From dp–(at)–sc.edu Thu Sep 15 17:05:11 CDT 1994
Article: 24092 of alt.guitar
From: dp–(at)–sc.edu (David P. Mottaz)
Subject: Review: THD Hot Plate (long)
Date: 13 Sep 1994 21:42:13 GMT
Organization: Minnesota Supercomputer Center
I just bought a THD Hot Plate and I thought I’d offer up a review.
The THD Hot Plate is a tube amp power attenuator
My situation/gear – I have a ’65 Deluxe Reverb combo and a silverface
Bassman head I use with a Peavey 2×12 cabinet w/85-watt Celestions.
I play a Strat with a Seymour Duncan Jeff Beck model humbucker in the
bridge position. I play part-time in a mainly ’70’s rock band. Both
amps sound terrific. The Bassman has a better overdrive/cranked up
sound (I replaced the 12at7 driver tube with a 12ax7). Both amps are
way too loud. I prefer the way they sound cranked. And that is just
My first attempt at controlling the volume – I have a Boss Turbo Overdrive
pedal. I have a Rat distortion box. I bought and then sold a RP-1. All
were used to create the distortion tones into either of my amps which
were kept at rather subdued/clean levels.
My second attempt at controlling the volume – I bought a Power Soak.
I have used this for quite some time now. It has done a reasonable job.
I used it to soak up just some of the power so it did not sound too bad.
My experience is that the more it soaks the worse it sounds. It does some
weird stuff when it is really soakin’. It still sounded better than the
distortion/overdrive boxes I used. I prefer a cranked tube amp.
I posted something about a Marshall Power Brake and I got some email from
Gary Watts (thanks again, Gary!) and he suggested I look into the Hot Plate.
The good stuff – Well, I bought one. I love it. It looks cool. It sounds
great. It is about 9″ wide, 5″ deep and 3″ tall. There are five models
which are the impedence your amp/speakers require. I got the 8-ohm model.
The 8-ohm model is purple. Bright purple.
The Hot Plate is an attenuator that provides a dynamic load to the amplifier
using “a network of resistors, capacitors and inductors”. It also provides
a line out. Let’s talk controls/features.
On the front, left to right:
A 5-position switch which determines the level of attenuation. 0db
(full power), -4db, -8db, -16db and LOAD. While switched to LOAD a
speaker is not required.
A toggle switch, “bright”. This directs more highs to the speaker.
In the middle of the front is a small window. 2 light bulbs the
shape of an auto fuse are visible. The glow more as you play louder.
They are a big part of the “noise reduction” circuitry. I removed
a bulb to break the circuit (an option mentioned in the owners
manual). I felt is sucked. Decaying notes fizzled. All the reasons
I don’t like any noise gate.
A toggle switch, “deep”. This directs more lows to the speaker.
A potentiometer. This is active when the attenuation chosen is
-16db. Fully-clockwise the attenuation is -16db. Fully counter-
clockwise the attenuation is infinite. Silent. The same as LOAD.
Real smooth. Real cool. Really works.
On the back, left to right:
Speaker input jack (from an amplifier)
Line out – 1/4″ jack.
Line out level potentiometer. Fully-clockwise it a pretty hot signal
THD says will drive a power amp. Fully counter-clockwise it is silent.
At the lower settings it can safely drive the instrument input of a
guitar amplifier. This really works. The line-out and the power
attenuation can be used at the same time.
(2) speaker ouput jacks.
A fan. It is powered by the guitar amplifier’s speaker output. It
spins while you play. It draws air in the bottom and directs it first
over the components, then over the massive heat sink.
Tone switches revisited – Interestingly enough, the bright and deep switches
work in an opposite fashion with the line out. With the line out, switching
the bright switch reduces highs because more highs are directed to the speaker
portion of the circuitry.
Review, opinions, observations and ramblings: It is very well built. It
sits on top of either of my amps perfectly. It has large rubber feet so
it stays put. I suspect THD took into account how wide most amps are. The
fit and finish, the pots and switches and knobs are all impeccable. The
tone switches really work and really enhance the sound at low volume levels.
The line out is pretty cool into a seperate amp but I don’t think I will
use it that way. I am going to run the line-out to the PA board in addition
to miking the speaker next gig to see if that enhances the sound. I suspect
it can add clarity in a muddled mix. I love the way it looks. The hot-purple
offers a contrast to the old Fender amps. It sounds dramatically better
than the Power Soak. I am very pleased with the tone.
The list price is $329.00. I got mine for list minus 29% from a THD dealer
in Illinois. THD is 5-6 weeks behind in manufacturing these so they are
difficult to find.
This seemed to me to be a much better value than the Marshall products.
They have the Power Brake which lists for $370.00 which only attenuates
and has only one control(volume). Marshall makes another model that adds
a speaker cabinet simulator but it lists for $650.00. Groove Tubes makes
a similar product but the attenuation is coarse, 25% or 50%.