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Impedance Adapters/Cables | Explained & Listed

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  1. WiR3D
    I created this thread because impedances can be very confusing to non-DIYers. an impedance adapter in the general actually refers to an impedance INCREASING adapter, and is often used incorrectly. Here is a good article explaining why impedance matching is important.
    Output Impedance
    Impedance Increasing adapters
    Generally referred to when referring to an impedance adapter, but often used incorrectly, myself included. It essentially increases the output impedance of the source or amp.
    Used to allow you to use more sensitive IEMs with your desktop amps. It lowers volume and raises the noise floor, essentially making your IEM's less sensitive.
    Etymotic ER4P -> ER4S adapter $50 75 Cabled
    Hisound Golden Impedance Cable $60 70 Cabled
    Ultimate Ears $50 100 Cabled
    APureSound Mini to Mini $45 75 Adapter
    APureSound Mini to Mini $45 120 Adapter
    APureSound Mini to 1/4" $55 75 Adapter
    APureSound Mini to 1/4" $55 120 Adapter

    Custom Resistance:
    APureSound $60 Mini to Mini Adapter
    APureSound $70 Mini to 1/4" Adapter
    Ebay: AW Audio Accessory $22 Mini to 1/4" Adapter
    Ebay: AW Audio Accessory $40 Mini L shaped Adapter
    Ebay: AW Audio Accessory $18 Mini to Mini Adapter
    Ebay: WeMakeAmp Audio Workshop $12 Mini to 1/4" Adapter
    Ebay: WeMakeAmp Audio Workshop $11 Mini to Mini Adapter

    I would like to update this list, so please add suggestions.
    (Faux) Impedance Decreasing Adapters
    What these would do is decrease the output impedance of a source or amp and allow it to pair better with certain low impedance headphones, which are affected quite a bit by bad impedance matching.
    Note: not impedance transformers, since they can degrade sound quality, it is not a problem in very high end Amps such as those from Woo audio.
    Note: The output impedance is not changed in any way, it appears lowers from the headphones perspective, and the load impedance appears higher from the amps perspective,
    What you need is an adapter that essentially has the following configuration(for each channel,) the downside is it wastes power, but using the ASUS Xonar essence STX as an example it will lower the output impedance of the soundcard from 10 ohms to about 4 ohms. And still have a maximum SPL of above 110db.
    Using a 24 ohm resister instead of the 20 ohm will result in a slightly higher LOAD impedance.
    This is relatively simple to make just as are the impedance increasing adapters above, I have yet to find any for sale, I will be making my own for experimental purposes.
    How do I build one and which resistors do I use?

    Disclaimer: I take no responsibility for any damage to your amp or source, it is your duty to ensure you are using the correct components, and to double check and tripple check.
    Thanks to:
    Chris J
    Steve Eddy
    scrypt, kidcharlemagne, ertai and 5 others like this.
  2. WiR3D
    wow no1 knows any others?
  3. Byakushiki
    There was this UE impedance adapter, not sure if it counts as a cable though. I believe it was rated at ~100 ohms.
  4. WiR3D
    I found it, thanks
  5. WiR3D
  6. WiR3D
    updated again
    EDIT: Weeee post 100
  7. WiR3D
    I'm contemplating stating the resistors used, it will take sum time to find out, if there is a demand for it, I will do it.
  8. WiR3D
    updated again
  9. WiR3D
    I'm amazed this isn't getting more attention, especially with the importance of impedance matching.
    CapnCook likes this.
  10. Chris J
    I'm not sure this does what you think it does?
    What are you trying to do?
    A true impedance matcher is a transformer.
  11. WiR3D
    well originally and from popular consensus, in the posts i read, it appeared that they would raise the noise floor, lower volume, and ADD to the resistance of the headphones.
    However I am currently being educated by stv014 and it seems its not the case.
    What the adapter does, is pretty much raise the noise floor and lower and the volume, BUT it adds to the AMPs output resistance not to the total resistance of the headphone.
    So I'm going to update the main post soon, after i understand a bit more of the minor details.
    My actual goal is to either increase the resistance of my headphones which now seems impossible,
    OR decrease the output resistance of an Amp to make it pair better with low impedance cans.
  12. Chris J
    Broadly speaking, if you have a good, low impedance desktop amp and you are using 32 ohm Grados or 600 ohm Beyers or anything in between, then you do not need an "impedance adaptor".
    An impedance adaptor made up of one or two (or more) resistors will not decrease the output impedance of an amp.
    If that is what you are looking for, then, unfortunately, you need a lower output impedance amp.
    Some guys use resistive networks they call "impedance adaptors" to allow them to use very sensitive IEM with their desktop headphone amp.
    Their headphone amp has too much output (actually has too much voltage gain) for their IEM, they have a hard time controlling the volume, i.e. volume control cannot be use above 9-10 o'clock, they hear too much hiss.
    this may be useful to you:  
    and this:
  13. WiR3D
  14. stv014
    I have already explained this, but you are wrong. If you still do not believe, here is a simple test with a source that has 100 Ohm output impedance, and a 250 Ohm headphone. The left channel was connected directly to the headphone, but its level was reduced by 20 dB. On the right channel, I used a 680 Ohm potentiometer as a serial resistor, and a 27 Ohm parallel resistor. I adjusted the potentiometer so that the levels were matched. At that setting (~220 Ohm), the source "saw" a roughly similar impedance load on both channels. I have then created a frequency response and 40 Hz distortion graph, recording the voltage from the headphone. The result is:
    adapter1.png     adapter2.png
    As you can see, the frequency response is nicely flattened out, and the THD is reduced by a factor of about 4. This is consistent with what would be expected from an output impedance reduction from 100 Ohm to 25 Ohm.
    paulindss and CapnCook like this.
  15. Chris J


    I think you mean you can use MORE sensitive IEMs with your high gain desktop amp.
    This is because the resistive network will decrease the apparent gain of the headphone amp
    WiR3D likes this.
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