iFi Audio Pro iESL - The Official Thread

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  1. iFi audio

    Dear greenkiwi

    It works with cables that 100% implement the HDMI Standard, as for example detailed here:


    Unfortunately, we found that few commercial cables follow this standard. So the issue is not that we stepped outside the standard, but that in many cases the standard is simply not followed.

    For any customer needing details for a custom cable to be made, please open a ticket with our support team who will assist in clarifying which exact connections are needed. Here's the link: http://support.ifi-audio.com

    Best wishes

    iFi audio Team
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  2. paolin
  3. paolin
    A question about the function :
    the right hand to change the impedance also works with the electrostatic headphones or just with the dinamic or planar ?
  4. iFi audio
    Yes, said impedance knob works with e-stats.
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  5. paolin
    Ok, i would use it for a Stax Headphone with a loudspeaker amp of 100+100 W (a Mark Levinson N°27), so it is advisable to adjust the impedance on 96 ohms for safety, right ?
  6. Matez
    There's a room for some tinkering on your own, I think. My bet is that you won't fry your cans.
  7. paolin
    Maybe that's not the case :
    from iFi PRO iESL user manual : " the amplifier rating should not exceed 100W / 8ohms rating for safe operation, or care must be taken when setting the volume. Rating below around 10W / 8ohms may not deliver satisfactory playback levels"
  8. rumina
    when i look at the schematics of the no 27 it's running at (relative) high voltage of -+ 46 v with max output of 128 w / 8 ohm (http://www.diyaudio.com/forums/solid-state/198509-mark-levinson-27-schematic-requites.html), so you can fry your cans when you set the volume to max and the impedance switch to low. as long you use the 96 ohm and don't set your volume knob to max (normaly you are deaf long before frying your cans :wink: ) it should be fine.

    @iFi audio

    does it matter if the power amplifier is voltage or current driven?
    Last edited: Oct 24, 2017
  9. analogsurviver
    Please do take care when using Pro iESL with more powerful amplifiers. One of the advantages of the high voltage direct coupled amps/ES headphones combo combinations is inherent built in overload protection - NONE required, as properly designed ES amp/headphone combination is made to withstand without damage anything amp can possibly put out - for an indefinite amount of time - full DC output included.

    The standard "killing mode" for electret headphones of the yesteryear was switching the "energizer" aka transformer from "low" to "high" setting when driven by anything above say 30-40 W output - during the playback. It was usually 1:2 ratio switch, effectivelly doubling the output voltage > frying the permanently polarized electret, decreasing the output to but a fraction of what it should be - end of story. Bias powered electrostatics are somewhat more electrically robust - but NOT that much more. Certainly not for 1:2 ratio overloads ...

    Pro iESL has more than one position for impedance = step-up ratio of the transformer. It is perfectly possible to reach destructive voltage output if too powerful amp for the impedance/step-up ratio setting combination is used. As noted above, it helps if you know which output rails power your amp - and then calculate which impedance / step-up ratio is still safe to be used with your ES phones.

    One CAUTION - for those who play analogue records = vinyl trough your ES phones with energizers aka transformers when using relatively big amps .
    If you have any experience with vinyl, you would know there can be a tick or two somewhere on any given record - that IS way louder than any recorded music. Please do look a couple of lines above once more ... it takes just ONE loud tick !

    I will be getting the Pro iESL for a 3 week review this Friday - and will try my best to put it trough its paces, At least voltage levels / step-up ratio for various settings of input impedance should be then known trough measurements - as well as frequency response for those various settings, as they can not be the same over so vast range as covered by the Pro iESL. Please note that whatever results obtained will not be posted before say 20th of November - due to my recording schedule.
    Rayzilla likes this.
  10. paolin
    same, if i set the volume to max also the loudspeakers (sensitivity 87 dB/W/m) jump in the air and the neighbors shoot me
  11. iFi audio
    There are way too many variables to answer this question. Headphones used come into play, a circuitry itself, components and a number of other things as well. In the end, if you enjoy a certain amplifier, it doesn't matter what's under its hood. What matters is that you like it.:L3000:
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  12. paolin
    In summary is possible for you or risky to connect the iESL to a 100+100W amplifier to listen to a Stax headphone to a normal volume by adjusting of course the impedance to 96 ohms ?
  13. iFi audio
    A 100W/8 ohm amplifier will output 28V at rated power.

    Using the 64 ohm setting, this will translate into around 450V RMS, somewhat less with 96 ohm.

    This is the same as the Stax SRM-727 MKII amplifier is rated at.
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  14. Khragon
    Can someone help me with what is the recommended setting for stax sr007a for use with iESL + iCan Pro? What's the max settings?
  15. Rayzilla
    I am interested to hear your opinion on the iESL. I need a big upgrade to me lowly SM-323S. Have you ever tried any of the KG amps?
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