What is an "ohm-adaptor" and should/where do I get one?

[jaredtkatz]

Pretty self explanatory. I know "ohms" are associated with impedance, but why do people get ohm adaptors? I currently have an ibasso d2 boa and super fi 5 pros. I use the d2 boa as a DAC when using my laptop and use an LOD to connect my iphone 3g to the boa (both set ups go to the SF5Ps). Should i be interested in an ohm adaptor? I know my SF5P are low impedance and the d2 boa can drive higher impedance. This may or may not be related, but I'll ask anyway: should I (i do) use the attenuator that came with my SF5P out of the D2 boa if i get a hissing noise? Is this reducing the sound quality?

Sorry if that was convoluted. Thanks for the help in advance.

 

[S J]

People typically get impedance adapters to eliminate background hiss from very sensitive IEMs on noisy sources. Whether or not you should get one/use the attenuator you have depends on whether or not you can hear background hissing (i.e. when no music is playing, you still hear a bit of static in the background), and whether or not it bothers you.

I've never heard a D2, so I don't know if hissing is a common problem with it; try turning up the volume of your PC/iPhone (~2/3 or so) to get a better signal to noise ratio going to your D2, then use the D2 to control volume. If that doesn't make the hissing go away, by all means, try the attenuator. I doubt it will make a noticeable difference in SQ unless the potentiometer in it is really really crappy, but maybe your ears are more discerning than mine

If you do hear a difference in quality, then you could look into plug-style impedance adapters that have a set impedance; these are probably built to tighter specs than your typical Radioshack volume control.

Something like this or this. I one of the ones off ebay, works great

 

[Ishcabible]

You use resistors. It lowers the amount of bass (it does more things, but bass is one of the more drastic changes, however the change isn't VERY drastic) in iems (also reduces hiss) and vice versa in full sized headphones.
I'm making one for myself and haven't ordered the parts yet. PM me if you would like me to make a 50 ohm impedance adaptor for about $15.
I know this post might not make sense so I'll edit it if you want me to.
Ugh I got beat for the first answer by 3 minutes. I really took a long time writing this apparently.

 

[jaredtkatz]

thanks for all the help

 

[jaredtkatz]

ok, still have a question. it sounds like an impedance adaptor does the same thing as the attenuator that came with my SF5pros (am i wrong?). To answer SJ's question, yes, there is a little hiss from the D2, but my attenuator eliminates it. What would an impedance adaptor do and how is it different?

 

[S J]

Quote:

Originally Posted by jaredtkatz /img/forum/go_quote.gif ok, still have a question. it sounds like an impedance adaptor does the same thing as the attenuator that came with my SF5pros (am i wrong?). To answer SJ's question, yes, there is a little hiss from the D2, but my attenuator eliminates it. What would an impedance adaptor do and how is it different?

Yes, they do the same thing. When I say "impedance adapter" I mean a fixed impedance, plug-style adapter like the two I posted above. By "attenuator", I meant something like a in-line volume control with a potentiometer (flywheel that spins to control volume--spinning it changes the impedance added to the line), like what comes with your SF5P's. The terms are largely interchangeable, and I don't know if others use them the same way I do, but this is what I mean when I use the terms in my first post. The only difference is form-factor. I don't like dealing with the short jumper cables attached to variable attenuators, so I use the plug-style fixed resistance adapters.

 

[jaredtkatz]

this makes sense. thanks for the explanation. yeah, the super fi attenuator is at a fixed impedance, no potentiometer (essentially a volume knob?). thanks again.