sample rates in low bit samplers

[colmon]

Is there any sonic difference between sampling at a low rate vs. sampling at a high rate then lowering the sample rate afterwards? is there some colouring in the DAC stage that you'd miss by sampling high then lowering the rate afterwards in low bit samplers? been thinking about this all day but I'm far away from my gear and can't test

[Stab Frenzy]

Yes, other things like anti-aliasing filters effect things as well. If you sample at 22kHz with a 10k filter it'll sound very different to sampling at 44k and then dropping to 22k, giving you aliasing on the 10k-20k information.

[madtheory]

Well it depends on the sampler. Each company implemented the whole instrument in vastly differing ways.

Some resampling algorithms will implement a filter, some won't. For example, when Typhoon was upgraded to the 2000 version, they put in a filter for the resampling so it sounded cleaner. I stopped using that feature A lot of samplers are actually resampling in order to change pitch, so that bit of code can be used for offline resampling too.

[colmon]

hey thanks for the info guys. trying to work out how to take full advantage of my sampler's sonic character without sacrificing too much of the sample source and this is helpful stuff

[aeon]

Sampling at 2x speed and then playing back 1 octave lower is also a great way to conserve memory on older samplers.

Also, depending on the sampler, that playback will be achieved via variable clock rate or (more likely) some kind of interpolation. In either case, the opportunity for character-yielding artifacts is at hand!

Some later samplers have good tools for achieving artifacts as well. For example, the Yamaha A5000 can sample at 44.1, 22.05, 11.025, or 5.5125 KHz. For the rates lower than 44.1KHz, you have the option of turning the anti-aliasing filter off. It also offers a handful of post-fx that offer digital artifacting algorithms.

In an EOSUltra sampler with the RFX board you have access to an algorithm that offers resonant multimode filtering at the beginning and end of the processing, and between, five processes that can appear in any order - hard/soft clipping, rectification, crossover distortion, downsamping/decimation, and bit reduction/quantizing. Nothing too fancy at first glance, but the decimator has variable interpolation routines - one that just drops samples and replaces their values with zero, one that does the same but applies an exponential pulse decay to the remaining samples, a hold where the remaining samples are duplicated across the discarded sample periods, linear interpolation (as in many vintage samplers), and a mode that inverts every Nth sample.

If your sampler is fairly good about re-pitching samples, the sample-at-2x trick won't work as well as it does on more primitive machines. That said, there's no reason you can't do 4x, or other things for that matter.

Experiment and have fun!


cheers,
Ian

[madtheory]

Cool! aeon, which is better for this sort of thing- the Yamaha or the EOS Ultra?

[aeon]

Cool! aeon, which is better for this sort of thing- the Yamaha or the EOS Ultra?

I honestly couldn't pick one over the other. Each has its PsITA, and each one has its charm.

The EOSUltra w/RFX is a bit more "purist" in its vintage sampler aspirations when using Grungulator in terms of sound processing.

The A5K is less so, but the benefit being it has many other ways to introduce digi-artifacts, lo-fi, and "dirt" effects.

Both handle live input, so they work nicely as "preamps" for other synths.

And well, while it is not a sampler at all, the live inputs on the Clavia Nord Modular can be (ab)used in all sorts of ways if you want to digi-hash your audio.

Sometimes it is the synergy of devices that gives the best flavor, e.g., create a bleepy sound on the Nord Mod that uses LFOs for FM as driven by severely quantized envelopes - good cheap toy sounds there, then sample or process live thru one of the above samplers.

Throw in a pedal or two, like Foxrox ZIM using Clean Smile, Vintage Tube, and/or Buffered Boost ZIMcards, to add some analog grunt and grit, just enough to give it a kiss of drive, and it interacts nicely.

Then resample, rinse, and repeat.


cheers,
Ian

[piRoN]

Some later samplers have good tools for achieving artifacts as well. For example, the Yamaha A5000 can sample at 44.1, 22.05, 11.025, or 5.5125 KHz. For the rates lower than 44.1KHz, you have the option of turning the anti-aliasing filter off.

The EPS also allows you to set the input antialiasing filter frequency manually. Putting it up as high as it'll go with a low sample rate sounds fantastic on stuff like snares - much, much more interesting then using the downsampling feature with its excessively aggressive filtering.

[colmon]

do you know if that is a feature also included on the later ensoniq samplers?

[colmon]

would i be right in saying that there is essentially 4 fundamental factors that contribute to colouration in vintage samplers: the dac/anti-aliasing filter on the way in, the native resampling algo, the pitching algos, and the dac on the outputs?

as well as certain features specific to certain samplers such as those that aeon has described, what other factors are there to take into consideration?

[RyanC]

Some resampling algorithms will implement a filter, some won't. For example, when Typhoon was upgraded to the 2000 version, they put in a filter for the resampling so it sounded cleaner. I stopped using that feature

Does anyone know if the earlier 1.0 version of Typhoon is available to download anywhere?

I've searched high and low, or at least what's seemed like it, and I've not had any success in tracking it down. I prefer low sample rates to lack filtering and would love to have the resampling on the TX16W be filter-free. After resampling a sound in Typhoon 2000, applying Emph+ in an attempt to compensate for the filter can really only go so far. =\

[madtheory]

It was never originally downloadable. I think I might have it, but it's on a floppy with the sampler at a friend's studio so the chances of going to the trouble of copying the floppy etc. are slim, because it's copy protected and needs a DOS utility to make copies. PITA.

What you could do is look at some freeware sample editors, surely Audacity has a crappy resampler algo available?

[piRoN]

Wavosaur gives a large variety of resampling algos, including a "none" option which does nearest-sample conversion. Good fun to run stuff through 3-4 conversions of arbitrary sample rates.

[RyanC]

It was never originally downloadable. I think I might have it, but it's on a floppy with the sampler at a friend's studio so the chances of going to the trouble of copying the floppy etc. are slim, because it's copy protected and needs a DOS utility to make copies. PITA.

Ahh, I didn't realize that it was never made available and remained copy protected when the 2000 version was released. Maybe I'll ask the kind folks over at the TX16W yahoo group if someone might have a copy readily on hand. I was hoping it might have been part of a TX16W disk lot that a fellow offered here a couple months back, but I never heard back from him.

What you could do is look at some freeware sample editors, surely Audacity has a crappy resampler algo available?

Wavosaur gives a large variety of resampling algos, including a "none" option which does nearest-sample conversion. Good fun to run stuff through 3-4 conversions of arbitrary sample rates.

I haven't considered software options as I'm trying out a modest all-hardware approach, but I may make an exception after I try the resampling in each of those editors. Thanks for the heads up!

[colmon]

Some resampling algorithms will implement a filter, some won't. For example, when Typhoon was upgraded to the 2000 version, they put in a filter for the resampling so it sounded cleaner. I stopped using that feature

Does anyone know if the earlier 1.0 version of Typhoon is available to download anywhere?

I've searched high and low, or at least what's seemed like it, and I've not had any success in tracking it down. I prefer low sample rates to lack filtering and would love to have the resampling on the TX16W be filter-free. After resampling a sound in Typhoon 2000, applying Emph+ in an attempt to compensate for the filter can really only go so far. =\

I actually found a disk of the og typhoon 1.0 os amongst some other disks and was curious about this so tried out the resampling function. You're honestly not missing out on much that you can't recreate on any random sample rate conversion software. The real grit and gristle in this machine comes from transposing samples imo, particularly at the lower sample rates. There's definitely some low pass filtering going on when transposing down though, I think this contributes to the dark sound of the sampler as much as it's dac on the way out. I find using one of the high pass filters as opposed to the emphasis function (which can introduce clipping) helps accentuate the effect. And of course it's entirely source dependent, I've found pitching harmonically rich stuff like guitars can end up sounding pretty terrible. Skipping out the adc on the way in via midi sample dump can also contribute to a brighter crunch -- which reminds me, does anybody know of a Mac OSX software dithering thing to dither samples down to 12bit? Everything I've tried thus far goes straight from 16 to 8...