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Output impedance: small and fast question.

Discussion in 'Sound Science' started by PDVJAM, Jul 17, 2019.
    Hi Guys, please, help me. If I have AMP with output impedance like, for example, 1 Ohm and a cable with it's own impedance, say, 3 Ohm, will they sum for a total of 4Ohms or only the last value does matter to calculate dumping factor for headphones?
  2. castleofargh Contributor
    when stuff are added in series they add up. the driver of the headphone "sees" a source of amp's output impedance+cable's impedance. but at the same time, the amp "sees" a load with an impedance value of cable+headphone.
    so it's really a matter of what you're trying to calculate.

    and to help your future online searches about this, it's damping ratio instead of dumping :wink: .
    Steve999 and TronII like this.
    Ah, yeah, damping, sorry :beyersmile:
    Well, I have Campfire Audio Solaris, and these IEMs have very low impedance at 1kHz - 10ohms, plus there is info that they have impedance 3ohms <100Hz and about 9ohms beyond 1kHz. My source have output impedance 0.1ohms. But it has very noticable hiss, so I've bought ifi iematch, which adds another 1ohm of impedance to the chain. And now I'm thinking of to change IEMs cable to a very thin and almost invisible one from Linum company, but the cable also will add 1.5ohms.
    So I try to figure out how much this total impedance can change the sound of the headphones...
    Steve999 and TronII like this.
  4. bigshot
    You could also trade the IEMs for ones that don't have such a strange impedance.
    pstickne likes this.
  5. TronII
    What do you mean by "strange"? Even though impedance is usually rounded to the nearest multiple of 2, when you actually measure headphones' impedance, they often have strange numbers
  6. bigshot
    I mean non-standard. I'm sure a lot of people buy these expecting them to plug into their DAP or headphone amp and then find out they hiss like a snake because they've been designed to work only with esoteric impedances.
    Steve999, pstickne and TronII like this.
  7. castleofargh Contributor
    there are a few unknowns here, but the biggest one might be the IEMatch. even if it's a simple voltage divider, the vague values on the specs assume a given amp output and IEM impedance, but they don't really tell us what they use, we can only try to guess that it's probably something in the area of maybe like 6 and 1ohm for the 2 resistors. it certainly doesn't make answering you any easier.

    BTW on their site they write this:
    again a little vague because based on assumptions we have not been told about, but not reassuring.

    so my answer is going to be IDK. if the exact resistors were known and we were sure there is no extra circuitry in the plug, I could summon my inner high school memories and try to estimate the variations under a few different scenarios(given that somebody accurately measured the impedance graph of the IEM, and that the amp has a relatively steady impedance per frequency value(or also something measured in a way we can use).
    but beside how the adapter's manufacturer himself doesn't recommend using it with such an IEM, I have to agree with @bigshot and say that I'm not a big fan of IEMs with so very low impedance values. when did stability and compatibility become irrelevant factors in making IEMs? I'm sure they do it for a reason and it helps measure slightly better when plugged into that one ideal amp they got for lab measurements, but then we consumers have to deal with real world conditions. I don't like that trend one bit.
    Steve999 and TronII like this.
  8. theveterans
    I saw a post in the Solaris thread that AK Kann Cube in balanced sounds incredibly well with Solaris. Also, the Kann Cube has gain modes to ensure your Solaris will play hiss-free.
    Or you can just use a decent smartphone or iPhone or iPod Touch and enjoy hiss-free playback with Solaris too, but won't sound to its full potential of course.
    pstickne likes this.
    Yeah, I could, but they sound so freaking amazing, love them:frowning2:
  10. PDVJAM
    What does mean full potential? How we can tell if this sounds as a fully potential?
    pstickne likes this.
  11. BassicScience
    He means that driving the Solaris with a smartphone won't sound as good as driving them with a dedicated, well-matched amp. OTOH, I auditioned that IEM at CanJam with my Galaxy 10 and thought it sounded amazing. As long as you're someone who can listen to and enjoy music without always wondering if it could sound better, it might be a reasonable option to consider.
    Steve999 likes this.
  12. bigshot
    I don't know much about IEMs, but I find it hard to believe that there aren't alternatives that aren't quite so temperamental when it comes to impedance. I think since you already have them, you're stuck finding a non-standard amp to work with your non-standard IEMs. There may not be a lot of selection,
  13. jagwap
    If your numbers are right, the ifi iematch alone is going to give you a 1.5dB drop in response at 100Hz compared to the 1Khz. Depending on how broad this 3R dip is around 100Hz, this is likely to be audible. Put the new 1.5R cable in AFTER the ifi iematch then this will increase to 3dB. However if you put your new cable on, and can have the ifi iematch next to the earpeices (unlikey I suspect) then you only lose 1.6dB.

    So in general, get rid of the ifi iematch, unless you like the reduced bass, and find a lower output amp with lower noise (these two things tend to go together, as higher outputs mean higher gain of the DAC, meaning amplification of noise. Make sure it has a similarly low output impedance though. Or get an IEM with lower sensitivity so the noise is less noticeable.
    PDVJAM likes this.
  14. Steve999
    Sorry to post on this since it’s been a while since this was discussed. If you love the sound I would say don’t sweat it too much, but I understand you are trying to address the hiss. We have one poster here who says that (apparently on a relatively brief audition) they sounded great from his smartphone. Have you tried them with just your smartphone to see if the hiss is greatly lessened? There are so many variables at play here the easiest way to tell is just to plug them in to your smartphone and see how the hiss is.

    If so and you love the sound that much I would say hang on to them and listen on your smartphone and if or when you can afford to, buy another pair of IEMs or other headphones that you know with your new knowledge will be compatible for a wider range of gear. In my experience it’s not that easy to find a pair of headphones that suit your preferences just right and fit you personally just right to get that sound (at least not without tweaking with EQ a little). So if you’ve got that far and using just the smartphone reduces the hiss enough I’d say you’ve got a pair of keepers. :)

    I wouldn’t worry about “full potential.” This is one scenario where I’d say use your ears. Headphones are always a bag full of compromises to meet preferences anyway.
    Last edited: Aug 25, 2019
    TronII likes this.
  15. bfreedma

    By coincidence, I just picked up a Solaris. Running out of my iPhoneX, no hiss whatsoever. These are extremely sensitive IEMs and I can’t go beyond 30% volume on the phone before they become too loud.

    Been doing a lot of long flights recently and wasn’t happy with the SQ of my QC-35s. Also found that after lengthy listening sessions, I was getting a headache which I suspect may be due to the noise cancellation.
    TronII and Steve999 like this.

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