there is very little effect on the frequency response of those headphones whose impedance varies a lot with frequencies (this is often true of balanced armature types).

The rPAC amplifier is rated to drive loads of 16 ohms or greater (actually it will work into even lower impedances than that). Maximum output power is typically in the order of 140mW per channel into 16 ohms and 80mW per channel into 32 ohms. Into higher impedance loads, say above about 100 ohms, the maximum undistorted voltage swing approaches 1.8V rms per channel. For most headphones this is very loud indeed (and not recommended for long term listening).

The distortion at normal listening levels is very low (<0.01%) and is benign in terms of high order crossover distortion artefacts - not all headphones amplifiers are! Signal to noise ratio into 16 ohms is about 98dB ref 35mW (104dB ref full power output), well below the noise floor of even the best CDs.

So whilst it is not a huge high voltage class A amplifier it is (in my opinion) pretty darned good as part of a 150UKP package which includes an asynchronous transfer protocol USB DAC :)

Hope this helps,

John Dawson (Arcam)
Thank you, it certainly helped! Also, congratulations on your new dac, its certainly making waves in the industry....wish you all the best with it.
 

shafesk

New member
Sep 18, 2010
136
0
0
Andy Clough said:
shafesk said:
Thank you so much Andy. Is there any chance that future headphone amplifier reviews will contain a brief description of their power? (I know I'm getting greedy here :pray:)

Sincerely,

Shafin
I'll raise the issue in my next meeting with the test team. In the meantime, hopefully John Dawson's reply from Arcam is suffcient.
That is music to my ears, indeed any headphone loving forum member here.
 

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