LSA HP2 Ultra stream of consciousness

Discussion in 'Headphones' started by bilboda, Mar 19, 2021.

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  1. bilboda

    bilboda Florida boomer

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    Picked up an LSA HP2 from Underwood Hifi that I had been reading about.
    A biocellulose driver with graphene coating that is horn loaded.
    Made by Kennerton, it is mostly closed with a pinhole in the center of the flat wood cup.
    Spring steel headband with a leather strap and soft leather earpads.
    Kennerton's model is the Gjallahorn, is more expensive, may be better? I don't know.

    Using a Jot2 and HP1 from Neurochrome.
    Easy to drive at 33 ohm 105dB/mW efficiency.
    Very comfortable for long term wear. They go on and don't move around.

    The midrange is exceptional. Great separation and timbre. No bass or mid bass bleed.
    Details and plankton galore. Seriously hearing detail I haven't heard before, easy to distinguish different simultaneous decays, guitar cavities. There may be treble roll off, I can't say cause my ears are already rolled off.
    All I can say for sure is everything I can hear, I can hear better and there is quite a bit that I wasn't hearing before.

    Bass is clear, timbre is great , it goes down low and clear, bass nuances clearly audible, not a bass cannon but not needed either when it is so musical. Much more so than I am used to.

    Some sites describe this as a 40mm compression driver and I don't now how the horn loading is configured nor understand much about it. Front loaded? Rear loaded?. All I can picture is the RCA horn and I'm the dog.

    Occasionally, some vocals can resonate a bit and be less nice. I lower the volume a bit and don't lose a thing.
    Piano? A piano player would have to say if it is natural or not, it is certainly more detailed, solo or as accompaniment.
    The lower keys vibrate clearly and cleanly. The headphone may be the best I've heard that keeps instruments separated and well resolved. Will have to do a comparison but these may be reference to detect other's flaws.

    The headband was creaky in the beginning doing a little flex on it's own and microphonic if you tap on it. It has broken in and I don't tap on it.

    I'll chime back in with Verum, HD800s and Verite on their best amps at some point.
     
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  2. k4rstar

    k4rstar Done his time

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    thanks for the impressions @bilboda
    I was very interested in the Kennerton Gjallarhorn but the low impedance voice coil was holding me back. but it has terrific efficiency on paper so maybe a good headphone to use with a dongle amp/dac?

    it appears the driver is simply sunken a bit into a cavity, so maybe more correct to call it a miniature waveguide than a front-loaded horn

    [​IMG]

    interestingly, one owner noted the same thing you did about mid-range resonance and introduced a modification of felt diffusers around the edge of the diaphragm to address it. Kennerton apparently liked it so much they adopted it as an official alternative model: https://kennerton.org/shop/gjallarhorn-jm-edition/

    [​IMG]

    anyway, look forward to more impressions and comparisons.
     
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  3. bilboda

    bilboda Florida boomer

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    hp2.jpg Read JM's Magni Vs Gjallahorn review and his mod thread. The HP2 are using Magni cups with a circular hole vs the heart shaped one in the Magni.
    Got curious, opened her up saw the bass port has a cutout with thinner foam than used for the rest of the cup and the driver looks the same as the Gjallahorn. So a horn loaded driver in a Magni cup. Never saw a Magni driver though.
     
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  4. crenca

    crenca Friend

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    @bilboda , how do the detail and transient attack/decay of these compare to your ZMF's Verite would you say? If they are not up to Verite's level, do they exceed the biocellulose driver found in the Auteur/Eikon?
     
  5. purr1n

    purr1n Finding his inner redneck

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    This is a front loaded horn. The driver is not a compression driver. It's a traditional dynamic. I think some folks may have gotten confused because most horn speakers that people know of from the likes of Klipsch and JBL use compression drivers.

    This is on my list to pick up next.

    Many people who DIY horns will put felt at the outer areas and lip of the horn to smoothen FR.
     
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  6. bilboda

    bilboda Florida boomer

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    A cursory comparison shows they exceed Verite's detail and resolution using an EC ZDS and SW51+. I have to spend more time on this as my first comparison was likely with a tube going bad. Heck , I got time, let me get started. I can repair an rca cable later.
     
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  7. skem

    skem Friend

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    I would be worried about the “horn” part changing dimensions in different humidities and over time. Non-engineered wood moves a lot (furnitures builders know this well... it causes sticking drawers, etc) and the circular opening in which the driver is mounted will readily become oval over time, perhaps compressing the driver. I can’t quite tell from the photos how the driver is mounted. A pliant glue with sufficient room for movement would probably make it OK. A close-fit rabbet (<2mm) might not.

    edit: you can even see it happening in @k4rstar’s first image.
     
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    Last edited: Mar 22, 2021
  8. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    A waveguide, maybe, but are you really expecting any acoustic impedance matching from that thing? I have a feeling that the front loading of the driver will be completely overwhelmed by the relatively small cavity between the membrane and ear.
     
  9. purr1n

    purr1n Finding his inner redneck

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    LOL, absolutely not. Need a CD and a proper throat. Shallow horn or more proper term waveguide - it still works though.
     
  10. Armaegis

    Armaegis Friend

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    I wonder if it's possible at all to do any kind of schlieren imaging of headphone drivers.

    A quick google search brings up a couple things like this for speakers or general ultrasonic study:
    https://www.semanticscholar.org/pap...bb5868976ba1f54a62f161b9985fe0142671/figure/1
    https://www.researchgate.net/figure...and-lower-harmonics-Excitation_fig5_248396259

    I'm sure in loudspeakers you could do some interesting things like axis mapping and coherence from 2 or 3-ways, but I'm more curious about the ultra near field like in a headphone driver. So much of our theories of impedance matching, waveguides, etc really apply more on the larger macro scale but kinda don't look at the boundary layer and surface effects. Not so much a concern on speakers, but on a headphone scale I'd be really curious to see how baffle mounting, fazors, etc affect the produced waves when those objects are all on a scale potentially smaller than the wavelengths in question.
     
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  11. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    That's the problem - the headphone/ear cavity should act largely as a resonant chamber with very little room reflection/diffraction and other wave-ey stuff. Pretty sure that someone handy with COMSOL could do fluid dynamics sims, if real-life materials/geometry can be faithfully copied. At the moment there still isn't a complete compression horn mathematical model, so all of the horny designers I know make do with COMSOL.

    When I said I'm skeptical about the claims of front horn loading made by the mfg., I should've added that even as a waveguide I can't see it working in a wide bandwidth. A 40mm driver will beam at around 8500Hz, but below that the space in front of the membrane will act as a resonant chamber.

    P.S. Is it me or the driver below has a regular stamped mylar membrane? Biocellulose is never that clearly translucent. There seem to be some elements behind the membrane which look more like it.

    [​IMG]

    Here's a Nighthawk membrane for comparison.

    [​IMG]
     
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  12. Lyander

    Lyander Too sensitive for SBAF

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    Was about to say that that doesn't look anything like the biodyna drivers I've seen. I've nowhere near as much experience playing with them as most but I am a bit of a fanboy.

    Also on the topic of how much can go on between a baffle and one's ears: I went from finding the Klipsch HP-3 tolerable to thinking they were sizzly as a screaming-hot grill in the space of a couple hours. Bassier too, sure, but also with far more pronounced upper octave.

    The only difference was that I got a haircut in between those listening sessions— same volume, same position. I'm not quite so daft as to cover my ear holes up with hair so I think @Serious, for one, may certainly be on to something with how skin and hair may go a long ways towards absorbing high frequencies; this is one reason I like to keep my hair at least medium length nowadays :))
     
  13. Taverius

    Taverius Smells like sausages

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    I mean, is there a lot of difference acoustically between felt and a bunch of hair?

    Thin fibres packed somewhat closely.
     
  14. Roderick

    Roderick Facebook Friend

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    I think it's a broken telephone phenomenon with that biodyna driver. On LSA site it says "horn loaded 50 mm driver with a bio-cellulose and paper membrane with a graphene coating." But according to kennerton gjallahorn driver is "hybrid of mylar and powdered graphene".

    Original kennerton Vali uses that well known peerless driver with a paper dome. I bet that is somehow where the talk about bio-cellulose driver originates.
    [​IMG]
     
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  15. Armaegis

    Armaegis Friend

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    I think when we're looking at the small scale like a headphone cup, it will inevitable be some awful combination of both resonant chamber and atrociously difficult boundary layer turbulence/drag effects. I did two years of fluid dynamics in undergrad and hated it, and you don't even touch turbulence at that level.

    I only mentioned schlieren analysis because it's a "simple" visual technique to examine what's happening at that scale.
     
  16. Hrodulf

    Hrodulf Prohibited from acting as an MOT until year 2050

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    I dunno, man - my uneducated gut feel is that SPL's are too low to have problems like they encounter in proper compression horns. Something like super early reflections would be my main concern with headphones.
     
  17. bilboda

    bilboda Florida boomer

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    Verite with ZDS
    Janey needs a Shooter, Bruce Springsteen Letter To You
    Lots of soun.d Verite presents it well holding it all close in to your ears, resolving the instruments and presenting it comfortably for this wall of sound production, think REO Speedwagon.
    HP2 with Jotunheim 2
    Definitely a different presentation, instruments more distinct, spaced out, individual decays more apparent.
    I suspect sometimes that the timbre of pianos may either be correct or incorrect, different for sure , upright with the lid off vs on in the Verite. No way to know which is correct but the lid off in the HP2 gives more internal detail, decay.

    Bass guitar on both hp's is about the same, the HP2's are definitely broken in.

    I think the HP2's could use some tubes or a different ss amp, Black Amp, where are ye?
    Using ZDS with low Z setting. Wil try SW 51+ as well.
    Move On Up, Curtis Mayfield, Keep on Keeping On
    Yep, tubes give a better tone to the HP2, not gonna comment too much on this because it's fine but SW51+ does much better.
    SW 51+ Curtis Mayfield
    Verite and HP2
    Hp2 more open, as if room treatment was applied, less meaty? Not negative, it makes it easier to focus on the instruments, keeps the vocalist and chorus more separate, horns are more lively, less overall bass but clear and defined with timbre. It goes as low as this song needs, no boom, no bloom. Stage stretches for the boundaries where the Verite seems pushed in from the boundaries, cloudy day vs sunny day. Percussion punchy, cymbals clearer decay, extend further into space.
    The Verite is not failing here, I like the vocals better, with the chorus and falsetto, I like the HP2 better, separation is better.
    Kick drum kicks a bit harder wit the Verite, it is felt and heard. Tom toms, congas are more distinct in the HP2, Verite is like a jazz club venue. HP2 like a large dance hall, more room tp play in. If I has to write the lyrics from the song I would choose the HP2.
    If I was sipping whiskey and laying back I might like the Verite better, depends on mood.

    I don't know which one resolves better with SW51+, It has great synergy with both. Gonna have to put the Verite back on the ZDS for my next evaluation and add the HD800s too.

    While posting, Giovanni by Jamila Woods, Legacy! Legacy! got queued up.
    Nice low low, rolling dominant bass while Verite wins overall presentation and tone the bass was better covered by the HP2.
    Vocals more clear with the HP2 but I liked them better with Verite even though I think I know her voice better with HP2. I think incisive describes the HP2.
     
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    Last edited: Mar 22, 2021
  18. yotacowboy

    yotacowboy McRibs Kind of Guy

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    How's the isolation, both from external noise and leakage from the headphones themselves?
     
  19. Armaegis

    Armaegis Friend

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    Eh, my interest was more in the modeling of pressure wave behaviour in the small scale. Didn't arnaud do a bunch of this years ago back on headfi?
     
  20. bilboda

    bilboda Florida boomer

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    Isolation is very good, earpads are thick and plush. Soft leather. Can barely hear a television and can easily listen to music with the tv on. I don't hear the sous vide alarm. I'd say outside sound is reduced at least 50%. Norah Jones is crystal clear. I could write her lyrics from what I hear, something that is not true with every setup. Leakage? I put the on mu bicep and couldn't hear anything from a foot away at normal listening volumes. These perform well at low volumes. They can be cranked but that's not my way.
     
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