rdp@teddy.UUCP (10/15/85)
As a service to the audio community at large (or at small), I am hereby taking the initiative to start a semi-regular feature while I have access to the net. True stories in the insanity of audi. Yes, it's Audio Anecdotes! For my own ground rules, the stories I present are true, and are selected not only to amuse and entertain, but to inform as well. Today's topic: Where oh where is the tome coming from. Back in the days when I was involved with a retail outlet, Nakamichi was just getting there US market going. At the time they had but a few products, the Nakamichi 1000, the 700, the 550 and the 500. Of interest to several musical type people was the 550, which was a portable, fairly high-quality casette unit with Dolby-B. One customer type bought one and, after a week or two, brought it back complaining that he could hear a faint tone in the backround during very quite passages. Well, after much fiddling and waiting for trucks to pass, yes we could, by straining wuite a bit, hear this tone. Into the lab I and the recorder went, where I proceeded to measure the S/N ratio. It was supposedly rated at 56db (or some such figure, the exact number is unimportant, just the relative values are). Well, there on the bench, it was cranking away at some 59 or 60 db S/N. ANd the scope showed no trace of any regular waveform in the noise. A call to Nakamichi generated an immediate request for the recorder, as they wanted to know what was going on. After a week or so, Nakamichi called back and said, "There is nothing wrong with the recorder, it meets spec." I asked, "Did you solve the problem?" "It meets spec", came the inappropriate response. "Did you find the tone?" I pushed. "It meets spec", came the obviously practised reply. "send it back and I'll check it out", I asked. A day or two later, back it came, and, by the looks of screw heads, it had never been opened. Back up on the bench it went, and it did, indeed meet spec, and out into the showrrom it went, and sure enough the tone was still there. AT this point we decided to give the customer a new unit and try to resolve the issue with Nakamichi. Unfortunately, the new unit, and all others in stock, suffered from exactly the same problem! Time to bring the heavy weaponry to bear! I fired up the HP narrow band spectrum analyzer! A spetral analysis of the noise revealed, in addition to the perfectly normal noise floor, a nice, sharp prominent peak at 400 Hz. Why 400 Hz? Well, it seems, that happened to be the frequency of the Dolby calibration oscillator. Seems that Nakamichi had designed the calibration oscillator so that when you turned it off, it was not turned off, but merely disconnected from the record amps. The rest of the time, it was oscillating happily away, generating enough cross-coupling to find it's way into the playback amps where it's micro-volt level was dutifully amplified to barely audible levels. Now, armed with real information, I was able to call Nakamichi service directly and tell them exactly what was wrong. The technicians were very interested in my description of the problems. However, Nakamichi as a corporate being said "If the noise", meaning, I guess, any extransous information, "is below the spec for signal to noise, then the unit is perfectly OK." Here, the customer and ourselves were left high and dry. We had a unit with a definite and identifiable design defect, and the manufacturer tells us in no uncertain terms that it is not interested in the problem. After several weeks of haggling, Nakamichi simply refused to provide any help in solving the problem. By this time, several units were returned, all complaining about the problem, so we had a multi-thousand dollar issue to deal with. At this point, we had several choices. 1) Tell the customers what Nakamichi told us, and tell them that life is tough all over, and keep their money, 2) Take the units back and give the customers a refund (which, under Massachusetts law they had the right to demand), and end up eating them, because Nakamichi wouldn't take back what it considered OK merchandise, or 3) try to solve the problem. The tack that we took involved part of #1 and all of #3, that is, relate to the customer the difficulties of trying to get Nakamichi to handle the problem, and, hoping that their sympathies would be in our favor, buy time to try to solve the problem. The solution was to re-wire the Dolby tone switch to disconnect the power from the oscillator, rather than disconnecting the oscillator from the rest of the recorder. This completely eliminated the tone problem, but gave rise to the issue that it took some 30 minutes to effect the repair, and the unit, thus modified, was unacceptable to Nakamichi for warranty service, even though we were a Nakamichi-authorized service station. The lesson to be learned here is manifold: 1) Just because a manufacturer might be highly regarded does not make him infallible. 2)Some of these manufacturers, when presented with what they might consider embarrasing information (as Nakamichi would later admit was the case), will stand fast and find anything to defend their position (I believe after MANY people complained, they finally incorporated my change into the product, but that took several YEARS!), 3) Much of the problem that customers have in trying to get these sorts of problems solved are due to the intransigence of the original manufacturer, not the dealer (although many dealers can be accused of complete incompetance in this area). Dick Pierce
rdp@teddy.UUCP (10/21/85)
AUDIO ANECDOTE
of the
<interval>
(this time it was a week)
Way back when I was working in our retail store (about 1974),
the search was on for a high-quality line of receivers that
would meet our criteria of high-performance, low-distortion,
high-reliability, and good manufacturer support. After lots
of trials, the new Yamaha line was selected (this was the
CR/CA-400, 600, 800, 1000 line). In fact, we turned out to
be the first dealer in the Northeast to carry this line, and
did quite a bit of legwork to promote and support it.
The units were quite good. Typically, they were underrated,
power-wise, by nearly 40%, they had vanishingly low distor-
tion, good, wide bandwidth amplifiers that were intelligent-
ly designed, excellent tuners for the price, and were very
pleasing, in their conservative garbs, to look at. The phono
preamps had good transient characteristics and were essen-
tially overload-proof under all but the most bizarre of con-
ditions.
We sold quite a few of them. Everybody that bought them
loved them. Sure, their was the occasional complaint that
the tuner cursor was sticking at times (due to the teflon
track becomming unglued at spots) and the ever-present noisy
switch now and then, but overall, the customer satisfaction
was very, very high. At least for a while, it was.
One day, about a 18 months after we started selling the un-
its, a customer brought her CR-800 back, complaining (quite
apologetically) that there might be something wrong with
hers. She was quite unable to articulate exactly what the
problem seemed to be, but she settled on an analogy, "It
sounds like I live next to Logan Airport". Well, we agreed
to look her unit over, and lent her a replacement in the
meantime. We set up her receiver with a pair of speakers,
and listened. AFter an hour, nothing happened. We gave up
went home.
Later, a call to the owner revealed that it only happened
while playing records. Ok, so we'll listen to records. After
another hour or so, still nothing happened. We were about to
give up again when everybody got this very frightened look
on their faces. The room started shaking. Soon, what sounded
like a Boeing 747 on final approach was heard. It seemed
like it was but yards away! The roar was deafening! I hur-
ridly shut off the speakers bringing relief to all.
Into the lab we went, where we set it up again. Looking at
the output of the power amp, we saw nothing unusual. Then,
looking all the way back to the phono input, again, nothing
unusual. The output noise was equivalent to about .8 micro-
volts total broadband noise on the input. For a while. After
about 2 or 3 minutes, the noise started slowly increasing,
then more rapidly. After about another 30 seconds, the ef-
fective input noise level was now equivalent to almost 1/2
volt, severely clipping most gain stages after the phone
preamp!
Well, says us, that's an easy one, just find out which com-
ponent is getting noisy with temperature, and replace it.
This took one or two blasts of the spray cooler, and a sin-
gle NPN signal transistor, a 2SC1345, was found to be the
culprit. Wizz bang, out it came, a new one went in, and,
presto, problem gone, customer happy, no charge, and Yamaha
pays me $24 for 5 minutes work!
But, and this would be a truly boring anecdote without a
but, the unit came back about a month later, same problem
(but different channel). Culprit? A different 2SC1345.
Another 5 minutes, another $24 dollars. Boy, says I, this is
one way to make a living.
Soon, several others brought theirs back with the same prob-
lem. I notified Yamaha, and they say they are unfamiliar
with the problem. Now, other problems are starting to show
up. Tuners are drifting (AFC driver happens to be a
2SC1345), stereo lights don't light up (lamp driver from MPX
chip is a 2SC1345). Output stage blows up, taking tweeters
with it (bias regulator is 2SC1345). Turntable starts run-
ning at erratic speed, sometimes as much as 100 RPM (you
guessed it, 2SC1345 is tacho sensor in turntable speed con-
trol).
I'm replacing 2SC1345's left and right, making a bundle on
in-warranty repairs. It turns out that EVERY Yamaha unit we
sold with a 2SC1345 somewhere in it came back for repairs.
The Yamaha pulls a fast one. They say that they will no
longer pay for repeat repairs on units with defective
transistors. What this really means is they require repair
centers to replace ALL 2SC1345's when the unit comes in for
repair. A job that might take 3 to 4 hours on some of the
more complex units. And how many repair people will butcher
a board replacing upwards of 20 transistors?
Interstingly enough, at the same time, Burwen Labs is having
a similar problem in their noise reduction units, uncon-
trolled noise after warmup. ALL Burwen units eventually had
to be repaired.
The connection: Both manufacturers were using semiconductor
devices manufactured by Hitachi during a certain period of
time. It was discovered that there was an impurity in the
curing resin for the plastic cases that proved corrosive on
the more delicate parts of semiconductor fabrications.
I solved the Yamaha problem of not enough money/time to
repair by simply sending the whole motherboard or the entire
receiver back and let them handle the problem. Interestingly
enough, they never officially admitted that this problem
ever existed.
As an aside, one CR-800 came back, also very noisy, but with
different symtoms. Opening the case revealed a white residue
covering much of the interior, along with what might have
been very minor fire damage in an area that a fire could not
have gotten started in (the tone control/tape switch board).
I suspected that this was not a warranty repair, and we then
questioned the customer. After grueling cross-examination,
it turns out he was trying to free-base some coke on the
shelf above and ended up spilling the whole mess into his
receiver, and nearly burnt his apartment down in the pro-
cess!
Dick Piercerdp@teddy.UUCP (10/29/85)
Audio Anecdote
of the
<interval>
This <interval>'s topic:
Chrome-Dome
and
The Use of Loudspeakers
as
Offensive Weapons
The last two anecdotes dealt with the problems dealers and custo-
mers face when dealing with manufacturers. This <interval>, we
take a look at some of the the problems dealers and manufacturers
face when dealing with customers.
The main character in our story here was a young (high-school)
kid subsequently dubbed "Chrome-dome". Here is his (our) story:
Way back when, shortly after I and several others had started a
high-end hi-fi store in Boston, we were selling, amongst other
things, the then completely new Yamaha electronics line and
Celestion speakers. For those who may not be familiar with them,
Celestion, at that time, made a line of speakers that combined
reasonable accuracy with high efficiency and remarkable power
handling. The top of the line speaker, the Ditton 66, consisted
of a 12 inch woofer/passive radiator bass system, a phenominal 2"
dome midrange that would handle untold power, and a very wide
band uncollored 1" dome tweeter.
One day, this kid walks in, carrying a copy of Pink Floydd's
"Dark Side of the Moon". Seems he's looking for a killer hi-fi
system. He had been sold on JBL speakers and Phase Linear amps
and Crown preamps at another store. His budget, unfortunately,
was about 40% shy. We suggested he listen to a system comprised
of the Celestion 66's and a Yamaha CA-1000 integrated amp. The
combination (once he got done with turntable, et al) was within
his budget, the only remaining task was to convince him that the
system met his needs.
He handed us his record, and we said we already had a new copy.
"No," he said, "I don't trust stores' records, they're usually
awful." OK, we say, we'll play yours. To this person, record care
was something you did with stuff you scrape of your sneakers and
apply with 40 grit sandpaper! He agreed that his record was "a
bit worn", but that was done by another store. We put our copy
on, and he was happy.
While it was playing (fairly loud), he asked that it be turned
up. Up it went. Not loud enough for him, he wanted it even
louder. At this point the level was approaching painful, but
there was plenty of reserve left in the Yamaha, so we didn't care
much. It was far louder than we had ever listened to things, but
we were amazed at how the speakers were managing to handle
things, and they showed no signs of distress. Louder and louder,
he wanted things.
He was not convinced until the strangest thing happened. The
Celestion speakers were sitting on a couple of short pieces of
2x4's because, sitting directly on the floor, the bass could
sometime be overwhelming. The 2x4's seemed to cure the problem.
Well, whoever had set up the speakers didn't have them seated
squarely, and, during a particularily loud passage, the left
speaker slipped of one of the 2x4's, and, rocking on the verge of
total imbalance, proceeded to walk forward about a foot or so!
Well, this kid was impressed beyond recovery. At that point, he
took out his and paid us for the system, cash! This despite our
repeated attempts to convince him that the speaker had merely
slipped, and wass not walking under its own bass prowess!
He took the system home, and immediately called us up to tell us
how wonderfull the system was.
For several weeks we heard nothing. In the interim, it seems his
father had gotten sick and tired of his hippy kid playing that
rock music at deafening levels. So he grapped our hero, dragged
him to a barber shop, and had his hair cut. This kid ended up
with a crew cut the of which there has never been any whicher,
before or since. I doubt there existed a single folicle exceeding
1/16"! At his next visit, we didn't even recognize him. He said
of his fate, "Well, I guess you guys can call me Chrome-dome!"
The name, of course, immediately stuck fast.
This visit of his was not all that humorous. It seems that the
speakers didn't sound as clear as they once did. A quick listen
revealed the problem: the tweeters were very thoroughly fried. We
replaced them no charge, and advised him that he should excersize
some caution. He went away happy, while we tried to figure out
how he had managed to fry two tweeters.
A week later, our friend was back. Same problem. New tweeters
were installed. This time, he was required to pay for them,
since the problem seemd not with the equipment. At $36 a crack,
this was to become an expensive lesson to learn. The next day,
he was back again. This time he brought his amp along. I checked
it out, just to make sure that it was not unstable or oscillating
or anything like that. Well, we had warned him, and told him to
get his $72 ready. I retired to the lab to replace the tweeters.
WHen new units had been installed, I tested the speakers. There
was no high frequencies still, and the midrange sounded truly
strange!. I quick checked the feed to the tweeters and found
nothing. So, out came the woofer, and all the damping, and there
was the crossover before me, or what remained of the crossover.
Both high frequency pass capacitors were gone. Simply not there
anymore, quite totally in absentia. One of the midrange caps
looked more like a sausage than an electronic component. There
was the unmistakable odor of burnt plastic, and the rear wall of
the enclosure looked like it had been hit by shrapnel. And there
was a lot of paper and aluminum confetti just floating about!
Well, Chrome-dome was put on the hotseat. "What happened?", we
drilled. After a few minutes of questioning, he revealed that he
like to play his harmonica along with whatever music was playing.
And, conveniently, the Yamaha amp had a nice microphone jack on
the front panel. Well, visions of infinite feedback squeal danced
in our heads. Sure, I thought, that might be enough abuse to send
an amp so far into clipping that it might destroy some tweeters.
He even agreed to demonstrate. We, instead, suggested that we
show him how, if he really had to do it, how it should be done.
He hauled out his microphone, and we plugged it in, and carefully
turned it up until it was at the level he wnted it at. The volume
control was at about 2/3 full. He said, "No, that's not how I do
it." At which point, he removed his microphone, turned the volume
all the way up, and proceeded to slam the microphone plug back
into the jack. There was, of course, a deafening "KABOOM", ac-
compinied by a very sharp but muffled "CRACK". Simultaneous to
this was the unmistakeable ring-like flash of light acround the
periphery of the tweeter domes, signalling that the tweeters in
our floor models had gone to join their compatriots in some
direct-radiator nirvahna. A few seconds later, we detected the
strong odor of burning plastic, tempered by a slight acid smell.
Our floor models were destroyed! The capacitors had been blown
apart, in one case fracturing the crossover PC board!
And there, next to the Yamaha, which had shut down in protest,
was Chrome-dome, smiling his toothy grin, saying, "Wasn't that
awesome?"
Dick Pierce