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What is a load box?
</h1>
<p>
When using a tube amplifier, you should always connect it to a speaker cabinet before
turning it on – or a loadbox. The speaker cabinet (2, 4, 8 or 16 Ohms) must always be
connected to the corresponding speaker output of your amplifier. Not doing so can lead to
partial or complete destruction of the output stage of the tube amplifier. Most tube amp
designers protect their products with fuses etc, but some amps do not have sufficient
protection in place. Our general moto is that “It is impossible to predict the behavior
of all the amplifiers on the market in case of use without a load (a speaker cabinet or a
load box)”.
</p>
<p>
The electronic term that describes the speaker cabinet with respect to the amplifier
is the “load”: we say the cabinet “loads” the amplifier. The term “load box” fits
any product that embeds an electronic load. The main parameter of the load box is its
impedance, and that is rated in “Ohms”. An 8-Ohm <a
href="http://www.mktester.com/transformer-test-system/load-box/" target="_self">load
box</a> must be plugged to the 8-Ohm speaker output of the amplifier.
</p>
<p>
When using a Torpedo load box, the power sent to the load is turned into heat, so
please follow the cooling recommendation of the load box – failure to do so may cause
overheating which can lead to damage, both to the load box and to the amplifier. The
Torpedo Reload, Live, Studio, Captor and Captor X are load boxes. This term indicates that
these products feature a load which can electrically replace the speaker cabinet while
safely dissipating (transforming into heat) the power coming out of the amplifier.
</p>
<p>
The embedded load in the Torpedo products is reactive: it embeds a specific circuit to
simulate the complex impedance of a real speaker. This kind of system is widely used in
the industry to silently test amplifiers.
</p>
<h2>
Is the use of a loadbox totally silent?
</h2>
<p>
We usually talk about “silent recording” when a load box is involved. If we compare
the load box solution to a traditional cabinet miking solution, it is obviously several
orders of magnitude quieter, but you will still experience some minor sounds, noises, that
have to be taken into account:
</p>
<p>
Your guitar or bass strings can be heard. This is obvious, but it can be disturbing,
depending on your environment if you are not used to it.
</p>
<p>
You may hear some noise coming out of your Torpedo when playing, like there is a tiny
speaker inside the box. This is perfectly normal and there is no reason to worry. The
sound is produced when power goes through the coil of the reactive load embedded on the
Torpedo. The vibration is related to what power comes out of the amplifier connected to
the Torpedo and to the signal’s frequency content (notes played are heard). Your
amplifier may also produce similar noise, at the output transformer’s level. Such noise
is usually not heard, simply because it is normally overcome by the sound coming from the
loudspeaker.
</p>
<p>
The Torpedo embeds a fan, as there is quite a lot of power dissipated into heat inside
the box. We selected a “silent fan”, but as it is running fast, it is never entirely
silent. This said, you can consider that, in normal use (hearing your guitar through
monitors, or headphones), you can barely hear that fan.
</p>
<h2>
Care should be taken when using a load box
</h2>
<p>
The correct use of your amplifier with a load box requires some precautions. Because
of the fact that you may be playing “silently,” it is much easier to accidentally run
your amplifier beyond the reasonable limits set by the manufacturer than when you are
using an actual speaker cabinet. This can lead to faster tube wear and, in some cases, to
more serious issues.
</p>
<p>
Keep in mind that the “sweet spot” — the perfect running point of the amplifier,
the one that will give you the tone you are looking for—is rarely obtained at maximum
volume. In addition, the volume control of the amplifier is usually logarithmic, which
means that the volume goes up quickly on the first half of the potentiometer’s rotation,
reaches its maximum at 12 o’clock, and will not change much beyond that point. Therefore,
you can<br style="box-sizing: border-box;"/>reach the maximum volume of your amplifier
even if the volume potentiometer is not set at maximum.
</p>
<p>
By reaching the maximum output power of your amplifier, you will hear a lot of
distortion, which may not sound as good as you could hope. In fact, most amplifiers do not
sound great at maximum volume. Always keep in mind that your amplifier may not have been
conceived to be used at maximum volume for a long time. Running an amplifier at high
volume will cause premature wear of the tubes and possible malfunctions or damages to the
output stage.<br style="box-sizing: border-box;"/>
</p>
<p>
When first testing the amplifier at high volume, monitor the color of the tubes and
the general response of the amplifier. Red-glowing tubes or any appearance of smoke are
signs of a problem that may result in partial or complete destruction of the amplifier.
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