EHP-O2 Portable Headphone Amplifier The EHP-O2 is a battery powered, portable headphone...

Epiphany Acoustics EHP-O2

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  • EHP-O2 Portable Headphone Amplifier

    The EHP-O2 is a battery powered, portable headphone amplifier. The electronics have been designed by blogger NwAvGuy. The amplifier measures superlatively and they speak for themselves when describing the quality of the amplifier. This has been achieved by very careful component selection, taking advantage of their specific performance characteristics as well as shrewd electronic engineering.

    It comes equipped with 2 rechargeable NiMh batteries for portable use as well as an AC adaptor for desktop use and charging purposes.

    A built in gain switch allows the user to choose the appropriate gain for the source and headphones/earphones being used.

    The EHP-O2 has:

    1 x 3.5mm input jack
    1 x 3.5mm output jack
    1 x power inlet
    1 x gain switch

    The electronics in the EHP-O2 were designed to offer superior performance in every key specification possible. A snapshot of the measurements are:

    THD @ 1kHz: 0.0017%
    Noise level (ref 400mV): -105dB
    IMD: 0.001%
    Power output @ 33Ω : 641mW
    Crosstalk: 65dB
    Channel balance 0.6dB
    Battery life: 8 hours

    The EHP-O2 portable headphone amplifier is hand built in the UK.

    DIY Builders: Unassembled PCBs are available for DIYers to build the EHP-O2 themselves.

Recent User Reviews

  1. cokker
    "Great piece of equipment, highly reccomended!"
    Pros - Sound stage, clarity, build quality.
    Cons - Nothing
    Where do I start? Everyone who likes audio reproduction has heard of the Objective 2. Epiphany Acoustics has done a great job of building this amp and I'm a very happy owner!
  2. vrln
    "Good starting point into the headphone amp world"
    Pros - Low noise floor, high value and solid build quality
    Cons - Gain even on 1x mode is too high for some sensitive IEMs, input 3.5mm jack is in the front (bad ergonomics)
    This is a traditional Benchmark DAC-1 style "wire with gain" sound for a very low price. Not the last word in emotional expression, but the O2 has a very silent inky background and good clarity. 
    For people new to Head-Fi, you can now get an amazing budget rig by getting this and the EDAC. Pair them with good mid-range headphones like the Sennheiser HD 600/650 and you have a fantastic beginners setup. For those who don´t want to make headphone audio a more serious hobby it´ll even be a good "buy, use and forget about" setup.
    registradus likes this.
  3. REvandenBERG
    "What an amp!"
    Pros - audio & build quality
    Cons - Portability & battery life?
    Over a period of time I bought a FiiO E5, a CMoy and a FiiO E11, which all raised the soundbar. I bought the O2 because of NwAvGuy's writing.
    The amp turned up one and a half month late and initially without an AC-AC power supply. But thanks to good communication with Epiphany's Oliver this was not such a very big deal.
    The O2 drives my Audio-Technica ATH-M50 easily. My iPod touch V4 32GB is connected to the O2 with a simple FiiO line out dock L9 connector. Expensive cables are no longer necessary, I assume because of the high input impedance of the O2. I have attached the iPod to the O2 with 2 pieces of sticky double sided foam tape. I have put an old belt on an old leather bag to carry the two.
    You notice immediately that the O2 is totally silent when music is not played.But when it plays... I have never heard bass, mid range, treble, sound stage and instrument separation of this quality.
    Thanx NwAvGuy and Epiphany!!!
    registradus likes this.
  4. svyr
    "Very nice for the money. (and overall)"
    Pros - Clear sound across the FR, portable(ish - size but battery), drives both IEMs and full size can well. Low noise floor
    Cons - you may want RCA-ins when you get it(I did).but portable :D ! Australian wall wart, 2RCA-3.5mm plug and 3.5mm to 3.5mm short interconnects would be g
    Pre-Ordered from Oliver (EA) in Oct(?). Received the unit about 2w ago.

    The bad
    The volume pot tracking is not very smooth (catches a bit on some positions (tactile feel, not audibly)). (will check whether pot knob gets caught on the case) (edit: yep, that's it, no real quality issue there)

    To my surprise, the unit does not come with a 2RCA->3.5mm or 3.5mm to 3.5mm .I only had a fairly long and rigid one. I wish Oliver would include at least some cheap interconnects :D

    I'd probably also like a small manual explaining what not to do. (e.g. will it explode if I leave it plugged in for a weekend at work, and come back on mon to find my building charred. Or does the charging circuit cut off at a certain voltage? does it get powered from AC or via batter when AC is plugged in?), or is pressing the gain button while the unit is on bad or not, etc. How to change the NIMH batteries or something. (and rules of when to charge them for longer life or something. What warranty do we get? What are the return conditions for the warranty claims (who pays shipping where), etc)

    I also wish Oliver could source Australian wall warts, but he couldn't at the time. The AC-AC 15v 0.5A adapter with the UK plug is huge. I could only find replacements w the AU plug at Jaycar and Mwave, and they're $30+ shipping ($50...). To be fair, he did give me an option of a small partial refund and me finding my own PSU, but it's probably best to just use the UK one with a socket adapter :D

    The good
    That aside, I've been playing with it for a week now, and the sound is great.
    Crips,extended bass and highs, present mids, great perceived soundstage and dynamics.
    The low output impedance and the decent max output let me drive my GMP 450 PRO (300ohm, no idea what sensitivity. Sound great at hi-gain/about 3/5 of the vol) and UM Mage (demo)/Shure se425.

    Both the IEMs and full size cans sound a lot better than my Musiland MD11 and MD30 - much lower noise floor and perceived sound clarity, fr linearity and bass quality (tales of folksy better extension and depth :D go here). I did expect that for the IEMs, since the hp jack on MD11 and 30 is 2-3ohms, but certainly didn't expect that much of a difference for GMP450 PRO. I'm also rather surprised, just how much of a difference a low impedance output makes for IEMs.

    For IEMs, O2 also sounds noticeably better than my Cowon d2 portable. (hmph, I might have to start carrying it around :D )

    The build/case all look and feel very sturdy.

    Despite the designer's comparisons to Benchmark DAC, I did not find the sound to be similar (I thought DAC1 was awfully bright, almost serrating, which was not the case with the O2). edit: there is a slight qualification to this, MD11 has slightly rolled off HF as per the RMMA, so YMMV on this a bit, but I don't expect it to become awfully bright on straight (+-0.1db) FR sources.

    I wish I bought a desktop version (6.5mm out, 2RCA in) and a portable version :D, but Oliver/EA and NwAvGuy did very well.

    PS I will be cracking it open next week at home and maybe posting some pics on what's inside (part quality and all, not that NwAvGuy approves :D ), tho I'm not sure if there's any point, since the O2 thread probably has some
    gopack87 likes this.
  5. msjjr
    "Epiphany Acoustics EHP-O2 "
    Pros - Great sound.
    Cons - None.
    I have mine and it's fabulous. I imagine especially good for harder to drive cans. Better bass, not just more bass, but tighter and better defined. Better 'air' around the instruments, ie, improved separation. Maybe some golden-eared individuals will do a better review. One poster described sibilance and I definitely do not find that with my setup. I used it with my Cowon x7 and the Shure SRH-940, comparing with and without using the outboard amp. This combination has superb synergy. One needs to spend a heap more money to get even more realism from a setup. ( I should add the the Cowon does a great job driving these cans all on it's own, but it's simply better with the amp). As always, YMMV.
  6. turokrocks
    "Best semi-portable for its price and sound"
    Pros - Excellent workmanship and wonderful amp
    Cons - I own only one
    When I first read about this amp, I was skeptic about the sincerity of the  measurements at first, but I had to try it myself after his claims. After preordering, it came about  6 weeks later, and what an amp, I just now knew how wonderful this amp is, esp. with my Centrance LX Dacport, they were made for each other.
    Music never sounded so good. Natural sounds, beautiful and precise instrument separation, the most important thing is balance nothing overwhelms neither the Bass or the treble, but the mids are really what I enjoy, along with the soundstage, not big but it is there and what a stage! My advice to anyone thinking of getting his first amp, is to make this one on the top of his list.
    The nice thing about both the amp and the Dacport LX is the size , where both can be carried in a pc/any bag easily and you can enjoy audiophile quality music anywhere & anytime. The sound you will be getting from these two is phenomenal in respect to their size, price ratio. Thank you Epiphany and thank you Centrance, you made me happy, and that's what is important.
    msjjr likes this.

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