THD Electronics Hot Plate - Manual

THD HOT PLATE OWNER’S MANUAL
To avoid damaging your amp, speaker(s) or the Hot Plate, please read this manual thor-
oughly before operating the Hot Plate.
INTRODUCTION:
The Hot Plate is a power attenuator that sits between your amp and speaker(s). It allows
you to obtain the full output distortion of a tube amplifi er at lower volumes, without sacri-
fi cing tone.
The Hot Plate can also function as a high quality direct box, allowing you to send the amp’s
signal to a mixing board, a separate power amplifi er or to rack mount effects without mik-
ing the speaker(s).
There are fi ve different Hot Plate models in fi ve colors: The 2Ω (gold), the 2.7Ω (green),
the 4Ω (red), the 8Ω (purple), and the 16Ω (blue). To optimize the tone and function of the
Hot Plate the impedance should be the same on your amplifi er, Hot Plate and speaker
cabinet.
OPERATING THE HOT PLATE:
I. AS A POWER ATTENUATOR TO ONE SPEAKER CABINET:
1. Turn the amplifi er off or to standby. (If your amp is switched on and is not connected to
speakers or to a load, this will strain your amp and can result in blown output tubes and
output transformer.)
IMPORTANT: WHEN AMP IS ON IT MUST BE CONNECTED TO A SPEAKER.
The only exception to this is if the amp is connected to the Hot Plate and the Hot Plate is
set at load.
2. Connect the Speaker Output on the amplifi er to the Input on the Hot Plate using speaker
cable.
IMPORTANT: DO NOT USE INSTRUMENT CABLE - IT IS NOT DESIGNED TO HANDLE
THE POWER THAT SPEAKER CABLE CAN.
3. Connect Speaker Output 1 or 2 of the Hot Plate to the speaker cabinet. If you are plac-
ing the Hot Plate between the amplifi er section and the speaker(s) of a “combo,” you may
need an extender cable that has a “male” end (to go into the Hot Plate) and a “female” end
(that connects with the cable running from the speaker(s). If your amp does not have a
“speaker out” jack (the speaker(s) are wired directly to the amp), have a qualifi ed techni-
cian install one.
IMPORTANT: WHEN USING JUST ONE OF THE SPEAKER OUTPUTS FROM THE HOT
PLATE, THE SPEAKER CABINET SHOULD HAVE THE SAME IMPEDANCE AS THE
HOT PLATE.
4. Adjust the rotary switch on the Hot Plate to attain the volume you desire. At -0 dB the
loudness is the same as it would be if the amp were running directly to your speakers. The
effective volume will drop in increments of 4 dB as you turn the switch counter-clockwise.
At the -16 dB setting, the potentiometer on the right is activated (at all other settings this
pot has no effect so it does not matter where you set it). When the rotary switch is at -16
dB and the pot is turned fully clockwise, the effective volume will be 16 dB less than your
unattenuated volume. As you turn the pot counter-clock wise, the volume drops smoothly
down to -∞ dB (no sound).
When the rotary switch is at Load, there will be no sound coming through the speakers,
but your amp will still be safely running at full output.
5. At -8 dB and below the deep and bright switches will have a no tice able effect. You may
want to activate both or either of them (by switching them up) to com pen sate for any loss
of high and/or low frequencies.
II. AS A POWER ATTENUATOR TO TWO SPEAKER CABINETS:
Same as above, except connect cables from both speaker outputs on the Hot Plate to your
two speaker cabinets. These output jacks are wired in parallel, so if both speaker outputs
are being used, the 2Ω Hot Plate would be needed for two 4Ω speaker cabinets, the 4Ω
Hot plate for two 8Ω cabinets and the 8Ω Hot Plate for two 16Ω cabinets.
IMPORTANT: WHEN USING BOTH SPEAKER OUTPUTS FROM
THE HOT PLATE, THE TWO SPEAKER CABINETS SHOULD HAVE THE SAME
IMPEDANCE AS EACH OTHER, AND THAT IM PED ANCE SHOULD BE DOUBLE THE
IMPEDANCE OF THE HOT PLATE.
III. AS A DIRECT OUT:
1. Connect amp to Hot Plate.
2. Connect the Hot Plate to one or two speaker cabinets as outlined above.
3. Connect guitar cable from line out on Hot Plate to line in of mixing board, rack mount
effects or a separate power amp.
4. Adjust the line out level as necessary.
5. If you do not want to hear any sound coming from the speaker(s), set the Hot Plate
rotary switch to LOAD. At this setting alone it is safe to disconnect your speakers from the
Hot Plate and still operate your amp.
IMPORTANT: ONLY WHEN THE HOT PLATE IS SET AT LOAD IS IT SAFE TO OPERATE
YOUR AMP WITHOUT SPEAKERS CONNECTED.