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Smaart Fundamentals Welcome

Smaart Fundamentals Welcome. Instructors. Jamie Anderson EducatorGuy Jamie@RationalAcoustics.com Harry Brill Pro Audio Guy ProAudioGuy@yahoo.com. Rational Acoustics LLC www.RationalAcoustics.com. Who Are You?. Basic ground rules. Class is informal - Get comfortable

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Smaart Fundamentals Welcome

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  1. Smaart Fundamentals • Welcome

  2. Instructors Jamie Anderson EducatorGuy Jamie@RationalAcoustics.com Harry Brill Pro Audio Guy ProAudioGuy@yahoo.com Rational Acoustics LLC www.RationalAcoustics.com

  3. Who Are You?

  4. Basic ground rules • Class is informal - Get comfortable • Ask questions (Win valuable prizes!) • Stay awake • Be Courteous- Don’t distract! (TURN THE CELL PHONES OFF, PLEASE.)

  5. Rational Training Class Formats • Smaart Fundamentals • Measurement Theory • Basic Smaart Operation & Measurements • Application Seminars • System Alignment Theory • Advanced Applications • Advanced Seminars • On-site system alignment: for experienced users only.

  6. Continuing Education • RTFM • Do the example applications: SmaartLive Basic Meas.pdf • Online at www.RationalAcoustics.com • Rational Support Forums • Online at www.EAW.com/Smaart And again, do some measurements.

  7. What Are Our Goals Today? Understanding how Smaart works – and how we can use it as a tool • Basic measurement theory – Platform Agnostic Single Channel vs. Dual Channel Measurements Time Domain vs. Frequency Domian • Understanding how to get a useful measurement How to improve data quality How to check our work EQ 101

  8. The Only Math You Need Today: T=1/ƒ & ƒ=1/T ƒ = 100 Hz T= 10 ms ƒ = 250 Hz T= 4 ms T= .1 ms ƒ = 10 kHz T= .1 ms ƒ = 10 kHz ƒ = 20 Hz T= 50 ms T= 1 ms ƒ = 1 kHz T= .5 ms ƒ = 2 kHz ƒ = 500 Hz T= 2 ms

  9. What is wrong with this system?Why doesn’t it sound good?

  10. System Alignment

  11. System Alignment:Engineering Task with Artistic Goal • Art is a subjective experience. • The system alignment needs to fit the goal • The artistic goals set your priorities • One size does not fit all. • Make the right compromises • Listening is Key!!!!!!!!!

  12. System Alignment “Smaart-ing” a System

  13. System Alignment “Smaart-ing” a System

  14. System Alignment Smaart: Is an Analyzer Is a Tool System Alignment: Is a Series of Decisions Made in Context Is Optimising Your Comprimises

  15. System Engineering Key Concepts: • Solve problem at source • The closer to the source . . . the more effective the solution.

  16. Source X-over Amp Speaker EQ Example: The speaker you are measuring has a relatively flat response except: HF is 6 dB lower than LF above 1.6 kHz Substantial HF noise Target response: nominally flat 6dB 0dB 125 250 500 1k 2k 4k 8k -6dB

  17. X-over Amp Speaker EQ Example: Source The speaker you are measuring has a relatively flat response except: HF is 6 dB lower than LF above 1.6 kHz Substantial HF noise Potential Solutions EQ: Bring up HF on EQ Add extra HF to program material 6dB 0dB 125 250 500 1k 2k 4k 8k -6dB

  18. Source X-over Amp Speaker EQ Example: The speaker you are measuring has a relatively flat response except: HF is 6 dB lower than LF above 1.6 kHz Substantial HF noise Potential Solutions Level: Turn up HF on Amp Turn up HF at X-over output 6dB 0dB 125 250 500 1k 2k 4k 8k -6dB

  19. Source X-over Amp Speaker EQ Example: The speaker you are measuring has a relatively flat response except: HF is 6 dB lower than LF above 1.6 kHz Substantial HF noise Potential Solutions System Maintenance: Loss of 6 dB and in crease in HF noise a good indication of a bad cable on X-over HF out. 6dB 0dB 125 250 500 1k 2k 4k 8k -6dB

  20. Our goal is to fix our system . . .. . . not the trace on the screen! Smaart is NOT a video game!

  21. System Engineering Key Concepts: • Use the right tool • “Every item in your tool box is a hammer . . . except your wood chisels, they’re screwdrivers.”

  22. 1 Tools in Order of Use • Acoustic Design / Treatment • Equipment Choice / Maintenance • System Design - “Design to align”

  23. 1 2 Tools in Order of Use • Acoustic Design / Treatment • Equipment Choice / Maintenance • System Design - “Design to align” • Level • Delay

  24. 1 2 3 Tools in Order of Use • Acoustic Design / Treatment • Equipment Choice / Maintenance • System Design - “Design to align” • Level • Delay • And lastly . . . EQ

  25. System Engineering Key Concept: • Interactions are greatest where signals are equal level - Crossover Points

  26. System Engineering Key Concept: • Interactions are greatest where signals are equal level - Crossover Points • Phase determines the interaction • Phase Shift (Filters) • Polarity (Wiring) • Delay (Time Alignment)

  27. Analyzers

  28. Analyzers • Analyzers are our tools for finding problems • Different measurements are good for finding different problems RTA Spectrograph SPL History Transfer Function (Frequency Response) Impulse Response (Delay Locator)

  29. Single Channel vs. Dual Channel RTA Transfer Function (Frequency Response) Spectrograph ETC Impulse Response (Delay Locator) SPL History Lin NC Signal Measurement System Measurement

  30. Time Domain vs. Freq. Domain Spectrum (RTA) Waveform Spectrum Dual Channel vs. Single Channel Frequency Response (TF) Impulse Response

  31. Why Dual-Channel? The measurements have a reference – they can tell: • Arrival time of direct signal • Signal from noise • Direct from reflected … And they are Signal Independent

  32. An analyzer is only a tool: YOU make the decisions You decide what to measure. You decide which measurements to use. You decide what the resulting data means. And you decide what to do about it.

  33. Any idiot can get squiggly line to appear on the Smaart screen. Our goal is to make measurements we can make decisions on. Case & Point: The Ground Bounce . . .

  34. The Ground Bounce Reflection arrives ~ 4 ms 4 ms Comb filter frequency = 1/4 ms = 250 Hz

  35. The Ground Bounce Two Solutions Block the reflection Remember: Baffle must be large enough to be effective above 100 Hz. Think 5’x 5’ (1.5 m x 1.5 m) Ground-plane measurement

  36. To use Smaart, we must: • Verify that we are making our measurements properly. • Verify that it is an appropriate measurement for our purpose. Remember: Computers do what we tell them to do, not what we want them to do. We must be aware of what we are telling our computers to do – Be aware of what our measurement really represents

  37. FFT’s & Our Friend the Sine Wave

  38. System engineering is managing interactions • Acoustically • Multiple Drivers, Speakers, Systems • Reflections/Acoustics

  39. Fourier & Signal Addition • Jean Baptiste Joseph Fourier • All complex waves are composed of a combination of simple sine waves of varying amplitudes and frequencies • Adding signals is sine wave addition Time Domain Freq. Domain (Amp vs Time) (Amp vs Freq) Waveform Spectrum

  40. The Big Question + = ? or or

  41. The Big Question + = ? The interaction is determined by relative LEVEL & PHASE or or

  42. Transforms A transform converts data from one domain/view to another: Time Domain to Frequency Domain • Same data • Is reversible via Inverse Transform • Unlike a conventional RTA using a bank of analog filters, FFT’s yield complex data: Magnitude and Phase data Time DomainFrequency Domain Waveform Spectrum* Amp vs Time Amp vs Freq (*Fractional Octave Banded View)

  43. Linear vs. Log Banding Pink Noise (equal energy per octave) shown w/ linear and log banding. Fractional–octave (log) banding has an equal number of bands per octave, resulting in equal energy per band. Linear banding has an increasing number of bands per octave as frequency increases, resulting in less energy per band in the HF.

  44. FFT Resolution • Reciprocal Bandwidth: FR=1/TC Frequency Resolution = 1/Time Constant • Larger Time Window: • Higher Resolution • Slower (Longer time window and more data to crunch) • Smaller Time Window: • Lower Resolution • Faster • Time Constant = Sample Rate x FFT Length * Decimation – Varying SR & FFT to get constant res.*

  45. FFT Parameters:Time Constant (TC) vs. Frequency Resolution (FR) Linear Frequency Scale TC = FFT/SR FR = 1/TC

  46. FFT Resolution • FFT’s yield linear data • Constant bandwidth instead of constant Q • FFT data must be “banded” to yield fractional-octave data. • FFT must be windowed • FFT’s assume data is continuous & repeating so wave form must begin and end at 0. • Windows are amplitude functions on data

  47. FFT Parameters:Time Constant (TC) vs. Frequency Resolution (FR) Log Frequency Scale

  48. FPPO24 Fixed Points Per Octave(Only available in Transfer Function Mode) TC = 3 ms TC = 683 ms FPPO mode utilizes multiple FFT’s of varying TC to produce data that has a constant 24th oct. resolution.

  49. System Measurements

  50. Our System Measurement Model Input System Output

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