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Walrus Audio Mantle Bass Preamp and DI - Black - Preorder
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About Inventory Status
About Inventory Status
Questions? Call or text us at 301-946-8808.
♫ In stock: It is in stock and available to ship or pickup. Apparel must be shipped from another location and is not available for in-store pickup. We can usually ship or have these items available for pickup by the next business day if they don't require inspection, special handling, or setup. Our pickup location is 11151 Veirs Mill Rd. Silver Spring, MD 20902.
📆 Preorder: It is on the way to our warehouse. We can't predict when preorder items will arrive due to current supply chain issues. If you place an order for one of these items someone will contact you to estimate the delivery date.
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About Item Conditions
About Item Conditions
Questions? Call or text us at 301-946-8808.
New: The item is brand new as received from the manufacturer with a full manufacturer warranty. Instruments such as guitars, snare drums, drum kits, brass and woodwind instruments may be opened for photography and quality control inspection and may not be in a factory sealed box.
Mint or Open Box: The item may have been opened and tested but has been repackaged. The original packaging may have superficial issues but the item itself and any originally included accessories are in perfect, like new condition.
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Demo: These items have been on our sales floor for demo purposes and will likely show signs of use. The original packaging may no longer be included, but you can be assured that you are receiving an awesome item and an awesome price.
Used: The item is used. These item may have varying degrees of wear. Please read the description for information about the condition of the item. Used items do not carry a warranty.
B or C Stock: Factory refurbished. These items were purchased from the manufacturer in a refurbished condition. They will show some cosmetic issues, but nothing that would impact performance. Being that these are sealed from the manufacturer, we generally do not open these to photograph the cosmetic issues. They are guaranteed to work and may have a limited warranty or you may purchase an extended warranty in some cases. Please see the listing description for item specific information.
Description
Description
Refined Tone Foundation – The Walrus Audio Mantle Bass Preamp and DI
The Mantle is a premium preamp and DI for electric bass, created in close collaboration with Ian Martin Allison. Designed to give your instrument an impeccable sonic foundation, the Mantle brings studio-grade refinement to any environment—whether you’re stepping onstage, tracking in the studio, or shaping your tone at home.
- High-impedance JFET input buffer for articulate, touch-sensitive response and exceptional clarity
- Up to +23dB of transformer-based gain offering clean, magnetic, harmonically rich amplification with premium depth and detail
- Custom-tailored bass and treble controls co-designed with Ian, utilizing a sophisticated blend of shelving, bandpass, and selectable LPF/HPF behaviors
- Transformer-balanced XLR output ensures expansive headroom, uncompressed dynamics, and commanding low-frequency extension
- High-headroom +24V internal power supply for clean dynamics and effortless low-end
- Active/passive pad and ground lift switches for enhanced compatibility to allow for more headroom if needed when using an active bass
- Flexible routing with 1/4-inch in/out and balanced XLR direct output for modern routing needs
At the heart of the circuit are proprietary, custom-wound Sapphire transformers, engineered to deliver the authoritative low-end and midrange push reminiscent of a classic Neve circuit, paired with an airy, articulate top end inspired by revered API preamp architecture. Together, they provide a harmonically rich canvas that elevates your playing while preserving every nuance of your instrument.
The Mantle empowers players to sculpt their signal with intention, offering musical gain, smartly tuned EQ, tremendous headroom, and transformer-balanced outputs. Every component and stage of the signal path is built to ensure whatever comes next—amp, interface, or mixer—receives your bass in its most confident, fully realized form.
Signal Path Overview
Input → JFET Buffer → Low-pass/high-pass filters or dry path → Input transformer (-6dB to +23dB) → Boost EQ → Output transformer
The Mantle’s architecture is meticulously voiced to maintain clarity, delivering musical transformer coloration, and giving users control over both the front end and final output of their tone.
Transformers
The Mantle features proprietary custom-wound “Sapphire” transformers. With more than a year of research, listening, and refinement, the Walrus engineering team has set a new benchmark with input and output transformers reflecting a commitment to providing creators with cutting-edge tools that inspire innovation and creativity.
Based on Neve designs, the input transformer is capable of handling large signals without added distortion while maintaining a clean, strong, and quiet signal. High-quality core material and copper windings were used to achieve the gain needed for pristine performance across the frequency spectrum.
The output transformer is based on the output stage of an API 312. This serves two functions: it balances the signal quietly and effectively while also providing rich harmonic content to the amplified signal. Like the input transformer, the style of core and customized winding method result in a strong signal that can be transmitted over long cable runs without signal loss.
Connections
1/4-Inch TS Unbalanced Input (Hi-Z): Optimized for electric bass and buffered by a high-quality JFET stage to maintain impedance, detail, and instrument integrity.
1/4-Inch TS Unbalanced Output: Send your shaped signal to an amp or additional pedals.
Male XLR Balanced Output: Transformer-balanced for elevated DI tones that feel at home in high-end studio and live environments.
Power: 9VDC, 500mA center-negative. Internally boosted to +24V for massive headroom and clean, authoritative bass response.
Controls
Bass and Treble (Boost/Cut Filter System): The Mantle’s EQ is a sophisticated dual-behavior design. Both bass and treble controls feature eleven-position rotary switches with a true flat response at noon (position 6).
Boosting (positions 7–11): Begins as a shelf, gradually transitioning into a broad, musical bell as gain increases. Each increment adds +3dB, up to +15dB.
Cutting (positions 5–1): Introduces a steep -18dB/oct HPF or LPF at selectable points—30Hz to 120Hz (bass) and 8kHz to 1kHz (treble).
Gain Control
The gain control adjusts the amount of transformer-based gain applied to the signal. Ranging from -6dB to +23dB, this control draws directly from the input transformer, resulting in a tone that feels alive, dimensional, and expressive.
Switches
Active / Passive (-10dB Pad): Introduces a -10dB input pad for active basses or instruments with high-output preamps.
Ground Lift: Separates the XLR output ground from circuit ground to eliminate hum and ground-loop noise.
SPECIFICATIONS
- Power Requirements: 9VDC, 500mA, center-negative, 2.1mm
- Internal Boost Voltage: +24V
- Recommended Power Supply: Isolated
- Input Impedance: 1M ohm
- Output Impedance: 150 balanced, 150 unbalanced
- Noise Floor: Balanced -101dBV, Unbalanced -94dBV
- THD at 1kHz 1Vrms: 0.04%
- Frequency Response: 20Hz – 20kHz
- Gain Range: -6dB to +23dB
- EQ Boost Range: 0dB to +15dB
- Enclosure Size: 6.09 x 4.7 x 2.28 inches (154.78 x 119.35 x 57.98 mm)
Manufacturer: Walrus Audio
Model: 900-1103
SKU: I876683-N-2-WHXA
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