[dimm0k]

Looks like I finally made the Etymotic ER4P -> S cable with the help of a coworker, shrink tubes, 2x 75ohm resistors and a gold plated RadioShack headphone extension cable. Tried to duplicate what Xin did, but it looks like RadioShack changed up their cables and so I had to cut the cable in the middle rather than at the tip. Anyone know where I can get the 1/8" connectors so I can make some more of these?

 

[dimm0k]

Well I wasn't satisfied with having the resistor in the middle of the cable so I decided to change it up a little bit. After looking at my older RS headphone extension cable that was secured with wax I noticed that it looks similar to the one I modded for the 75ohm cable so I decided to brave it and remove the cable entirely from the connectors. In the end I was able to duplicate the cable on Xin's site with the RS cable, however it took a lot of time probably because it's my first time and I was working with some crude tools. Made me realize that I need a better solder than this cheap piece from RS.

 

[Logistics]

Could you explain to me what the purpose is of this resistor? What effect does this have on the cable? Could you instead simply use 75-Ohm fixed impedance cable such as those used for Video? Or perhaps even move to CAT cable which is 100-Ohm fixed?

 

[dimm0k]

It is supposed to convert the Ety ER4P to ER4S, which has a more accurate representation of what the recording is supposed to sound like... The following threads should explain better than I can...

http://www.head-fi.org/forums/showth...light=etymotic
http://www.head-fi.org/forums/showth...&threadid=1375

 

[mephisto]

Quote:

Originally Posted by Logistics /img/forum/go_quote.gif Could you instead simply use 75-Ohm fixed impedance cable such as those used for Video? Or perhaps even move to CAT cable which is 100-Ohm fixed?

No - what you're talking about is the cable's Characteristic Impedance not its Impedance. These are two completely different quantities which just happen to both be measured in ohms. Characteristic Impedance is a measure of how electromagnetic waves propagate along the cable and has no relevance to audio.

 

[DouglasQuaid]

Quote:

Originally Posted by mephisto /img/forum/go_quote.gif No - what you're talking about is the cable's Characteristic Impedance not its Impedance. These are two completely different quantities which just happen to both be measured in ohms. Characteristic Impedance is a measure of how electromagnetic waves propagate along the cable and has no relevance to audio.

Tell that to every person who has owned both the er4p and the er4s, which are separated only by a different set of resistors located mid-length of the cable.

 

[mephisto]

Quote:

Originally Posted by DouglasQuaid /img/forum/go_quote.gif Tell that to every person who has owned both the er4p and the er4s, which are separated only by a different set of resistors located mid-length of the cable.

uh? You've completely missed the point.
I know that the only difference between the er4p and er4s is the 75 ohm resistance. 'Logistics' was asking whether the discrete resistors in the adaptor could be eliminated by using '75 ohm' video cable instead. The answer is 'NO' because 75 ohm cable doesn't actually have a resistance of 75 ohms - it's just wire, 0 (ish) ohms. okay?