Wow Thanks for the explanation.
I am aware of the fact that analog volume control is not perfectly linear but on Nano iDSD it seemed to be too steep in the lower volume.
The graph explains
I ordered Micro iCAN and I just hope it won't be this bad.
Hi,
A usable volume control range of 60dB (that is a 1:1000 Ratio) is commonly more than sufficient to achieve good control over the volume levels. To be witty, it covers the loudness range between extremely loud factory or rock concerts to something slightly above a quiet whisper. So it should be fine in pactice. Many traditional analogue potentimeters have even less usable adjustment range.
If the maximum volume is (say) 105dB peak with an 85dB average sound level (this is quite loud) attenuating by 60dB means that the sound level of the music would be around 25dB, or within the region of the noise of a quiet PC Fan or the background noise of a very quiet room.
The problem is that many IEM's and other headphones these days seem to be in a loudness race, with some headphones approaching 120dB/mW output.
If we take an example of a IEM from Brand X with Model Y we find that Model Y has 119dB/1mW efficiency and 36 Ohm Impedance. The iDSD nano outputs 1.7V with the volume control at maximum and with this IEM this equals 138dB (yes, this is totally insane)! By comparison a Chainsaw closeup is usually considered equal to 100dB, meaning this IEM with the iDSD nano volume control all the way up will be 100 times as loud as a chainsaw close up.
Worse, if we turn the volume down by 60dB, we are left with around 78dB peak levels and if the program material is modern, heavily compressed music the actual average at the minimum possible voolume setting of the iDSD will be around 68dB, which is already quite loud.
There is a simple solution (other than changing the headphones), namely adding an iEMatch attenuator in line with your headphone. They are available in 12dB and 24dB.
In the case of the previous 138dB IEM, using a 24dB attenuator reduces the maximum (peak) SPL to a still loud but sensible 114dB, which with well recorded high dynamic range music (20dB crest factor) means an average music level of 94dB (quite loud) and for modern heavily compressed music a level of around 104dB, which is similar to the noise levels in the cabin at takeoff for some of the louder Passenger Jets (getting dangerous here if played long term at this level).
Equally, with maximum attenuation of the volume control the lowest output would be around 44dB for heavily compressed music, which is pretty quiet, similar to a normally quiet office or living room. So locate the ideal attenuator, would be our recommendation.
Conclusion
No audio component manufacturer can halt the gradual "loudness race to the top." Given the spectrum between IEMs and headphones, we can all only aim for somewhere in the middle. If a specific headphone or IEM needs to be dialled in, then we recommend an attenuator.
