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.
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.
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 …
Our cable and broadband had been furnished by Insight
Digital for a number of years. That has changed, and with the
change the purchaser of consumer base (Comcast) has changed our
e-mail address. The new e-mail address is bfshifi@comcast.net.