What
is a power attenuator?
A
power attenuator is a device placed between the amp’s speaker
output and the speaker cabinet. It acts like a huge master
volume control and permits the amp to be turned up most or
all the way while absorbing most of the power generated by
the amplifier and turning this power into heat. It passes
a small part of the power to the speaker.
Why do I want one?
Our
customers use attenuators because their amps sound good at
high volumes, especially with full distortion, but in rehearsal,
small clubs, or at home, they can’t turn the amp up. They
are also used in recording studios for better separation between
the instruments, and for use when the speaker sounds best
at low levels, or if it can’t handle the amp’s power output.
The Hot Plate® also makes a perfect dummy load.
We
needed a good attenuator for our in-house testing of THD amplifiers.
The amps have to be tested at all volumes, clean and pure
to wild distortion, and we were tired of our ears hurting.
We tried all the attenuators on the market, but they muffled
the sound and made even THD amps sound dull. Now our design
engineers don’t have to worry as much about hearing loss,
and neither do you.
How
does a Hot Plate®
work?
A
THD Hot Plate® is a tuned network of capacitors, resistors
and inductors which adjusts the overall EQ as the volume is
turned down to compensate for the human ear’s frequency response.
Your ear perceives sounds differently at different volumes:
the louder the sound, the more sensitive your ears are to
highs and lows. As the volume drops, your ear becomes more
sensitive to the mid-range, and less so for highs and lows.
The Hot Plate® compensates for this, working like the
“Loudness” switch on a hi-fi. The THD Hot Plate® is the
first, and for now, the only attenuator that is frequency
compensated.
How do I use it?
The
THD Hot Plate® is designed for use strictly with vacuum
tube guitar amplifiers, and each version is optimized for
a specific impedance (2, 2.7, 4, 8, or 16 ohms.) These inductive
loads are frequency compensated, which means it will give
you the best possible sound for that impedance speaker and
amplifier combination.
To
use one: connect the speaker output of the amp into the input
of the Hot Plate®, then connect the speaker cabinet to
one of the two speaker outputs of the Hot Plate® (doesn’t
matter which one). The amp thinks the Hot Plate® is a
speaker, so the sound stays true even when you turn the volume
down.
What else does it do?
Built-in Noise Reduction
The
THD Hot Plate® is the only attenuator on the market with
built-in noise reduction to reduce the hiss and hum between
notes. We’ve designed a passive, single-ended noise reduction
system which provides approximately 10 dB of broad band noise
reduction without gating or pumping, and without affecting
the tone of the amp. A by-product of the noise reduction circuit
is that it generates light as you play. The harder you play,
the brighter it glows.
Tone
Controls
The
Hot Plate® is also the only attenuator offering a Bright
switch and a Deep switch for tailoring your sound. The Bright
switch gives you two different high frequency levels so you
can compensate for an overly bright, or dull speaker cabinet.
The Deep switch offers two distinct bass settings to help
you fill out the bottom end, or reduce the bass in a cabinet
with too much low end.
Adjustable
Line Out
THD
Hot Plates® also feature a Line Out, which is adjustable
by its own volume control giving it a wide range of applications.
At higher settings, it can provide enough signal to drive
the input of a separate power amp for slaving. The middle
range of settings is useful for most rack mount effects. And
turned most of the way down, the Hot Plate's® Line Out
will drive the instrument input of another guitar amplifier
for extra power and volume.
Will it hurt my amp?
The
THD Hot Plate® will not damage your amplifier. When you
play continuously at full output, you cause your tubes to age
more quickly than they would at lower volumes. Using a Hot Plate®
will maintain the life of your tubes at exactly the same rate,
no more or less, as when you play straight through the speaker.
Using
a Hot Plate® will also not hurt your amp’s transformer
any more than playing through a speaker, as long as the impedances
are matched (i.e. 8 ohm setting on the amp, 8 ohm speakers
and an 8 ohm attenuator). If you are using a well-made amp,
then the transformer should last indefinitely, regardless
of whether you are driving a speaker or attenuator. If you
are using an inferior amp and the transformer blows, it would
have done this whether you play through a speaker or an attenuator.
The Hot Plate® puts the same load on the transformer
as a speaker (which is why it makes such a good dummy load).
