Mahalo Katy66

One of a series of amplifiers from Mahalo, the Katy66 name is a play on the KT66 tubes that are deployed in the output stage of its hand-wired circuit.
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ONE OF A SERIES OF AMPLIFIERS FROM MAHALO, the Katy66 name is a play on the KT66 tubes that are deployed in the output stage of its hand-wired circuit. The pots, switches, jacks, and large electrolytic caps are solidly mounted to the aluminum chassis, which also features a front panel overlay of white plastic that plays well with the cabinet’s two-tone covering scheme and white piping. The rear panel speaker jacks and impedance switch are hand labeled with a felt pen, which seems a little funky given the amp’s otherwise classy appearance, and a few other niggles include the raspy metal screen on the back cover, the use of drywall screws to hold said cover in place, and the fact that the chassis doesn’t have captured nuts, which means you have to use a socket or press the blade of a screwdriver against them when loosening or tightening the bolts.

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The circuit board is populated with high quality components, and the amp features a lot of U.S.-sourced elements, including the transformers (Illinois), chassis (North Carolina), faceplates and logos (Indiana), and cabinets (Georgia and Florida). The Katy66 we tested was in standard trim, though it can be ordered with an effects loop and/or a slave out for $150 extra (each).

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The single-channel amp is easy to navigate, and Mahalo uses its own tone stack design in the preamp to deliver a range of sounds that make best use of the Katy66’s gain structure and dynamic response. The Bass control is very effective—I found that settings of around 2 yielded plenty of heft with humbuckers—and the Presence circuit coaxes enough brilliance from the power stage that I only needed to barely turn the knob up to put some zing on a PRS SC58. With the Volume above 2 the distortion is already coming on, but keeping the guitar turned down allows for plenty of clarity as long as the Master is up enough to let the bold-sounding (and extremely rugged) JJ KT66 tubes flex their muscles. The cleaner tones are bright and balanced with midrange punch aplenty, and going from pristine to gritty rhythm tones is just a matter of adjusting your guitar’s volume and/or picking strength.


The Katy66’s aluminum chassis houses a clean handwired circuit with high-grade components.

This amp can get very loud, and since KT66s deliver even more headroom and girth than their close-cousin 6L6s (as used in Mahalo’s AEM50), the Master proved highly useful for keeping the loudness under control—and it doesn’t rob tone in doing so either. With the Volume control fully cranked, the grind is intense, though some players may still need to use a booster or distortion pedal to kick the sustain into the full metal shred zone. There’s also some bite in the Katy66’s distortion voice, so getting buttery tones requires keeping the Treble knob on the low side and using only as much Presence as is necessary to maintain good definition.

The Katy66 definitely exhibits some raw British attitude, but has its own sonic thing going too, and could be a nice contrast in a band with another guitarist who uses a Marshall or other Brit-style amp. A ballsy sounding tube head in the medium power range, the Katy66 is a cool choice for classic and heavier rock. The abundant gain and big low-end is great for single-coil guitars, yet the amp also has plenty of slice to let humbuckers stand tall in the mix. All said it’s a worthy U.S.-made tube head that comes in at a reasonable price for a boutique product.


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PRICE $2,499 retail/street price N/A




CONTROLS Volume, Bass, Mids, Treble, Master, Presence

POWER 50 watts

TUBES Three 12AX7 preamp tubes, two JJ KT66 output tubes running in class AB

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SPEAKERS Tested with PRS Stealth 2x12 and Bad Cat 4x12

EXTRAS Dual speaker jacks with 4/8/16Ω impedance selector

WEIGHT 24.9 lbs


KUDOS Good tonal range. Hand-wired circuitry. Lightweight for a tube amp of its power.

CONCERNS Some minor issues that have nothing to do with tone.