THD Hot Plate

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 amplifier at lower volumes, without sacrificing 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 amplifier or to rack mount effects without miking the speaker(s).

There are five different Hot Plate models in five colors: The 2ohm(gold), the 2.7ohm(green), the 4ohm(red), the 8ohm(purple), and the 16ohm(blue). to optimize the tone and function of the Hot Plate the impedance should be the same on you amplifier, Hot Plate and speaker cabinet.

Operating the Hot Plate:

I. As a power attenuator to One speaker cabinet:

1. Turn the amplifier 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 a Hot Plate and the Hot Plate is set at load.

2. Connect the Speaker Output on the amplifier 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 placing the Hot Plate between the amplifier section and thespeaker cabinet. If you are placing the Hot Plate between the amplifier section and the speakers 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 speakers. If your amp does not have a "speaker out" jack (the speakers are wired directly to the amp), have a qualified technician 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-clockwise, the volume drops smoothly down to -45(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 noticeable effect. You may want to activate both or either of them (by switching them up) to compensate for any loss of high and/or low frequencies.

II. As a power attenuator to two speakers 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 2ohm Hot Plate would be needed for two 4ohm speaker cabinets, the 4ohm Hot plate for two 8ohm cabinets and the 8ohm Hot Plate for two 16ohm 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 IMPEDANCE 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 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 speakers, 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.

Specifications:

I. Main Output:

Attenuation: 0 dB to -16 dB in four dB increments; -16 dB to -dB(zero output) continuously variable.
Impedance: Depends on the model.

II. Line output:

Type: Mid-impedance (approx. 35Kohm), unbalanced, negative ground.
Connector: 1/4' phone jack.
Level: Continuously variable line out level (+10dB(V) to -40dB(V)).

III. Input:

Impedance: Depends on model.
Continuous power dissipation: 150W RMS
Max. recommended amplifier power: 185W RMS.

IV. General:

Size: 2 7/8" high x 8 1/4" wide x 7 1/4" deep (7.3 cm x 20.9 cm x 18.4 cm).
Weight: 4.2 lbs(1.9 kg).

A THD Hotplate is a definite must have. We highly recommend this accessory for it's versatility and ability to control high power output without coloring the sound. We have Hotplates in stock and available in 2.7ohm, 4, 8, and 16ohm Please call for pricing.

Email for price and ordering

Frequently asked THD questions

plexi@vintageamps.com
21065 Bear Valley Rd. #2, Apple Valley, CA 92308
760-961-8324

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