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Inspire IHA-1 tube headphone amp

Discussion in 'Headphone Amps (full-size)' started by burn1, Oct 18, 2014.
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  1. Xcalibur255
    The volume pot is out of the circuit completely when it's turned all the way up, so if you prefer to manage volume somewhere else in the signal chain there's nothing wrong with doing this.
  2. DelsFan
    Thanks, I guess my question is: With the volume pot out of the circuit, isn't the volume by default at "full" then? And, as long as my DAC has a volume control, is this any big deal? I assume these aren't like a guitar tube amp, where the more volume = the more distortion. Does the IHA-1 behave any differently at full volume? More distortion? Tubes last less long? Etc. Or is a headphone amp a completely different design (as I expect) than a guitar amp.
  3. Xcalibur255
    There is no easy way to fully answer your question to be honest but the short version is no. Distortion isn't connected to signal attenuation in the way you're thinking. The amp isn't running "wide open" amplifying as much as it can just because the volume pot is all the way up in this particular scenario. The relationship in the circuit is more complex than that. Now if you had nothing else upstream attenuating the volume it would be a different story.

    There's no problem at all with maxing out the volume pot and using your DAC to control volume, it won't cause more distortion. The only tangible difference is that you've removed a resistor from the signal path that would otherwise be there, so if you have keen ears you'll actually notice a subtle improvement in resolution assuming the volume control in your DAC is lossless.
  4. Aornic

    I just got the amp yesterday and it's been hard to pry myself away from my desk since. Current tube sets are:

    1) Raytheon 6SN7 (stock)
    2) JJ Electronic 5Y3S (stock)
    3) Ken Rad 6SN7GT
    4) Tung Sol 6SN7GT
    5) RCA 7n7 into a 6SN7 converter

    3-5 I've been using with my Feliks Audio Elise, an OTL.

    I'm very impressed with this amplifier. It has an effortless presentation of detail, and it reaches far and brings so much to my attention. It has transformed my listening experience with my Focal Utopia + Schiit Gungnir Multbit considerably.

    I have these in the mail currently, looking forward to them.


    The only issue I seem to be having is with using the pre-amp outs with my powered Focal Alpha 50 studio monitors. Seems I'm getting strong feedback/hum because of a ground loop. I had been using the balanced pre-outs of my Audio-GD NFB-28 till now without an issue.

    And to clarify, I opted for the pre-outs and Lundahl transformer upgrades. This amp deserves more attention and I look forward to reviewing it comprehensively.

    P.S: I also filmed an unboxing, but I'm not very proud of it due to how long it took me to unwrap the thing. I appreciate the amount of protection though.

    Last edited: Aug 10, 2017
    Adu and porkfried like this.
  5. Rossliew
    Can anyone advise what is the safe operating parameters for the amp in terms of current/voltage draw?

    Am thinking of other types of rectifier tubes may be used safely.

    For example 4 volt tubes with the appropriate adapter.
  6. Xcalibur255
    I answered you over on Glenn's thread but I'll recap here. The transformer tap for the rectifier is 5V with a capacity of 3A. There is some overhead tolerance built in and Dennis has told me you can go a little bit above 3.0A without getting into trouble, but I would not push my luck in this department. 4 amp rectifier tubes are definitely off limits, the tranny would get too hot.
  7. Levanter
    Interested in your impressions on the NFB28 vs iHA-1 vs Feliks Elise. But I'm using HD800S & 650, so not sure if it'll be relevant with what you are using though.
  8. pedalhead Contributor
    Drew posted earlier in the thread that they are able to "fix" the hum on the original version of the Dragon IHA-1. Is anyone able to articulate what form this fix takes please? Cheers.
  9. DaveUpton
    @Aornic did you ever get a chance to try the Mullard rectifier? I'm curious what you found.
  10. Aornic
    Hi there. I compared a reissue with an old black Base in this comparison video and I have a metal base on its way to me currently that I'll compare to them later.

  11. DaveUpton
  12. Aornic
    Won't be buying any more tubes for a while I'm afraid. The Metal Base GZ34 wiped me out.
  13. comzee

    iha2 :fingers_crossed:
    is it right that this amp is not good for any iems?
  15. MoonAudio Contributor
    Which IEMs?
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