Sandcastle 7.2 FA 4740: TRANSDUCER THEORY

Transcription

1 Sandcastle 7.2 FA 4740: TRANSDUCER THEORY Eric Bartos April 27, 2016

2 Table of Contents FUNCTIONAL DESCRIPTION 4 GOAL 4 LISTENING ENVIRONMENT 4 SIZE/PORTABILITY 4 LISTENING PURPOSE 5 VISUAL AESTHETICS 5 SPL OUTPUT 5 SUBJECTIVE DESCRIPTION OF SOUND QUALITY 5 DESIGN BALANCE 6 TECHNICAL GOALS & SPECIFICATIONS 7 VISUAL AESTHETICS 7 SIZE 7 SPL 8 USAGE OF STANDARDS 8 PERSONAL PREFERENCES 8 SENSITIVITY 9 FREQUENCY RESPONSE 9 OPTIMAL RESPONSE 9 BASS MANAGEMENT SYSTEMS 10 PERSONAL LF FREQUENCY RESPONSE 10 SHAPE & VOICING 11 COLORATION & TIME RESPONSE 12 RESONANCE 12 CABINET DESIGN & REFLECTIONS 12 CABINET MATERIALS & BRACING 14 MOUNTING 14 DISPERSION 15 DRIVER SELECTION 16 TWEETERS 16 TWEETER #1: SCAN- SPEAK DISCOVERY D2606/ TWEETER #2: SEAS PRESTIGE 19TFF1 18 TWEETER #3: VIFA/PEERLESS XT25SC TWEETER #4: DAYTON AUDIO DC28F MIDRANGE 21 MOREL MDM 55 SOFT DOME MIDRANGE 22 HI- VI DMB- A FABRIC DOME MIDRANGE 23 DAYTON AUDIO CLASSIC DC50FA- 8 DOME MIDRANGE 24 DAYTON AUDIO RS52AN- 8 2 DOME MIDRANGE 25 WOOFERS 26 WOOFER #1: SB ACOUSTICS SB17NRXC

3 WOOFER #2: DAYTON AUDIO RS WOOFER #3: SCANSPEAK 15W/8530K- 00 REVELATOR WOOFER 29 WOOFER #4: DAYTON AUDIO RS SUBWOOFERS 31 SUBWOOFER #1: DAYTON AUDIO RSS265HF SUBWOOFER #2: EMINENCE LAB 12C SUBWOOFER #3: PEERLESS XXLS 34 SUBWOOFER #4: DAYTON AUDIO UM12-22 ULTIMAX DVC 35 CROSSOVERS 36 STARTING POINT 36 CENTER SPEAKER CROSSOVER 38 BAFFLE STEP ERROR! BOOKMARK NOT DEFINED. CROSSOVER DIAGRAMS 40 BIBLIOGRAPHY 44 3

4 Functional Description Goal Being an avid movie watcher I would like to build a very nice set of surround sound speakers, I have yet to do enough research to determine what configuration, either 5.1 or 7.1 is the best for home theater use. Since these speakers will be used mostly for listening to music and movies I would like to design the speakers and system to follow the THX Home or Cinema audio standard to allow listening backwards 1 for reproducing the movie soundtrack as accurately as possible. Listening Environment The plan for my speakers are to be used in a home theater. My current room is a large living room, measuring about 20 x40. Ideally the room would be properly isolated from the outside world, but this is rather impractical. Now this being said, the bit of background noise in my listening environment should not cause major issues to the way the system sounds. There are no constant noises that will have to be dealt with, just the occasional car and other noises from living in an apartment building. One thing that must be considered is the size of future rooms for this system. Also there is no guarantee that I will ever have the proper space to setup the system in a true surround configuration. Until I will be able to have a dedicated room for a theater the speakers will need to be able to be positioned in the best possible spot to offer the full surround sound experience. Because of this the speakers will need to be very versatile for the room, meaning good off- axis response may be required. One final consideration is the form factor of the speakers. My first thought is to a larger bookshelf style for the surround speakers and a landscape center speaker, however this may change based on further research and budget analysis. Size/portability Overall I am not very worried about the size and portability of the speakers since once they are setup they will always be in the same place. The only reason the speakers will ever need to move is when I move from one house or apartment to another, and I don t plan on that happening so many times that I should worry about making them small or portable. I am planning on making the speakers as large or as small as they need to be to fit within my specifications determined later in this paper. 1 David Moulton, Total Recording (Sherman Oaks, CA: KIQ Productions, Inc. 2000). 4

5 Listening Purpose I intend on using these speakers mostly for playing back movies and music, there may be a rare occasion that I would use the system to check a mix, but never to actually mix on. Therefore, my goal for the design is to have a high enjoyment system that will be able to reproduce movies at the THX reference level. Visual Aesthetics As far as the visual aesthetics go, I am not majorly concerned about the way the speakers will look. The visual aesthetics will take a back seat to the sound of the system. However, I have always enjoyed the look of professional cinema speakers, very minimal design with a satin black finish. Since I prefer speakers without grills or covers I will not be putting any kind of covering on the front of the speakers, since I am not worried about them getting damaged from sitting in one place in my apartment. SPL Output The SPL output of my speakers at the very minimum will meet the standards for film sound reproduction, the THX reference level. In addition, I would like the option to be able to really crank up the system to be able to listen to my favorite music at the magical dB 2. Subjective Description of sound quality I would like to fit into the following subjective sound quality standards. First I would like my speakers to have excellent frequency extension. This falls into the idea of designing something with cinema sound in mind. I would like to be able to reproduce every bit of the sound in a film in order to achieve the full immersive experience of surround sound. Second I would like to have the best ambiance reproduction possible, since that is the main idea behind a surround sound system. I would like to actually be able to hear everything that is going on in the background of a film soundtrack, not just the music and actors like you would hear when listening to a film on TV speakers or inexpensive home theater in a box systems. Finally I would like to focus on being able to reproduce dynamics properly. This would be my least important quality to focus on, however I am not saying that it is not important since all movies have many large dynamic changes. I would like to be able to design a speaker that will be able to run at a reference level with plenty of head room for changes in dynamics. 3 2 Richard Newell and Keith Holland, Loudspeakers for Music Recording and Reproduction. 1 st Edition (Oxford: Focal Press, 2007). 3 AES Standards and Practices (New York: Audio Engineering Society, Inc. 1996). 5

6 Design Balance DESIGN BALANCE CHART Size 25% SPL 37% Low Frequency 38% Figure 1. Design Balance Chart 6

7 Technical Goals & Specifications Visual Aesthetics For the design of my speaker system, as stated above in my functional description I would like them to look similar to professional cinema speakers. Even though black is a very standard color when it comes to cinema, or any pro audio speakers I plan on finishing the speaker in a very dark purple textured coating, similar to truck bed liner. In figure 2 a & b are some examples of how I would like my finalized design to look. Figure 2 b. Is very close to the style I would like to go for. I will discuss my cabinet design choices later on in this section. Note that in both of the designs below, a horn is used for the tweeter. This is due to the average distance of the audience from the speakers in a standard cinema. Because I will be listening relatively closely to my speakers the use of a horn is not necessary. Figure 2 a. Meyer Acheron 80 Figure 2 b. Alcons Audio CRMSC- SR Size Due to my chart (figure 1) in my functional description, the size of my speakers is not a very big problem for me. Ideally the will be on stands or have flying hardware to allow for maximum positioning flexibility. If I were to make my speakers floor standing, the would work in my current room layout, but there is no guarantee that they would work in other room layouts in the future. Ideally the 4 matching side, rear surround, speakers shall be no larger than 24 x24 x18 This will allow adequate bass response and allow for stand mounting. Ideally the front pair will be matching, for a grand total of 6 matching speakers, however if they are not matching the front pair shall be no bigger than 24x30x20. The center speakers shall be no bigger than 31 x31 x20 allowing for a possible larger driver, MTM layout, and table top or TV 7

8 stand mounting options. The surround, front and center speakers will be reflex or ported style boxes. The subwoofer shall be no bigger than 31 x36 x20, this would allow for several options as follows: Space for multiple large drivers for adequate LF response Mounting of the front Left and Right speakers on top of the subwoofer for a complete system look, if I were to build 2 of the subwoofer units. Additionally, the subwoofer(s) shall be designed as a reflex box allowing for a more practical low frequency roll off. Personally I am comfortable lifting between 50 and 75 pounds, I would like to keep my speakers within this range if at all possible. However, if this will not allow me to achieve the goals for the speakers I will not allow the weight to be a limiting factor. Along with weight and size comes portability. I am not at all concerned about portability due to the fact that the only time that the speakers will move is when I am moving homes, at this time the speakers will be packaged correctly for moving. Therefore, I am not worried about the overall portability of my speaker system. However, even with this consideration I would like the exterior of my speakers to be a robust material to prevent any kinds of damage to the cabinet itself in normal use. SPL Usage of standards In my speaker system I would like to focus on surround sound movie listening, thus I shall be following the THX standards that are publicly available to the best of my abilities. Without the full documentation of the THX standards, some assumptions will have to be made, however these assumptions do not concern the SPL. From my research I have been able to find that the basic THX SPL standard reference level is 85dB SPL with 20 db of headroom 4 for the surround and front speakers, thus following the K20 headroom specifications, but with a slight boost in output for a max peak of 105dB. The THX specifications for the LFE channel are the standard reference level of 85dB SPL with 30dB of headroom for a max peak of 115dB. 5 Personal Preferences Below, in figure 3 I have laid out the average listening level for me. In order to define these values, I measured them for 3 days at approximately the same time to get the average level for that particular time of day and type of music. For the levels of movies, I watched several movies and jumped around to different parts of the movies with different dynamics to come up with my average of 75.8 db SPL. 4 THX. THX Reference Level technology/thx- reference- level/ (accessed January 17, 2014). 5 Tomlinson Holman Surround Sound: Up And Running. 2nd Edition. Burlington: Focal Press,

9 Morning Afternoon Evening Jamming out Movie Max Level Figure 3: Measured average personal SPL Levels Sensitivity Due to my SPL needs and the amount of headroom needed to achieve the THX reference level specifications I need to look at drivers with a minimum sensitivity of 85dB if I am to pair the speakers with a 100 watt amplifier. With a 100 watt amplifier and a driver sensitivity of 85dB at 1 meter the 20 db of headroom, for both the K20 standard and the THX reference level will be met. I would like to drive my speakers with a watt amplifier, however if that is not available I will use what I have on hand, that being 200 watts. It is also important for me to keep in mind that if I am to use a more powerful amplifier the sensitivity of my speakers does not need to be as high due to the higher dbw output of the amplifier. In order to understand the relationship between the sensitivity and amplifier power figure 4 shows the dbw chart, the area that has been boxed in is between 100 and 200 watts, my target power amplifier range. 6 Figure 4. dbw chart Frequency Response Optimal Response In film monitoring and playback frequency response is very important. The speakers must be able to reproduce a very wide range of dynamics and a even wider frequency range. To do this my speakers shall end up having a frequency response of at least 45Hz, but hopefully lower up to 22kHz for the surrounds and at least 20 to 250Hz for the subwoofer(s). However, 6 Christopher Plummer, discussion on dbw and logarithmic equations, (January 21, 2015) 9

10 this is a range that will most likely be limited by price and size. To further understand my reasoning for at least 45Hz in the surrounds we must take a look at bass management systems. 7 Bass management Systems In most home theater surround sound systems, a system called bass management is in effect at all times. Bass management systems take the mid bass out of the surround speakers, routing it as a summed signal to the LFE or subwoofer channel in addition to the standard LFE signals. This system is assuming the surround speakers cannot reproduce sounds below 40-80Hz, because of this not all of the low rumble that was intended in the mix would be produced. To combat this, a bass management system is added. 8 If at all possible I would like to avoid using a bass management system in order to have the clearest and most accurate reproduction of the film soundtrack. To accurately achieve this goal, the woofers and cabinets of my surround speakers will need to be able to reproduce sounds below 50Hz, however this may become impractical for size and price. If it is not possible to avoid using a bass management system the surround speakers will be designed to produce at the vary least 45Hz unless cost prohibits. Personal LF Frequency response To further document the desired frequency response of my speakers, I ran some experiments to determine what I felt was noticeable roll off, acceptable roll off and unacceptable roll off. To do this I took some music samples and played them back on a system that was virtually flat to 20Hz and applied a filter emulating the roll off of a sealed and ported box, 6dB/octave and 18dB/octave respectively. Below in figure 5 are the results of my testing. 7 Tomlinson Holman Surround Sound: Up And Running. 2nd Edition. Burlington: Focal Press. 8 Tomlinson Holman Surround Sound: Up And Running. 2nd Edition. Burlington: Focal Press,

11 LF Roll Off Roll off freqency (Hz) Rock Bass Heavy Bluegrass Indie Rock Electronic Piano Figure 5. LF roll off frequencies for different genres of music. As shown in the chart above, it is clear that there is an average frequency that I will start to notice the roll off effect, that frequency being 52.8Hz for 6dB/octave roll off and 48Hz for 18dB/octave roll off. We can also look at the average acceptable roll off frequency of 75.4Hz for 6dB/octave and 65.8Hz for 18db/octave, even though this is an acceptable roll off, it is important to me that my speakers are designed with more than just my acceptable values in mind. Even with the noticeable roll off values, it really was noticeable after listening at that roll off for a while and then removing the filter. For these reasons I would like to design my system as a whole to be able to operate well below my noticeable roll off. Shape & Voicing Noticable 6dB Acceptable 6dB Unacceptable 6dB Noticable 18dB Acceptable 18dB Unacceptable 18dB For reproducing movie audio as clearly and as accurately as possible, I would like to build my speakers with as flat of a frequency response as possible, ideally with ±3dB across the enter frequency range 9. I would like to design the system to have a balanced response throughout the frequency spectrum before applying any film standards to the system, such as the extra boost in the LFE channel and the differences between the center, and front left and right surround sound speakers Tomlinson Holman Surround Sound: Up And Running. 2nd Edition. Burlington: Focal Press, Ibid.,

12 Coloration & Time response Resonance As far as resonance goes in a theater surround system there really isn t much to speak of, the speakers are designed for the least amount of resonance possible. With this there is hardly any coloration of the sound coming from the box. However, this is rather impractical because to do this the enclosure would be prohibitively expensive, therefore I will have to get as close as I can by using a combination of the cabinet design and the bracing to mitigate as much of the cabinet resonance as possible. I would like for my speakers to not have a very live sound, but not be so dead that the natural sounds in the films (or music) that I will be listening to are changed. I will also be planning on designing my cabinets for an extended LF response and this will need to be taken into consideration when designing the internal structure of the cabinet. Cabinet Design & Reflections When looking at cabinet designs there are many factors to take into consideration, however in this section I will focus on the reflections on all parts of the cabinet. Before moving on with the design of the cabinet reflections from all surfaces must be taken into account. Lets first look at edge reflections, if there are edge reflections on a speaker, they act essentially as a smaller transducer radiating from the corners or sides of the enclosure. 11 In order to help with this it is essential the the cabinet is not a perfect cube design. While a round exterior provides the best edge reflection mitigation, it is not very practical to design a round speaker since I don t really want my speakers to roll off of the stand. Along with it being very impractical, a round enclosure provides the worst internal reflections, thus causing a standing wave. To better understand how the external cabinet shape effects the edge reflections figure 6 shows how different cabinet designs change the reflections and driver responses. 11 Richard Newell, and Keith Holland, Loudspeakers for Music Recording and Reproduction. 1 st Edition (Oxford: Focal Press, 2007). 12

13 Figure 6. Effects of cabinet shapes on driver responses 12 In figure 6 it is clear that there are some compromises on cabinet shape in order to achieve the best frequency response from your drivers. I have hi- lighted L in the diagram above, this is the design I will be going for when I build my cabinets, looking back at figure 2 b, this design has been implemented in other types of surround speakers. One final resonance to be aware of is port resonance. Since I will be going for a ported box, it is important that I minimize the air noise from the port. In order to do this, the port on the surrounds will have to be a flared port, not only will this help with the reduction of resonance but it will also help remove the noise associated with ported enclosures at lower frequencies. On the subwoofer I will be using multiple ports, one in each of the 4 corners to help eliminate this problem. Driver mounting will also play a roll in how the external reflections work, one key to this is to flush mount my tweeter, thus removing any edge reflections from the difference in height of the tweeter and the rest of the cabinet. Mounting drivers off center can also help in reducing diffraction, however due to the design choice of my box, it will not work very well to mount the driver off center, therefore I will keep the drivers centered on the face of the box, keeping in mind that if there is a problem with this before the design is complete that I could always move the position of the driver. 12 Richard Newell, and Keith Holland, Loudspeakers for Music Recording and Reproduction. 1 st Edition (Oxford: Focal Press, 2007). 13

14 Cabinet Materials & Bracing The cabinet for the surround and center speakers will be built out of 1/2 inch Baltic Birch plywood with an 1/2 inch MDF interior. This will provide a good combination of rigidity and dampening. The cabinet will be braced from front to back on either side of the front baffle to provide more structural strength. I will also run 1 strips in each corner to help additionally seal the box and help keep everything square during construction. This bracing will help with not only the rigidity and structure of the cabinet, but also help with the dampening and allow for minimized internal reflections. 13 The subwoofer cabinet will be built out of 1/2 inch Baltic birch plywood, just as the surrounds, however the interior will be 3/4 inch MDF. This will help provide more structural integrity and better dampening at the high levels the subwoofer will be running at. Mounting Mounting of the speakers is critical to the performance of the speakers, In order to achieve the best performance and remove as much vibrations as possible the system must be mechanically grounded. To do this, a stand with a ridged pole needs to be used, along with spikes to help the stands transfer mechanical energy away from the speakers. 14 Keeping in mind my ideal final environment the speakers will all be hung around the sides of a home theater. Because of this I will be installing flying rails on each of the surround speakers. These rails will allow for the best versatility when it comes to being able to fly the speakers. Most of the speakers in my system, save for the center and subwoofers will be mounted on stands. Mounting the speakers on stands will allow for the most flexibility and most practical mechanical grounding. The subwoofer will need spiked feet in order to prevent a floating situation, and to help mechanically ground them as well. The most challenging speakers will be the front Left and Right speakers, I would like the flexibility to mount them on stands, however being that my next install environment may differ from my current environment using stands may not be practical. If it is not possible to use stands for the front speakers, I would like to build 2 subwoofers with mounting attachments for the front left and right speakers. These attachments would not need to hold the weight of the speaker, but allow for proper mechanical grounding of the system. The final challenge will be the center speaker. If it is just set on top of my TV stand there may be a chance that it slides around on the wood surface. In order to combat this effect the speaker will need feet made of a hard plastic with some grip in order to allow the vibrations to transfer into the TV stand and then into the ground, rather than just allowing the speaker to vibrate. 13 George Short, North Creek Cabinet Handbook, (Old Forge: North Creek Music Systems, 1992), Ibid, 4. 14

15 Dispersion Dispersion in theater surround speakers is tricky, there is a fine balance between getting the best spatial balance and the best coverage. However, in my situation I am not concerned about covering a cinema with hundreds of seats, all I am looking to do is cover my living room seating. In order to have the best spatial balance, the speakers will need to have a dispersion that is not too wide, but not too narrow. If the dispersion pattern is too narrow, the image will not blend well, thus creating a non- immersive surround sound experience. On the other hand, if the dispersion is too wide, the image will become blurred and more room effects will be apparent. The ideal dispersion for surround sound monitors is ±15 and ±30 horizontally and ±15 vertically Tomlinson Holman Surround Sound: Up And Running. 2nd Edition. Burlington: Focal Press,

16 Driver Selection Tweeters For selecting tweeters, I was looking for the following: +/- 5 db max from at least 1kHz to above 20Khz ability to go over 20kHz medium to wide coverage price between $20- $50 After looking at a total of 12 tweeters, I have narrowed it down to 4 that could possibly be used. I have to also keep in mind that I will need 7 tweeters, one for each of my surround speakers. Figure 7 shows the a list of the four tweeters I looked at in detail with the chosen tweeter in orange. Breakup Sensitivity Price Scanspeak Discovery 20kHz 91.4dB $34.10 D2606/9200 Seas Prestige 19TFF1 21kHz 88dB $31.60 Vifa/Peerless 20kHz 90.1dB $21.90 XT25SC90-04 Dayton Audio DC28F- 8 20kHz 89dB Figure 7. Chart of the 4 tweeters looked at in depth and the chosen one in orange. Breakup Sensitivity Price Audex TW025A0 19kHz 90dB $30.00 Seas Prestige 25TFFN 20kHz 89dB $42.70 Fountek NeoCD1.0 Above 25kHz 90dB $45.00 Ribbon Tweeter Tymphany 20kHz 85.2dB $38.39 XT19TD00-04 Tymphany BC25SG kHz Figure 7.1. Showing possible tweeters not looked at in depth 16

17 Tweeter #1: Scan- speak Discovery D2606/ Specifications 1 Textile Dome tweeter $34.10 (madisound) 200 watt long- term max power Sensitivity 91.4dB 100 watt 100 hour RMS noise test Breakup starts at 20kHz Fs at 1.100kHz This scan speak tweeter looks like a nice tweeter for the money, It has a decently flat response from approximately 1kHz to 22kHz, with very little smoothing on the chart. With such high power handling, this tweeter would fit well into my planned bi- amped system. The one area I feel that this tweeter is lacking is how low it will go, while some of my woofer drivers will work efficiently at that high of a frequency, I would like to see something just slightly below 1kHz to leave some room to play with the crossovers. However, this tweeter, like most of the tweeters I have looked at have a built in roll off in them, this makes for easy crossover tuning. Overall this is a solid driver and its price point makes it even higher on the scale since I will require 7 tweeters total. 16 Scan speak Discovery D2606/9200 Soft dome tweeter. Accessed January 30, soft- dome- tweeters/scanspeak- discovery- d2606/ textile- dome- tweeter/ 17

18 Tweeter #2: Seas Prestige 19TFF1 17 Specifications 3/4 Textile Dome tweeter $31.60 Madisound Sensitivity 88dB Short term power handling 220 Watts Long term power handling 90 watts Breakup starts at 21kHz Fs 1.7kHz The Seas Prestige 19TFF1 is a great tweeter for the money, it has a high break up frequency, decent power handling and is relativity flat, with little noticeable smoothing on the chart. However, the only drawback as with the scan- speak tweeter is the low end cutoff. This tweeter starts a roll off at 2kHz, this means my woofer will need to be able to efficiently reproduce up to about 2kHz to be able to properly crossover. There is one benefit to the roll off on this tweeter is the fact that it will take much less work to get the crossover to sound right since the tweeter is already rolling off at what looks to be about 6dB/octave. Overall a decent tweeter, that fits in my price range and will do what I need it to do with only minor drawbacks. 17 Seas Prestige 19TFF1 Soft dome tweeter. Accessed January 30, soft- dome- tweeters/seas- prestige- 19tff1- h0737-3/4- textile- dome- tweeter/ 18

19 Tweeter #3: Vifa/Peerless XT25SC Specifications 1 Ring Radiator Tweeter $21.90 (madisound) Sensitivity 90.1dB Rated Power 100 Watts Breakup starts around 20kHz Fs 825 Hz Vifa and peerless are both under the Typhany name, however this is a rather nice looking driver considering the way some of the other tweeters in the peerless line look on paper. This tweeter makes a good compromise between price and frequency response. I am not sure how well I the small bump at about 4.5kHz would behave when tuning the box, while it is only a +2 db peak, it is still a strange peak due to the associated impedance fluctuation. 18 Vifa/Peerless XT25SC90-04 Soft dome tweeter. Accessed February 2, radiator- tweeters/vifa- xt25sc ring- radiator- tweeter/ 19

20 Tweeter #4: Dayton Audio DC28F Specifications 1-1/8 Soft Dome Tweeter $19.75 (Parts- Express) Sensitivity 89dB Rated Power 50 Watts Breakup hard to tell based on response chart Fs 834 Hz Looking at the very low end of the price range is the Dayton audio DC28F- 8. I figured it would be nice to take a look at this range of tweeters, however I am not impressed. With the data given, it is very hard to tell what the breakup frequency is and what exactly is going on up there past 20kHz. Since I would like to go slightly above 20kHz this is a deal breaker for me. Overall it could be a good tweeter choice if better data was given. 19 DC28F /8 Dayton Audio Soft Dome Tweeter. Accessed February 1, express.com/dayton- audio- dc28f silk- dome- tweeter

21 Midrange Due to the design of my center channel speaker the use of a mid driver will be necessary, due to the already large size of my cabinet I would like to use a dome midrange driver. I could not find very many options, therefore in order to expand my possible drivers I did look at both dome and standard midrange drivers in the 2-3 inch range. The following specifications were required: Sensitivity either matching or close to my woofer selection +/- 3dB between $30 and $90 capable of operating beyond 2.5kHz minimum power handling of 50 watts Below is a table of the top 4 contenders for this driver that I was willing to look at in depth. Breakup start Fs Sensitivity Price Morel MDM 55 5kHz 380Hz 89.5dB $86.90 Hi- Vi DMB- A 6kHz 700Hz 93dB $24.50 Dayton Audio Classic 5kHz 371Hz 89dB $46.40 DC50FA- 8 Dayton Audio RS52AN kHz 341Hz 89.4dB $40.78 Figure 8. Midrange Drivers looked at in depth, the chosen driver is in orange Figure 8.1 Midrange drivers looked at but not considered 21

22 Morel MDM 55 Soft Dome Midrange 20 Specifications: 2.1 soft dome midrange driver Nominal power handeling 200 watts Sensitivity 89.5 Breakup starts at 5kHz This driver is slightly above my price range, however I wanted to take a look at it anyway because it is a dome driver with its own enclosure and that is exactly what I am looking for. This driver is a +/- about 4 db across the whole range, but only about +/- 2dB in the range that I am looking to use it in. It also has a surprisingly high power handling and the sensitivity is even a little higher than my woofer. Overall a solid choice, but slightly past my price range. If nothing else beats this I would 100% go with it. 20 Morel MDM 55 Soft Dome Midrange. Accessed March 1, midrange/morel- mdm55-2- textile- dome- midrange/ 22

23 Hi- Vi DMB- A Fabric Dome Midrange 21 Specifications 2 Fabric dome midrange driver power handling 60 watts sensitivity 93dB Breakup starts at 6kHz I am not really sure on the quality of Hi- Vi drivers, however I have some hope for this driver. The response graph looks okay, until I noticed that the scale was 10dB per devision. That means this driver is over my +/- 3dB requirement even though it is a dome midrange. My goal of adding a mid driver it to make the response flatter, not more colored. If this were flatter it would be a perfect driver, within my price range and a very high sensitivity, but its just not going to cut it. 21 Hi- Vi DMB- A Fabric Dome Midrange. Accessed March 1, midrange/hi- vi- dmb- a- 2- fabric- dome- midrange/ 23

24 Dayton Audio Classic DC50FA- 8 dome Midrange 22 Specifications: 2 soft dome midrange power handling: 80 watts Max power 160 watts Sensitivity 89dB Breakup start at 5kHz Fs 371Hz This driver is so close to what I am looking for but didn t quite make the cut. The price on this driver is amazing at $46.40, and for that price it looks really great on paper. The one major drawback to this midrange driver is that it is just not quite flat enough for the situation at +/- 6dB at its peak. The sensitivity is high enough to match my woofers and it would not be terribly difficult to crossover, however I would like something that could go just a little bit higher in frequency and be a little bit flatter. 22 DC50FA- 8 Dayton Audio Classic Midrange 8 Ohm. Accessed March 1, express.com/dayton- audio- dc50fa- 8- classic- series- 2- dome- midrange

25 Dayton Audio RS52AN- 8 2 Dome Midrange 23 Spcifications: 2 Aluminum dome midrange power handling 60 watts peak 120 watts sensitivity 89.4dB breakup starts at about 11kHz Fs 341Hz This driver right here is it. Coming in at $40.78 (on sale) it is 100% in my price range, and with that it looks great. This version of the Dayton dome mid cant handel qquite as much power, but it has a lower Fs and is much flatter in the higher frequencies. This driver will be perfect for crossing over at higher frequencies and will allow me to run just a little bit lower than the classic series. Overall for the price there is no beating this driver. 23 RRS52AN- 8 Dayton Audio Reference Midrange 8 Ohm. Accessed March 1, express.com/dayton- audio- rs52an dome- midrange

26 Woofers For selecting woofers, I used the following as my baseline. Woofers should be Between 5 and 8 inches +/- 5dB from 100Hz Up to at least 1kHz Be able to achieve an F3 below at or below 55Hz Between $30- $60 Be able to handle at least 60 watts For my testing in WinSpeakerz I was not trying to keep the box sizes similar since I have a very large box size limit. Instead, I was looking to get the best F3 out of the driver and box combination. For my price point I have to keep in mind that I need at least 7 of these drivers, one for earch of my surround sound speakers. All woofers have been tested in a ported box, and the best F3 has been chosen below. F3 Sensitivity Size Price SB Acoustics 44Hz 89dB 6.5 $57.85 SB17NRXC35-8 Dayton audio 30Hz 86.8dB 8 $53.00 RS225-8 ScanSpeak 72Hz 85.5dB 5 $ W/8530K- 00 Dayton Audio RS Hz 88.7dB 6 $35.00 (on sale) Figure 9. Woofer comparison, chosen woofer in orange. Fs Sensitivity Size Price Seas Prestige 36Hz 88dB 6.5 $89.50 L18RNX/P Fountek FW Hz 88dB 8 $60.45 Zaph Audio 65Hz 87dB 8 $39.95 ZA14W08 Dayton Audio 52.5Hz 86.6dB 5 $24.57 DS135-8 Peerless HDS- P $87.05 Figure 9.1. Showing possible tweeters not looked at in depth 26

27 Woofer #1: SB Acoustics SB17NRXC Specifications 6.5 coated Papyrus fiber cone $57.85 (madisound) +/- 4dB between 100Hz and 4kHz Breakup starts at 4kHz Sensitivity 89dB Power handling 60 watts Fs 32Hz Following the same idea for my tweeters, I have been looking at woofers under $100 each, this woofer falls within that price range at $57. It also falls within my desired frequency range for my surround boxes, however it is on the upper end of that range. For the rest of the tests on my speakers I will be adjusting the Q(tc) to achieve the best F3 frequency, taking note that the box must be under 5 cubic feet to fit within my desired size. This woofer fits my box requirements just fine coming in at a box volume of cubic ft with an F3 of ~44Hz. 24 SB Acoustics SB17NRXC35-8. Accessed February 4, acoustics- woofers- 6-7/sb- acoustics- sb17nrxc woofer/ 27

28 Woofer #2: Dayton audio RS Specifications 8 aluminum cone $53.00 (parts- express) +/- 5dB between 100Hz and 2kHz Breakup starts at 3kHz Sensitivity 86.8dB Power handling 80 watts Fs 28.3Hz This woofer is a really great option, and fits within my range for price, response, and box size. With a slightly lower F3 than the SB acoustics driver above at ~30Hz and a lower price tag I am highly considering this driver for my system. The only drawback with this driver is the high excursion at the 80 watts the driver is rated for. When I bump the power up in winspeakerz to the power of my amplifier it is past the exertion limit, however that is happening at 107dB, just slightly above the headroom that I am shooting for. However, if I need that little bit of extra headroom, I could always reduce my F3 slightly. 25 RS Dayton Audio Reference Woofer 8 Ohm. Accessed February 1, express.com/dayton- audio- rs reference- woofer

29 Woofer #3: ScanSpeak 15W/8530K- 00 Revelator Woofer 26 Specifications 5 paper cone $ (madisound) +/- 3dB between 100Hz and 2kHz Breakup starts at 4kHz Sensitivity 85.5dB Power handling 60 watts Fs 30Hz Looking on the higher end of drivers and the smaller side of drivers I chose to take a look at this scanspeak 5 driver to see if a smaller driver would fit my requirements. Honestly this is not bad for such a small driver with an F3 of 72Hz. However, this is at a rather low power level and would not be able to handle more power before passing the excursion limit. I was really surprised with this driver, if I was not limited by price I would highly consider using this driver. 26 ScanSpeak 15W/8530K- 00 Revelator Woofer. Accessed February 5, woofers/scanspeak- 15w/8530k revelator- woofer- low- qts/ 29

30 Woofer #4: Dayton Audio RS Specifications 6 aluminum cone $35.00 (parts- express on sale) +/- 5dB between 100Hz and 4kHz Breakup starts at 5kHz Sensitivity 88.7dB Power handling 40 watts Fs 47.8Hz I chose to take a look at the smaller Dayton audio reference driver just to compare the two. This driver really fits what I am looking for everywhere except for in the winspeakerz model. I had a terribly difficult time getting any kind of decent responses out of this driver. The main cultrate really is the extremely reduced Xmax and the lower power handling. This driver can only handle 40 watts, that is a lot lower than the 8 version of this same driver, and even at 40 watts I was unable to get anything lower than ~80Hz for my F3 value. To me this is rather disappointing considering that it is the same driver, just a little smaller. 27 RS Dayton Audio Reference Woofer 8 Ohm. Accessed February 7, express.com/dayton- audio- rs reference- woofer

31 Subwoofers For subwoofers I was using the following to help pick a suitable driver: Between 10 and 15 Between $100- $200 Power handling of at least 350 watts, 500 and up preferred +/- 5dB from 100Hz up to at least 400Hz F3 of at least 35Hz The most important thing I looked at when picking out subwoofer drivers was the ability to handle the frequency response and headroom I require, along with the ability to handle quite a bit of power. Ideally I would like to have 2 subwoofer boxes, one for left and one for right. Below is a chart showing a quick overview of the four drivers I looked at with the chosen subwoofer in orange. F3 Sensitivity Size Price Dayton Audio 19Hz 84.2dB 10 $ RSS265HF- 8 Eminence Lab 25Hz 88.9dB 12 $ C Peerless Hz $ XXLS Dayton Audio UM12-22 Ultimax DVC 18Hz $ Figure 10: Subwoofer selection chart. Chosen woofer in orange. Fs Sensitivity Size Price Dayton Audio 15.5Hz 91.2dB 15 Not Available ST385-8 Tang Band WT- 25Hz 85dB 10 $ G Dayton Audio 19.5Hz 91.2dB 15 $ RSS390HF- 4 Dayton Audio 26.2Hz 87.8dB 10 $39.56 SD270A- 88 DVC Tang Band WQ Hz 85dB 12 $ Figure Showing possible tweeters not looked at in depth 31

32 Subwoofer #1: Dayton Audio RSS265HF Specifications 10 aluminum cone $ (parts- express) +/- 5dB between 50Hz and 5kHz Breakup starts at 2kHz Sensitivity 84.2dB Power handling 350 watts Fs 24.9Hz This sub woofer is actually really impressive for a little 10, I didn t think it would be possible to get an F3 at ~20Hz. However, at that point the woofer will be almost at its excursion limit meaning it would have to have a high pass filter on it to stop that from happening. Overall this woofer really fits within all of the rages I have set, even with a bit of a large box this driver will get really put out on the low end even at 110dB SPL. 28 Dayton AudioRSS265HF subwoofer driver. Accessed February 10, express.com/dayton- audio- rss265hf reference- hf- subwoofer- 8- ohm

33 Subwoofer #2: Eminence Lab 12C 29 Specifications 12 Kevlar- reinforced paper cone $ (parts- express) +/- 5dB between 100Hz and 500Hz Breakup starts at 600Hz Sensitivity 88.9dB Power handling 100 watts Fs 22.85Hz This was one of the first woofers I looked at and was actually impressed with. While this woofer might not get as low as the Dayton audio 10, I really do like the power handling and size of this woofer. The F3 calculated in WinSpeakerz is ~25Hz. Even only powered at 500 watts, the power of the amplifier that I have for my subwoofer the max db SPL is 116 db SPL. That is plenty of headroom for anything that I would ever be doing. The only worry I have is if the speaker was to be powered at the full 1000 watts there would be some excursion issues. However, since I am not going to be powering it at full power there is no need for me to worry about this. Overall I am highly considering this subwoofer. 29 Eminence Lab 12C 12 Subwoofer Driver. Accessed February 5, express.com/eminence- lab- 12c- high- power- 12- subwoofer- speaker- driver- 4- ohm

34 Subwoofer #3: Peerless XXLS 30 Specifications 12 Aluminum cone $ (parts- express) +/- 3dB between 100Hz and 800Hz Breakup starts at 2kHz Sensitivity 86.4dB Power handling 350 watts Fs 19.4Hz Taking a look on the more expensive side of things, this peerless driver is a driver that almost fits my requirements for a subwoofer. The F3 of 24Hz is comparable to the Eminence driver, however the power handling is nowhere close. Even with the lack of power handling the max SPL output is 110dB SPL. Overall, other than the price of this driver it is a strong contender in my selection because it fits within the range of all other requirements for a subwoofer. 30 Peerless XXLS subwoofer driver. Accessed February 12, express.com/peerless aluminum- cone- xxls- subwoofer

35 Subwoofer #4: Dayton Audio UM12-22 Ultimax DVC 31 Specifications 12 Nomex / Glass Fiber cone $ (parts- express) +/- 3dB between 50Hz and 800Hz Breakup starts at 2kHz Sensitivity 86.7dB Power handling 600 watts Fs 26.2Hz Dual voice coil This was a very strange driver when it came to modeling it in WinSpeakerz. This driver needs a very large vent to work as shown in the chart above. If I were to use this driver, it would be right on the edge of my box size range, but its frequency response is beyond what I am looking for with an f3 of about 18Hz. 31 Dayton Audio UM12-22 Ultimax. Accessed February 10, express.com/dayton- audio- um ultimax- dvc- subwoofer- 2- ohms- per- coil

36 Crossovers Starting point Looking at the frequency responses of the I have chosen we can get an idea of where the starting point for our crossover should be. Below are the frequency response charts for the woofer and tweeter for all of the surround speakers. Figure 11. Dayton Audio RS225-8 Frequency response Figure 12. Seas Seas Prestige 19TFF1 frequency response In the figures above we can see that our tweeter begins rolling off at approximately 1.5kHz and the woofer beings breakup at approximately 3kHz, however it has a large dip beginning at 2.5kHz. Taking a look at the Winspeakerz plot for the woofer, the box has an f3 of approximately 30Hz. However, at peak levels at this frequency there is the possibility to over extend the driver. In order to avoid this, and avoid potentially blown speakers a slight roll off will need to be implemented. However, this roll off will most likely be changed one the box is built and measured for volume and possibly adjusted to prevent over excursion. This roll off will 36

37 also be the determining factor in my crossover point between my surround boxes and my subwoofers for normal listening. Taking into consideration there will be multiple crossover setups I will only be outlining my starting point for each system in this section. Based on this information, a good starting point for my woofer to tweeter crossover point is about 2.4kHz. Even though this will be into the range of the dip in the woofers frequency response this point will avoid any issues that may cause distortion from the tweeter. Based on the winspeakerz plot of my woofer the roll off that will most likely be required to prevent damage to the woofer will be starting at about 50Hz and will be a 12dB/octave slope, keeping in mind that these are starting points for the system and that during final construction I may remove enough volume from my enclosure to solve the problem of over exertion at high wattages. If that is the case and my driver is not at the point of damage the filter point will then be at 33Hz and will be at 18dB/ octave, this filter point will provide adequate bass response and help keep the driver from producing frequencies that it cannot handle. A crossover point between my surround box woofer and my subwoofer is also needed. This is going to be a challenging crossover to figure out. There are a few things that must be kept in mind, starting with the use of the subwoofer as an LFE channel vs using it as a standard subwoofer. When used as an LFE channel it must be completely separated from the surround speakers, and should have an overlapping crossover frequency well into the response of the surround boxes. When using the subwoofers as a standard subwoofer, the crossover point will be linked with the crossover of the rest of the system, this will also be the case for the bass management system design. Before a crossover point is determined we must look at the frequency response of the subwoofer above 100Hz, this can be found in figure 12 below. Figure 13. Eminence Lab 12C frequency response chart. 37

38 Looking at the response of the Eminence Lab 12C subwoofer above 100Hz, we can see it is relatively flat until around 400Hz, at this point we start to see a large bump in the response. According to the model of the box in Winspeakerz, the subwoofer should be able to hit approximately 26Hz. Keeping the above in mind, for our LFE setup our Low pass filter should start at around 300Hz and our high pass filter should start at 26Hz, both filters should be 12 db/octave filters to allow for a smoother, less noticeable roll off. When the system is acting as a standard subwoofer we also have to take into consideration the woofer high pass filter point. As stated previously it will start at 50Hz and will be a 12dB/octave filter, Now for general music listening I feel the best choice for this filter point would be to move it up to 120Hz and change to a steeper filter. In doing this our subwoofer will be handling more of the low end and there will be no danger in cranking the system up to jamming out levels. Finally, I will also be implementing an optional bass management system to be enabled if there just isn t enough low end in the surround speakers for a particular movie. For this system, there will need to be 2 separate crossover points within my subwoofer/lfe channel, in figure 13 is a sample of the processing blocks within my BSS program to make this system possible. Considering there are 2 crossover points to look at we have to determine what frequency and below to remove from the surround speakers. As a starting point I will be using the same frequency I used for the standard subwoofer setup, 120Hz. The bass management crossover will be set at 120Hz along with the crossovers for the surround speakers. Even while the bass management system is enabled, the LFE channel still needs to function as a separate entity, this is done with the Subwoofer 1 & 2 crossover set at the same starting point as above, 400Hz. Center speaker crossover For the center speaker, the crossover design will be slightly different than the rest of the system. The center speaker will feature an active/passive design to incorporate a midrange driver into the system. The passive component will be between the tweeter and the midrange driver. Looking more in depth at this we must consider the responses of all 3 of the drivers. Below is a response plot of the chosen midrange driver. Figure 13. Dayton dome mid spec 38

39 Because of the addition of this driver, the crossover point for the woofer will change in my DSP settings. I plan on bumping the woofer crossover point up to 380Hz as a starting point. 380Hz will be the crossover point between the woofer and the midrange driver. The tweeter will be passively crossed over at 3.5Khz with a 3 rd order Butterworth crossover. Bumping the crossover frequency up for the center channel will be necessary in order to use a passive crossover without having time domain or distortion problems. 39

40 Crossover Diagrams Below are several screen shots from the BSS program I will be loading on my processor for the first test of the speakers, the following screenshots are included below Crossover System overview Bass management system overview Standard woofer tweeter crossover point for surrounds Music listening / standard subwoofer to surround box crossover LFE mode subwoofer crossover points LFE mode without bass management subwoofer to surround crossover Crossover for woofer to midrange in center speaker Passive circuit diagram for center midrange to tweeter crossover in center speaker Figure 14. Crossover system overview 40

41 Figure 15. Bass management programming example in Audio Architect Figure 16. Standard surround woofer to tweeter crossover point Figure 17. Musical subwoofer to surround speakers crossover points 41

42 Figure 18. Subwoofer in LFE mode with no bass management. Figure 19. Subwoofer in LFE mode next to surround boxes in standard mode Figure 20. Left: Subwoofer in LFE mode. Right: secondary subwoofer crossover for bass management 42

43 Figure 21. Crossover between midrange/tweeter and woofer in center speaker Figure rd order LR crossover between tweeter and woofer for center speaker 43