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Dave in the studio with MXR analog phaser and flanger effects unit
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I decided to put my recently purchased Halion 3 sampler through it`s paces to determine what functions and features use the greatest amount of CPU processing power and consequently what you can do to reduce this in your music productions.

Front panel view of the Steinberg Halion 3.1 vst sampler instrument.
Background information: These tests were performed on an up-to-date version of the Steinberg Halion 3.1 VST soft-sampler plug-in running in Reaper v4.151 in February 2012. Computer spec.: Windows XP Pro Service Pack 3, AMD Athlon 64 X2 Dual 4200+ @ 2.2GHz, 2GB Ram, Sata Hard Drive. There was also anti-virus and e-mule running in the background, though not using many resources. The CPU percentage quoted is the Average Max. track CPU usage in Reaper.
Test 1 scenario: Single Halion 3 instance, one program
- same 100ms looped mono 24bit sample assigned to 64 key slots and triggered every 8 seconds by Reaper
Variation CPU %
Initial setup: Note mode normal, quality 100%, re-sampling good, no modulation 14.70
Sequencer stopped 0.00 / 0.11
Note mode raw 6.90
Note mode drum 6.74
Quality 50% 8.02
Quality 10% 2.68
Re-sampling best 16.01
Re-sampling fast 13.51
Transpose +2oct 16.48
Transpose +3oct 18.77
Transpose +4oct 18.77
Envelope 1&2 bypass 14.20
Glide 2.85sec 15.86
DCF bypass 12.54
DCF LP12, res 50 & sweep 16.82
DCF LP24, res 50 & sweep 20.78
DCF Waldorf LP12, res 50 & sweep 18.70
DCF Waldorf LP24, res 50 & sweep 21.61
DCF LP12, res 50 & fast lfo 16.52
Test 2 scenario: Stereo versus Mono - CPU load. As in Test 1 except -
A single stereo looped wav file mapped to 64 keys using a single stereo output.
Variation CPU %
Initial setup 11.57
Using only a single mono output 11.96
Using a mono version of the wav file: Similar results to above with either mono or stereo configuration
Test 3 scenario: Hard drive access speed test. As in Test 1, but 64 individual waves 120sec long.
Variation CPU %
Initial setup 11.44
Note mode raw (req extra RAM pre-load seconds) 7.10
Note mode drum 7.26
Quality 50 6.80
Quality 10 2.48
Re-sampling best 13.11
Re-sampling fast 10.65
Transpose +2oct 13.92
Transpose +3oct 15.91
DCF bypass 9.26
Conclusions: The functions that have the greatest impact on VST sampler CPU load (for Test 1).
Function % of initial settings CPU usage
Note Mode Raw 46
Quality 50% 54
DCF (filter) bypass 85
Transpose +2oct 112
DCF LP12 db/oct, resonance 50, freq. sweep 114
Front panel view of the Steinberg Halion 3.1 vst sampler instrument.
As you can see Note Mode Raw is the best improvement - this function disables all but the basic modulation settings including all filters and LFO's, but not DCA (volume) envelope. The Quality setting affects aliasing and digital processing distortion which is acceptable (just) at 50%.
The greatest users of CPU power are pitch transpositions above 1 Octave and Filters with resonance and strong frequency modulation.
Though not conducted under strict laboratory conditions I hope these test results give the average Halion user some idea of what functions are using the greatest computing power. This enables you to turn off those features that are not used for many basic track sounds. Of course these could be switched back in to render the tracks for the final mix, but this does give you a little more breathing room when working with an arrangement that requires a great many sampler channels simultaneously. It goes without saying that these results would probably apply to many other VSTi sampler instruments such as Kontakt, Ableton Live, Mach 5, Direct Wave and Emagic EXS24. Using these test scenarios you could easily determine what is causing your current computer sound sampler to consume excessive CPU load and resulting in audio drop-outs.
Postscript. At long last I have decided to move away from my trusty Emagic EXS24 sampler after Apple withdrew support for PC users - with great sadness I might add. This, and the accompanying Logic sequencer have produced a great many songs (150+) and several albums to a high standard. It is now time to embrace new software and working methods among which are the intriguing Reaper music production software.
As this does not include built-in VST instruments I have decide, after much research, to go for Halion as it appears to have the best user interface for sample construction - something I do a great deal of. I did look at Kontakt which, while impressive, didn't appeal to me regarding the GUI. Halion does have it's quirks and inconsistencies but has a good sound quality, nice Waldorf filters, acceptable CPU loading and quality key-zone editing - PLUS user defined key commands!.
Also on my to-rave-about list is the truly incredible Surge VST synth. Let me say only that every time I sit down and start programming this synthesizer I create really great sounds within minutes...
Any thoughts? You can e-mail me using the mail icon on the top left of this page, or leave a comment on the form below, thanks.
My free wav & exs samples can be found here.
Please link to this page, thanks.
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