Volume level

[zenki]

I got both cca c10 and kz zs5.
Using PC setup (PC->external DAC->RCA cable->Adapter->3.5mm->IEM), why is cca c10 loudnesss is around twice of the kz zs5 (using same volume level in PC)?
Using PC setup (PC->external DAC->RCA cable->AMP->[6.25->3.5mm adapter]->IEM), the loudness issue still persist. (using same volume level in PC)

This issue does not occur if I use a mobile phone for both IEMs. (c10 has boosted frequencies is some areas compared to zs5 but loudness about the same)
Any experts can help?

 

[elira]

I don't see any issue with that. It's a matter of impedance and efficiency.

 

[zenki]

but why is it the different between PC and mobile phone?
@amirm maybe you can help?

 

[solderdude]

The impedance and efficiency makes the difference here as @elira already mentioned.

The CCA = 108dB/mW = 123dB/V and 32 Ohm.
The KZ = 106dB/mW = 124dB/V and 16 Ohm.

So with the same voltage = volpot position they should sound equally loud.
This is the case with the phone as it most likely has a very low output resistance which is kind of mandatory for low impedance IEMs.

When connected to a device with a higher output resistance (say the line out of a DAC or a headphone output of an amp with a higher than usual output resistance) things change due to the lower impedance of the KZ which, due to voltage division, gets a lower voltage so also lower loudness with the same volume setting. Therefor the higher impedance earphone (the CCA) will be louder under these circumstances.

Case solved... no mysteries ... just science.

Begs the question which amp you used that has a high output resistance.

 

[zenki]

smsl sapii.
Not sure about the value of its output resistance though.

 

[solderdude]

Is a TPA6102A based and 10 Ohm output resistance which is too high in this case.

This means the KZ will sound -2dB less loud.

 

[zenki]

Can you show the calculations how to get that -2dB?

 

[solderdude]

Ohms law and log20 of the resistor divisions.

log(32/42) x 20 = -2,36dB
log(16/26) x 20 = -4.21dB
so 1.85dB difference.

It is actually -1.85dB if one wants to be more exact but the impedance will also not be Ohmic so in practice it will differ and be around the 1.6 to 2dB most likely.
In any case a noticeable difference.

When driving from the output of a DAC or 100 Ohm output R amplifier it is even worse and the difference will be 5dB.

 

[zenki]

Hmm I couldn't tell the difference between the DAC and amp output in terms of volume loudness.
so I would assume they got the same 10 ohm output?

and Thanks for the explanation.

so is there any way around this? (besides using a different amp?)

 

[digicidal]

so is there any way around this? (besides using a different amp?)

Reduce/boost the volume slightly? Sorry, not trying (at least not deliberately) to be a smartass... but I'm struggling to understand the actual problem in practice. Are you looking to level match the two sources (PC/Phone), or the IEMs in order to attempt ABX comparison? In normal listening I assume you are not going back and forth between the two all that often - though I admit that's quite possibly an erroneous assumption on my part.

As you should have digital volume control on the PC side... couldn't that simply be matched on the source output side to the level presented by the phone (I mean depending on which IEM you're using at the time). Or are you listening to both IEM's simultaneously somehow I can't imagine?

 

[zenki]

I'm using IEM for my PC, instead of speakers and found out that one is much louder then the other.
It's kinda annoying because I couldn't use it for long periods (it'll kill my ears) and have to tinker with the software volume level.

With the amp setup now, it still have the issue except that I have hardware volume knob but I can't even use it past 25% (25% is actually killing me ears in some songs) because it'll be too loud.

 

[Blumlein 88]

I'm using IEM for my PC, instead of speakers and found out that one is much louder then the other.
It's kinda annoying because I couldn't use it for long periods (it'll kill my ears) and have to tinker with the software volume level.

With the amp setup now, it still have the issue except that I have hardware volume knob but I can't even use it past 25% (25% is actually killing me ears in some songs) because it'll be too loud.

Assuming a log volume taper, which is the most common, 25% is about -12 db from max level. So that really isn't so bad. Sounds like -6 db in software might put your volume taper in a more comfortable position.

 

[zenki]

software volume is -10db and still too loud (btw this is for c10).
If I use zs5, I can crank up software to max(0 db) and 25% on hardware volume knob is still kinda ok.

 

[solderdude]

Hmm I couldn't tell the difference between the DAC and amp output in terms of volume loudness.
so I would assume they got the same 10 ohm output?

and Thanks for the explanation.

so is there any way around this? (besides using a different amp?)

As long as there is no change in tonal balance simply turn up the volume a bit.

A substantial difference in volume would mean a difference above 3dB but as the impedance can vary a lot over the audible range that could be possible.
When you want to get rid of it sell the SMSL and buy the Atom.

When your IEM is too loud I recommend to use a passive attenuator.
This cures both the high output resistance problem and volume control issue at once.

 

[zenki]

Got it.
Thanks to all who helped