The original Helios Type 69-500 mic preamp was designed by Dick Swettenham and was part of a series used by iconic artists like the Beatles, the Rolling Stones, Led Zeppelin, and Bob Marley, amongst others. The reissued classic is a three-band mic pre/EQ with modern appointments, such as +5dB steps on the preamp gain, an additional 16kHz of frequency selection, and balanced output. It sports similar circuitry, but has been updated to be more reliable and clear.