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Study: Headphone Amp Gains: Low or High?

PenguinMusic

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Probably not, but from a hearing safety I would stick to the lowest gain.

Hum... from a hearing safty ?
You mean not to listen too loud ?
That may indeed be a problem as the sensitivity is so that even at minimum volume, I alrady have decent sound.

The Oppo goes from 0 to 5. On hi-gin I have good listening level at 1.5.
In low-gin I must go up to 3.5/4 to achieve the same volume.

If there's a low signal, I can then hear the "hiss" background... which I can not if I use the hi-gain.
 

PenguinMusic

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First of all i don't see why you hear hiss but there can be some explanation with the hum.
One possible cause of this can be that the high gain allows you to use the volume pot at lower position which has less equivalent resistance. Hence the source impedance seeing from the amp itself(more possibly output stage) is smaller. In this case the input of the output stage has very small impedance to the ground, this way the hum will be reduced.
The hum can have several causes. As it's single ended this is very possible. Now the ha2 is battery powered (if you are not charging while listening, if you are, try without charging), the hum can come from the grounding design of asus essence. It's actually difficult to have the transformer inside the chassis and not getting interference. You can try plugin your ha2 to a dongle like meizu, apple, musiland anything like that, with your phone of course. And see if the hum is gone.
Hope this helps.

Hi,

Thanks for the detailed answer.

I don't know the words to use what I am experiencing.
So I'll try to be a little more explicit.

If I connect the headphones and play no music and then turn on the volume, at first I hear nothing and then , when the volume goes up I hear a sound like a "wind breeze". That is what I call the "hum" (or "hiss"'... it's probably between both sounds :))
That gets really audible when the volume reaches approximately half of max (on Oppo) and about 3/4 of max (on Asus Xonar).
Now, if I use low gain, I can reach those listening levels with the HD700. And if listening to classical music, where you have really quiet moments, then the "hum" is really audible...
This is why I choose to stick to "hi gain" with the volume turn to 20% of max (Oppo) and about 35% of max (Xonar). At those volume settings, I do not hear that hum and I like it better.

As I am no technician at all, I was wondering if doing that I am doing something "wrong" technically...

Regards.
 

JohnYang1997

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Hi,

Thanks for the detailed answer.

I don't know the words to use what I am experiencing.
So I'll try to be a little more explicit.

If I connect the headphones and play no music and then turn on the volume, at first I hear nothing and then , when the volume goes up I hear a sound like a "wind breeze". That is what I call the "hum" (or "hiss"'... it's probably between both sounds :))
That gets really audible when the volume reaches approximately half of max (on Oppo) and about 3/4 of max (on Asus Xonar).
Now, if I use low gain, I can reach those listening levels with the HD700. And if listening to classical music, where you have really quiet moments, then the "hum" is really audible...
This is why I choose to stick to "hi gain" with the volume turn to 20% of max (Oppo) and about 35% of max (Xonar). At those volume settings, I do not hear that hum and I like it better.

As I am no technician at all, I was wondering if doing that I am doing something "wrong" technically...

Regards.
So the hiss is only dependent to the volume pot position.
There shouldn't be anything that you are doing "wrong". I would like to see to track down what causes this.
So if you only hear hiss and the hiss is only audible at higher volume pot setting( as it's log taper, 75% is actually around the half voltage division position). So you are not going over that position here. Then when the volume is closer to 75%, the noise due to resistance increases.

Something you can try: does the noise decrease if you go over 75% when using low gain? If it does, that's the exact cause. If it still increases, there can be other causes.
 

PenguinMusic

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Hi,

Tried what you said... And my mistake. It seems the "hum" is on the recording, not on the DAC/Amp combos.
On both, there is absolutely no audible "hum" when no music is coming out from computer, even if volume is turned up to maximum.

But the test has still been really interesting.
Because on the Oppo DAC/Amp with the HD700, that "hum" is really audible, more in "low gain" than in "hi gain" but still audible.
But if I hook up the HD700 to the Xonar, the "hum" is really less audible... It is there, but it's really less :-( (to my ears, which is probably the most defective measurement device ever designed !).

Now if I use the Oppo PM-3 headphone, the "hum" almost vanishes... but then a part of the audio message also does :-( (same measurement device mentioned earlier).

Not sure what conclusions I should take out of this :-(
Should I say the Oppo DAC/amp is closer to fidelity and thus reproduces the "hum" on the recording ?
Or is it too "resistive" and thus amplifies the "hum" ?

Still, I am surprised at how good the Xonar sounds for a device I bought (used) for about 100 dollars...

Also, comparing headphones, I will make a statement that will be considered as pure Heresy...
But I think the B&0 H9i headphone is better than the Oppo, maybe better than the HD700 :-(
 

JohnYang1997

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Hi,

Tried what you said... And my mistake. It seems the "hum" is on the recording, not on the DAC/Amp combos.
On both, there is absolutely no audible "hum" when no music is coming out from computer, even if volume is turned up to maximum.

But the test has still been really interesting.
Because on the Oppo DAC/Amp with the HD700, that "hum" is really audible, more in "low gain" than in "hi gain" but still audible.
But if I hook up the HD700 to the Xonar, the "hum" is really less audible... It is there, but it's really less :-( (to my ears, which is probably the most defective measurement device ever designed !).

Now if I use the Oppo PM-3 headphone, the "hum" almost vanishes... but then a part of the audio message also does :-( (same measurement device mentioned earlier).

Not sure what conclusions I should take out of this :-(
Should I say the Oppo DAC/amp is closer to fidelity and thus reproduces the "hum" on the recording ?
Or is it too "resistive" and thus amplifies the "hum" ?

Still, I am surprised at how good the Xonar sounds for a device I bought (used) for about 100 dollars...
Like I said in the first reply, I was skeptical that you were hearing the hiss. The hiss can be audible if using high sensitivity iems.
In terms of the relationship between resistance and noise. First is the noise of the resistance itself, higher the resistance higher the noise. For the most part the noise is minimal and difficult to hear.

And I was again mistakenly thought you have the essence and you actually have xonar. Xonar has digital volume control meaning the noise is constant regardless of volume settings.
 

PenguinMusic

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Like I said in the first reply, I was skeptical that you were hearing the hiss. The hiss can be audible if using high sensitivity iems.
In terms of the relationship between resistance and noise. First is the noise of the resistance itself, higher the resistance higher the noise. For the most part the noise is minimal and difficult to hear.

And I was again mistakenly thought you have the essence and you actually have xonar. Xonar has digital volume control meaning the noise is constant regardless of volume settings.

Hi,
I have an ASUS Xonar Essence STU DAC/Amp combo and an OPPO HA2-SE DAC/Amp combo.
And several headphones : Sennheiser HD700, Audioquest NightHwak, B&O H9i, Philips Fidelio X2HR, Oppo PM-3 and B&W P5. I am tempted by the Meze 99 Classic... But not sure it will shine compared to what I alredy have (and of course some stuff I'll sell).

Regards.
 

JohnYang1997

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Hi,
I have an ASUS Xonar Essence STU DAC/Amp combo and an OPPO HA2-SE DAC/Amp combo.
And several headphones : Sennheiser HD700, Audioquest NightHwak, B&O H9i, Philips Fidelio X2HR, Oppo PM-3 and B&W P5. I am tempted by the Meze 99 Classic... But not sure it will shine compared to what I alredy have (and of course some stuff I'll sell).

Regards.
Oh ok. It is the big one. I thought it couldn't be that cheap. Anyway......

One the headphone side: I really like the pm3 and do not think meze 99 can provide anything better. But meze 99 is a well tuned headphone. So I personally won't recommend buying it. But it's quite inexpensive and good looking, the sound is pretty good as well. You can give it a try.
As you already have plenty of full size headphones, why not try moondrop chaconne? I was amazed by how good it sounds regardless of being an earbud type. It's quite comparable to full sized open back. No slamming bass tho.
 

PenguinMusic

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Hi,

Thanks for the time you took to reply.

For some reason (totally not rational...) I am not really into in-ear phones :-(
But I can always change my mind and will give the Chaconne a thought :)

Considering the bass amount that should be produced...
For that I have my own reference : and that is my stereo system.
That system can produce a nice amount of bass... but it also is somewhat a "Hi-Fi" system.
So it produces bass when the bass is on the record.
And then it is a nice, totally "dry" bass...
Else, it does not :)

I expect a headphone to do more or less the same.
That is why I am not a great fan of the Oppo PM-3. First it is a little too tight around my head and as such is not as comfortable as ALL others :-( I find it overall a little shy in all areas. It produces hat I would describe as a soft, well balanced sound, with an emphasize on mids. That is probably well for really really long listening sessions (except it is not comfortable enough for that) but I like it when the clocks in Pink Floyds "Time" rip my ears off with the trebles or when the big drum in "Cravanserai" (Loreena MacKennitt - Nights from the Alhambra) shakes the bottom of my belly with the bass it produces... And that, the Oppo PM-3 does not do :-(

On those respects, I think the Nighthaxk, the HD700 and even the H9i do a better job...

All in all, I'd say the Nighthawk and B&O have a nice sound to listen to rock/jazz/electro... but may lack some of the finesse of the HD700 when it comes to play Classicla music.

Of course, all the above written is purely subjective and does not depend on any measure... but my ears which is of course a highly controversial measurement reference device :)
 

JohnYang1997

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Hi,

Thanks for the time you took to reply.

For some reason (totally not rational...) I am not really into in-ear phones :-(
But I can always change my mind and will give the Chaconne a thought :)

Considering the bass amount that should be produced...
For that I have my own reference : and that is my stereo system.
That system can produce a nice amount of bass... but it also is somewhat a "Hi-Fi" system.
So it produces bass when the bass is on the record.
And then it is a nice, totally "dry" bass...
Else, it does not :)

I expect a headphone to do more or less the same.
That is why I am not a great fan of the Oppo PM-3. First it is a little too tight around my head and as such is not as comfortable as ALL others :-( I find it overall a little shy in all areas. It produces hat I would describe as a soft, well balanced sound, with an emphasize on mids. That is probably well for really really long listening sessions (except it is not comfortable enough for that) but I like it when the clocks in Pink Floyds "Time" rip my ears off with the trebles or when the big drum in "Cravanserai" (Loreena MacKennitt - Nights from the Alhambra) shakes the bottom of my belly with the bass it produces... And that, the Oppo PM-3 does not do :-(

On those respects, I think the Nighthaxk, the HD700 and even the H9i do a better job...

All in all, I'd say the Nighthawk and B&O have a nice sound to listen to rock/jazz/electro... but may lack some of the finesse of the HD700 when it comes to play Classicla music.

Of course, all the above written is purely subjective and does not depend on any measure... but my ears which is of course a highly controversial measurement reference device :)
Those are earbuds so not in ear type. That's why I like to recommend these. I used to recommend VX classic but chaconne is just another level(again).
 

PenguinMusic

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Those are earbuds so not in ear type. That's why I like to recommend these. I used to recommend VX classic but chaconne is just another level(again).

Hum... Yes. Earbuds.
Not too familiar with all those different kinds of things :)
Should indeed try some.
I have the B&W C5, but they're kinda in-ear I think.
 

Guetta

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Is it possible that I have bass distortion when I am using high gain on Atom, but don't have the distortion when using low gain at same listening volume? Can I say that I am 100% sure I can go higher in volume on low gain without bass getting distorted... I have Beyer DT990 Pro and Khadas Tone Board as a DAC
 

kidoman

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A little late with the question, but aren't the noise floors for the 2 amps which @amirm (with either gain setting) way below what a human can ever hear?
 

Robbo99999

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One question folks, why does Atom Amp show lower IMD distortion in High Gain Mode?
1629331938796.png

So although the SINAD goes down by 10dB using High Gain mode, the IMD improves using High Gain mode. Which is more important to sound quality: SINAD or IMD? I don't know a lot about distortion, but noise floor is being negatively affected (increased) by using High Gain which worsens SINAD, but is that more important to sound quality than lower IMD? I did some quick listening of Atom Amp in High Gain and it seems to sound a little cleaner than Low Gain......(roughly subjectively level matched only).
 

AnalogSteph

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One question folks, why does Atom Amp show lower IMD distortion in High Gain Mode?
Common-mode distortion on part of the opamp would be my guess. Sorta hard to get rid of entirely without a bootstrapped cascode input stage, though some more modern types are doing an admirable job.

IMD levels are very low either way, so I'd be unconcerned about the distortion part. Use whatever lets you keep the volume pot at about 10-11 o'clock at normal levels. The G6 has a decent amount of dynamic range, and none of your cans should exhibit audible noise from the Atom even at high gain, so you should have a considerable amount of leeway in terms of gain staging.

Kinda depends on your digital levels, too... if yours are like mine, not making it far above -10 dBFS too often (due to normalized levels including negative pre-gain), you won't have to pull down G6 output level as far as when playing everything at full tilt (which, mind you, I wouldn't recommend in this day and age).
 

Robbo99999

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Common-mode distortion on part of the opamp would be my guess. Sorta hard to get rid of entirely without a bootstrapped cascode input stage, though some more modern types are doing an admirable job.

IMD levels are very low either way, so I'd be unconcerned about the distortion part. Use whatever lets you keep the volume pot at about 10-11 o'clock at normal levels. The G6 has a decent amount of dynamic range, and none of your cans should exhibit audible noise from the Atom even at high gain, so you should have a considerable amount of leeway in terms of gain staging.

Kinda depends on your digital levels, too... if yours are like mine, not making it far above -10 dBFS too often (due to normalized levels including negative pre-gain), you won't have to pull down G6 output level as far as when playing everything at full tilt (which, mind you, I wouldn't recommend in this day and age).
Thanks for the response there, I got more to the bottom of what was going on with some posts by @JohnYang1997 over here where I was asking too:
https://www.audiosciencereview.com/...-jds-labs-atom-headphone-amp.5262/post-884836
Basically I was misinterpreting the IMD graph, I worked out that High Gain is about 7dB worse in distortion than the Low Gain mode. So I'm making sure I use Low Gain now.
 

Pechorin

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Guys, I'm not knowledgeable about these things and I can't find an answer to a question I've wanted to ask for some time.

If an amp at low gain has 0 db of amplification (Asgard 3, for example), why would you use an amp in that case if it's not providing any boost in volume? In my case, my Asgard 3 is connected to my iMac via an RCA cable.

Thanks.
 

Robbo99999

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Guys, I'm not knowledgeable about these things and I can't find an answer to a question I've wanted to ask for some time.

If an amp at low gain has 0 db of amplification (Asgard 3, for example), why would you use an amp in that case if it's not providing any boost in volume? In my case, my Asgard 3 is connected to my iMac via an RCA cable.

Thanks.
My understanding is that you would use a headphone amp to ensure a higher SINAD being transferred to your headphones - you're running the DAC at it's near max level where it gets it's best SINAD usually, and then you're controlling the volume with the analog volume control on the headphone amp, so the SINAD is being better preserved because if you just controlled volume digitally then the noise floor would stay at the same level and your useful signal decreases, so the signal to noise ratio worsens......but with analog volume control on a headphone amp the signal to noise ratio is staying the same (I think) & not decreasing when you lower the volume level on the analog pot of the headphone amp, so you're allowing the DAC to operate at it's best point of output and then you're preserving that aspect as you control the volume using the analog volume control on the headphone amp. Also a quality headphone amp can have better distortion figures and more optimal lower output impedances than generic headphone out ports on laptops & PC's & phones, etc. So using a dedicated good measuring headphone amp in Low Gain (no amplification, just attenuation) can provide a measurably "cleaner" signal and hopefully a "cleaner" sound when you use it with your headphones, although the last point is up for debate as to how measurably "good" it must be until you no longer hear an improvement or difference.

Then you've got the High Gain function of a headphone amp, which is all about boosting the signal just to make it loud enough for hard-to-drive headphones.....so as you've alluded to, the purpose of a headphone amp is obvious in this use case. There's still the benefits of the points raised in the previous paragraph that can also be associated with using a headphone amp in High Gain, but generally as Amir showed in his review - the High Gain function does make the measurements worse than the Low Gain.
 

Pechorin

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My understanding is that you would use a headphone amp to ensure a higher SINAD being transferred to your headphones - you're running the DAC at it's near max level where it gets it's best SINAD usually, and then you're controlling the volume with the analog volume control on the headphone amp, so the SINAD is being better preserved because if you just controlled volume digitally then the noise floor would stay at the same level and your useful signal decreases, so the signal to noise ratio worsens......but with analog volume control on a headphone amp the signal to noise ratio is staying the same (I think) & not decreasing when you lower the volume level on the analog pot of the headphone amp, so you're allowing the DAC to operate at it's best point of output and then you're preserving that aspect as you control the volume using the analog volume control on the headphone amp. Also a quality headphone amp can have better distortion figures and more optimal lower output impedances than generic headphone out ports on laptops & PC's & phones, etc. So using a dedicated good measuring headphone amp in Low Gain (no amplification, just attenuation) can provide a measurably "cleaner" signal and hopefully a "cleaner" sound when you use it with your headphones, although the last point is up for debate as to how measurably "good" it must be until you no longer hear an improvement or difference.

Then you've got the High Gain function of a headphone amp, which is all about boosting the signal just to make it loud enough for hard-to-drive headphones.....so as you've alluded to, the purpose of a headphone amp is obvious in this use case. There's still the benefits of the points raised in the previous paragraph that can also be associated with using a headphone amp in High Gain, but generally as Amir showed in his review - the High Gain function does make the measurements worse than the Low Gain.
Thank you for that detailed and fairly easy to understand explanation. Makes sense.
 

rarewolf

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For different IEM drivers, e.g., DD vs planar, and given only a slight 5db difference in volume for any given dongle volume setting, is their any reason at all to choose one gain setting over the other? For example, planar drivers are said to be “typically” difficult to scale down to low-power dongle amplifiers, and that increased voltage helps.

How is high gain generally achieved? E.g., doubling the voltage?

… tia :)
 
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