Alesis K2661 specifications 14-4

Sampling and Live Mode

Sampling Analog Signals

Another consideration in selecting sample rate is the K2661’s transposition range during sample playback. The K2661 transposes samples by changing the sample playback rate; the higher the playback rate, the higher the pitch of the sample. The K2661 can achieve a maximum sample playback rate of 96 KHz. Normally, a sample made at 48 KHz can be transposed up a maximum of one octave, since the playback rate doubles for every octave of upward transposition. If you set the SmpSkp (sample skipping) parameter (on the KEYMAP page in the Program Editor) to Auto or On, you can transpose up two octaves at 48 KHz. A sample made at 29.4 KHz can be transposed up approximately 21 semitones (an octave and a sixth)—or 42 semitones with SmpSkp set to Auto or On. There is no limit on downward transposition, regardless of the sample rate.

Each portion of a sample (each individual sample element made by the K2661 during the sampling process) takes up two bytes of sample memory. A one-second stereo sample at 48 KHz consists of 96,000 individual samples (48,000 x 2), taking up 192,000 bytes (about 188K) of sample memory. The same sample taken at 32 KHz takes up about 125K. A one-second mono sample taken at 32 KHz takes up about 63K.

If you plan to do a lot of sampling, you may be able to add more sample memory to your K2661 (if it’s not already maxed out at 128 MB). SIMMs (Single In-line Memory Modules) are available at your dealer, or at most computer stores or mail-order houses. Be sure to read Choosing and Installing SIMMs for K2661 Sample Memory in the K2661 Musician’s Reference before you go SIMM shopping, though.

At a sampling rate of 44.1 KHz, each megabyte of sample RAM that you add increases your sample time by about 11.5 seconds (5.5 seconds for stereo samples). At 48KHz, each megabyte gives you about 10 seconds of mono sampling, and about 5 seconds of stereo sampling.

Table 14-1lists the most common sample RAM configurations and their total sample time capacity (in seconds) at various sample rates.

Total	Sampling		Sampling Rate in KHz
RAM	Mode
		29.4		32.0	44.1	48.0
64M	Mono	18:40		17:04	12:16	11:12	Total
	Stereo	9:04		8:32	5:52	5:20	Sampling
128M	Mono	37:20		34:08	24:32	22:24	Time
							(min:sec)
	Stereo	18:08		17:04	11:44	10:40

Table 14-1 RAM and Sampling Capacity

Mode

Use the Mode parameter to select mono or stereo sampling. (Keep in mind that stereo samples take up twice as much memory as mono samples.) Use a value of Mono for a mono signal. You can use either Mono(L) or Mono(R) to isolate either the left or right side of a stereo signal.

Audio sampling input doubles as a two channel “drum” trigger, allowing audio signals to trigger samples. On the SampleMode page, set Mode to Trigger. Adjust Thresh to control triggering sensitivity. This triggers the currently assigned click program. The left input will trigger click key note number +1, right input will trigger click key +2. The click key and click program can be accessed on the Song-mode MISC page.

There’s also Live mode, which lets you connect any audio source to any of the K2661’s sampling inputs (assuming you have the Sampling Option), and use that input just like a regular VAST program (the input goes through a DSP algorithm, then through KDFX, then to the audio

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