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 New or Old, Part I I’ve immersed myself into the world of vintage audio
electronics, and in doing so have discovered some interesting things.
Having already written about a few of the more humorous aspects of playing
with old audio equipment in a tongue in cheek e-mail sent a few months
ago, now it’s time to get real: There is a modern day lesson to be
learned from listening to electronics considered candidates for the
Antique Roadshow; and it needs exploration. John Mallin’s letter addressed a number of issues, particularly those related to restoring vintage loudspeakers. This comment, however, was the one that really struck a chord:
The Jensen Model 15 renovation (as has a recent Sansui 771 purchase and recap), caused me to reconsider just how astute the designers of audio equipment were back in the 1970s and how far the last 40 years have brought us. It’s truly a mixed bag, and care must be given not to assert generalities for specifics. First of all, no broad brush strokes can be used to paint the picture I want to paint. It must be understood that there are exceptions to most rules, including those conclusions that I will be drawing here. I will therefore be very careful to couch my statements within specifics, so you know precisely where I am coming from and you can place these comments squarely within the context they are intended for. Before going into the details and comparisons of vintage to modern era equipment, a groundwork needs to be established. Because I covered a substantial amount of ground regarding vintage loudspeakers in the last issue (#199, 200) and will be covering more loudspeakers in the future, this article covers solid state electronics. These are just the basics: Aging Without Grace. Electrolytic capacitors: Vintage gear generally sounds bad upon first audition. I don’t care how wonderful the e-Bay seller says the gear he is selling sounds, if it hasn’t been serviced its performance will likely be lacking. If you are fortunate, that "wonderful" sounding amp will only be in need of recapping – new capacitors. Liquid electrolytic capacitors have an average use life of approximately fifteen to twenty years; that’s all they were ever designed for. Most of the caps used in modern, as well as vintage gear, are electrolytic caps containing an ionic fluid which stores the electric charge inside the cap. As opposed to the liquid electrolytic, some products use solid electrolytic caps made of mica or tantalum, which basically last forever but have an undeserved reputation for poor quality sound. Of the vintage electronics I’ve inspected so far, only the Epicure M1 power amplifier has exclusively used solid caps throughout, except, of course, for the soup cans in its power supply. With so much vintage equipment reaching 35 – 40 years of age, it should not be a surprise that many of the caps in those machines are leaking and bulging, making it impossible for them to stay anywhere close to specifications. Even if they look good, the potential exists for caps in any vintage unit to be wildly out of spec. If old caps don’t shut the machine down, they can make it sound every bit of its old age and worse. Electronics in need of recapping don’t have a generic sound to them, other than they sound wrong. A Kenwood integrated came in sounding all tight, pinched and totally lacking in depth; redoing the driver boards and most of the power supply worked wonders. An old Sansui receiver sounded muddy and bloated (just the opposite of the Kenwood) and a recap job of the driver board for both channels transformed it into something very special. Therefore, when it comes to the A/B comparisons done between new electronics and old, I am careful to check out the vintage gear for out of spec caps – almost every piece has them. In replacing caps in old equipment, I don’t cherry pick here and there, but instead simply assume that certain caps are going to be in need of replacing. I do a visual examination and when in doubt check the ESR of individual caps. If a bad cap is found (usually) the entire board is redone.1 So far, it has been my experience that power supply boards and driver boards are generally the ones most likely to be in need of cap transplants wholesale. Nor do I use super fancy "audio grade" designer caps since vintage gear didn’t originally come with high octane caps in the first place. Standard, "off the shelf" caps from reputable manufacturers are more than sufficient for most purposes and will still be better sounding than the originals installed 35 years ago. Transplanting new caps for old generally doesn’t cost a great deal of money, but you have to know how to do it right – doing it wrong can be disastrous particularly with electronics. Be especially aware of cap polarity. Film caps: Film caps are not electrolytics and as a whole do not grow old, wear out and leak. In most cases an old film cap will not jeopardize the performance of a loudspeaker the way an electrolytic can; which doesn’t mean that performance will not be substantially enhanced by replacing old film caps with new ones. Capacitor technology has advanced greatly over the years and a good film cap made now is well ahead of those caps made even ten to fifteen years ago. Film caps are generally used in better loudspeakers and sound substantially better than electrolytics. The main problem with film caps is that they are substantially larger than electrolytics for the same values. Inside of a loudspeaker, size is generally not a consideration, so I don’t hesitate to replace the old with larger high voltage film caps of the same uf value. But inside a cramped amplifier circuit board space is often at a premium, thereby eliminating film caps from many applications. . . . Remainder of article in BFS Report #201.
And while on the subject, there is a way for you to know the issue number of the last issue of your subscription. Simply look at the label on the outside of your envelope. Just to the right of your name is a number. That number corresponds to the number of the last issue of your present subscription. So, if it says 201, this would be your last issue. If, however, you don’t pay attention to the expiration number on the envelope, we always send two notices of expiration before you run out. After all, we want you to stay current …
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ISSUE #201 CAST OF CHARACTERS Contributors
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It’s been a source of confusion
in the past, and I think a word here can remedy the situation. On the front
page of every Bound for Sound is an issue number and a publication date. For
this issue the number is 201.. The publication date is May 2010. Even though
I would like to, we do not come out on a monthly basis. Hence, you will not
see covers with publication dates that closely correspond with consecutive
months. So, don’t be surprised when one issue says "July" and
the next one says, "September." It means nothing other than one issue
came out in July and the other in September. It doesn’t mean that you missed
the August issue. On the other hand, the issue number means everything. We
number our issues consecutively. Our last issue was #199/200 and this one is
#201. If you are missing #201, you have missed an issue. It’s as simple as
that.