TRANSDUCER THEORY LOUDSPEAKER DESIGN NC-17 REFERENCE MONITORS DESIGNED BY: NICK CECCONI

Transcription

1 TRANSDUCER THEORY LOUDSPEAKER DESIGN NC-17 REFERENCE MONITORS DESIGNED BY: NICK CECCONI MICHIGAN TECHNOLOGICAL UNIVERSITY FA 4740: TRANSDUCER THEORY CHRISTOPHER PLUMMER SPRING 2017

2 TABLE OF CONTENTS Functional Description... 3 Listening Purpose... 3 Environment... 3 Sound Quality... 3 Visual Aesthetics... 3 Prioritization... 4 Technical Specifications... 5 Crossover... 5 Size/Weight/Portability... 5 SPL... 5 Drivers... 6 Frequency Response... 6 Coloration & Time Response... 6 Construction Materials... 6 Driver Analysis... 7 SB Acoustics 26STAC... 7 SEAS Prestige... 8 Morel CAT ScanSpeak Discovery R ScanSpeak Discovery R SB Acoustics SB23NACS Peerless SLS Dayton Audio RS ScanSpeak 22W/8534G ScanSpeak 26W/8534G Final Driver Selection Acoustic Modeling Construction The Build Speaker Tuning Testing Method

3 Left Speaker Initial Response Left Speaker Woofer Only Left Speaker Tweeter Only Left Speaker Tuned Response Right Speaker Initial Response Right Speaker Woofer Only Right Speaker Tweeter Only Right Speaker Tuned Response Initial Performance Review Crossover Adjustment Final Tuning & Documentation Final Frequency Response Integrated Frequency Response Harmonic Distortion Minimum Phase Response Step Response Impulse Response FFT Waterfall Full System FFT Waterfall High Frequencies , 30, 45, 60 Degrees Off-Axis Tweeter Frequency Response Tweeter Harmonic Distortion Tweeter Minimum Phase Response Tweeter Step Response Tweeter Impulse Response Woofer Frequency Response Woofer Harmonic Distortion Woofer Minimum Phase Response Woofer Step Response Woofer Impulse Response Final Specs Bibliography

4 Functional Description Listening Purpose The system being designed for this project will be used for creating, mixing, and mastering audio for various media. They need to be sonically accurate and honest, and are to be used for critical listening of virtually any source material. For what I m putting into them, I want these speakers to be the best pair I ve ever owned, and serve their purpose for my everyday sound needs. Environment These speakers will most likely sit on a desk or a stand, set in a home studio. They are not to exceed more than 5 feet from the listener so that they may be able to rest in the ideal mix position. Although size is of lesser concern, these speakers must still be somewhat portable and relatively lightweight so that they may be transported easily. Sound Quality These loudspeakers must be Hi-Fidelity, creating an accurate and uncolored reproduction of audio. Under the AES Listening Standards 1, their frequency response will be flat. They are to achieve good image separation and depth, characterized by an even but wide stereo image. Visual Aesthetics The enclosure this system will be made out of is a combination of maple wood and MDF. I am not planning to build an overanxious design, but rather a more traditional shape like most standard upright monitors on the market. They are expected to be a little on the larger side so I have ample room to work with, while also taking in account the bass response I am pursuing. They will be eventually be painted a neutral gray. 1 AES Recommended Practice for Profession Audio. Standards and Information Documents, Print. 3

5 Prioritization To demonstrate how this loudspeaker will be prioritized, I used John Murphy s system from his book Introduction to Loudspeaker Design 2 to professionally address my speaker goals. This chart explains the three main focuses of the speakers, and also explains the tradeoffs that exist during the design process. Even though it was mentioned that I would like these speakers to be portable and of good size, extended low frequency and SPL are the most important aspects of my speaker s functionality and capabilities. 40% 40% 20% 2 Murphy, John L. Introduction to Loudspeaker Design. Andersonville: True Audio, Print. 4

6 Technical Specifications Crossover For this active 2-way system, this pair will utilize a built in minidsp to handle power and tuning for whichever drivers I end up choosing for this project. The PWR-ICE minidsp allows extensive control over both drivers crossover points and parametric EQ settings, which can be adjusted and tuned as needed. The approximate crossover point will likely be between 1 khz 2 khz depending on what tweeter and woofer I select for the pair. Size/Weight/Portability In terms of size, the goal for these speakers is to be larger than most traditional desktop monitors, but not so much that it loses its portability. Much time was spent considering the trade-offs of this project, and it was mentioned before that portability is the lowest priority. However, I still need to move these proficiently enough for them to be useful. Initially, I thought I would experiment with the box shape and try for a super wide front, but decided against it. I decided these should be your typical studio pair, even though they will end up being a little larger than what is typically found on the market. The approximate dimensions of the pair should be 12 x 15 x 17 (W x D x H). With respects to weight, I would like to keep each monitor under 30lbs. Currently, I own a set of monitors that are 20lbs each, and can be easily lifted. SPL Much like how these speakers will be tested, SPL levels are to adhere to the K-20 standard, established by legendary audio engineer Bob Katz 3. Although the K-system is made up of three headroom standards, the K-20 covers the widest dynamic range. When tuning, the K-20 system is commonly used for speakers in order to reach a level of 83 db SPL, effectively zeroing a loudspeaker for measurement. By this standard, my pair should be also able to reach the K-20 standard s peak at 103 db SPL. These levels should be more than sufficient, especially when comparing earlier data exploring my personal SPL preferences between music genres. 3 Bob Katz, Part II: How To Make Better Recordings in the 21st Century - An Integrated Approach to Metering, Monitoring, and Leveling Practices. AES Journal, September

7 Drivers Achieving generous lows and balanced high frequencies are ultimately my goal for this speaker, which will require a sizable woofer and reliable tweeter. I chose to use 8 woofers, which hopefully will give these monitors enough juice to reach Hz, and lower if possible. After going back and forth between ribbon and dome tweeters, I decided that I wanted to stick with traditional 1 soft dome tweeter for my high frequency needs. Frequency Response These speakers are to be used for intense critical listening and mixing, requiring max accuracy for any source material. The frequency response will be as flat as personally possible. My goal is to make them +/- 2dB from 40 Hz to 20 khz or better if I can, and no worse than +/- 2.5 db in that same range. Coloration & Time Response As mentioned before, the sound quality of these monitors must be Hi-Fidelity. They need to produce an accurate sound, conforming to a flat and honest frequency response. I aim to ensure that this system has hints of life or liveliness to them, representing a deep and colorful soundstage that translates to a higher quality listening experience. These monitors must also accomplish successful low frequency ranges, which will be supported by a vented port inside the enclosure. Transient Reponses are said to be much better with a sealed enclosure, but the needs of my low frequencies will do much better with the vented enclosure, which is a choice I am fine with making. For the reflections inside the box, foam, fiberglass, and/or other absorptive material will be used to help reduced unwanted complications within frequencies. Externally, because these speakers will be shaped rectangular, the front edges will be rounded off to eliminate potentially unwanted reflections, while also considering possible bafflestep. Construction Materials To build these speakers, I will need materials that are inexpensive, flexible, and easy to work with. For those reasons, I will be using 1/2 thick Maple wood with a veneer core and 1/2 thick MDF to construct these speakers. The challenge will be building a sturdy box that will hold up sonically while achieving the sound I am looking for, hopefully not being too dreadfully heavy. 6

8 Driver Analysis SB Acoustics 26STAC Model: SB Acoustics S26STAC-C Textile Dome Tweeter Price: $41.60 Sensitivity: 91 db FS: 750 Hz Frequency Response: This tweeter was one of the first drivers I looked at, and it s a good tweeter in terms of its flat frequency response and axis response. Some of the more high-end tweeters I have seen are in contention with this one s performance, but the price with this one is definitely much more affordable. Definitely a top choice to consider. 4 4 SB Acoustics S26STAC-C Textile Dome Tweeter. Madisound Speaker Store. Accessed February 5,

9 SEAS Prestige Model: SEAS Prestige 27TFFC (H0881) 1 Textile Dome Tweeter Price: $45.10 Sensitivity: 91 db FS: 550 Hz Frequency Response: This tweeter was another similar textile dome tweeter in the same price range as the SB Acoustics looked at above. It appears to seriously lack evenness in the frequency response from 1k to 20k, but does has a high sensitivity and lower FS than most of the tweeters I have seen. 5 5 SEAS Prestige 27TFFC 1 Textile Dome Tweeter. Madisound Speaker Store. Accessed February 5,

10 Morel CAT328 Model: Morel CAT Textile Dome Tweeter Price: $94.00 Sensitivity: 90 db FS: 650 Hz Frequency Response: The Morel CAT s is a more expensive textile dome tweeter that is on the higher end of my price range, but has a wide axis response that looks to perform quite well. However, it doesn t look visually pleasing, because the dome tweeter itself has been said to look like an eyeball that is uncomfortably staring back at the listener, which I completely agree with. 6 6 Morel CAT Textile Dome Tweeter. Madisound Speaker Store. Accessed February 15,

11 ScanSpeak Discovery R2604 Model: ScanSpeak Discovery R2604/ Textile Ring Radiator Price: $50.20 Sensitivity: 90 db FS: 500 Hz Frequency Response: I m a fan of ScanSpeak products, especially the ones we use at my university s recording studio. Compared to a Genelec speaker pair we recently invested in, I greatly enjoy the speakers with ScanSpeak drivers in them because of the added depth in sound the others simply do not have. This tweeter in particular is inexpensive and has a low FS. Its response is actually quite good too, but I m not a fan of the shape or look of this tweeter at all. 7 7 ScanSpeak Discovery R2605/ Textile Ring Radiator. Madisound Speaker Store. Accessed February 15,

12 ScanSpeak Discovery R2606 Model: ScanSpeak Discovery R2606/ Textile Dome Tweeter Price: $47.50 Sensitivity: 91 db FS: 850 Hz Frequency Response: This ScanSpeak driver is similar to the other ScanSpeak previously listed, but boasts a much higher FS while holding a similar price point. It rolls off quite a bit near the 20k mark, but it does look much better than its counterpart. Out of the ScanSpeak tweeters listed, I d take this one if I had to. 8 8 ScanSpeak Discovery R2606/ Textile Dome Tweeter. Madisound Speaker Store. Accessed February 15,

13 SB Acoustics SB23NACS Model: SB Acoustics SB23NACS Aluminum Cone Woofer Price: $ Sensitivity: 87.5 db Power Handling: 60W FS: 25 Hz The SB Acoustics SB23 is one of my favorite woofers I have researched. Even though it is on the pricier side, I really enjoy the looks of this driver and the fact that its FS reaches 25 Hz. The response is even enough at my potential crossover points, and has an adequate sensitivity level. The aluminum cone is also a plus. I only hope my budget doesn t squander my chances of considering this woofer when I make my final selections. 9 9 SB Acoustics SB23NACS Aluminum Cone Woofer. Madisound Speaker Store. Accessed February 5,

14 Peerless SLS Model: Peerless SLS Paper Cone Woofer Price: $66.30 Sensitivity: 86 db Power Handling: 90W FS: 64 Hz The Peerless SLS is a more affordable woofer that also possesses an 8 diameter. Unlike the SB, it has a paper cone and has a high power handling. My main concern with this woofer is that it s not low enough, and won t extend into the lower frequencies as much as I d like them to Peerless SLS Paper Cone Woofer. Madisound Speaker Store. Accessed February 5,

15 Dayton Audio RS225 Model: Dayton Audio RS Reference Woofer Price: $61.85 Sensitivity: 90 db Power Handling: 120W FS: 32 Hz The Dayton Audio RS225 s are one of the cooler drivers I have found, and also stays in the ranges I m ultimately looking for. It isn t too terribly expensive, has a sensitivity of 90 db, and reaches an FS of around 32 Hz. It s the second lowest 8 driver I have on my list, and is in close contention to be the woofer I might choose for this project. I think it looks pretty sleek too Dayton Audio RS Reference Woofer. Parts Express. Accessed February 15,

16 ScanSpeak 22W/8534G00 Model: ScanSpeak 22W/8534G00 Discovery 8 Woofer Price: $79.20 Sensitivity: 89 db Power Handling: 120W FS: 30 Hz As mentioned before, I enjoy ScanSpeak products and drivers. Even though a tweeter and woofer are only one aspect of building an overall successful speaker, I wanted to consider both of them during this research portion. The ScanSpeak 22W is not too terribly expensive, but has an FS of 30 Hz, the lowest of the 8 drivers on this list. It does have a huge step around 1k and beyond, but that s where the crossover point would be anyways. However, it looks pretty plain ScanSpeak 22W/8534G00 Discovery 8 Woofer. Madisound Speaker Store. Accessed February 15,

17 ScanSpeak 26W/8534G Model: ScanSpeak 26W/8534G 10 Aluminum Cone Woofer Price: $94.20 Sensitivity: 89 db Power Handling: 150W FS: 23 Hz Even though I decided that I would likely be going with an 8 woofer, I wanted to pull up another similar 10 woofer just to compare for fun. The ScanSpeak 26W looks to be one step above the 22W, and contain a 10 aluminum cone woofer. It is on the pricier side, but has a lot more power and an FS that reaches 23 Hz. I m not sure how well a 10 woofer would work with my project goals and design that I m seeking, but I still wanted to consider it in the final mix anyways ScanSpeak 26W/8534G 10 Aluminum Cone Woofer. Madisound Speaker Store. Accessed February 15,

18 Final Driver Selection I chose to go with the SB Acoustics SB23NACS Aluminum Cone Woofer, and SB Acoustics S26STAC-C Textile Dome Tweeter. A close second was the Dayton Audio RS225, but I decided to spend a little more for the sake of trying something different than what most students have done in the past, and for visual aesthetics. The SB Acoustics S26STAC tweeter was a popular choice due to its proclaimed image quality and flat response. Acoustic Modeling Below is a WinSpeakerz model of the SB Acoustics SB23NACS woofer, and the approximated cubic volume for inside of the proposed cabinet. 17

19 Construction The Build Since I was hand cutting all of my wood myself, I took extra caution to be sure I didn t make any mistakes and waste my material. During this process, small design changes were made to the speaker, which ended up changing some of my earlier drafts, such as adding an enclosure for the minidsp to prevent air from escaping the ports. Many small hurdles came up along the way, but the assembly came through as anticipated. I chose to build the outer box first, which was glued and clamped together. After this was completed, I added the inner layer of MDF, retrofitting it to the size of my box in case the dimensions weren t exactly perfect after the first round of cuts. Below is the assembled right speaker before it was sanded and painted. 18

20 Speaker Tuning Testing Method After breaking in the drivers with hours of music and pink noise, it was time to test and tune the pair. Each speaker was placed on top of a 10ft tall metal stand in Michigan Tech s McArdle Theatre, a flexible black-box space that cuts down the amount of reflections when measuring acoustics. In front of the speakers, an Earthworks M measurement microphone was elevated facing the drivers, placed 18 away from the front baffle, equally center between the woofer and tweeter. A computer running FuzzMeasure ran and recorded signal to the speaker and microphone through an Apogee Duet audio interface, with another laptop connected to the speaker by Ethernet, capable of making minidsp adjustments. Measurements were recorded with FuzzMeasure using sinusoidal sweeps from 1 Hz to 48 khz over a period of six seconds. (Tuning station) 19

21 Left Speaker Initial Response Left speaker frequency response with crossover set at 1.5 khz and no tuning. 80 Sound Pressure Level (1/24 Octave Smoothing) 70 Magnitude (db) k 10k Frequency (Hz) Left Speaker Woofer Only Left speaker frequency response with crossover set at 1.5 khz and no tuning, woofer only. 80 Sound Pressure Level (1/24 Octave Smoothing) Magnitude (db) k 10k Frequency (Hz) 20

22 Left Speaker Tweeter Only Left speaker frequency response with crossover set at 1.5 khz and no tuning, tweeter only. 80 Sound Pressure Level (1/24 Octave Smoothing) Magnitude (db) k 10k Frequency (Hz) Left Speaker Tuned Response Left speaker frequency response with crossover set at 1.5 khz, fully tuned. 80 Sound Pressure Level (1/24 Octave Smoothing) Magnitude (db) k 10k Frequency (Hz) 21

23 Left Speaker Tuning Documentation_v1 1.5 khz Test #: Note: _001 First test 002 Tweeter -3 db pad 003 Tweeter -4 db pad (subtracted 1) 004 Replaced port (LONG put in) 4.5 middle 005 Switched back port (SHORT put in) 2.5 middle 006 Tweeter only 007 Woofer only 008 Woofer only (added 0.02 time delay) 009 Woofer only (added 0.09 time delay) 010 Reset woofer delay... tweeter 0.08 time delay 011 Tweeter (0.06 time delay) 012 Retest 013 Full response 014 Tweet PEQ 2100 Hz, +1 db, Q db, Q db, Q3 017 Tweet -5dB pad 018 Tweet PEQ 3600 Hz, 2.5 db, Q Q4 020 Tweet PEQ 5850 Hz, +3 db, Q5 021 Tweet PEQ 5750 Hz, +2 db, Q4 022 Tweet PEQ 5700 Hz, +3 db, Q db, Q db, Q6 025 Tweet PEQ 9500 Hz, +3 db, Q db, Q db, Q db, Q2 029 Tweet PEQ Hz, -2 db, Q db, Q2 Tweet -6 db pad (subtracted 2) 031 Tweet -5 db pad (added 1) 032 Tweet PEQ Hz, +1 db, Q3 033 Woofer: Removed PEQ 600 Hz, -3 db, Q Woofer: Added 035 Woof PEQ 200 Hz, +1.5 Hz, Q Woof PEQ 75 Hz, -2 db, Q3 037 Woof PEQ 105 Hz, +1 db, Q Q3 039 Woof PEQ 90 Hz, +1 db, Q4 040 Woof PEQ 300 Hz, +1 db, Q Tweet -4 db pad 042 Final Test 043 Final Test 2 (added compression) 22

24 Final PEQ Settings minidsp (Left Speaker_v1) Woofer: 0 db Tweeter: - 4dB EQ1: 600 Hz, -3 db, Q1.2 EQ1: 2100 Hz, +3 db, Q3 EQ2: 200 Hz, +1.5 db, Q1.5 EQ2: 3600 Hz, -3 db, Q1.2 EQ3: 75 Hz, -2 db, Q3 EQ3: 5700 Hz, -3 db, Q1.2 EQ4: 105 Hz, +1 db, Q3 EQ4: 9500 Hz, -3 db, Q1.2 EQ5: 90 Hz, +1 db, Q4 EQ5: Hz,-1.5 db, Q2 EQ6: 300 Hz, +1 db, Q0.5 EQ6: Hz,+1 db, Q3 23

25 Right Speaker Initial Response Right speaker frequency response with crossover set at 1.5 khz and no tuning. 80 Sound Pressure Level (1/24 Octave Smoothing) Magnitude (db) k 10k Frequency (Hz) Right Speaker Woofer Only Right speaker frequency response with crossover set at 1.5 khz and no tuning, woofer only. 80 Sound Pressure Level (1/24 Octave Smoothing) Magnitude (db) k 10k Frequency (Hz) 24

26 Right Speaker Tweeter Only Right speaker frequency response with crossover set at 1.5 khz and no tuning, tweeter only. 80 Sound Pressure Level (1/24 Octave Smoothing) Magnitude (db) k 10k Frequency (Hz) Right Speaker Tuned Response Right speaker frequency response with crossover set at 1.5 khz, fully tuned. 80 Sound Pressure Level (1/24 Octave Smoothing) Magnitude (db) k 10k Frequency (Hz) 25

27 Right Speaker Tuning Documentation_v1 1.5 khz Test #: Note: _001 First test 002 Tweeter -3 db pad 003 Woof PEQ 600 Hz, -3 db, Q Tweeter Only 005 Woofer Only 006 Tweeter (0.06 time delay) 007 Tweeter (0.04 time delay) 008 Full response 009 Tweet PEQ 2200 Hz, +1.5 db, Q2 010 Tweet PEQ 2100 Hz, +1 db, Q db, Q db, Q Q Tweet PEQ 3600 Hz, +2.5 db, Q4 015 Tweet PEQ 5700 Hz, +3 db, Q db, Q6 017 Retest 018 Tweet PEQ 9200 Hz, +1.5 db, Q db, Q Woof PEQ 225 Hz, +2 db, Q Woof PEQ 78 Hz, -2 db, Q db, Q3 023 Woof PEQ 105 Hz, +1 db, Q3 024 Woof PEQ 88 Hz, +1 db, Q3 025 Woof PEQ 85 Hz, +1 db, Q2 026 Woof PEQ 235 Hz, +1 db, Q3 027 Retest 028 Tweet PEQ 2100 Hz, +1 db, Q2.5 à Q2 029 Tweet PEQ 2060 Hz, +0.5 db, Q2 030 Tweet PEQ 1500 Hz, +1 db, Q Misfire - Deleted 032 Tweet PEQ 5800 Hz, +4 db, Q db, Q db, Q Tweet PEQ 2550 Hz, -1 db, Q Q4 037 Bypassed 235 Hz 038 Bypassed 85 Hz 039 Woof PEQ 78 Hz, -1 à -0.5 Hz, Q3 040 Woof PEQ 1300 Hz, +1 db, Q db, Q Woof PEQ 1400 Hz, +2 db, Q db, Q db, Q1 26

28 Final PEQ Settings minidsp (Left Speaker_v1) Woofer: 0 db Tweeter: - 4dB EQ1: 600 Hz, -3 db, Q1.2 EQ1: 2100 Hz, +1.8 db, Q2 EQ2: 225 Hz, +2 db, Q0.5 EQ2: 3600 Hz, +2.5 db, Q4 EQ3: 78 Hz, -0.5 db, Q3 EQ3: 5800 Hz, +2 db, Q6 EQ4: 105 Hz, +1 db, Q3 EQ4: 9200 Hz, +1.8 db, Q2.5 EQ5: 1350 Hz, +1.5 db, Q1 EQ5: 2060 Hz, +0.5 db, Q2 EQ6: 235 Hz, +1 db, Q3 EQ6: 2550 Hz, -1 db, Q4 27

29 Initial Performance Review Crossover Adjustment After extensive testing and peer feedback, I was able to achieve a frequency response of +/-1 db, greatly exceeding my expectations. The vented port was working positively, and the layers of fiberglass inside each speaker helped improve harsh triangle edges that were showing up in the frequency response during tuning. These were now the most accurate reference monitors I ve ever owned, but they still needed further tweaking. For instance, it was determined that my initial crossover point put too much of an unnecessary load on my tweeter. 14 I decided to adjust this, and ended up raising my crossover points from 1.5 khz to 1.8 khz. Since this was the second time I would be tuning these speakers, I believed I could achieve an even flatter response compared to the first, and in less time. 14 Plummer, Christopher, Transducer Theory Testing. Michigan Technological University, April 26 th,

30 Final Tuning & Documentation Left Speaker Final Tuning_v2 1.8 khz) Test #: Note: _001 Loaded final 1.5 khz 002 Woofer & Tweeter 1.8 khz 003 Woofer & Tweeter 1.5 khz (repeated) 004 Changed Tweet EQ Hz, +2 db, Q3 à 1900 Hz, +1 db, Q db, Q HZ, +2 db, Q Q Q Tweet EQ Hz, +2.5 db, Q4 à 3800 Hz, +2.5 db, Q4 010 Tweet EQ 3700 Hz, +2.5 Hz, Q4 011 BYPASSED Woofer EQ 75 Hz, -2 db, Q3 012 Woof EQ 75 Hz, -2 db, Q3 à 75 Hz, -1 db, Q db, Q db, Q BYPASSED Tweeter EQ Hz, -1.5 db, Q db, Q3 017 Tweet EQ 3700 Hz, +2.5 db, Q4 Final PEQ Settings minidsp (Left Speaker_v2) Woofer: 0 db Tweeter: - 4dB EQ1: 600 Hz, -3 db, Q1.2 EQ1: 2000 Hz, +2 db, Q1.7 EQ2: 200 Hz, +1.5 db, Q1.5 EQ2: 3700 Hz, +2.5 db, Q4 EQ3: 75 Hz, -1.7 db, Q3 EQ3: 5700 Hz, +3 db, Q6 EQ4: 105 Hz, +1 db, Q3 EQ4: 9500 Hz, +1.5 db, Q2 EQ5: 90 Hz, +1 db, Q4 EQ5: Hz,-1.5 db, Q4 EQ6: 300 Hz, +1 db, Q0.5 EQ6: Hz,+1 db, Q3 29

31 Right Speaker Final Tuning_v2 1.8 khz) Test #: Note: _001 Untuned 1.8 khz 002 Tuned 1.8 khz (starting with 1.5 khz settings) 003 Tweeter +1 db pad (-3 db à -2 db) 004 Untuned 1.8 khz 005 Woof PEQ 650 Hz, -3 db, Q Woof PEQ 225 Hz, +2 db, Q Woof PEQ 260 Hz, +1 db, Q3 008 Woof PEQ 240 Hz, +1 db, Q4 009 Woof PEQ 77 Hz, -0.5 db, Q db, Q2 011 Woof PEQ 105 Hz, +1 db, Q2 012 Woof PEQ 100 Hz, +1 db, Q Woof PEQ 105 Hz, +1 db, Q2 014 Woof PEQ 1350 Hz, +1.5 db, Q1 015 Woof PEQ 1600 Hz, +1 db, Q1 016 Tweet PEQ 2100 Hz, +1.8 db, Q2 017 Tweet PEQ 2200 Hz, +1.8 db, Q4 018 Tweet PEQ 3700 Hz, +2.5 db, Q2 019 Tweet PEQ 3900 Hz, +2.5 db, Q4 020 Tweet PEQ 3800 Hz, +2 db, Q4 021 Tweet PEQ 6000 Hz, +1.5 db, Q db, Q4 023 Tweet PEQ 1000 Hz, +1.8 db, Q Tweeter -3 db pad (added 1) 025 Tweet PEQ 2800 Hz, +1 db, Q1 026 BYPASSED EQ Hz, +2 db, Q4 027 Tweet PEQ 3800 Hz, +2.5 db, Q7 028 Tweet PEQ 3750 Hz, +2.5 db, Q db, Q db, Q7 031 Tweet PEQ 2550 Hz, -1 db, Q db, Q db, Q db, Q Turned off low pass filter 036 Final test (low pass back on) Final PEQ Settings minidsp (Right Speaker_v2) Woofer: 0 db Tweeter: - 3dB EQ1: 650 Hz, -3 db, Q1.2 EQ1: 2200 Hz, +1.8 db, Q4 EQ2: 225 Hz, +2 db, Q0.5 EQ2: 3750 Hz, +2.5 db, Q7 EQ3: 77 Hz, -0.8 db, Q2 EQ3: 6000 Hz, +1.5 db, Q4 EQ4: 105 Hz, +1 db, Q2 EQ4: Hz,+1.8 db,q2.5 EQ5: 1600 Hz, +1 db, Q1 EQ5: 2800 Hz, +1 db, Q1 EQ6: 240 Hz, +1 db, Q4 EQ6: 2550 Hz, -0.6 db, Q10 30

32 Final Frequency Response Left Speaker: 100 Sound Pressure Level (1/24 Octave Smoothing) 90 Magnitude (db) k 10k Frequency (Hz) Right Speaker: 100 Sound Pressure Level (1/24 Octave Smoothing) 90 Magnitude (db) k 10k Frequency (Hz) 31

33 Integrated Frequency Response Harmonic Distortion 32

34 Minimum Phase Response Step Response 33

35 Impulse Response FFT Waterfall Full System 34

36 FFT Waterfall High Frequencies 15, 30, 45, 60 Degrees Off-Axis 35

37 Tweeter Frequency Response Tweeter Harmonic Distortion 36

38 Tweeter Minimum Phase Response Tweeter Step Response Tweeter Impulse Response 37

39 Woofer Frequency Response Woofer Harmonic Distortion 38

40 Woofer Minimum Phase Response Woofer Step Response Woofer Impulse Response 39

41 Final Specs Weight: Material: 40 lbs (per speaker) ½ Maple wood w/veneer core, ½ MDF Dimensions: 12 x 15 x 17 (W x D x H) Port Length: Finish: 4.5 (Outer & Inner Flare) Battleship/Military Gray Budget: $1000 Crossover: Frequency Response: Dampening Material: Power: Drivers: 1.8 khz +/- 1 db from 56 Hz to 18 khz Fiberglass PWR-ICE125 minidsp SB Acoustics SB26STAC 1 Textile Dome Tweeter SB Acoustics SB23NACS 8 Aluminum Cone Woofer 40

42 Bibliography AES Recommended Practice for Profession Audio. Standards and Information Documents, Print. Murphy, John L, Introduction to Loudspeaker Design. Andersonville: True Audio, Print. Katz, Bob, How To Make Better Recordings in the 21st Century - An Integrated Approach to Metering, Monitoring, and Leveling Practices. AES Journal, SB Acoustics S26STAC-C Textile Dome Tweeter. Madisound Speaker Store. Accessed February 5, SEAS Prestige 27TFFC 1 Textile Dome Tweeter. Madisound Speaker Store. Accessed February 5, Morel CAT Textile Dome Tweeter. Madisound Speaker Store. Accessed February 15, ScanSpeak Discovery R2605/ Textile Ring Radiator. Madisound Speaker Store. Accessed February 15, ScanSpeak Discovery R2606/ Textile Dome Tweeter. Madisound Speaker Store. Accessed February 15, textile-dome-tweeter/ SB Acoustics SB23NACS Aluminum Cone Woofer. Madisound Speaker Store. Accessed February 5, Peerless SLS Paper Cone Woofer. Madisound Speaker Store. Accessed February 5, Dayton Audio RS Reference Woofer. Parts Express. Accessed February 15, ScanSpeak 22W/8534G00 Discovery 8 Woofer. Madisound Speaker Store. Accessed February 15, ScanSpeak 26W/8534G 10 Aluminum Cone Woofer. Madisound Speaker Store. Accessed February 15, Plummer, Christopher, Transducer Theory Testing. Michigan Technological University, April 26 th,