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Do any DACs apart from RME have equal-loudness features?

JohnYang1997

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Basically the fourth one from the bottom. And I don't recommend boosting lower bass.
so roll the lower bass off a bit, +4db at 50hz, +3db at 100hz then follow the curve til 1khz.
 

Certainkindoffool

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8.5 Loudness

Another legacy of HiFi amplifiers: there has not been a single one missing a feature called Loudness. It tries to address the changes in frequency-dependent hearing sensitivity over different volume levels. If one listens to music loud, then drops the level by at least 20 dB, sound loses punch and glitter. HiFi amps tried to fight this effect by adding more bass and treble the lower the volume was set.

Unfortunately that never worked as intended, and just became an additional bass/treble booster. Reason: the manufacturer of the HiFi amp could not know what volume any position of the volume knob equals at the customer’s home. Room size, room dampening and efficiency of the used speakers are all unknown.

But the effect of loss in perceived sound exists (read about the Fletcher-Munson curves), and can be easily reproduced with any serious gear by comparing normal volume and DIM state (usually -20 dB).

The ADI-2 Pro offers Loudness for both analog stereo outputs, and probably is the first time that Loudness works as intended. The user can decide how much maximum gain in Bass and Treble should occur at lower volume settings.

The user also sets the Low Vol Reference, where maximum gain is achieved. After extensive tests a 20 dB range has been defined as range for maximum gain to no gain while increasing volume. That seemed to be the perfect definition of the range that needs to be addressed by Loudness.

Here is an example on how it works: the user’s typical lowest level listening volume is at -35 dB at the unit. This value is now set by the user as Low Vol Ref in the Loudness menu.

Then Bass and Treble Gain can be set between 0 and +10 dB. Default is +7 dB for both. Increasing the volume by turning the Volume knob causes the gain in Bass and Treble to be lowered smoothly over a range of 20 dB.

So when Volume is set to -15 dB, the music is not only quite loud, but Loudness’ Bass and Treble are then at 0 dB gain. See chapter 34.12 for graphs.

No matter how sensitive the connected phones or speakers are, no matter how much increase in Bass and Treble are desired – with the ADI-2 Pro one can finally adjust it to meet the personal hearing and taste. Loudness finally works as it should have worked from the start - another unique feature in the ADI-2 Pro.

https://archiv.rme-audio.de/download/adi2pro_e.pdf

Thank you for this post! Happened to read it the evening before I found an open box RME ADI-2 for $1050 Canadian. Jumped on it, despite already having a more than capable dac.

This is a brilliantly implemented feature and I love it. My wife happens to have super human hearing, and it's always been a struggle to find a volume level that works for both of us. We are both very happy right now.
 

wisechoice

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This is a very interesting feature and discussion.

It appears to me that something close to the version of loudness compensation that @JohnYang1997 is suggesting here has been implemented, deliberately or not, in the SRH 1840 headphones. This was measured by @solderdude, who called it a design error in his otherwise positive review of the headphones. Maybe it is an error from the perspective of linearity, or maybe there is another way to look at it.

I now have the ADI-2 Pro in my office and look forward to testing this feature with my speakers. If I’m using my SRH 1840, it may be redundant or the adjustment may need to be more subtle. The ADI-2 is also connected to a UCX II via optical, and I can easily AB a 20dB difference with the dim button in TotalMix as suggested by @MC_RME. [EDIT: There's actually a dim button on the ADI-2 remote, too. Duh. And it triggers the loudness compensation, whereas dimming on a device upstream wouldn't.]
 
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solderdude

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The SRH1840 has a max. excursion problem.
There is no other way to look at it alas. :(

1: it is not elevating bass at lower levels, certainly not up to the needed levels. It is compressing (flattening) at higher SPL which also affects all other frequencies (modulates them)
2: treble also does not increase slightly at lower levels.
3: Distortion rises at higher levels which becomes even more obvious and unwanted at higher levels.

As long as one doe not play very loud the 1840 sounds fine and does not get more bassy at lower levels.
 

wisechoice

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The SRH1840 has a max. excursion problem.
There is no other way to look at it alas. :(

1: it is not elevating bass at lower levels, certainly not up to the needed levels. It is compressing (flattening) at higher SPL which also affects all other frequencies (modulates them)
2: treble also does not increase slightly at lower levels.
3: Distortion rises at higher levels which becomes even more obvious and unwanted at higher levels.

As long as one doe not play very loud the 1840 sounds fine and does not get more bassy at lower levels.
Interesting, thanks. I agree that it sounds fine as long as you don't play it very loud. And it's really excellent for classical and jazz, second to almost no other headphones that I've heard.

Would you amend anything that you wrote in the review? e.g.:

at low listening levels there will be more bass than at higher listening levels. This is caused by non-linearities at higher excursions of the membrane. We hear it differently because of equal loudness contour effects.
Anyway… this should not be there and can be seen as a design error.

By the way, I used the ADI-2 to dial in your suggested trim for those headphones around 8kHz. It sounded audibly better, even though I never found them particularly sibilant before. So I might take you up on ordering the analog filter, if you're still making them.

I also dialled in more bass and very slight warm tilt. Digital parametric EQ can be really powerful, and I find the knobs on the DAC a very appealing way to adjust and experiment. And it's also very useful to compare directly with a second set of headphones.

This is getting further off topic, but I had an opportunity to try out the Dan Clark Stealth, the HD 800S and the HE-1 (!) recently. I was ready to spend the money on one of the first two, but although they both sounded excellent (and quite different from each other), I didn't feel they were giving me anything that I yearned for terribly after a year with the 1840.

The HE-1 sounded perfect to my ears, though. I couldn't detect anything wrong with the music playing through them. Phenomenal engineering.
 

wisechoice

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To steer things back on topic, I noticed the DAC/amp for the HE 1 had very good adjustable crossfeed, but no loudness dial that I remembered (I checked my photos of it to be sure). However, the manual for the HE 1 states:

Sennheiser headphones sound exceptionally good at low and medium levels.

If it's true, I wonder why that is.
 

solderdude

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Would you amend anything that you wrote in the review? e.g.:

At low (background) listening levels there will be 3dB more bass than at higher (loud) listening levels. This is caused by non-linearities at larger excursions of the membrane.
We hear it differently because of equal loudness contour effects which only just partly 'compensates' for the perceived loudness difference in the bass.
Anyway… this should not be there and can be seen as a design error.

So I might take you up on ordering the analog filter, if you're still making them.
Yes.

To steer things back on topic, I noticed the DAC/amp for the HE 1 had very good adjustable crossfeed, but no loudness dial that I remembered (I checked my photos of it to be sure). However, the manual for the HE 1 states:
Sennheiser headphones sound exceptionally good at low and medium levels.
If it's true, I wonder why that is.
That is a marketing talk excuse for 'Sennheiser headphones start to distort more at higher listening levels' which they do. Granted... at higher levels than the Shure.
 

wisechoice

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At low (background) listening levels there will be 3dB more bass than at higher (loud) listening levels. This is caused by non-linearities at larger excursions of the membrane.
We hear it differently because of equal loudness contour effects which only just partly 'compensates' for the perceived loudness difference in the bass.
That's helpful, thanks. And more or less what I was thinking, even though I understand that it's a design error.

I see you also updated the review itself. Wasn't expecting that :)
 
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