Graph Feppar
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- Nov 19, 2018
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One very common belief in "high end" audio community is that the more power amplifier has,the better.I saw this being applied to both voltage and current.They say "dynamics is power so more powerfull amp = more dynamics".Bellow I will give reasons why this is not true,that its waste of money at best,degradation of signal,headphone destruction and hearing damage at worst.
1. For me,anything over 85db average SPL or 95db peak is uncomfortably loud with modern music.People rarely reach 100db + even in transients,generally average listening loudness is around 80db.Audiophools,except those with significant hearing damage or old tend to over estimate how much loudness they require.
2. Impedance of headphone have nothing to do with how hard is it to drive,its all about efficiency.
3. Even cheapest portable player and tiny amp + dac combinations have atleast 2 V rms output.
4. High end portable headphone players have over 6 V rms output.
5. Balanced desktop headphone amps like Violectric V281 have 35 V rms output.
6. Relatively high voltage requiring Sennheiser HD800 needs 250 mV for 90db SPL,they have 360ohm impedance and use 0.16 miliwatts to reach 90db.This large Sennheiser flagship is more power hungry than 99% of all headphones.
8. Most powerhungry headphone in the world,the infamous Hifiman HE6 needs 1 volt for 90db,with its 50 ohm impedance,it draws 20 miliamperes for combined power of 20 miliwatts.
9. Amplifiers are trade off between voltage and current capability,for given size,weight,cost and power,the higher the max voltage ( Gain),the lower max current becomes,the higher the output impedance becomes which causes decreased damping (bad) and increased noise.
Furthemore this excessive gain causes the need to strongly attenuate the signal either digitaly in DAC which result in more increased noise or with analog resistive pot which wastes power and if its not exotic high precision matched resistor stepped attenuator like the DACT or the one in Benchmark HPA4,its going to cause channel imbalance.The higher the amp voltage,the stronger the attenuation must be,the larger the imbalance gets.
Ideal amplifier should have just enough voltage to drive headphone to realistic listening level,voltage any higher than that degrades signal.The audiophile mega volt amps have capability to instantly destroy headphones,HD650 will get damaged past 8 volt rms,furthermore 35 volts even through most inneficient headphone in the world,the HE6,will make them play at 120 db SPL which will cause instant permanent hearing damge.
Increasing current capability is better,higher current capable amplifier will produce lower distortion and have better damping factor due to lower output impedance.But there exist other way to lower output impedance and decrease distortion... the feedback.That means big heavy desktop amps are not needed.
To give example,portable player iBasso DX200 have 0.28ohm output impedance.Wallet sized desktop DAC Pro Ject S2 Pre Box which have headphone output with two ESS ES9603 headphone amplifier ICs have 0.1 ohm impedance,I believe same IC is used in certain smartphone like LG V.Chord Mojo,the tiny portable ampDac have 0.2 ohm.
People really need only half a volt and couple miliamperes of current,even 2 volt will drive HE6 to uncomfortably loud levels,2 volts will drive relatively high voltage requiring HD600/650 to 110db which is pain threshold at ear resonance frequency of 3 KHz.Most headphones would reach or approach 120db,at 2 volts.
It is completly irrelevant if amplifier have capability to spit out over 9000 jigga watts of juice,what matters is its THD+N at realistic listening volume which is couple of miliwatts for 99% of people.
1. For me,anything over 85db average SPL or 95db peak is uncomfortably loud with modern music.People rarely reach 100db + even in transients,generally average listening loudness is around 80db.Audiophools,except those with significant hearing damage or old tend to over estimate how much loudness they require.
2. Impedance of headphone have nothing to do with how hard is it to drive,its all about efficiency.
3. Even cheapest portable player and tiny amp + dac combinations have atleast 2 V rms output.
4. High end portable headphone players have over 6 V rms output.
5. Balanced desktop headphone amps like Violectric V281 have 35 V rms output.
6. Relatively high voltage requiring Sennheiser HD800 needs 250 mV for 90db SPL,they have 360ohm impedance and use 0.16 miliwatts to reach 90db.This large Sennheiser flagship is more power hungry than 99% of all headphones.
8. Most powerhungry headphone in the world,the infamous Hifiman HE6 needs 1 volt for 90db,with its 50 ohm impedance,it draws 20 miliamperes for combined power of 20 miliwatts.
9. Amplifiers are trade off between voltage and current capability,for given size,weight,cost and power,the higher the max voltage ( Gain),the lower max current becomes,the higher the output impedance becomes which causes decreased damping (bad) and increased noise.
Furthemore this excessive gain causes the need to strongly attenuate the signal either digitaly in DAC which result in more increased noise or with analog resistive pot which wastes power and if its not exotic high precision matched resistor stepped attenuator like the DACT or the one in Benchmark HPA4,its going to cause channel imbalance.The higher the amp voltage,the stronger the attenuation must be,the larger the imbalance gets.
Ideal amplifier should have just enough voltage to drive headphone to realistic listening level,voltage any higher than that degrades signal.The audiophile mega volt amps have capability to instantly destroy headphones,HD650 will get damaged past 8 volt rms,furthermore 35 volts even through most inneficient headphone in the world,the HE6,will make them play at 120 db SPL which will cause instant permanent hearing damge.
Increasing current capability is better,higher current capable amplifier will produce lower distortion and have better damping factor due to lower output impedance.But there exist other way to lower output impedance and decrease distortion... the feedback.That means big heavy desktop amps are not needed.
To give example,portable player iBasso DX200 have 0.28ohm output impedance.Wallet sized desktop DAC Pro Ject S2 Pre Box which have headphone output with two ESS ES9603 headphone amplifier ICs have 0.1 ohm impedance,I believe same IC is used in certain smartphone like LG V.Chord Mojo,the tiny portable ampDac have 0.2 ohm.
People really need only half a volt and couple miliamperes of current,even 2 volt will drive HE6 to uncomfortably loud levels,2 volts will drive relatively high voltage requiring HD600/650 to 110db which is pain threshold at ear resonance frequency of 3 KHz.Most headphones would reach or approach 120db,at 2 volts.
It is completly irrelevant if amplifier have capability to spit out over 9000 jigga watts of juice,what matters is its THD+N at realistic listening volume which is couple of miliwatts for 99% of people.
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