[kramer5150]

Bit of a noob here.... Can someone help me make a 75 ohm adapter? I want to use the resistors inline with my KSC75.

What radio shack part number or digi-key part number resistor do I need? Id like to use highest quality resistors, but I dont want this little project to cost more than say ~$20.

I already know I can buy one, but I want to make my own.

Thanks!!
Garrett

 

[aeriyn]

It's really quite simple.

All you have to do is get some 1/8 watt 1% metal-film 75ohm resistors. Unless you have an uber meter, you're not going to be able to match them any closer than they already are (1% of 75ohms is .75ohms, so the imbalance will likely be negligible, it has been in all the adapters I've made).

Take a 1/8" miniplug and an inline 1/8" minijack... basically, you're making a very short interconnect here. Three wires from the left, right and ground to the plug. Except with this project, you need to put those resistors somewhere between the L and R signal wires. Best place I've found to put them is to solder them directly to the lugs of the miniplug, then solder the wires to the other side leads. This will prevent them from being in a place where the cable will bend because the body of a good miniplug will encase them. Heatshrink them to prevent shorts, clean up the little cable, heatshrink it up or put techflex on it, however you want to go.

 

[Syzygies]

I'd agree with aeriyn's description of the mechanics of making one of these; I've made several. However, using RadioShack parts between Ety 4p canalphones and a railsplitter CMoy, I didn't like how mine sounded. I had a chance to audition Etymotic's $65 cable at their booth at MacWorld, and theirs sounded better. I had my iPod but not my CMoy along, and at full volume the iPod sounded pretty bad. (People who scrimp on buying a line out generally settle at 85% to 90% iPod volume to their amp, a definite sweet spot.)

My plan is to put two output jacks in my PIMETA, and wire one of them with 75 ohms resistance, so I can choose 4p or 4s with no extra cables.

I'd use the best resistors you can find.

 

[kramer5150]

Thanks for the details aeriyn!!!

It didnt sound all that difficult.

Garrett

 

[looser101]

If your soldering skills are pretty good you can make an ultra compact adapter by following Sijosae's example. It's actually a compact crossfeed but you get the idea.

http://www.headphoneamp.co.kr/bbs/zb...esc=asc&no=131
http://www.headphoneamp.co.kr/bbs/zb...esc=asc&no=133

Good Luck

 

[CRS401]

What does the 75 ohm adapter do?
sorry for my noobness.

 

[jerb]

amps sometimes have problems driving low impedance (sp?) phones. this cable adds 75 ohms to the impeadance (sp?) making theme easyer for the amp to drive.

 

[nikongod]

as an almost relivant thought:

has anyone thought of putting the resistor on the side of the ground chanel? ie where the 2 headphone drivers share a comon wire. with only 1 resistor, you could probably fit everything (resistor, and all necessary wires) into a jack that resembled an extension cable...

just a thought.

there is probbly some excelent reason NOT to do this. skool me.

 

[Syzygies]

Quote:

Originally Posted by CRS401 What does the 75 ohm adapter do?

Etymotic's flagship canalphone is the 4s, which requires a good amp, and trades bass for detail. Their 4p has 75 ohms less resistance, and can be driven e.g. straight from an iPod.

In my opinion this resistor belongs in an amp, because it's only useful with an amp, and who needs another adaptor to juggle?

 

[aeriyn]

Quote:

Originally Posted by nikongod there is probbly some excelent reason NOT to do this. skool me.

Yeah, the reason is it won't do anything. The ground wire doesn't carry a signal.

 

[nikongod]

Quote:

Originally Posted by aeriyn Yeah, the reason is it won't do anything. The ground wire doesn't carry a signal.

yes it does cairy a signal.

i think it would be a bad idea though for situations when the music plays un-evenly for one reason or another. example:anything by pink-floyd.... or this half awsome, half crap nirvana cd set i got my hands on.

in this instance, all of the resistance would be added to one driver. where if both were playing nearly equally the resistance would be divided nearly equally.

some may even like the sound. dunno. some thigs which are perfect are only perfectly terrible. where some screwups are totally acceptably screwed-up.

 

[barqy]

Hi, sorry to bring up and OLD thread but didn't want to start a new one.

What is sufficient wattage for resistors (75ohm)?

I thought 1/4W would be enough, but was told 1/2W is better just in case the amp needs it?

Also, does the brand of the resistor matter in this situation?

Thanks in advance.

 

[threEchelon]

Yes, the brand matter since the resistor is right in the signal path. Go botique!

 

[mADmAN]

Quote:

Originally Posted by aeriyn /img/forum/go_quote.gif It's really quite simple. Best place I've found to put them is to solder them directly to the lugs of the miniplug, then solder the wires to the other side leads. This will prevent them from being in a place where the cable will bend because the body of a good miniplug will encase them. Heatshrink them to prevent shorts, clean up the little cable, heatshrink it up or put techflex on it, however you want to go.

ive always wondered how u manage to fit the resistors in the plugs..i cant seem to fit them in my neutriks. too little space.

is it ok to solder 1 on the male side (left channel) and the other resistor on the female side (right channel)? or do they have to be at the same spot?

 

[wgr73]

1/4W would do. I doubt you would need any more than that. If you want to be safe, they are a little bit more money(not much, a few cents). So, to be safe just go for that.