AKG K-712 Audiophile Stereo Headphone review

Discussion in 'Headphone Reviews' started by dalethorn, Aug 3, 2014.

  1. dalethorn

    dalethorn Active Member

    Jul 3, 2011
    Charleston South Carolina
    Youtube review: http://youtu.be/uYSNYaEpNks


    Sources: iPhone5 with Portaphile Micro/PA2V2/Decware Zen Head amps using the LOD, various computers using Microstreamer/Beyer A200p/v-moda Verza DAC/amps.

    Review notes: My first impressions of the sound of the K712 headphone are based on direct comparisons to other headphones - the v-moda M80 and M100, the FAD Pandora IV and VI, the Beyerdynamic T1 and T90, and notes I've accumulated from many prior reviews. I describe how I relate to the K712 (i.e. my personal tastes and how I use the headphone) only after covering all of the objective issues.

    Summary of sound: I find the K712 sound to be excellent, and it only gets better with the better quality amplifiers**. I haven't followed the K7xx series at any time in the past, so this is my first experience with any of the K7xx series headphones. My comparisons to the best headphones I have or had show a small (4 db) emphasis at approximately 2 khz, and a rather lean bass I've boosted 6 db, centered at 45 hz. Given my preferences for a warm bass, anyone else may find the bass to be OK as is, given that it's very clean and detailed. On an overall basis, the only thing that stands out that users may find limits their playlists or maximum volume with the K712 is that small emphasis around 2 khz, which can make some voices sound louder than expected.

    **Don't expect different amplifiers to strengthen the K712's bass or add a significant impact, since I've already determined the lower bass to be very light with a variety of headphone amps. You may find that different amps will increase the musical satisfaction in various ways, but if any amp produces a strong bass without an explicit bass boost control, I'd be concerned about what else that amp might be doing besides amplification.

    One of my most demanding music tracks is David Chesky and Wonjung Kim's "Girl From Guatemala", and the extreme treble percussion beginning at 3 minutes into that track is delineated near-perfectly by the K712. Another track that's a stress test for treble is 'Time' from Pink Floyd's Dark Side of the Moon, and the K712 plays that cleanly, although I'd recommend setting the volume low in advance of playing it the first time. The K712 bass is more-or-less neutral overall, and users who prefer a really warm sound with extra impact may want to add a small boost with an amp that has the ability to boost bass cleanly. The midrange is unremarkable in the sense that it reproduces what's in the recording faithfully, with proper musical tone. Two tracks not listed below that show off the outstanding midrange reproduction are Ed Palermo's 'Crazy' and Michael Buble's 'Nice-n-Easy'. The sound is such that I have no reservations in recommending it.

    The K712 has seen significant price discounts recently (I got one for $350 USD), and given what I've seen and heard that sells in the $400 to $500 range today, I'd say that the K712 is by far the best deal in that range. Physically the K712 seems to be mostly or entirely metal, but if there are any plastic parts I can't tell what parts those are, so that's a testament to the excellent build quality. The K712 is not at all heavy given its size, and due to the excellent design that includes a soft self-adjusting headband and extremely comfortable velour earpads, the fit and comfort are perfect. The K712 is an open-back design, so isolation and leakage are non-issues. The 62-ohm impedance suggests a medium efficiency, but the K712 will not play at audiophile volume levels on many music tracks from an iPhone, iPod, or other similar music players. More importantly, the sound quality that the K712 can deliver with a good headphone amp should not be ignored - the better amps will make a dramatic improvement.

    The detachable cable uses a locking XLR-type connector at the left earcup, so replacements would likely have to be ordered through AKG. Many users of pricy audiophile headphones purchase expensive custom replacement cables in order to get a cleaner or "purer" sound. My take on the K712 cable is that it's more than adequate for audiophile reproduction, since I've heard some excellent-sounding headphones that have much thinner cables. It's not that I'm diminishing the importance of good cables and connectors - users should give attention to every component and connection in the electronic chain, from running their amps on battery power whenever possible, using the shortest interconnects possible, and making sure that when they do replace the headphone cable that it doesn't have an adverse effect on the sound.

    The comments in the music tracks listed below can be compared to other headphone reviews I've done, to get an idea of how the K712 plays the different music tracks listed here compared to other headphones. My suggestion is instead of reading each comment below as an absolute unto itself, you could compare these notes to other reviews as they get posted, and see how the K712 compares with each individual track.
  2. dalethorn

    dalethorn Active Member

    Jul 3, 2011
    Charleston South Carolina
    AKG K-712 review part 2 - music samples

    Animotion - Obsession (1980's New Wave/Techno): The upper bass synth has excellent detail and tone with a light weight, and both male and female vocals sound natural without favoring either. The K712 plays this extremely well.

    Bauhaus - Bela Lugosi's Dead (~1980): Strong midrange sound effects - this is a good worst-case test for resonant-type sounds in the most sensitive midrange area. Handled very well by the K712.

    Beethoven Symphony 9, Solti/CSO (1972): Excellent overall sound. Of special note here are the bass impacts beginning around 10:30 of the fourth movement. Those impacts are soft and well in the background, but you can feel a little of the weight they carry with the K712.

    Black Sabbath - Iron Man (Classic Rock): Very good instrumental detail and the vocal sounds very natural. As with most classic rock tracks, there is very little or no deep bass. The K712 plays this music smoothly, and the lack of deep bass doesn't unbalance the treble.

    Boz Scaggs - Lowdown (1976): Good sound quality - this is a great test for any nasality in the midrange. Handled extremely well by the K712.

    Cantus - Danny Boy (Traditional/Male Choral/Acapella): The K712 plays the voices with enough low end warmth and weight to sound very natural, yet there is no added emphasis of the lower register of the male voices on this track.

    Cath Carroll - Moves Like You (1980's New Wave/Techno): This track's percussion and voice are crisp and well-balanced, and there's a good sense of space or soundstage around the voices and instruments. The K712 reproduces the space and detail beautifully.

    Catherine Wheel - Black Metallic (~1991): Goth with industrial overtones - I like this since it's a great music composition and the sound effects are smoothly integrated into the mix. This may sound distorted or mushy with some headphones, but the K712 renders the deliberate instrumental distortions clearly.

    Chris Isaak - Wicked Game (Pop/Rock): The K712 plays this high treble energy recording very smoothly - the voice and instruments are very detailed but not edgy - very musical in fact.

    Chromatics - I'm On Fire (Synth-Pop, female lead): This track has a good amount of space around the voice and instruments, making for a very pleasant stereo image. The voice is excellent, and the tambourine sound is as realistic as I've heard with any other headphone since doing these detailed reviews.

    David Hazeltine - Fur Elise (Jazz): A very high-quality recording from HDTracks. The K712 reproduces the instruments smoothly with a spacious ambiance. The wire-brush-on-cymbal harmonics are very extended and detailed.

    Grieg (Beecham-Royal Philharmonic) - Peer Gynt-Solveig's Lullaby (Classical): This very old (late 1950's) stereo recording must have been made on the most expensive gear in the world, since the overall sound quality and especially Ilse Hollweg's amazing voice are as close to "being there" as I've heard with some of the better classical recordings made since the year 2000. The K712 plays this music perfectly.

    Hans Zimmer - Dark Knight-Aggressive Expansion (Soundtrack): The percussion in this track hits really hard, and the bass tones beginning around 0:45 *should* have the ultra-deep "shuddery" kind of sound and feel that indicates a good deep-bass response, but the deep-bass impact is quite lean here. The K712 plays this music well overall.

    Heaven 17 - Let Me Go (1980's New Wave/Techno): The bass instrument (guitar?) has excellent detail, and the voices and ambiance have a "you are there" quality that's uncommon in early 1980's pop music. The K712 plays this track perfectly.

    Hugo Audiophile - 15-16 (Electronic): I'm not sure what the 15-16 stands for - perhaps track numbers from a CD album. The deep-bass tones that start around 33-34 seconds into the track reproduce lightly with the K712. This is a great recording for evaluating whether a headphone's bass will be sufficient for most environments, since for many headphones that have a weaker bass, the deep bass gets absorbed and mostly lost when the environment contains a lot of low-frequency energy.

    Jimmy Smith - Basin Street Blues (early 60's): This track has several loud crescendos of brass and other instruments that don't sound clean and musical with some headphones. The K712 provides excellent detail. Listen particularly to the second crescendo at 15 seconds in for maximum detail effect. I'd like to emphasize that these crescendos are probably the worst-case test I have for instrument separation and detail, and the K712 does those extremely well.

    Kellogg Auditorium, Battle Creek Michigan, Aeolian-Skinner Organ (1933) - Pedal, 32', Resultant, Arpeggio: This 16 hz organ pedal tone differs from other music tones in that you won't "hear" the tone - you'll only feel it. Although most music tones have harmonics (including this one), the harmonics from this tone will be too weak to provide any "feel", so whatever you actually hear would not be part of the fundamental 16 hz tone. There are ~30 hz sounds in the outdoor environment in big cities, generated by large trucks, buses, and subway trains, and they have a quality of "rumble" that's similar to some deep-bass tones found in music. This 16 hz organ tone is easily distinguished from those sounds when compared on a headphone that has good undistorted response at 16 hz. The K712 reproduces the fundamental tone with clearly discernable weight, albeit less so than many full-size headphones.

    Mantovani - Sunrise Sunset (Easy Listening, ca. 1972): A master musician and conductor who specialized in light classics and orchestral pop music, Mantovani's accomplishments were overshadowed by music critics who couldn't tolerate the notion of "light classics" or "semi-classical" music, even when those recordings were no threat to the classical music genres. In any case the later Mantovani recordings from the mid-1960's through mid-1970's had the advantage of being mixed for much better hi-fi systems than those which the music critics possessed at the start of the Long Playing (LP) record cycle. Here in 2014, at least some of those digital remasters have improved the sound further, although it's not always the case. This track as played on the K712 is a perfect example of the sheer musicality lurking in those later recordings, and is highly recommended for soundstage, instrumental tone, and musical balance.

    Michael Tilson Thomas - Rhapsody In Blue (20th Century Classic): Great sound and soundstage, and terrific piano playing and tone. There are some very deep bass impacts starting around 38 seconds into the 17:24 length track, and the weight of those impacts is very subtle with the K712.

    Pinback - Non Photo Blue (Pop-Rock): Crispy sound with "crunchy guitars and bashing drums" - the K712 renders this music as perfectly as I've heard an energetic pop-rock recording played with any headphone.

    Porcupine Tree - Trains (Pop-Rock): This track opens with some nicely-detailed string sounds and a forward-sounding male voice with a higher-than-average register. There are a series of "clip-clop" effects starting at 3:19 that should sound like they were made with wooden blocks of some kind. The K712 reproduces those sounds extremely well.

    Richard Strauss (Mester-Pasadena) - Also Sprach Zarathustra (opening) (Classical): The granddaddy of bass is in the opening 1:50 of this recording, and I've heard it only once on a large and expensive loudspeaker system in Cleveland. For most people, that experience would be indistinguishable from being in a fairly strong earthquake. The K712 provides some of that experience, but the low bass is fairly lean. The tympani have good impact here.

    Scarlatti-Kipnis - Sonata in E Major K381 (Classical, Harpsichord): The harpsichord here is fairly bright and highly detailed, and the K712 renders the tones and transients perfectly.

    Tiger Okoshi - Bootsman's Little House (Jazz): The trumpet here is recorded fairly close up and is somewhat bright with a significant "bite". The K712's reproduction is near-perfect, and the close-miked piano is also a treat. For comparison, I have several Maynard Ferguson tracks that feature a similarly strong trumpet with lots of brassy bite.

    Trombone Shorty - Backatown (Jazz-Funk): The deep bass impacts here are strong and work very well with the horns and other instruments. The K712 delivers the impacts with great weight and detail, and the horns have the kind of bite that gives them a wonderfully realistic sound.

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