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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. smitty1110
    Had a great time today listening to my HD 800's with this amp, especially with the new Sylvania tubes. 6BX7GT, chrome dome top mica, matched traces and internal structure, but different date codes. I started Glenn Gould's Goldberg Variations, an old recording but a classic. The hiss of the old mics don't bother me through this amp, unlike some amps where it becomes really fatiguing. Also, the microdetail like sympathetic resonance on the other piano strings and room echos were not obscured by the amp. I then queued up the funeral march from my Decca recording of Nabucco to test the soundstage. Holy crap, the soundstage is wide, this song makes it really feel like it stretches more than 10 meters in both directions. It wasn't the deepest soundstages I've heard, but it's by no means flat or two dimensional. Room echoes were also well recreated. I then listened to The Modern Jazz Quartet, live at Carnegie Hall from MFSL. Bass extension  was great, and it's not rolled off like some amps with lower-quality output transformers. Whoever makes Dennis' transformers knows their stuff.
    I tested the highs with EDM, and that gave me a horrible headache. Suffice to say, extension on the high end is good, but that's ultimately a bad thing for the HD 800's. That also ended the serious listening session, might do some comparisons with other amps I have on hand later.
    EDIT - Quick 'n dirty comparison with a Liquid Crimson
    Turned on my Cavalli Liquid Crimson and gave that a listen with the same tracks, switching the headphones between them. The mains differences I notic ed is that the Bass on the Cavalli is faster, and the Highs are clearer. Things like cymbals sound more natural on the Cavalli, like there's a bit better attack and decay. Bass is clearer and has faster decay, but not by much. These differences are probably caused by the very different topologies of the amps, I know the LC has no output transformers and uses MOSFETs for the input stage.
  2. Xcalibur255
    Missed this somehow.  If you haven't already looked up the specs, the relevant ones are higher gain (32 vs 20) and higher heater current draw (0.9A vs 0.6A).  I believe the plate resistance is different too.
    For those who bought the Dragon version from Moon Audio, did your amp ship fairly quickly or did you have to wait for it to be built? 
    I ordered my IHA-1 a week ago and so far I have nothing but the initial order confirmation email to show for it.  If the amp is built to order that is completely understandable, but given that the charge is already on my card I think a courtesy email from Moon to clarify my shipping lead time would be appropriate at least.
  3. BlakeT
    My Dragon IHA-1 from Moon Audio took around 2 1/2 weeks to arrive from the time I ordered it.  
    I seem to recall Dennis makes these in small batches (at least that is how the first batch for Moon was done, as I was one of the last people in the first batch, if I recall correctly).
    On a positive note, Dennis and Drew are very prompt in technical answers to questions when you have them (tube questions, etc.).  
  4. Xcalibur255
    Okay, thanks. I'll just sit tight for now.
  5. Schopenhauer
    I think I got it in around three days.
    EDIT: I think. 
  6. Xcalibur255
    I got a shipping notification today.  So if I had waited one more day to ask my question there would have been no need.  :)
    I have a full lineup of tubes waiting for this amp, it'll be fun to do some tube rolling again.
  7. Xcalibur255
    Got it setup today.  My initial quick listen was pretty much in line with my expectations for the amp.  I am a little concerned about having insufficient gain using 6BX7s.  After plugging in the LCD-2s I found my nominal listening volume only 3 clicks from maximum, and this was with 6SN7s in the amp.  I was expecting a "just enough" situation with gain given it is a single stage design but with low sensitivity cans it's really cutting it close to not having enough volume.
    I'll reserve any other listening thoughts for after it has had some time to break-in.  My ears are telling me this amp needs some run time to find it sound, especially in terms of tone.
    Also, those tube sockets pins grip like a bear.  I was using force that made me uncomfortable to get tubes in and out, and I'm not a fan of rocking or rolling the tube as some people suggest.  With NOS tubes it's a great way to break the glue in the base of the tube loose.
  8. smitty1110
    I feel youabout rocking tubes, i killed a matched pair of RCA 345s that way...

    $300 down the drain because of impatience.

    Honestly, i took some craptacular dead 6sn7s and just spent a while working thwm in and oit of the sockets, it got better after a while.
  9. Xcalibur255
    I just threw the 6BX7s in...... yeah, I have the volume all the way at maximum and it's just loud enough.  With a gain factor of only 10 I'm sure this is normal with a planar headphone, but just to be sure is this the experience of other owners too?
    On the plus side these tubes sound really nice.  I was a bit surprised when they presented themselves as better sounding than my favorite Sylvania 6SN7GTs.
    After this I'll try the 6BL7GT flatplates, then give my BGRP Tung Sol 6SN7s a try.  Then onto rectifier experimentation.... everything so far has been with a Brimar 5R4GY that generally my go-to tube for any amp needing a 5U4G type.  I did find myself a very nice WWII era 5Y3G in the ST style glass I'm eager to try out though.  :)
  10. smitty1110
    My Sylvania 6BX7GTs were fine for my LCD-X, but I didn't even bother trying my HE-6 with this amp. Those are only used with speaker amps or the Decware Taboo Mk. 3.  What is your source, and do you know it's output voltage? my Yggy is 2V, which might help me squeeze a bit more out of the amp.
  11. Xcalibur255
    I have 2.25V output on my Channel Islands VDA-2.
    I gave my Beyer DT880 600ohms a spin, and it's definitely a no go.  Even at max volume they are downright quiet.  It's enough with the LCD-2 for all but quietly recorded tracks, with some classical pieces I've tried I have found there isn't enough volume.  The claim was that this amp can drive 600 ohm headphones, but in all honestly I can't say that is the case here.
    Most amps have way more gain than they need.  This is the first time I've ever encountered an amp that doesn't have enough.  I do respect Dennis's design intent, configuring both sections of the tubes in parallel as a single gain stage is a very purist approach that keeps the number of parts in the audio signal to a minimum.  In terms of transparency and keeping distortion down this is probably about as good as it gets in a tube amp.  The only way to do better would be to use tubes with lower distortion than the 6SN7/6BX7 and there aren't very many on that list.  The downside is that it doesn't give the amp enough flexibility to be able to drive any and every headphone.  The LCD-X is way more sensitive than the LCD-2 (103db vs. 90db) so I can see why you aren't having any trouble smitty.  I would suggest to others considering the Inspire to consider their headphone collection.  Very high impedance or anything below 90dB isn't going to work it seems.
    My next headphone purchase will probably be the Ether, and they are somewhat more efficient than the LCD-2 so that should take care of things.  I do think the amp sounds very nice so far.  It's very tonally correct to my ears, and presents an extremely layered and grain free sound.  The only weakness I hear right now is bass, which is both lacking in slam and control for an amp at this price range.  I'm probably a little spoiled by my 45 amp though.
    I think this amp would be killer with a pair of Mullard ECC32s, they have considerably more gain.  Too bad they are a thousand bucks a pair these days in good condition.
  12. Xcalibur255

    The current family of tube amps including the new addition.
  13. BlakeT
    Hmmmm, that is strange.  I was able to run my 600 ohm T1's at levels that were as loud as I would want, although at this volume level (on the verge of being too loud to handle for more than 5 seconds) I had the volume knob perhaps 3 clicks or so from being maxed out, if memory serves.  
    I would try again to find out exactly how many volume clicks but I've since sold my T1's. I'd send a note to Moon Audio about this as it seems something is definitely wrong here.  
    Note the above comments were without my preamp in the chain.  
  14. smitty1110
    Quick aside, what is that 45 amp anyways, and what brand of 45 globes are in it?
    And yeah, that's strange that it's so quiet for you. Where did you get the tubes, sounds like you're not getting enough gain out of them.
  15. Xcalibur255
    Are you running 6SN7s Blake?  My comments are primarily aimed at using the 6BX7GT which is half the gain of a 6SN7.  With a gain of only 10 and a reduction through the output transformer what I'm hearing seems about right to me and doesn't give me any reason to suspect something is wrong with the amp per se.  I'd just like to hear the experiences of the other owners as a sanity check.
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