bartzky, post: 14022154, member: 406035 a écrit :Alright guys: Let's talk about cables
First of all Fibae IEMs take a special position as their impedance responses are basically flat. Many times existing sound differences of cables can be attributed to a different cable resistance in combination with the IEM's impedance response. Let's take a look at one of the most prominent examples: The Campfire Audio Andromeda. The diagram below show's it's impedance response.
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It can easily be seen that the impedance varies wildly across the frequencies. The Andromeda's stock cable has a resistance of 1 Ohm in total. If you now add resistance by changing to a different cable or using a source, the frequency response will change according to the IEM's impedance response. Take a look at the following graph:
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The curves represent the deviation in frequency response relative to the stock frequency response measured with the stock cable and a ~0 Ohm source. So the straight yellow line is stock and therefore flat. From there on it goes 2, 4, 8, 16, 32 and 64 Ohm from top to bottom. The higher the added impedance gets, the more the frequency response changes. By comparing this graph to the above impedance response there easily can be seen that the changes in frequency response perfectly follow the shape of the impedance response.
So as the impedance response of Fibae is basically flat, there won't be any changes to the frequency response by adding or reducing the resistance of the cable or output impedance.
Though people in this thread claim to hear differences between cables with their Fibaes. Probably they're all deaf and blessed with a great amount of imagination, one might say. That may be, but let's dig a bit deeper.
I gonna concentrate on the Fibae 1 as it's most prone to the following effects due to it's lowest impedance of the Fibae lineup. CA's specs for the F1 tell us it's impedance is 5.6 Ohm @1kHz, which is extremely low. The stock cable is from PlasticsOne and has got a resistance of 3.2 Ohm in total. So the F1's impedance minus it's cable is just 2.4 Ohm. That low number leads to some unusual effects.
Let's say you change the cable to one that's resistance is 1 Ohm total, which is not an unusual number. As the voltage drop across the cable decreases, you will instantly gain about 5 dB of volume without touching your volume control at all. Usually more volume equals better sound, so the other cable is most likely considered to be better sounding.
Another effect occurs due to how the stock cable is constructed. PlasticsOne uses three independent wires, so both channels share the ground wire. I won't go to much into detail, but there's a voltage drop across the ground wire, that does actually drive the respective opposite earpiece. This effect is called crosstalk. Usually the amount of cable introduced crosstalk is very low as the IEM's or headphone's impedance is high in comparison to the resistance of the shared wire. In this case, however, things are different. Calculations with 2.4 Ohm for the F1 w/o cable and 1.6 Ohm for the shared wire resistance lead to the following result: The PlasticsOne cable actually introduces a crosstalk of about -11 dB to the F1.
Crosstalk is often equated with unintended crossfeed, but actually those two are quite different. Crossfeed adds a bit of the signal into the opposite channel, while crosstalk is usually 180° out of phase and therefore subtracts a bit of the signal from the opposite channel. As a result the stereo center loses some volume, as everything on the sides get's louder. If you like to experience what crosstalk sounds like you may test a DSP setting I made for the EQ Apo:
If you chance to cable with 4 wires and therefore no shared ground wire, the cable introduced crosstalk will be (mostly) gone. Same is true for balanced connections. Btw. cables with 4 wires are very common, so you most likely will have got one if you bought an aftermarket cable.
,d'où une méfiance croissante et la constatation que jeter l'argent par les fenêtres est un excellent moyen de s'intéresser à l'impédance :mrgreen:
Ca tourne en boucle... 
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