Eventide DDL 1745M (1970s)
Little is documented about the Eventide DDL 1745M, but what survives points to a milestone. It's described as Eventide's first digital delay and one of the first dedicated digital delay line units ever made. One enthusiast called it the "grandfather of all Eventide delays." The DDL 1745M was a portable, rack-mount unit built like a tank, with rocker switches instead of knobs and BNC connectors on the front panel. It was a 12-bit design with an output sample rate of 22.050 kHz and a frequency response from 20 Hz to 10 kHz. That gives it a gritty, early-digital sound that many musicians still find desirable, especially on drums.
The most unusual feature of the 1745M was its reliance on tape. The unit was designed to work with 15ips 1/4" tape recorders as a storage medium. An optional interface recorded the delay line's output data to tape to extend the delay time, up to 40 seconds. Without the tape extension, the internal delay ran to roughly 1.6 seconds (sources give it as either 0-1600 ms or 1.6 seconds).
The 1745M is rare, and no current market pricing has been found. Production years, original price, and detailed specifications like THD or power consumption are not documented. The standard "DDL" model number appears in period references. Pro-Sound (June 2014, p.9) noted that a stack of Eventide DDLs delayed the audio feeds to the speaker towers at the 1973 Watkins Glen festival. Most surviving technical detail applies specifically to the 1745M variant.
- Type: Digital delay line, 12-bit
- Delay time: ~1.6 seconds internal; up to 40 seconds with tape interface
- Sample rate: 22.050 kHz output
- Frequency response: 20 Hz – 10 kHz
- I/O: BNC connectors; optional interface for 15ips 1/4" tape recorders
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