The Tone King "Ironman" is a precision power attenuator designed to preserve the tone and feel of a guitar amplifier while reducing its volume level at the speakers. It achieves this through a sophisticated design incorporating a tuned reactive load and transformer-coupled power division circuitry.
Function Description:
The primary function of the Ironman is to allow guitar amplifiers to operate at full output power, enabling natural power tube overdrive and distortion, while controlling the actual volume delivered to the speakers. This is achieved by dissipating a portion of the amplifier's output power within the attenuator itself, sending only the desired amount to the speakers. The device can also be used as a dummy load for recording or "slaving" an amplifier, where no speakers are attached.
Important Technical Specifications:
- Attenuation Range: 0dB to -40dB, selectable via a Range switch (0-30dB or 0-40dB).
- Amplifier Input: Standard 1/4" speaker cable, rated for 100W RMS MAX.
- Impedance Matching: Dual impedance controls for both amplifier input and speaker output. Amplifier Impedance switch (2) matches the amplifier's impedance (4, 8, or 16 ohms). Speaker Impedance switch (4) matches the total combined impedance of connected speakers (4, 8, or 16 ohms).
- Speaker Outputs: Two parallel 1/4" speaker jacks (3).
- Line Out: Provides a line-level signal (approx. 0-1V p/p, adjustable) with 10K Ohms impedance, unbalanced mono 1/4" connection. This signal is generated from the amplifier input and does not change with attenuation knob adjustments. It includes basic EQ to simulate speaker sound but lacks sophisticated speaker simulation.
- Power Handling: Designed for amplifiers up to 100W RMS MAX.
Usage Features:
- Attenuate / Bypass Switch: This front panel switch allows users to engage the attenuator ("Attenuate" mode) or bypass it entirely ("Bypass" mode). In Bypass mode, speaker outputs connect directly to the amplifier input, and attenuator circuitry is disconnected, rendering impedance matching switches ineffective.
- Attenuation Knob & Range Switch: The Attenuation knob (front panel) adjusts the amount of power sent to the speaker, from 0dB (no attenuation) up to -40dB (maximum attenuation). The Range switch selects between two attenuation ranges: 0-30dB or 0-40dB, providing finer control within specific attenuation levels.
- Dual Impedance Controls: A unique feature allowing independent impedance matching for the amplifier input and speaker output. This enables users to match their speaker to their amplifier even if their impedances differ. This matching can be performed even without attenuation by setting the attenuation knob to 0dB and ensuring the Attenuate/Bypass switch is in "Attenuate" mode.
- Line Out with Adjustable Level: The rear panel Line-Out jack (5) provides a signal for driving other amplifiers, mixing boards, or computer sound inputs. An adjustable level control (6) allows users to fine-tune the output level, particularly useful when driving another guitar amplifier to prevent overdriving. The line-out signal is present even when the amplifier is bypassed and its level is independent of the attenuation knob.
- Dummy Load Capability: At the maximum -40dB attenuation setting (with the Range switch in 0-40dB position), nearly all amplifier power is dissipated within the Ironman, allowing users to safely unplug speakers and use the device as a dummy load. This is ideal for silent recording or "slaving" an amplifier.
Maintenance Features:
- Safety Instructions: The manual emphasizes reading and following safety instructions, including avoiding use near water, cleaning with a dry cloth, not blocking ventilation, avoiding heat sources, using manufacturer-specified attachments, and referring all servicing to qualified personnel.
- Warranty: A five-year limited warranty covers defects in material and workmanship from the date of sale. Exclusions include cosmetic damage after delivery, damage from accident or unreasonable use, unauthorized repairs, shipping damage after initial delivery, and vacuum tubes (warranted for 90 days). Speaker warranty is void if connected to an amplifier other than the intended one. The warranty covers labor and material expenses for repairs, with the customer responsible for shipping to the company, and the company covering return shipping if repairs are covered.
- Obtaining Warranty Service: Users are instructed to contact Tone King Amplifier Company for return authorization before sending units for service.
The Ironman's design focuses on maintaining the amplifier's natural tone and feel by addressing how an amplifier interacts with a complex speaker load, rather than a simple resistive one, and by using transformer coupling for power division to avoid frequency response alterations common with resistor ladder designs. However, users are advised that perceived tone changes can still occur at lower volumes due to factors like speaker breakup/compression, the ear's natural response curve, and changes in playing style.
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