During a brief period of insanity during the mid to late 90's, synth and sampler manufacturers decided that we as musicians didn't need resonant filters anymore. While not every manufacturer did this, a good number did, and sadly, some otherwise great instruments suffered for their lacking. I was just getting serious about music around this time, and for a good many years, my sole instrument was an Ensoniq EPS-16+ (and indeed, this is the only instrument used on the first Assemblage 23 album). The EPS-16+ was a very cool sampler that offered great bang for the buck, but it also lacked resonant filters. (Although an enterprising third-party named WaveBoy did eventually make a resonant filter software add-on which was really nice sounding.)
I was a big fan of analog sounds, especially stuff that modulated and sweeped a lot. But without a resonant filter, I was kind of locked out of that sound. That is, until I found a nifty way to do exactly what I needed. By starting with a sample of a synth sweeping it's filter, I could simulate these modulation effects by assigning velocity or my modwheel to modulate the start of the sample, thus changing where in the filter sweep sample the sound played.
Most every software sampler these days has a bevy of cool filters, but this is still a useful technique, as it can be used to not only simulate filter modulation, but it can replicate the gated 'transforming' effect made popular in the 90's as well as letting you do interesting things with drum sounds. (Not to mention that it sounds a bit different from 'real' filter modulation...) Here's how to do it in Native Instruments Kontakt
1. Find a long, resonant sweep synth sample online, or if you have a hardware synth, record your own.
2. Import the sample into Kontakt and set the root key so that it is in tune.
3. Beneath the instrument header, click the small green box marked 'Modulation' in the lower lefthand corner. This will open the modulation section for the sampler module itself. In this section, the grey drop down menu on the left represents the modulation source (ie what you use to change the sound). The slider in the middle represents the amount of modulation this source will apply when it is activated. Finally, the drop down menu on the far right represents the Modulation Destination, or what you specifically want to modulate.
4. What destinations are available is dependent on which of the sampler types (ie DFD, Sampler, Time Machine, Tone Machine) you are using. In order to do sample start modulation, you have to select the Sampler module (assuming it is defaulted to DFD).
5. In the Modulation section, select 'midi CC' as your source and change the number in the window next to it to '1'. This selects the modulation wheel as your Source.
6. Move the modulation amount slider fully to the right. You may have to adjust this, as the appropriate setting depends on the speed and length of the sweep sample.
7. Finally, select 'Sample Start' as your Modulation Destination from the drop down menu to the right.
Now play a few notes while you are rocking the modwheel back and forth and you should hear the simulated filter mod. Below is an audio example with the first bit being the original sweep sample, and the second being the same sample with sample start modulation applied to it.