Harman/Kardon HK6950R Amplifier
The dividing line between mid-fi and high-end audio is often a narrow one. When crossed, the resulting improvement in sound quality is a matter of diminishing returns, with more and more expenditure yielding smaller and smaller sonic benefits. At times, there are no audible returns at all: The audiophile pays for snob appeal, the extra cost of import, or the higher overhead from less efficient production and small production runs.
Yet, crossing that line usually yields a real difference in musicality and pleasure, like the difference between vin ordinaire and a grand cru, or between an economy sedan and a sports car. The finer nuances of sound make all the difference in bringing the pleasure and impact of a live performance into the home. The returns may diminish with each extra dollar, but they're still worth getting.
The Harman Kardon HK6950R integrated amplifier is a good case in point. It sells for about $1,300 and is a mass-produced component from one of the most respected names in the business. At the same time, many of its specifications qualify it as high-end. It will deliver 170 watts into 4 or 8 ohms over a bandwidth of 10 Hz to 100 kHz, with less than 0.08% THD. Its transient intermodulation (TIM) distortion is rated as unmeasurable, and it has a high instantaneous current capacity of ± 90 amperes. Its slew rate is 280 V/μS and rise-time is 1.8 μS. The preamp has a moving-coil input with a sensitivity of 120 μV into 56 ohms and a signal-to-noise ratio of 76 dB as well as a moving-magnet input with a sensitivity of 2.5 mV into 47 kilohms and S/N of 83 dB.
Like many other Harman Kardon components, it has several high-end design features. The amplifier circuitry is discrete, very low feedback is used, switching is electronic, and circuit boards are very well laid out and well shielded. The amplifier section's high current capacity and wide bandwidth allow the HK6950R to deliver its power into a wide variety of speakers; the preamp section has switches to defeat the tone controls or bypass all preamp stages except the volume and balance controls and the selector and monitor switches, which allows the audiophile either to reduce or to minimize the amount of circuitry that affects the signal.
There are no "trick" or unnecessary features that do nothing for the audiophile but complicate the circuit at the cost of sound quality. At the same time, the HK6950R has all the features any audiophile is likely to need. It has four high-level inputs plus phono (with a front-panel "MM/MC" switch) and connections for two tape decks. The tape connections include full monitoring and dubbing facilities plus the ability to tape one source while listening to another. Its tone-shaping facilities include bass and treble controls, loudness contour, and a subsonic filter, all defeatable. And output choices include a headphone jack and a selector for two sets of speakers. The HK6950R also comes with a remote control that can operate many of the tuners, CD players, and cassette players in the Harman Kardon line.
The rear panel is well labelled and conveniently laid out. In addition to all the usual RCA jacks, it provides facilities for using the power amp separately from the preamp, two sets of speaker terminals, a switch to select between 4- and 8-ohm loads, and three a.c. outlets.
This is an impressive package of performance and features by any standard, and it is delivered at about half the cost of comparable high-end equipment. The HK6950R also provides excellent overall sound quality when it is judged by mid-fi standards, easily outperforming the conventional range of receivers, integrated amplifiers, and audio/video units that claim comparable power at 8 ohms but find it very difficult to deal with real-world speaker loads.
The Harman Kardon HK6950R provides more dynamics and more bass power and control than virtually all mid-fi competition. It has an energetic and slightly forward sound with a great deal of upper mid-range information. It will do an excellent job of pairing off with virtually any really good mid-fi speaker that has moderate or slightly soft highs, and phono buffs looking for affordable electronics will find it an excellent match for Grado, Sumiko Blue Point, and Shure cartridges. The V-15 from Shure is a particularly good match.
What happens, however, if we make unfair comparisons between the sound quality of the HK6950R and that of high-end units costing twice as much or more? What do we really sacrifice relative to the sound of the best competition in this elevated price range?
The HK6950R does not exaggerate any aspects of timbre, but it does mix a slightly warm, uncontrolled mid-bass with an apparent increase in upper midrange energy. This is typical of most well-designed transistor mid-fi electronics.
This unit does not have the deep-bass energy, dynamics, or control of far more expensive high-end basic power amplifiers. Its mid-bass is also slightly warm and relatively lacking in definition and control. Much, however, depends on the speaker. The HK6950R can perform very well with speakers having extended bass or with smaller bookshelf or monitor speakers whose response does not rise just above their bass cutoff point, which are relatively reasonable loads and which do not need a lot of control from the amplifier. It works well with speakers having simple to moderately complex crossovers and impedances above about 4 ohms.
One of the things high-end buyers most willingly pay a premium for is a combination of upper midrange sweetness and natural musical detail. Mid-fi electronics tend to sacrifice these for "apparent" upper midrange detail. The HK6950R is no exception, although it performs better in this regard than most of the equipment in its price range. As with the upper midrange, the treble is just a bit hard but in no sense aggressive.
The HK6950R does lack some of the transient detail and transparency of its high-end competition, and this is only slightly affected by the tone-defeat and preamplifier-bypass controls. The importance of this loss will depend a great deal on the quality of your program material, signal sources, and speaker, but this is an area where you do get something worthwhile for spending twice as much. This is particularly true with soft or very complex passages, massed strings, and choral music. As might be expected from this, the HK6950R does not have the same ability to resolve the finer nuances of musical harmonics as the best high-end components do. This shows up with solo violin, guitar, piano, and harpsichord.
This character seems to lie primarily in the preamp section, however. If you are upgrading and on a budget, you can start with the HK6950R as is, then substitute another preamp later while continuing to take advantage of the amplifier section's relatively superior performance.
At the same time, the HK6950R does not exhibit the lack of overall musical coherence common in mid-fi equipment and some high-end equipment. A Steinway consistently sounds like a Steinway. Complex percussion music, strings, woodwinds, and voices are equally coherent. I find this consistency far more satisfactory than the kind of sound reviewers praise by having to say that a unit is "interesting" or "performs very well" with one kind of voice or recording but not another.
The HK6950R presents a good wide soundstage, but with only moderate depth, and the apparent listening position is moved a bit forward. This does not always suit classical music, particularly if it is close-miked, but it can be very involving and enjoyable with popular music and rock. Left-to-right imaging is very good, although location sometimes seems a bit over-defined or fixed in place. The amplifier's ability to place instruments and voices in layers of depth from front-to-back location is moderate.
If you pay any attention to speaker compatibility, the HK6950R is capable of very life-like musical dynamics, outperforming in this regard a number of moderate-power high-end amplifiers that cost far more than the Harman Kardon.
The HK6950R sounds very quiet, particularly when used with its line and moving-magnet inputs. It is better than a number of high-end preamp and amplifier combinations in this respect. It does not, however, have the same musicality in very soft musical passages as its high-end competition, nor does it provide the same soundstage detail. The lack of apparent noise does not always translate into increased musical pleasure.
I would not advise the use of a low-output moving-coil cartridge with the preamp in the HK6950R. The moving-coil gain stage sounds harder and more aggressive than the moving-magnet stage, and most low-output moving-coil cartridges in a price range compatible with this unit already have resonance problems in the upper midrange.
I do suggest mating this amp with a CD player, phono unit, and speaker with soft or slightly rolled-off upper octaves. Component matching, of course, is critical to getting good sound even with far more expensive high-end equipment, and choosing the right mix of components to provide musical enjoyment is the whole point of being a high-end audiophile.
In comparing the Harman Kardon HK6950R to very expensive high-end sound, we must not miss the point and focus on the unit's weaknesses instead of its strengths. So let me emphasize two things: First, the HK6950R is extremely competitive within its price range. Second, comparisons with electronics costing twice as much or more are only part of the story in terms of value. I auditioned the HK6950R on a range of speakers that cost two to six times as much as any audiophile buying this unit is likely to spend, and with phono and CD units that each cost as much as an entire mid-fi system. The fact that the HK6950R performed as well as it did under these conditions is an endorsement of the product, not a criticism. There are few mid-fi products I would use in making such a comparison, and many of the nuances I have discussed will have limited relevance to audiophiles who cannot afford an entire high-end system. Most important, the HK6950R delivers the same overall sound quality as many expensive transistor high-end preamps and amplifiers did only a few years ago. You can have a lot of fun with music if you make the HK6950R the center of a well-balanced system.
