Harman Kardon HK250 Stereo Tube Amp:
Easy to maintain and easy on the ears
Harman Kardon HK250 Stereo Tube Amp:
Easy to maintain and easy on the ears
I frankly did not know of and had never before set my eyes on the Harman Kardon HK250 amp. What I was actually looking for at that particular time, before I was cleverly diverted to this amp, was the Harman-Kardon Citation II tube amp, a stereo unit that provided me with my first educational experience in owning tube components. You could say I wanted to reminisce. Anyhow the seller did not know what he had, and so I looked and bit at the bait as a lark. It looked intriguing especially with its distinctive copper chassis and old logo of Harman Kardon.
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Technical Description |
The HK250 is a stereophonic tube amp that uses two 6L6GB's per channel in self biased tetrode connected in push-pull mode to deliver an output level of 25 watts per channel at less than 1% harmonic distortion. As a special feature, the amp may be parallel for 50 watt monaural operation using a switch located at the back of the unit and strapping the speaker terminals.
The amp has the most extensive selectable output impedance I have seen so far with 4, 8, 16 and 32 ohms per channel. The controls located on top of the chassis consists of two output tube balance trimpots for the left and right channels. There are two input receptacles and a Separate/Parallel slide switch at the back. For stereo operation, the switch should be on the Separate side and for monaural 50 watt operation it should be on the Parallel side. The fuse is also located at the back of the chassis, and is externally accessible. Overall there are six tubes: 4-6L6GB and 2-6CG7. Four silicon diode rectifiers are used as well. The unit is rectangular in shape, a little bigger than a typical shoebox with the following dimensions: 15"Wx6"Hx7"D. The chassis and side plates are made of copper, and a black metal cage completes the package. Power consumption is 190 watts. The shipping weight is 30 lbs.
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First Impression |
The following components were used to evaluate the HK250 amp: Audible Illusions Modulus 3, Music Reference RM5 MkII, and Audio Research SP6B preamps, Pink Triangle Turntable with Sumiko MMT and Promethean Green cartridge, JVC XL-Z1050 compact disk player all connected through an Inouye power conditioner, Sound Dynamics 300Ti or Castle Isis speakers with Target stands, Kimber 8TC speaker cables and MIT interconnects.
Cosmetically, the HK250 does not inspire. That's no surprise considering its shoebox size and design simplicity. Moreover, given the array of amps I've had it side by side with (such as the VTL 225's and 120/50, Quicksilver KT88's, and ARC D76) the HK250 in physical appearance seems to be in a subservient class. Frankly, I had second thoughts about the unit's ability to satisfy.
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Simple as Simple Does |
Great things spring from simple ideas. The HK250 is certainly a vivid example.
From the start, it established its musical credentials. But I was unsure. I was being cautious because I had not had the opportunity to compare it with others in our stable. Equally important, I had not listened to live music for sometime, and had lost my musical compass. So months later, I found myself stuck and unable to proceed with this review. It was frustrating.
Anyhow, since then I have been able to savor the music of the Dallas Symphony Orchestra on two separate occasions. I particularly enjoyed Marvin Hamlish when he was in town for the Memorial Day weekend. I knew that he had received numerous accolades for his creativity and musical talent. I was pleasantly surprised to discover that he also has a very entertaining way about him. The exposure to live music motivated me to continue where I had left off.
The HK250 is a refined music player. I suspect the choice of tube is a major contributing factor. From my own personal experience, the 6L6 tube and its military 5881 equivalent sound very smooth and rounded. In fact, it reminded me of the VTL 50/50 amp.
Buddy Holly/The Crickets 20 Golden Hits (MCA 3040) a LP that I had not listened to for quite sometime was still a joy. The music then was pure and unadulterated by too much electronics. The arrangement typical of that era required fewer instruments than what we are accustomed to hearing today. There was a feeling of innocence that was conveyed in the overall musical rendition, an ambience lacking from later rock music. The HK250 felt at home with Buddy Holly and The Crickets. There were no bothersome sibilance and coolness in the vocals and mid-high frequencies. The guitar notes were conveyed with body and dimensionality. The bass notes were sometimes flabby and soft. It did not bother me because I have heard live bass sound this way.
The Best of Sam Cooke (RCA AYL1-3863) was likewise enthralling. On several cuts I simply had to savor the song instead of focusing on its elements. Summertime was like that. I felt like being in a small night club with Sam Cooke playing on center stage. It had that goose bumps effect. Wonderful World, perhaps one of the songs Sam Cooke is best known for, was equally captivating.
Listening to this amp is a revelation. I was pleasantly surprised with the Best of the Beach Boys Vol 1 (Capitol DT 2545). It was sensational! The HK250 was a chameleon. It did not miss a beat in Fun, Fun, Fun, Surfin' USA and Little Honda. It was both mellow and romantic when it needed to be in Wendy and Surfer Girl. The Beach Boys are known for their vocal harmony, and the HK250 excels in the vocal range so there was this palpable synergy. Don't get me wrong. The details were there, like the snare drum, cymbals, lead guitar, etc. They all blended together.
One of my favorite LPs is Van Cliburn Beethoven Sonatas (RCA LSC-4013). I have heard many play the Moonlight Sonata, but I consider his to be divine. His deftness and mastery of the piano were also demonstrated in his lyrical rendition of Appasionata. It was like the piano and Van Cliburn were in perfect unison. There was no overhang, the timing and finger pressure just right. This is an exemplary recording by a superlative pianist. Frankly, I was amazed that the small and ancient HK250 could convey all of these nuances.
| Weaknesses |
While the HK250 is a commendable performer, it nevertheless has a number of weaknesses. Top among these is its relatively low resolution. It lacks the crispness of the VTL 120/50 or the ARC D76. Through the HK250, the leading or fading edge of the harmonics is less discernible and softer. It is not irritable and in fact one would only notice it on a one-to-one comparison, but if you are the type who places harmonic extraction very high on your priorities, then look elsewhere. The second notable weakness of the HK250 is its dynamic contrast. I suspect this is related to its power rating and power supply design. The effect is a shorter scale and less grandeur to the music. Thirdly, it falls short in bass definition. This is not a surprise given the weaknesses described earlier. Typically, these weaknesses affect one another.
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Conclusion |
The HK250 is an easy to maintain and easy on the ear tube amplifier from a company that has successfully transitioned from tube, to transistor, to digital. It is engineered for durability judging from the unit that I obtained, and from past experience with their Citation tube line. It does not require bias adjustment or frequent tube replacement. In fact the unit I purchased still had the original factory tubes. The transformers run cool and parts are said to operate below their rating.
The HK250 is not often seen in the used market. As I mentioned, I obtained it accidentally. I would say that a unit in excellent condition would fetch $250 or slightly more given their rarity, durability, and build quality in comparison to other stereo tube amps of that era. I would rate this amp 2 and a half clefs, and worth every economical dollar.
by Rome Castellanes
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