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Very confused about HPAs

tifune

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I currently own the Meizu Hifi non-Pro, TempoTec Sonata HD/Hidisz S8, and E1DA 9038S. When I look at the power output of these devices, I certainly see some areas where they don't make sense - the Meizu w/ planars probably would be lacking. But, my Sennheiser HD25 (75ohm, 120db/V measured) should sound fine on the Meizu Hifi Non-pro up to 123dB if we go solely by the power output/THD.

But, let's take a random headphone that's a little more hungry: AKG K601. Per https://www.headphonesty.com/headphone-power-calculator/ we "need" 99mW, 3.56V and 27.2mA to achieve 110dB. That's a bit loud, I can't see myself listening at that level for long but in such a scenario I can see the case for an outboard amp. If we back down to a still loud but more realistic 105dB, we have headroom for peaks and our power requirements are 2V and 31mW (again per headphonesty.com). At this point the E1DA has no issues at all with 100dB SINAD, per Amir's review.

Now, I'm sure there's more power hungry headphones out there - I searched a little but didn't find too many cans that would justify a Archel2 or JDS Atom, even at the low price of $110-150. (Yes I'm sure you can compile a list of dozens, but remember there's literally thousands of headphone/IEM models) Ignoring the 9038S' EMI issues and balanced cable requirement, it seems powerful enough to drive pretty much anything in existence and even includes a DAC for $75 USD.

Perhaps one thing throwing me off is most of Amir's measurements seem to be based on 2V but once in awhile we end up with something far beyond like the THX 789 which shows 5.7V in the review. Does that mean the 2V devices are not capable of driving higher to the 4V+ range? I find that unlikely given the glowing reviews of the Archel2/Atom.

Setting aside the sighted placebo effect of audio equipment, what's a common scenario where a HPA is objectively justified? Even in the HPA reviews the Sennheiser HD650 seems to be one of the go-to's but doesn't require more than 32mW/1V to hit 108dB which should be a breeze according the posted measurements of the S8/9038/Meizu Pro?

There's probably a simple article out there, maybe even on ASR, that clarifies this but I haven't stumbled on it. When I do the math myself I just can't find many scenarios where you need more than a thumb drive DAC, and even less for IEMs. The most likely explanation is I'm doing the math wrong, but how?

Thanks!

Thanks!
 

solderdude

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Don't stare yourself blind on the 110dB. These are not comparable to the common seen average SPL levels on the web.

Those are peak levels and when listening to music average levels will be 15 to 20dB lower so with 110dB peaks you could well be at 95 dB average.
I have written some things about this but is too big to simply cut and paste. You can read the blurp HERE

It certainly doesn't do any harm to over-dimension an amplifier ensuring that when listening to very dynamic recordings you can be sure the amplifier never runs out of steam and stays well below higher distortion levels.

Of course it is a good thing to look at power handling of certain headphones and understand the difference between high and low efficiency and high and low impedance headphones as well.

For high efficiency (dB/V, don't look at db/mW) headphones a simple dongle or phone will be enough. Not for driving a HD650 to impressive levels.
Of course the HD650 will also play nicely to certain levels from a phone.
 
Last edited:

bobbooo

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I currently own the Meizu Hifi non-Pro, TempoTec Sonata HD/Hidisz S8, and E1DA 9038S. When I look at the power output of these devices, I certainly see some areas where they don't make sense - the Meizu w/ planars probably would be lacking. But, my Sennheiser HD25 (75ohm, 120db/V measured) should sound fine on the Meizu Hifi Non-pro up to 123dB if we go solely by the power output/THD.

But, let's take a random headphone that's a little more hungry: AKG K601. Per https://www.headphonesty.com/headphone-power-calculator/ we "need" 99mW, 3.56V and 27.2mA to achieve 110dB. That's a bit loud, I can't see myself listening at that level for long but in such a scenario I can see the case for an outboard amp. If we back down to a still loud but more realistic 105dB, we have headroom for peaks and our power requirements are 2V and 31mW (again per headphonesty.com). At this point the E1DA has no issues at all with 100dB SINAD, per Amir's review.

Now, I'm sure there's more power hungry headphones out there - I searched a little but didn't find too many cans that would justify a Archel2 or JDS Atom, even at the low price of $110-150. (Yes I'm sure you can compile a list of dozens, but remember there's literally thousands of headphone/IEM models) Ignoring the 9038S' EMI issues and balanced cable requirement, it seems powerful enough to drive pretty much anything in existence and even includes a DAC for $75 USD.

Perhaps one thing throwing me off is most of Amir's measurements seem to be based on 2V but once in awhile we end up with something far beyond like the THX 789 which shows 5.7V in the review. Does that mean the 2V devices are not capable of driving higher to the 4V+ range? I find that unlikely given the glowing reviews of the Archel2/Atom.

Setting aside the sighted placebo effect of audio equipment, what's a common scenario where a HPA is objectively justified? Even in the HPA reviews the Sennheiser HD650 seems to be one of the go-to's but doesn't require more than 32mW/1V to hit 108dB which should be a breeze according the posted measurements of the S8/9038/Meizu Pro?

There's probably a simple article out there, maybe even on ASR, that clarifies this but I haven't stumbled on it. When I do the math myself I just can't find many scenarios where you need more than a thumb drive DAC, and even less for IEMs. The most likely explanation is I'm doing the math wrong, but how?

Thanks!

Thanks!

A lot of people on here and in the audiophile community at large are obsessed with huge amounts of power when it comes to headphone amps, when the fact is you rarely need it, especially for IEMs and most reasonably efficient headphones, unless you listen at very high levels that will long-term likely cause hearing damage. Unfortunately there's no hard evidence on here that there's even an audible difference between an average modern smartphone and a dongle / USB 'thumb drive' DAC with IEMs / efficient headphones, as the only smartphone measured so far is the LG G7, despite many dongles etc. having been measured, which is a shame as it would save consumers a lot of money if it could be shown with measurements that the device in all of our pockets is likely just as good as an external DAC/amp within the limits of audibility.
 
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