Seymour Duncan SFX-04 preamp 'defines metal'

Making its debut from Seymour Duncan is the SFX-04 Twin Tube Mayhem, a high gain guitar preamp. According to Gearwire, the SFX-04 uses twin sub-miniature USA-made Phillips Sylvania 6205 vacuum tubes to achieve a heavy sound that screams pure metal.

Seymour Duncan SFX-04

Here's an excerpt from the Seymour Duncan Press Release:

"The new-old-stock, USA-made Phillips Sylvania 6205s represent the pinnacle of tube technology. They were designed and manufactured to meet the U.S. Governments MIL-E-1 spec for reliability under conditions of severe shock, vibration, and temperature. They provide extremely long service life and exhibit virtually no tendency toward microphonics."

"High-quality vacuum tubes are only part of the key to a great-sounding tube preamp. Too often, inexpensive tube gear runs in starved plate mode, where the tubes function like clipping diodes and do not actually amplify. The Twin Tube Mayhem employs a fully encapsulated, toroidal transformer to achieve the high plate voltage required for true tube amplification and maximum dynamic range. Additional gain is achieved with a high voltage, low noise, discrete Class A input stage. The solid state input stage increases the resistance of the stomp-box to microphonics. The result is maximum dynamic range, the most gain, the smoothest tone, and the low-order harmonics one expects from a great tube preamp."



Before Level Compensation 97 dB

After Level Compensation 71 dB

*Gain measured at 1 KHz

Nominal Output Level 0.25 Vrms (-10dBu)

*Nom. Output level measured with 100mV 1 KHz input signal and all controls set to 12 oclock

Max. output level before clipping 5 Vrms (16dBu)

*Max. output measured with gain set at 50% and all other controls set full up and boost footswitch set to 8dB

Input Impedance: 100K?

THD @ 100mV RMS output .5%

Noise @ Output 4mV (< 3dB hum content)

Boost Footswitch Gain

Two selectable boosts, 4dB and 8dB. No effect on tone, just increased level.

Active Equalization Section:

Bass Control: 126 Hz, Q = 1.5, Gain = +/-12dB

Midrange Control: 596 Hz / 1389 Hz, Q = 1.5, Gain = +/-12dB

Treble Control: 2.93 KHz, Q = 1.4, Gain = +/-12dB

Power consumption 11 W

External Dimensions 7.50 X 6.62 X 1.96 (190mm X 168mm X 50mm)

Weight 3.15 lbs. (1.43KG)

[VIA] Gearwire

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