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Harman/Kardon CD491

I remember somewhere near the end of ’80s when my good friend brought me HiFi catalogues from Vienna. He gave me Sony, Pioneer and other marketing materials, but the one them was so special. “This one was not on the desk, they were hiding it underneath, but I asked them to give one to me.” It was Harman/Kardon catalogue with beautiful CD491 deck, CD7600 player and these wonderful amplifiers, starting with 6900 model. I still have it and it is in great shape.

But, I have to admit I am not a Harman/Kardon fan. Very aristocratic name and such big company that swallowed many good names. I like diversity and different bosses and ideas, maybe HK doesn’t, or simply wants to rule everything. I also don’t like much of their products, not counting member firms: too many places in which they spared the money, too many cheap controls, switches, and other stuff. And the metal boxes… they also tend to be not worse, but also not any better than any other competitive company.

So, let’s return to CD491. CD means Cassette Deck in this case, not Compact Disc. Later models have TD prefix which stands for Tape Deck, but You figured this already. What is different is that CD491 is the very special of the kind. It was made in black or silver finish. I like silver, many like black, but the main difference is that silver one also has metal buttons for transport control, and black one uses black plastics. Printed names of the controls could be erased relatively easy on the black one.

Other controls include separate record level potentiometers and the master one. You could also play with two microphones, since there are two inputs on the back. Tape selector is not automatic, it is manual like on most Nakamichi decks. Dolby circuits are B and C type, with HX Pro always turned on. Nice touch is “Wait” LED signal when You switch on the deck – it waits a few seconds until all is activated, including a little lamp for the whole display.

What I didn’t like is response of master record control: it jumps very fast from small to higher values looking at the LED peak meters. This means You have to be very, very precise when using it, or play with separate left/right potentiometers, which is annoying.

Harman/Kardon CD491 comes with the user manual, of course. But there is another thing: it came with measured frequency response, every piece of CD491 was precisely taken care in the factory  and data graph was shipped with it. Marvelous, as far as I am involved with decks only Alpine and some Nakamichi models had this sort of information packed together with their products.

Cassette transport mechanism of CD491 is one of the most popular regarding higher class tape decks, but it has some flaws. It is Sankyo made three motor transport. Harman/Kardon CD491 uses something that looks like an older version. Main capstan is directly drive (DD motor) but is smaller in depth than, say, the one on Teac V7000 which uses almost the same mechanics, or Nakamichi CR5/CR7.

It also uses idler rather than gear to turn reels and this is the good but also the bad point: idlers are good in vibration cutting but are generally unreliable when comparing with gears which, on the other hand, make vibrations. The one used on CD491 is almost the same as on Alpine AL85/90, previously mentioned Nak decks and many others. This means it will last a few years and then need a replacement even if deck is not working. It looks like idler originally assembled in the factory is of much better quality than these we can find as a replacement part. Anyway, gear upgrade is possible on CD491, You just have to find donor deck with more advanced Sankyo transport of the same kind.

Regarding serviceability, Harman/Kardon’s deck is not a champ. Since it was made in Japan (like almost all Harman/Kardon stuff these years) Japanese liked to make small depth boxes for many great decks, there are many examples. The CD491 is not an exclusion: according to the service manual, You have to disassemble the whole power/transport logic circuit board in order to put mechanism out of the deck. Could You believe it? I can’t imagine what was the reason for this except to cut costs down for a few dollars by making smaller metal housing.

Head conductors are soldered directly to the board pins, no connectors here. It means You have to desolder them before completely removing mechanism. Good for head contacts, bad for repair. Cassette door is made of casted metal, at least on silver model.
Harman/Kardon CD491 display is one of the most beautiful I have seen: nice light green counter (digits plus real time although just for play/rec) and long rows of three colour LEDs. Meter weightening is supported and rec/bias calibration with included 400/10.000 Hz oscillator, sensivity can be adjusted for both channels independently. Nice, but I would like independent bias as well. It is interested that Harman/Kardon CD491 comes with the special tool, basically a little plastic screwdriver to adjust recording sensivitythrough two little holes during calibration process. Buttons would be more appreciated, but this thing also works. In the case You loose screwdriver, any similar would help. These bias trimmers are actually the ones that are supposed to be trimmed during factory calibration, they are just accessible by the user on this deck. Simply and clever, like on Nak 680ZX, for instance.

Monitor switch is another weak spot: it is a pure mechanical switch, prone to dust. Cleaning helps but a relay solution would be much better.

Despite all this, CD491 has marvelous sound: extremely detailed and transparent in upper frequencies. Timing is very good and 3D soundstage is one of the best I have ever heard. Bass is strong, with solid impact and very good extension, not emphasizing any part of it. Harman/Kardon CD491 bring no specific colour to the recorded material – crisp and clear without softening any passages of music, it is indeed a beautiful deck. Moreover, HX Pro is installed and adjusted correctly, not sounding like the one on those middle or low class decks: emphasized higher frwuencies, with annoying unnatural tones that makes You ears burn. Harman/Kardon CD491 works this well.
I had problem on my CD491 and the symptom was not being able to calibrate to the tape and high level of distortion on both channels during monitoring recording or playing material recorded on this deck. At first I thought it was the power supply problem or bias circuit not working well. After several attempts to repair it (even replacing it’s rec/play combo head) it was no better. But on of highly skilled technicians found that electrolytic capacitors in recording and playback amplifier were bad, so he replaced around eight of them and fixed issues on this deck. So, I recommend anybody who plans to get or uses CD491 to replace as much electrolytic capacitors as possible.

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