I value SOS’s opinion
very highly and, when I wanted to add a versatile, quality compressor
to my arsenal, I thought about the review in SOS July 2010 of the Slate
Pro Dragon [see www.soundonsound.com/sos/jul10/articles/slateprodragon.htm
for the full review]. On the first unit I got I identified something
that I thought was weird, so I got it replaced — but the second unit
displays the same behaviour, which apparently hasn’t been noted by
anyone, so I’m kind of puzzled.
The
noise that reader Eric heard coming from his Slate Pro Dragon is most
likely from the transformer. It’s very common in modern devices with
these kinds of transformers, and is nothing to worry about.
The behaviour is this: if I send a track to the unit
(it’s more obvious with something like a guitar or vocals) with a normal
level, have the input at around six, the output at around three to
four, and the saturate knob on three, you can hear the track feeding the
unit acoustically from within the Dragon itself. What I mean is, if you
don’t even connect the output of the Dragon to anything, and there’s
not a single monitor turned on, you clearly hear the sound feeding
the unit, produced by something acting as a transducer inside the
Dragon. When the saturate knob is on a lower setting, you really have to
put your ear on the unit to hear something, but it’s actually there.
It’s
so strange that, after having seen this on the first unit, I contacted
Slate Audio, but, apparently, they were not aware of this either. That’s
why I thought that this first unit had a problem. So I was hoping you
might have noticed something during your review.
Eric Robert via email
SOS
Technical Editor Hugh Robjohns replies:
I would suspect that the output
transformer is rattling; the laminations move slightly in response to
the audio signal passing through it, which create a varying magnetic
field and cause the laminations to vibrate in sympathy, hence generating
an acoustic output. Depending on the way the transformer is mounted,
those vibrations can be amplified acoustically by the circuit board or
case metalwork and become surprisingly audible. It’s the same thing that
makes small mains power transformers buzz annoyingly in so much modern
equipment.
It’s not unusual, and it’s nothing to
be concerned about. I hadn’t noticed it in the review model, but I’m
not surprised at that: there was always other noise going on when it was
on test, I expect, to mask this effect. I have come across it in many
other products, though. It’s really not that unusual in devices with
output transformers.
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