L-1 - Discrete Vocoder

The L-1 Discrete Vocoder is a fully analogue 16-channel vocoder built around 23 of Aleksei Laman's Blacksea discrete VCAs. They sit across three stacked circuit boards and handle the filterbank, the input compressor and the output mixing stages.

Modulator signals come in either through the XLR microphone input, running on a THAT1512 preamp, or through a second input with attenuator for line-level sources. Both have their own level control and can be used together. A direct output after the preamp lets you run the voice through outboard gear and bring it back via the MOD input. From there a compressor evens things out before analysis, with an adjustable threshold and fixed attack, release and ratio, so quieter syllables still drive the bands properly. On the carrier side, two attenuated inputs share a gain control offering up to six times more level for quiet sources. A noise gate mutes the filterbank output when nothing is coming in, which keeps the noise floor of sixteen summed channels out of the way.

Odd and even bands leave the filterbank separately, each feeding its own stereo mixer, with a third mixer for the dry modulator signal. All three have CV over level and pan. The even-band pan input is normalled to the odd-band CV through an inverter, so a single modulation source can move the two groups in opposite directions across the stereo field. Two switches set how the bands are mapped: in normal mode each modulator band drives its opposite number on the carrier side, while alternate mode hands that decision over to jumpers on the board, letting you build unusual pairings. A stereo send and return sits ready for effects as well.

A complete and unusually flexible vocoder, which, together with it's send+return options is capable of some truly far out sounds.

Features:

• Fully analogue 16-channel vocoder
• 23 Blacksea discrete VCAs
• Three stacked circuit boards: control, odd channels and even channels
• XLR microphone input with THAT1512 preamp and adjustable gain
• Additional modulator input with attenuator, usable alongside the mic input
• Direct output after the microphone preamp
• External processing can be returned through the MOD input
• Compressor with adjustable threshold
• Fixed compressor attack, release and ratio
• Two carrier inputs with attenuators
• Shared carrier gain of up to x6
• Noise gate on the filterbank output
• Compression, overload and gate-status LEDs
• Separate odd- and even-band outputs
• Semi-exponential filterbank VCA response
• Individual level trimmer for each channel
• Normal and alternate band-order switching
• Alternate band mapping configured with on-board jumpers
• Three stereo output mixers
• Voltage control over mixer level and pan
• Inverted normalling between odd and even pan CV
• Stereo effects send and return