Transducer Paper #6 - Tech Speakers · PDF fileTransducerPaper# 5! TransducerTheory! FA4740! ... Technical&Prioritization& ... mixing!speakers,!they!will!also!be!required!to!meet!film

Ben Jaszczak

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Transducer Paper #5 Transducer Theory

FA4740

1/17/14

Ben Jaszczak

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Table of Contents

Table of Contents .................................................................................................................................. 2

Functional Description ....................................................................................................................... 3 Technical Goals ..................................................................................................................................... 4 Technical Prioritization ............................................................................................................................... 4 Physical Specifications: ................................................................................................................................ 4 Visual Aesthetics ............................................................................................................................................. 4 Material: .............................................................................................................................................................................. 4 Protection: .......................................................................................................................................................................... 5

Hardware ........................................................................................................................................................... 5 Power ................................................................................................................................................................................... 5

Cabinet Design ................................................................................................................................................. 6 Shape: ................................................................................................................................................................................... 6 Bracing & Wall Strength: .............................................................................................................................................. 6 Wall Relationships & Edge Diffraction: ................................................................................................................. 6 Internal Reflections: ....................................................................................................................................................... 6

Cabinet Design ................................................................................................................................................. 7 Room dimensions and details: ................................................................................................................... 8 Mounting ............................................................................................................................................................ 8 Audio Characteristics .................................................................................................................................... 8 Frequency Response ...................................................................................................................................... 9 Low Frequency Response ............................................................................................................................................ 9 High Frequency Response ........................................................................................................................................... 9 Shape and Voicing ........................................................................................................................................................ 10 Coloration, Time Response ...................................................................................................................................... 10 Frequency Bandwidth ................................................................................................................................................ 10

SPL ..................................................................................................................................................................... 10 Standards ......................................................................................................................................................................... 10 Personal Standards ...................................................................................................................................................... 11 SPL Usage ......................................................................................................................................................................... 11 Speaker Sensitivity ...................................................................................................................................................... 11 dBW .................................................................................................................................................................................... 11 Safety ................................................................................................................................................................................. 12

Woofer Analysis ............................................................................................................................................ 13 Tweeter Analysis .......................................................................................................................................... 23 Crossover Analysis ....................................................................................................................................... 28

Bibliography ........................................................................................................................................ 29

Ben Jaszczak

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Functional Description

I will be building a pair of desktop loudspeakers for personal use for the purpose of film

mixing. These speakers will be designed with high fidelity as the top priority. As film

mixing speakers, they will also be required to meet film-‐mixing standards. As desktop

speakers the weight and size will be constrained to fit on my desk and remain within its

weight tolerance. The speakers will be designed with a single intended listener at close

listening proximity. The loudspeakers will be used as a stereo pair in my bedroom,

occasionally functioning as front left and right sides in a 5.1 surround system. Largest

source of noise in my room is the cold water main that runs through the outside corner

wall producing blue noise. My bedroom is next door to the family room where there are

frequently people and movies producing noise. The speakers will be designed with the

intent of listening forward, and anticipating how the mix will be heard in different

environments with different speakers as to best design sounds for a variety of

circumstances.

Low Frequency Response

SPL

Size

Prioritization

Ben Jaszczak

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Technical Goals

Technical Prioritization For my speakers, Hi-‐Fidelity is my first priority. I am looking to achieve ±1.5dB within the

50Hz to 17kHz range. My next priority is SPL, as I want to meet the THX Studio reference

level1 at 85dB with 20dB of headroom. My last priority is size and weight, which are

limited primarily by cost.

Physical Specifications: Dimensions2:

Based off of the ratio:

• Width: 11.5” • Height: 20.25” • Depth: 12” -‐ x • Tang Band W6-‐1721 6 ½” Woofer • SB Acoustics SB26STAC Soft Dome 1” Tweeter Max weight: 45 lbs. per speaker

Visual Aesthetics

Material:

The speaker boxes will be made of ½” Baltic birch plywood sides back and bottom,

purple heart hardwood face and top, and will be finished with a natural colored oil.

Beveled edges will hide wood seams as well as aid with edge reflections.

1THX. THX Reference Level. 2014. http://www.thx.com/consumer/thx-‐technology/thx-‐reference-‐level/ (accessed January 17, 2014). 2Weisstein, Eric W. Golden Rectangle. January 17, 2014. http://mathworld.wolfram.com/GoldenRectangle.html (accessed January 17, 2014).

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Protection: My drivers will not be protected with grills. Because Hi-‐Fidelity is prioritized over mobility

my speakers will have no built in protection. I will not be purchasing or building cases

because my speakers will only transport with changing residence and will be packaged

appropriately in that event.

Hardware

Power

I am currently planning on purchasing two of MiniDSP’s PWR-‐ICE125’s for my loudspeakers. At 140W listed apiece out of the 100W needed, these plate amplifiers will allow me to program my crossover while also internally power my speakers.

Ben Jaszczak

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Cabinet Design

Shape:

Vertical rectangular prism with beveled face edges.

Single driver and single tweeter.

Bracing & Wall Strength:

The loudspeaker cabinet will be braced with Baltic Birch plywood ribs.

The walls of the cabinets will be ½” thick Baltic Birch plywood, and the structure of

the cabinet will be reinforced by the rib bracing inside of the cabinet.

Wall Relationships3 & Edge Diffraction:

The loudspeaker cabinet walls will be joined with wood glue and finishing nails.

Internal seams will be filled with either caulking or beveled battens to eliminate 90˚

angles where the cabinet walls meet. Rounded ribs will reduce edge diffraction

within the cabinet along with filled and rounded seams to remove 90˚ angles within

the cabinet. The cabinet will be a rectangular prism using dimensions calculated

with “The Golden Ratio” with an approximate

Internal Reflections:

The application of “The Golden Rule” in choosing the cabinet dimensions is intended

to minimize internal reflections. The use of insulation will also be utilized to absorb

and diffuse high frequencies.

3 LaLena, Michael. DIY Audio Speaker Box Building FAQ -‐ Tutorial. http://www.diyaudioandvideo.com/FAQ/Build/ (accessed January 17, 2014).

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Cabinet Design

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Room dimensions and details: Depth: 12’

Width: 11’

Height: 7’

All walls and ceiling are drywall with fiberglass insulation. The two outside corner walls

are followed by cinder block. There is a bookshelf, a desk, and a futon in the way of

furniture.

The majority of the concrete floor is covered with thin mat rugs.

Mounting Positioning

The speakers will be set upon a desktop approximately 1.5m apart. They will be angled at a single listener approximately 1m away.

Dispersion

Because of the near, single listener, the loudspeakers will need only a relatively narrow dispersion. With the listener moving only about 45 degrees off center at most. Vertically, the user should always be sitting, particularly when monitoring for accurate response.

Audio Characteristics The primary purpose for these speakers will be mixing audio for film. The speakers will be

designed with the intent of listening forward, and anticipating how the mix will be heard in

different environments with different speakers as to best design sounds for a variety of

circumstances. For this purpose, my speakers will be designed to prioritize Hi-‐Fidelity over

enjoyment.

Ben Jaszczak

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Frequency Response4

My target frequency response is 50Hz – 17KHz ±1.5dB My low frequency preferences are based on my personal findings below.

General Low Frequency Perception:

Noticeable low frequency loss: 33Hz

Still enjoyable: 50 Hz

Unbearable low frequency loss: 70 Hz

Low Frequency Response

Low frequency goals generally pertain to sound effects for film mixes as well as soundtrack music generally falling under the orchestral/classical genre.

Sound Effects (Variable)

Cellos (56Hz)

Bass Guitar (41Hz)

Kick Drum (50Hz)

High Frequency Response

High frequency response is based off of speaking voices, soundtrack and orchestral music, as well as sound effects for film.

Sound Effects (20KHz)

Voices (16KHz)

Violin (16KHz)

4 IRN. Frequency Chart. 2014. http://www.independentrecording.net/irn/resources/freqchart/main_display.htm (accessed January 25, 2014).

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Shape and Voicing

As mixing speakers my I am aiming for a flat frequency response without biasing towards perceived bass. I want a flat frequency response with smooth roll off for both my low and high end

Coloration, Time Response

The loudspeakers will be designed to be relatively dry, minimizing coloration that

would take away from fidelity to the original sound.

The cabinet will be a sealed box to achieve a smooth low frequency roll off and

overall better low frequency fidelity. These speakers will be used with a subwoofer

if additional low frequency response is desired.

The Speaker cabinet will be standard shape rectangular prisms, built with Baltic

birch 7-‐ply plywood.

Frequency Bandwidth My high frequency response goal is the standard 20KHz. Based on my own listening

preferences I need the low frequency response to be able to produce classical instruments

such as stand up bass and cello with good detail, as well as sound effects for film, which will

be my primary need from my speakers.

SPL

Standards K-‐20: For dynamic range fitting to the demands of film mixing.

This is my primary basis for my SPL goal, which is to have 83 dB for my “0” with 20

dB of headroom, making my goal a peak of 103 dB.

THX: To meet standards currently used for film mixing.

Ben Jaszczak

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Personal Standards5 Average Morning Listening SPL: 60 dBA

Average Afternoon Listening SPL: 76 dBA

Average Evening Listening SPL: 61 dBA

Average Music/Film Mixing SPL: 67 dBA

Average Loud Enjoyment SPL: 86 dBA

SPL Usage

o SPL required for home use and home mixing and mastering

o Average listening levels during daytime: 76dB

o Average peaks during daytime levels: 84dB

o THX Studio Reference Level6: 85dB with 20dB Headroom

Speaker Sensitivity 83 dBA in order to meet “0” for K-‐20

dBW7 dBW = 10log(x)

x = 100 Watts

dBW = 20dB

5 Jaszczak, Benjamin. SPL and Frequency Response as Observed in Individual Living Conditions. Hancock, MI, 2014. 6 THX. THX Reference Level. 2014. http://www.thx.com/consumer/thx-‐technology/thx-‐reference-‐level/ (accessed January 17, 2014). 7 Plummer, Christopher. "SPL Standards, Safety, Equations." Houghton, Michigan, January 22, 2014.

Ben Jaszczak

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In order to achieve the k-‐20 standard with speakers bearing a sensitivity of 83 dB, I need

20 dB of headroom. To achieve this I will use a 100-‐Watt amplifier to gain 20 dBW or the

starting sensitivity of 83 dB.

Safety8 According to NIOSH Reccomendations, 88 dBA is the first SPL level where hearing loss is measured. At 100 min. of exposure, hearing sensitivity is measured to be lost at approximately 1-‐2 dB. Being that my speakers goal is for the “0” level (loud) of my speakers is 83 dBA, and on the basis of my typical listening, it is unlikely that I will ever use my speakers to expose myself to levels above 83 dBA for periods of time longer than a single song.

8 U.S. Department of Health and Human Services. Criteria for a Recommended Standard: Occupational Noise Exposure. Cincinnati, Ohio: National Institute for Occupational Safety and Health, 1998.

0

5

10

15

20

25

30

35

40

45

50 Watts 100 Watts 150 Watts 200 Watts 1000 Watts 10000 Watts

Diminsishing Return of Additonal Wattage

dBW

\\

Ben Jaszczak

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Woofer Analysis Focal 6 W4311 B 6 ½”

Price: $125 Fs: 52.3 Hz F3: 78Hz

Pros: ±2dB from 200 Hz -‐2 kHz Good off axis response (though it only shows 30 degree off axis) Cons: Graph smoothing makes reading less accurate 3 kHz 3dB peak Moderately high F3 Expensive

Ben Jaszczak

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20 50 100Hz 200 500 1k 2kMag -20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0 dB

2

4

6

8

10

mmExc

Linear Exc Limit

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30TATATATA

Driver ParametersDriver ParametersDriver ParametersDriver Parameters Box ParametersBox ParametersBox ParametersBox ParametersDriver:

Nominal DiameterNominal PowerSensitivity (1W/1m)Free Air ResonanceTotal QElectrical QMechanical QEquivalent VolumeNominal ImpedanceDC ResistanceMax Thermal PowerMax Linear ExcursionMax ExcursionVoice Coil Diam.

D =P =

SPL =f(s) =

Q(ts) =Q(es) =Q(ms) =V(as) =

Z =R(e) =P(t) =

X(max) =X(lim) =D(vc) =

6.5087.8352.30.48000.656800903.300

inWattsdB SPLHz

cu ftOhmsOhmsWattsmmmmmm

Driver Notes:

NOTE: X(max) was estimated based on the nominal driver diameter.NOTE: S(D) was estimated based on the nominal driver diameter.

System Type: 2nd Order Closed Box

Box VolumeClosed Box QSystem ResonanceCompliance Ratio

V(B) =Q(tc) =F(sc) =alpha =

0.95420.7480.631.377

cu ft

Hz

System ParametersSystem ParametersSystem ParametersSystem Parameters

No. of DriversIsobaric FactorInput PowerSPL Distance

N =I =

P(in) =D =

211001

System Notes:

(1=normal, 2=iso)Wattsm

Michigan Technological UniversityMichigan Technological UniversityMichigan Technological UniversityMichigan Technological University1104 Summit StreetHancock, MI 49930United States 906 370 7180

2nd Order Closed Box

System Name:

Designer:

Title:

Rev Date: Rev:

Ben JaszczakDriver Comparison

Ben Jaszczak

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SB Acoustics Satori MW16P-‐8 6 ½” Price: $125 Fs: 750 Hz F3: 63Hz

Pros: ±2.5dB from 200 Hz -‐2 kHz Excellent off axis response at 30 and 60 degrees Flat response up to 3kHz makes cross over simpler Cons: 3.5 kHz 3dB peak

Ben Jaszczak

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20 50 100Hz 200 500 1k 2kMag -20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0 dB

2

4

6

8

10

mmExc

Linear Exc Limit

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30TATATATA



D =P =

SPL =f(s) =


Z =R(e) =P(t) =


6.5087.5290.33001.69500603.300

inWattsdB SPLHz


Driver Notes:





0.96880.761.523.5

cu ft

Hz



N =I =

P(in) =D =

211001

System Notes:




System Name:

Designer:

Title:

Rev Date: Rev:


Ben Jaszczak

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Tang Band W6-‐1721 6 ½” Price: $92.70 Fs: 40 Hz F3: 65 Hz

Pros: ±2.5dB from 200 Hz -‐3 kHz Good response up to 3kHz makes crossover simpler Good F3 Cons: Some graph smoothing makes reading less accurate No off axis response shown

Ben Jaszczak

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20 50 100Hz 200 500 1k 2kMag -20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0 dB

2

4

6

8

10

mmExc

Linear Exc Limit

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30TATATATA



D =P =

SPL =f(s) =


Z =R(e) =P(t) =


6.5088400.43001.03800503.300

inWattsdB SPLHz


Driver Notes:





1.2580.765.121.65

cu ft

Hz



N =I =

P(in) =D =

211001

System Notes:




System Name:

Designer:

Title:

Rev Date: Rev:


Ben Jaszczak

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Scan Speak Classic P17WJ00 6 ½”

Price: $76.90 Fs: 37 Hz F3: 75 Hz

Pros: ±1.5dB from 200 Hz -‐3 kHz Smooth roll off helps crossover Excellent off axis response at 30 and 60 degrees Cons: Moderately high F3

Ben Jaszczak

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20 50 100Hz 200 500 1k 2kMag -20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0 dB

2

4

6

8

10

mmExc

Linear Exc Limit

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30TATATATA



D =P =

SPL =f(s) =


Z =R(e) =P(t) =


6.5088370.35001.225001503.300

inWattsdB SPLHz


Driver Notes:





0.79560.70774.743.08

cu ft

Hz



N =I =

P(in) =D =

211001

System Notes:




System Name:

Designer:

Title:

Rev Date: Rev:


Ben Jaszczak

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Aurum Cantus AC165/50C2C 6 ½”

Price: $120.59 Fs: 37 Hz F3: 150 Hz

Pros: ±1dB from 200 Hz -‐2 kHz Cons: Atrocious F3 Graph smoothing makes reading less accurate No off axis response shown 5dB peak at 3.5kHz

Ben Jaszczak

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20 50 100Hz 200 500 1k 2kMag -20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0 dB

2

4

6

8

10

mmExc

Linear Exc Limit

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30TATATATA



D =P =

SPL =f(s) =


Z =R(e) =P(t) =


6.5090370.19001.13001503.300

inWattsdB SPLHz


Driver Notes:





0.17590.707137.712.85

cu ft

Hz



N =I =

P(in) =D =

211001

System Notes:




System Name:

Designer:

Title:

Rev Date: Rev:


Ben Jaszczak

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Tweeter Analysis

Vifa NE19VTT Titanium Silk Surround Tweeter

Price: $34.21 Fs: 806Hz

Pros: ±2dB from 1-‐20 kHz Good roll off below 1kHz makes crossover simpler Good off axis response, particularly at 30 degrees Decent crossover point at 1612 Hz Cons: Small peak at ~25kHz

Ben Jaszczak

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Vifa NE19VTS ¾” Silk Dome Tweeter Price: $32.75 Fs: 816Hz

Pros: ±2.5dB from 1-‐20 kHz Good roll off below 1kHz makes crossover simpler Good off axis response at 30 degrees Decent crossover point at 1632 Hz Cons: Small peak at ~25kHz Poor off axis response at 60 degrees

Ben Jaszczak

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SB Acoustics SB26STCN Soft Dome Tweeter

Price: $34.85 Fs: 960 Hz

Pros: ±1dB from 1-‐20 kHz Good roll off below 1kHz makes crossover simpler Good off axis response at 30 degrees and decent at 60 degrees Decent crossover point at 1632 Hz Cons: Smoothing makes graph less accurate Crossover point at 1920 Hz

Ben Jaszczak

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SB Acoustics SB26STAC Soft Dome Tweeter

Price: $43.85 Fs: 750 Hz

Pros: ±1dB from 1-‐20 kHz Good roll off below 1kHz makes crossover simpler Great off axis response at 30 and 60 degrees Very good crossover point at 1500 Hz Cons: Some smoothing

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SB Acoustics SB26ADC Aluminum Dome Tweeter

Price: $39.00 Fs: 680 Hz Pros: ±1dB from 1-‐20 kHz Good roll off below 1kHz makes crossover simpler Very good off axis response at 30 and 60 degrees Great crossover point at 1360 Hz Cons:

Ben Jaszczak

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Crossover Analysis SB Acoustics Satori MW16P-‐8

SB Acoustics SB26STAC Soft Dome Tweeter

3rd order Crossover, with the crossover point at 2kHz.

Mini DSP ICE 125 Settings: The Mini DSPs will be set up to cross over at 2kHz with a 3rd order crossover as shown in

the graph above.

The tweeter will be padded 2dB to match the crossover points of the woofer and tweeter.

The baffle step set up through the Mini DSP will be a –3 dB low pass filter at 1200 Hz,

approximately the frequency where the wavelength will exceed the horizontal baffle of the

speaker. From there the baffle step will be tuned as the speaker is tested.

30

40

50

60

70

80

90

100

500 1K 2K 3K 4K

Tweeter X Over

Woofer X over

Sum

Frequency (Hz)

Response (dB)

Ben Jaszczak

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Bibliography Davis, Gary, and Ralph Jones. Yamaha Sound Reinforcement Handbook. 2nd Edition. Hal Leonard Corporation, 1989. Howard, David M., and James Angus. Acoustics & Psuchoacoustics. 2nd Edition. Focal Press, 2001. IRN. Frequency Chart. 2014. http://www.independentrecording.net/irn/resources/freqchart/main_display.htm (accessed January 25, 2014). Jaszczak, Benjamin. SPL and Frequency Response as Observed in Individual Living Conditions. Hancock, MI, 2014. LaLena, Michael. DIY Audio Speaker Box Building FAQ -‐ Tutorial. http://www.diyaudioandvideo.com/FAQ/Build/ (accessed January 17, 2014). Newell, Philip, and Keith Holland. Loudspeakers: For Music Recording and Reproduction. Jordan Hill, Oxford: Taylor & Francis, 2006. Plummer, Christopher. "SPL Standards, Safety, Equations." Houghton, Michigan, January 22, 2014. THX. THX Reference Level. 2014. http://www.thx.com/consumer/thx-‐technology/thx-‐reference-‐level/ (accessed January 17, 2014). U.S. Department of Health and Human Services. Criteria for a Recommended Standard: Occupational Noise Exposure. Cincinnati, Ohio: National Institute for Occupational Safety and Health, 1998. Weisstein, Eric W. Golden Rectangle. January 17, 2014. http://mathworld.wolfram.com/GoldenRectangle.html (accessed January 17, 2014).

Documents

Transducer Paper #6 - Tech Speakers · PDF fileTransducer*Paper*# 5! TransducerTheory! FA4740! ... Technical&Prioritization& ... mixing!speakers,!they!will!also!be!required!to!meet!film

Transducer Paper #6 - Tech Speakers · PDF fileTransducerPaper# 5! TransducerTheory! FA4740! ... Technical&Prioritization& ... mixing!speakers,!they!will!also!be!required!to!meet!film