Not Your Grandpa s Speakers

Transcription

1 Not Your Grandpa s Speakers Mike Schmitz

2 Contents 1 Functional Description 2 2 Technical Specifications 3 3 Driver Selection Woofers Mid-range Tweeters Driver Selections Crossover Design 34 5 Cabinet Design 34 6 System Tuning 35 7 Final Performance Documentation 37 8 Bibliography 51 Drafting Package 1

3 explaining that the focus is on a balanced speaker all around. 3 The strongest way that the 1 Functional Description These speakers will be used in an urban environment where background noise can get high. They will primarily be used as surround sound fronts and stereo music on the same system. They will be accompanied by a sub and satellite speakers to fill the system out. The room varies a lot potential spaces are bedrooms and living rooms. Floor standing speakers are what is desired in this design to allow them to become TV height. Portability while not a major concern, transportation during moves is important to be able to do safely. The physical design aesthetic of the speakers will be that they will not look conventional. This rules out the normal idea of stained wood boxes but something more interesting and visually eye-grabbing. The function will be playback of film and music mostly. Connecting these ideas with those of studio monitors Moulton talks about listening forward monitors emulate end user experience and that is what these speakers are trying to do. 1 The SPL levels that are being looked at are between home theatre use to a small party playing music loudly. If there was emphasis in any area spelled out in the AES Subjective Loudspeaker Test the major focus areas would be spaciousness and good off-center line. 2 The focus on not being on center is so that the sweet spot is no longer focused on a single point in the room but the whole couch could potentially exist in the sweet spot. Below shows a pie chart like Murphy uses speakers could be described is a very high enjoyment buttery smooth system. the idea behind these is that they will sound great and will be good to listen to for general listening. mixing and mastering are not the focuses of these speakers. 1. David Moulton, Total Recording, ed. Nick Batzdorf (KIQ Productions, 2000), pp Subjective Evaluation of Loudspeakers, technical report AES (r2007) (Audio Engineering Society, 2007), pp John L. Murphy, Introduction to Loudspeaker Design, Second Print (True Audio, 1998), pp FUNCTIONAL DESCRIPTION 2

4 2 Technical Specifications The speakers size defined first and foremost by the fact that they are floor standing speakers. The ideal height of the tweeter would be at about 42 inches, a height measured by sitting on my couch. The height that is desired is slightly changeable but the idea is that the sweet spot is right in that range. The total size is ideally about 18 inches wide and total height up to 5 feet tall. The depth is negotiable but i think that the width of 18 inches gives the speakers presence in the living room next to the TV. This puts speaker into half space and desiring a wide dispersion. The weight of the speakers can be anything that can reasonably be moved. they do need to weight enough to mechanically ground them. They don t need to be exceptionally portable just need to be transportable in the event of moving them around. The SPL that is desired for these speakers is built from their intended purpose of film viewing. The THX standard says that the reference level for their standards is 85 db SPL for the zero point with 20 db of headroom. 4 This is the start and basis of my desires. This level is the standard but not what is usually listened at. Through experimentation i found that my average listening level is 65 to 70 db SPL. I do get to listening levels up to 85 and beyond in few cases. these are mostly while creating and mixing content, which is not what these are designed to be used for. This means that if i match the THX standards then i am able to cover most listening scenarios that come up in my regular pleasurable listening experiences. This leads to defining sensitivity for the drivers. The amplifier that is going to be used initially is a 100 watt amplifier. that leads to about 33 watts per driver if they are all running at full volume at the same time. the sensitivity that would lead to on average is 90 db SPL at 1 watt. this will change if one is high or lower than that number and allowing for a distribution of sensitivities. The frequency response is then the next thing that must be defined. For the low end of the spectrum the ideal is always 20 Hz as defined by the low end of human hearing. if you relate this to a bass guitar that puts the tuning of the lowest string at 40 Hz. then final low end search came from experimentation. As I moved a low cut filter on a system flat to 20 Hz up, I did not notice a true change until the filter reached around 30 Hz. this says to me that the desired low end is around 30 Hz as that is where i can hear the results but below that would also be desired because that gives room in the drivers and response to be flat as possible at that point. For the high end, the desired response is up to 20 khz. This response is the extend of human hearing. while above this humans may not be able to hear 4. THX Reference Level, 2016, accessed February 26, 2016, www. thx. com/ consumer/ thxtechnology/thx-reference-level/. 2 TECHNICAL SPECIFICATIONS 3

5 above that it does give the ability to know that it is flat to the extents of human hearing. As for coloration in frequency the desired response if flat so that the coloration can be added through equalization and then is more truly represented through the flat system. The shape of the box is what will mostly influence the reflections in the speaker. The shape being a diamond allows the reverse waves to bounce around the box as apposed to bouncing forward out the woofer. The downward facing port will assist in not having reflections bounce forward out of the port combining undesirably. The sound i am looking for is more of a live but not boxy sound and for the low end to hopefully not influence delay too much. 2 TECHNICAL SPECIFICATIONS 4

6 3 Driver Selection 3.1 Woofers The woofer selection below is a collection of drivers that were considered. All the drivers looked at were within the budget of the project. The ideal woofer will allow for an F(3) below 30 Hz and will have a reasonable group delay. Looked at were 10 in, 12 in, and 15 in drivers. The driver must be able to produce 105 db SPL at a power of 50 Watts or less. The high end only needs to go up to 300 Hz at most because of the crossover with the mid-range. 3 DRIVER SELECTION 5

7 Driver Cost Size Fs Qts Ratio Fs/Qts Passband +/- 3 db Sensitivity Thermal Power Dayton $ Hz Hz-2 KHz 88.2 db DA W 107.2dB Scan-Speak $ Hz Hz-1 KHz 90.5 db 26W4534G 90W 110dB Dayton $ Hz Hz-700 Hz 91 db DS W 111.3dB Dayton $ Hz Hz-1800 Hz 88.7 db RS W 108.7dB Dayton $ Hz Hz-1 khz 90.3 db RSS315HF-4 400W 116.3dB SB Acoustics $ Hz Hz-800 Hz 88 db SB29NRX W 111dB SB Acoustics $ Hz Hz-250 Hz 86 db SB29SWNRX-S W 109dB Peerless $ Hz Hz-1000 Hz 86.8 db SLS W 106.8dB Dayton $ Hz Hz-1500 Hz 92.2 db ST W 116.1dB Dayton $ Hz Hz-400 Hz 91.2 db ST W 116dB Mechanical Power 65W db 60W db 80W 110 db 65W db 400W 116.3dB 400W 116.3dB 100W 106dB 100W 106.8dB 275W 116.1dB 400W 111.2dB F(3) Box Size 29 Hz 3.7 ft 3 30 Hz 3 ft 3 31 Hz 3 ft 3 28 Hz 4.5 ft 3 24 Hz 3 ft 3 24 Hz 2 ft 3 30 Hz.91 ft 3 30 Hz.92 ft 3 35 Hz 3 ft 3 25 Hz 5.94 ft 3 3 DRIVER SELECTION Woofers 6

8 Dayton Audio DA Cost: $49.35 Size: 10 +/- 3 db in bandpass 100 Hz to 2000 Hz Breakup starts at:3.5 khz Breakup amplitude peak:+13 db Recommended crossover:3rd Order at 200 Hz Thermal power handling:80 watts at db 1m This driver is not suited for use in a sealed box as the F3 is not low enough to give the desired response. In a vented box this will give the desired low end. The cost for this low end is a very high transient response. The delay at its highest is upwards of 26 ms. This delay will be this drivers biggest downfall. Vented Box tuned to 24 Hz Box Size of 3.7 ft 3 F(3) = 29 Hz Sealed Box with a Q=.5 Box Size of 10.8 ft 3 F(3) = 50 Hz Sealed Box with a Q=.7 Box Size of 2.3 ft 3 F(3) = 45 Hz 5. Dayton Audio, DA in Aluminum Cone Woofer Specification Sheet (Dayton Audio). 3 DRIVER SELECTION Woofers 7

9 Scan-Speak Discovery 26W 4534G 6 Cost: $94.20 Size: 10 +/- 3 db in bandpass 100 Hz to 1000 Hz Breakup starts at:1.5 khz Breakup amplitude peak:+14 db Recommended crossover:3rd Order at 200 Hz Thermal power handling:90 watts at 110 db 1m This driver is not suited for use in a sealed box as the F3 is not low enough to give the desired response. The vented design would yield a low F3. The delay presented is not very low but for a vented design is acceptable at close to 20 ms. Vented Box tuned to 25 Hz Box Size of 3 ft 3 F(3) = 30 Hz Sealed Box with a Q=.5 Box Size of 5.93 ft 3 F(3) = 50 Hz Sealed Box with a Q=.7 Box Size of 1.98 ft 3 F(3) = 45 Hz 6. Scan-Speak, Discovery 26W/4534G00 Specification Sheet (Scan-Speak). 3 DRIVER SELECTION Woofers 8

10 Dayton Audio DS Cost: $75.78 Size: 12 +/- 3 db in bandpass 100 Hz to 700 Hz Breakup starts at:1.5 khz Breakup amplitude peak:+8 db Recommended crossover:3rd Order at 200 Hz Thermal power handling:120 watts at db 1m This driver will not work in a sealed box because if the F3 over 50 Hz. In the vented design the extended bass shelf is implemented to get such a low F3. this also has a reasonable delay peaked at 18 ms. The low bandpass frequency is acceptable because of where the crossover is. Vented Box tuned to 30.5 Hz Box Size of 3 ft 3 F(3) = 30 Hz Sealed Box with a Q=.5 Box Size of 3.5 ft 3 F(3) = 60 Hz Sealed Box with a Q=.7 Box Size of 1.37 ft 3 F(3) = 55 Hz 7. Dayton Audio, DS in Designer Series Woofer Specification Sheet (Dayton Audio). 3 DRIVER SELECTION Woofers 9

11 Dayton Audio RS Cost: $90.94 Size: 10 +/- 3 db in bandpass 100 Hz to 1800 Hz Breakup starts at:2 khz Breakup amplitude peak:+5 db Recommended crossover:3rd Order at 200 Hz Thermal power handling:100 watts at db 1m This drivers sealed response is not awful but could be better. The vented design has an amazing low F3 of 28 Hz and a nice slow roll off. The delay in the vented design prohibitive. with a delay of 30 ms puts this driver well beyond acceptable in a vented situation. Vented Box tuned to 22 Hz Box Size of 4.5 ft 3 F(3) = 28 Hz Sealed Box with a Q=.5 Box Size of 25.9 ft 3 F(3) = 50 Hz Sealed Box with a Q=.7 Box Size of 2.8 ft 3 F(3) = 45 Hz 8. Dayton Audio, RS in Reference Woofer Specification Sheet (Dayton Audio). 3 DRIVER SELECTION Woofers 10

12 Dayton Audio RSS315HF-4 9 Cost: $ Size: 12 +/- 3 db in bandpass 100 Hz to 1000 Hz Breakup starts at:1.5 khz Breakup amplitude peak:+15 db Recommended crossover:3rd Order at 200 Hz Thermal power handling:400 watts at db 1m This drivers sealed and in vented operations is a viable option. The sealed operation gives very good F3 for a sealed enclosure. The vented operation of this driver, while it delivers superb F3 of 24 Hz but gives a delay of almost 30 ms. This delay is prohibitive and will most likely warrant it not being used vented. Vented Box tuned to 22 Hz Box Size of 3 ft 3 F(3) = 24 Hz Sealed Box with a Q=.5 Box Size of 4.6 ft 3 F(3) = 47 Hz Sealed Box with a Q=.7 Box Size of 1.3 ft 3 F(3) = 44 Hz 9. Dayton Audio, RSS315HF-4 12in Reference Subwoofer Specification Sheet (Dayton Audio). 3 DRIVER SELECTION Woofers 11

13 SB Acoustics SB29NRX Cost: $ Size: 10 +/- 3 db in bandpass 100 Hz to 800 Hz Breakup starts at:2.3 khz Breakup amplitude peak:+10 db Recommended crossover:3rd Order at 200 Hz Thermal power handling:200 watts at 111 db 1m This driver has high possibilities as a sealed or vented driver. The sealed response is good with a very low F3. The vented designs will lead to a good F3. The vented design stands out with this driver when we compare the delay to the F3. The delay being only 20 ms means that it is a decent candidate for a vented design. Vented Box tuned to 24 Hz Box Size of 2 ft 3 F(3) = 27 Hz Sealed Box with a Q=.5 Box Size of 3.5 ft 3 F(3) = 47 Hz Sealed Box with a Q=.7 Box Size of 1.2 ft 3 F(3) = 43 Hz 10. SB Acoustics, 10in SB29NRX75-6 Specification Sheet (SB Acoustics). 3 DRIVER SELECTION Woofers 12

14 SB Acoustics SB29SWNRX-S Cost: $ Size: 10 +/- 3 db in bandpass 100 Hz to 250 Hz Breakup starts at:2.3 khz Breakup amplitude peak:+7 db Recommended crossover:3rd Order at 200 Hz Thermal power handling:200 watts at 109 db 1m This driver only really looks suitable in a vented design. The sealed performance is no where what is desired for these speakers. The vented design goes nice and low and the delay on it is very a good at 18 ms. The downside to this driver is that it is similar to other drivers while costing much more that them along with its less than flat response even in its low end. Vented Box tuned to 25.2 Hz Box Size of.92 ft 3 F(3) = 30 Hz Sealed Box with a Q=.5 Box Size of 1.5 ft 3 F(3) = 50 Hz Sealed Box with a Q=.7 Box Size of.57 ft 3 F(3) = 46 Hz 11. SB Acoustics, 10in SB29SWNRX-S75-6 Specification Sheet (SB Acoustics). 3 DRIVER SELECTION Woofers 13

15 Peerless SLS Cost: $97.35 Size: 12 +/- 3 db in bandpass 200 Hz to 1000 Hz Breakup starts at:2 khz Breakup amplitude peak:+8 db Recommended crossover:3rd Order at 200 Hz Thermal power handling:100 watts at db 1m This driver could work in either a vented or a passive enclsure. The sealed Q of.7 is of a reasonable size and has a fantastic delay for its F3 of 40 Hz. A crossover of about 200 to 300 Hz would be chosen because this crosses over with the mids well and this driver is very flat on all axis. Its price is within my budget and handles the power well. Vented Box tuned to 25.2 Hz Box Size of.92 ft 3 F(3) = 30 Hz Sealed Box with a Q=.55 Box Size of 125 ft 3 F(3) = 43 Hz Sealed Box with a Q=.7 Box Size of 6.9 ft 3 F(3) = 40 Hz 12. Peerless, SLS Specification Sheet (Peerless, November 2009). 3 DRIVER SELECTION Woofers 14

16 Dayton Audio ST Cost: $94.80 Size: 12 +/- 3 db in bandpass 100 Hz to 1500 Hz Breakup starts at:2 khz Breakup amplitude peak:+8 db Recommended crossover:3rd Order at 200 Hz Thermal power handling:275 watts at db 1m This driver has a lot going for it in a sealed scenario. The sealed designs lead to a reasonable box size and a fantastic F3 of 39 Hz for a sealed design. Its response drops of a little much but where it is being crossed over it wont be an issue. The vented design in the smooth roll off give an acceptable F3 for a vented box and a great delay of 16 ms. Vented Box tuned to 30 Hz Box Size of 3 ft 3 F(3) = 35 Hz Sealed Box with a Q=.5 Box Size of 8.4 ft 3 F(3) = 42 Hz Sealed Box with a Q=.7 Box Size of 3.5 ft 3 F(3) = 39 Hz 13. Dayton Audio, ST in Series II Woofer Specification Sheet (Dayton Audio). 3 DRIVER SELECTION Woofers 15

17 Dayton Audio ST Cost: $95.60 Size: 15 +/- 3 db in bandpass 200 Hz to 400 Hz Breakup starts at:0.6 khz Breakup amplitude peak:+10 db Recommended crossover:3rd Order at 200 Hz Thermal power handling:300 watts at 116 db 1m This driver is very similar to its 12 little brother in the sealed boxes/ in the vented configuration it is a much bigger box and a similar F3. The big thing is that the transients went down a bit. The big hindrance is that they have stopped selling this driver since research has started. Vented Box tuned to 21.6 Hz Box Size of 5.9 ft 3 F(3) = 35 Hz Sealed Box with a Q=.5 Box Size of 8.4 ft 3 F(3) = 42 Hz Sealed Box with a Q=.7 Box Size of 3.5 ft 3 F(3) = 39 Hz 14. Dayton Audio, ST in Series II Woofer Specification Sheet (Dayton Audio). 3 DRIVER SELECTION Woofers 16

18 3.2 Mid-range The mid-range drivers looked at vary from 7 in. down to 5 in. This driver does not have to go low. the F(3) can be as high as 300 Hz because of the woofer. The high end is at least 1 khz to cross over with a tweeter. the higher that the mid-range can go the more possibilities that there are for tweeters. The flatness in the desired range is the most important part. The desired level just like the woofer is 105 db SPL at no more than 50 Watts. 3 DRIVER SELECTION Mid-range 17

19 Driver Cost Size Fs Qts Ratio Fs/Qts Passband +/- 3 db Sensitivity Thermal Power Scan-Speak $ Hz Hz-1 KHz 88.7 db 18W8434G00 170W 111dB Fountek $ Hz Hz-4 KHz 87.3 db FW168 50W 104.3dB Dayton $ Hz Hz-1000 Hz 94.4dB PM W 109.2dB Peerless $ Hz Hz-2000 Hz 87dB PPB W 105.8dB Dayton $ Hz Hz-1 khz 94.8 db PS W 109.6dB Dayton $ Hz Hz-3000 Hz 88.7 db RS W 104.7dB Dayton $ Hz Hz-4 khz 91.8 db RS150P 40W 107.8dB SB Acoustics $ Hz Hz-4000 Hz 82 db SB17NRXC W 109.7dB Mechanical Power 30W db 30W 102.1dB 30W db 25W db 10W 104.8dB 10W 98.7dB 10W 101.8dB 30W 109.7dB F(3) Box Size 90 Hz 1.96 ft 3 90 Hz.99 ft Hz.45 ft Hz 1.25 ft Hz.5 ft Hz ft Hz.38 ft 3 85 Hz.86 ft 3 3 DRIVER SELECTION Mid-range 18

20 Scan-Speak Discovery 18W8434G00 15 Cost: $67.90 Size: 7 +/- 3 db in bandpass 200 Hz to 1000 Hz Breakup starts at:1 khz Breakup amplitude peak:+10 db Recommended crossover:3rd Order at 1 khz Thermal power handling:170 watts at 111 db 1m This driver as a mid can not be crossed over any higher than 1000 Hz because the breakup starts happening around then this could be good for some tweeters but not others. In the band pass the frequency response is quite flat among all of the angles. For a low cut crossover is a bit low. Sealed Box with a Q=.7 Box Size of 0.42 ft 3 F(3) = 80 Hz Sealed Box with a Q=.5 Box Size of 2.0 ft 3 F(3) = 90 Hz Sealed Box with a Q=1.2 Box Size of 0.1 ft 3 F(3) = 100 Hz 15. Scan-Speak, Discovery 18W8434G00 Midwoofer Specification Sheet (Scan-Speak). 3 DRIVER SELECTION Mid-range 19

21 Fountek FW Cost: $45.95 Size: 6.5 +/- 3 db in bandpass 400 Hz to 4000 Hz Breakup starts at:4 khz Breakup amplitude peak:+14 db Recommended crossover:3rd Order at 2 khz Thermal power handling:50 watts at db 1m This driver with its very high band pass range allows for a higher crossover with some tweeters that may not go as low. The band pass is not bad in frequency response but does bounce around quiet a bit up and down. on the low end the f3 is high in some respects but usable. Sealed Box with a Q=.7 Box Size of 0.28 ft 3 F(3) = 80 Hz Sealed Box with a Q=.5 Box Size of ft 3 F(3) = 90 Hz Sealed Box with a Q=1.2 Box Size of 0.07 ft 3 F(3) = 100 Hz 16. Fountek, FW168 Midbass Driver Specification Sheet (Fountek). 3 DRIVER SELECTION Mid-range 20

22 Dayton Audio PM Cost: $97.40 Size: 6.5 +/- 3 db in bandpass 200 Hz to 1000 Hz Breakup starts at:2 khz Breakup amplitude peak:+20 db Recommended crossover:3rd Order at 1 khz Thermal power handling:30 watts at db 1m This driver on the high end does not go very high cleanly this requires the crossover to be around 1 kh and not getting in the range of all the tweeters. the low end is great at and F3 of 150 or greater gives the woofer a lot of room to work before it crosses over to the mid. Sealed Box with a Q=.7 Box Size of 0.19 ft 3 F(3) = 140 Hz Sealed Box with a Q=.5 Box Size of.45 ft 3 F(3) = 150 Hz Sealed Box with a Q=1.2 Box Size of 0.06 ft 3 F(3) = 170 Hz 17. Dayton Audio, PM in Neo Wideband Midbass Driver Specification Sheet (Dayton Audio). 3 DRIVER SELECTION Mid-range 21

23 Peerless PPB Cost: $38.50 Size: 6.5 +/- 3 db in bandpass 200 Hz to 2000 Hz Breakup starts at:2 khz Breakup amplitude peak:+4 db Recommended crossover:3rd Order at 1 khz Thermal power handling:30 watts at db 1m This driver does well for an on axis response up to 2 khz but the issue is that the off axis response starts to get less than desirable compared to other choices. the low end is good with a 100 to 120 Hz F3. The crossover was set to 1 khz so that we can eliminate the poor off axis response. Sealed Box with a Q=.7 Box Size of 0.27 ft 3 F(3) = 95 Hz Sealed Box with a Q=.5 Box Size of 1.25 ft 3 F(3) = 100 Hz Sealed Box with a Q=1.2 Box Size of 0.07 ft 3 F(3) = 120 Hz 18. Peerless, HDS-P Specification Sheet (Peerless, September 2009). 3 DRIVER SELECTION Mid-range 22

24 Dayton Audio PS Cost: $99.80 Size: 6.5 +/- 3 db in bandpass 200 Hz to 1000 Hz Breakup starts at:3 khz Breakup amplitude peak:+15 db Recommended crossover:3rd Order at 1 khz Thermal power handling:30 watts at db 1m This driver fine in the high end but does not stand out with a 1 khz band pass region. If desired to use up to 2 khz there would be coloration but the driver would not be in breakup yet. On the low end the driver does well in giving room to the low end driver and picking up in the late 100s. Sealed Box with a Q=.7 Box Size of 0.28 ft 3 F(3) = 130 Hz Sealed Box with a Q=.5 Box Size of.75 ft 3 F(3) = 140 Hz Sealed Box with a Q=1.2 Box Size of 0.08 ft 3 F(3) = 160 Hz 19. Dayton Audio, PS in Point Source Full-Range Neo Driver Specification Sheet (Dayton Audio). 3 DRIVER SELECTION Mid-range 23

25 Dayton Audio RS Cost: $35.00 Size: 6 +/- 3 db in bandpass 200 Hz to 3000 Hz Breakup starts at:3 khz Breakup amplitude peak:+10 db Recommended crossover:3rd Order at 2 khz Thermal power handling:40 watts at db 1m This driver has a very wide band pass which makes it desirable for specific tweeters lacking the 1 khz range. the low end goes down to about 100 Hz this is not bad but could go a bit higher. The crossover of 2000 Hz is where it can go to pickup one of the tweeters with poor low end response. Sealed Box with a Q=.7 Box Size of 0.18 ft 3 F(3) = 100 Hz Sealed Box with a Q=.5 Box Size of.5 ft 3 F(3) = 115 Hz Sealed Box with a Q=1.2 Box Size of 0.05 ft 3 F(3) = 120 Hz 20. Dayton Audio, RS in Reference Woofer 8 Ohm Specification Sheet (Dayton Audio). 3 DRIVER SELECTION Mid-range 24

26 Dayton Audio RS150P-4 21 Cost: $43.00 Size: 6 +/- 3 db in bandpass 200 Hz to 4000 Hz Breakup starts at:4 khz Breakup amplitude peak:+8 db Recommended crossover:3rd Order at 2 khz Thermal power handling:30 watts at db 1m This driver is a very similar to its sister driver the RS-150. The primary difference is that this driver uses a paper cone. this changes the frequency response to go a little bit farther in the band pass and not breakup as bad as the other driver. Its F3 data is about the same compared to the other. Sealed Box with a Q=.7 Box Size of 0.14 ft 3 F(3) = 100 Hz Sealed Box with a Q=.5 Box Size of.38 ft 3 F(3) = 110 Hz Sealed Box with a Q=1.2 Box Size of 0.04 ft 3 F(3) = 120 Hz 21. Dayton Audio, RS150P-4 6in Reference Paper Woofer 4 Ohm Specification Sheet (Dayton Audio). 3 DRIVER SELECTION Mid-range 25

27 SB Acoustics SB17NRXC Cost: $57.85 Size: 6.5 +/- 3 db in bandpass 200 Hz to 4000 Hz Breakup starts at:4 khz Breakup amplitude peak:+9 db Recommended crossover:3rd Order at 2 khz Thermal power handling:30 watts at db 1m While this drive can band pass up to 4 khz the off axis response starts to get very inconsistent and the drive to keep that as consistent as possible puts the crossover at 2 khz. the low end goes a little too low and this forces the low end driver to not function as as much as it can where it is flatter than this driver. Sealed Box with a Q=.7 Box Size of 0.33 ft 3 F(3) = 77 Hz Sealed Box with a Q=.5 Box Size of.86 ft 3 F(3) = 85 Hz Sealed Box with a Q=1.2 Box Size of ft 3 F(3) = 95 Hz 22. SB Acoustics, 6in SB17NRXC35-4 Specification Sheet (SB Acoustics). 3 DRIVER SELECTION Mid-range 26

28 3.3 Tweeters The tweeters looked at range from soft dome to ribbon tweeters. The desired parts of a tweeter are its dispersion because the hope is for a wider sweet spot. The SPL desired is still 105 db but it should be able to produce this at no more that 20 Watts. flatness is key for these speakers. The lower the driver can go the more choices I have with a mid-range but there is no hard line for the low end of the tweeter. Driver Cost Passband +/- 3 db Sensitivity Thermal Power Fountek Neo X 2.0 Fountek Neo X 3.0 Fountek NeoCD 3.0 SB Acoustics SB26ADC-C000-4 Peerless DA25BG08-06 Dayton RS28A-4 SB Acoustics SB26STAC Dayton RS28F-4 Tang Band S Scan-Speak R2604/8320 $ kHz to 30 khz 94dB $ kHz to 10 khz 95dB $ kHz to 10 khz 93dB $ kHz to 10 khz 90dB $ kHz to 17 khz 90.8dB $ kHz to 10 khz 90.4dB $ kHz to 10 khz 91dB $ kHz to 20 khz 90.6dB $ kHz to 20 khz 90dB $ kHz to 20 khz 90dB 25 Watts 108.0dB 30 Watts 109.8dB 17 Watts 105.3dB 120 Watts 110.8dB 100 Watts 100.8dB 100 Watts 110.4dB 120 Watts 111.8dB 100 Watts 110.6dB 8 Watts 99.0dB 100 Watts 110dB 3 DRIVER SELECTION Tweeters 27

29 Fountek Neo X Cost: $ /- 3 db in bandpass 2 khz to 30 khz Breakup starts at:> 40kHz Breakup amplitude peak:- db Recommended crossover:3rd Order at 2 khz Thermal power handling:25 watts at db 1m This ribbon has a crossover point placed at 2 khz to help adjust for the bump at between 1 khz and 2 khz. After that point the Response curve starts to pull up at about 10 khz. while not bad it not as flat as it could be. its true breakup being over 40 khz is a good bonus. Fountek Neo X Cost: $ /- 3 db in bandpass 2 khz to 10 khz Breakup starts at:> 40kHz Breakup amplitude peak:- db Recommended crossover:3rd Order at 2 khz Thermal power handling:30 watts at db 1m This Tweeter shares a big resemblance to its older brother the Neo X 2.0 to the left. the Neo X 3.0 has a slightly different frequency response that technically puts the band pass smaller but it is made up it only being +/-4 for much longer. the other minor difference is power handling. the Neo X 3.0 can run at a higher power with a slightly higher db SPL. 23. Fountek, Neo X2.0 Ribbon Tweeter Specification Sheet (Fountek). 24. Fountek, Neo X3.0 Ribbon Tweeter Specification Sheet (Fountek). 3 DRIVER SELECTION Tweeters 28

30 Fountek NeoCD Cost: $ /- 3 db in bandpass 2 khz to 10 khz Breakup starts at:> 40kHz Breakup amplitude peak:- db Recommended crossover:3rd Order at 2 khz Thermal power handling:100 watts at 109 db 1m This ribbon is similar to the other two Fountek ribbons. they all differ a small amount in the frequency response. the benefit of this tweeter is that it is while maybe not super big in band pass it is fairly flat outside of that region. beyond its generic flatness most of the changes are nice and smooth in this tweeter. SB Acoustics SB26ADC-C Cost: $ /- 3 db in bandpass 2 khz to 10 khz Breakup starts at: 20kHz Breakup amplitude peak:5 db Recommended crossover:3rd Order at 1 khz Thermal power handling:120 watts at db 1m This Tweeter being a dome tweeter and being made of aluminum has a breakup. The breakup actually moves the more off axis you get so by the time you are 60 degrees off axis the breakup is about 16 khz. While that is not good, one can hope that you aren t listening off axis that far. this also goes quite low so it can hit some of those mids that may not be able to go as high 25. Fountek, NeoCD3.0 True Ribbon Tweeter Specification Sheet (Fountek). 26. SB Acoustics, SB26ADC-C000-4 Specification Sheet (SB Acoustics). 3 DRIVER SELECTION Tweeters 29

31 Peerless DA25BG Cost: $ /- 3 db in bandpass 1 khz to 17 khz Breakup starts at: 17kHz Breakup amplitude peak:+8 db Recommended crossover:3rd Order at 2 khz Thermal power handling:100 watts at db 1m This Tweeter like many is very good in the band pass region and is fairly smooth. as soon as it gets to the breakup frequency it really starts to fall apart. The breakup frequency being so low is probably this drivers lowest point overall. Dayton Audio RS28A-4 28 Cost: $ /- 3 db in bandpass 1 khz to 10 khz Breakup starts at:> 20kHz Breakup amplitude peak:- db Recommended crossover:3rd Order at 1 khz Thermal power handling:100 watts at db 1m This Driver has a response that far exceads what it is in the band pass. outside of that it is running all the way up to 30 khz. it also reaches the low end that some of the drivers need if we were t o use it. 27. Peerless, DA25BG08-06 Specification Sheet (Peerless, September 2014). 28. Dayton Audio, RS28A in Aluminum Dome Tweeter 4 Ohm Specification Sheet (Dayton Audio). 3 DRIVER SELECTION Tweeters 30

32 SB Acoustics SB26STAC 29 Cost: $ /- 3 db in bandpass 1 khz to 10 khz Breakup starts at:> 20kHz Breakup amplitude peak:- db Recommended crossover:3rd Order at 1 khz Thermal power handling:120 watts at db 1m This Driver has a response that far exceeds what it is in the band pass. outside of that it is running all the way up to 30 khz. it also reaches the low end that some of the drivers need if we were t o use it. Dayton Audio RS28f-4 30 Cost: $ /- 3 db in bandpass 1 khz to 20 khz Breakup starts at:> 20kHz Breakup amplitude peak:- db Recommended crossover:3rd Order at 1 khz Thermal power handling:100 watts at db 1m This is driver has phenomenal range and allows any mid to work well. It is also very smooth along its curve there isn t really a breakup because it is a soft dome tweeter. 29. SB Acoustics, SB26STAC-C000-4 Specification Sheet (SB Acoustics). 30. Dayton Audio, RS28F in Silk Dome Tweeter 4 Ohm Specification Sheet (Dayton Audio). 3 DRIVER SELECTION Tweeters 31

33 Tang Band S 31 Cost: $ /- 3 db in bandpass 1 khz to 20 khz Breakup starts at: 30kHz Breakup amplitude peak:+10 db Recommended crossover:3rd Order at 1 khz Thermal power handling:120 watts at 109 db 1m A 1 khz crossover is chosen for this driver because it will make a nice clean roll off across most of its spectrum. the breakup on this driver is at 3o khz and it will start breaking up above where we hear. the low end gets to 1 khz and that means most any driver can pick up the slack. Scan-Speak R2604/ Cost: $ /- 3 db in bandpass 1 khz to 20 khz Breakup starts at:> 22kHz Breakup amplitude peak:+6 db Recommended crossover:3rd Order at 1 khz Thermal power handling:100 watts at 110 db 1m This tweeter is a fine candidate in the low end and lets me get to those low as need be. the second thing to consider is that it breaks up just close enough the audible range winch means tat it could get blown or moved easier.it is besides that region that we are quite flat and is a quality driver 31. Tang Band, TRW Series S Specification Sheet (Tang Band). 32. Scan-Speak, Discovery R2604/ Tweeter Specification Sheet (Scan-Speak). 3 DRIVER SELECTION Tweeters 32

34 3.4 Driver Selections Manufacturer Model Cost Sensitivity Thermal Power Mechanical Power Impedance SB Acoustics SB29NRX25-6 $ dB 200 Watts dB 200 Watts dB 6Ω SB Acoustics SB15MFC30-4 $ dB 50 Watts dB 50 Watts dB 4Ω Fountek Neo X 2.0 $ dB 25 Watts 108.0dB 25 Watts 108.0dB 8Ω Above are the drivers that were selected. The SB Acoustics woofer was selected because in a vented design the F(3) was 27Hz with a reasonable box size of 2 cubic feet. This driver also yielded a group delay of only 22ms at 20 Hz compared to some of the other drivers at similar F(3)s being up to 30ms. While the driver is at the top end of my budget it was by far the best performing. The SB Acoustics mid-range driver selected was selected because of its power handling and achieved SPL. The SPL peak of 106 is in the range that i am looking for and also fell within my budget. The F(3) being down below 100 allows for the crossover to be set at any frequency desired. The Fountek Neo X 2.0 gave a fantastic frequency response going mostly flat up until over 30kHz. Being a ribbon tweeter gives a good high frequency transient response. Its high sensitivity allows it to go very high in SPL without using a lot of power. While a graph for the off axis response is not listed in the spec sheet it did say that it had a very high off axis response. 3 DRIVER SELECTION Driver Selections 33

35 4 Crossover Design The Crossover design is detailed in the drafting package on Plate No. 8. The woofer has a Zobel impedance compensation circuit on it. The Crossover for the woofer is at 250Hz and is set at a second order crossover. The mid-range driver has a Zobel impedance compensation circuit on it. It then has an L-pad of 3dB to help manage its high sensitivity and its potential band-pass gain. The fourth order crossover set at 2500Hz is to cross the mid over with the tweeter. the second order crossover at 250Hz crosses over with the woofer. The second order crossover gives the driver a 180 degree phase offset. this is corrected by flipping the polarity of the driver, which is why it is flipped. The tweeter does not need a Zobel impedance compensation circuit as this is handled in the tweeter. The L-Pad is to help make up for this drivers exceptionally high sensitivity of 94dB. the fourth order crossover at 2500Hz crosses it over with the mid-range driver and because it is a fourth order Linkwitz-Riley and that has no polarity change within it. The part at the input is the baffle step compensation circuit. it is tuned to 250 Hz and is a 6 db shelf. this is to help compensate for and boost the baffle gives the speaker 5 Cabinet Design The cabinet design is detailed in the drafting package on plates 1 through 7. This package contains construction notes along with the design. the major parts of the design worth noting are that the mid-range cabinet is diamond shape. this is to prevent reflections from the back of the driver to bounce back forward. This cabinet has no bracing but because of its size and thickness of the outer wall should not be a problem. The woofer cabinet is a box shape. the bottom portion is a storage location for the crossover and for cable routing. The top section is the main section the driver sits in and has some bracing within it. The section in between is the port. The ports shape is 1.25 in. high and 16 in. wide. The total length is 42.5 in. long. this can be tuned by removing the part of the port in the upper section and cutting the board shorter. The tweeter is free floating and set back to be time aligned. Above and below the tweeter will be acoustically dampening material to help stop any reflections that are coming bouncing off of the woofer or mid-range cabinet. 5 CABINET DESIGN 34

36 6 System Tuning There were many considerations throughout system tuning that helped to make the choices. To start with the response of the tweeter alone with no crossover was less than would be desired it got a little lumpy in the high end that was less than desirable. The midrange and the woofer both produced a very nice even flat response with very little other things needed to be done to them. The crossover that was initially constructed produced a few problems but the main one was that it was giving a very not flat response to the woofer and midrange. At one point I rebuilt the crossover so that it only had the woofer crossover in it and still I continued to get the non-flat response from those drivers. This lead to now trying to figure what can be done to mitigate the effects of the crossover and produce a desirable response. In the process of discovering the issues with woofer I borrowed a few amps and a DSP to test everything. With very little work i was able to achieve a very flat response but after listening to them flat for a short amount of time I found that they were not very pleasurable to listen to. This discovery lead me to find that I did not prefer a flat response but that a bit of a bass tilt was what I desired. This was good because the crossover was giving it a bass tilt already. The boost in the bass was a bit more than it needed to be. Using a pad on the woofer was what helped shape the curve and bring it down a bit to be a reasonable boost. Also finding that the Zobel circuit on the woofer wasn t changing the response much at all and decided to remove it. Tuning the midrange was a simple process. Removing the L-Pad to get it to a desired level with the woofer was first key and then removing the Zobel circuit, which too wasn t doing anything noticeable to the response, were all that was needed on the midrange. The tweeter has a boost in the high end that was of particular concern. There were many different circuits that were tried to remove it ranging from just an L-pad to another crossover. The final solution to the problem was to use a high shelf circuit of a resistor and an inductor in parallel this was able to bring it down just enough that i got it to go as high in frequency as I wanted yet keep that high end under control. tweaking the L-pad to keep level it with everything else was needed but the crossover didn t need to be touched to much. On a first listen there was a bit too much reverberation in the sound this was fixed by adding wool to the midrange box to help calm down the reverberation. Nothing in this respect was needed for the woofer cabinet as they sounded as they should after the midrange got its dampening. The tweeter placement was very important. There was a lot of reflections if placed in the back area under the midrange vs the front. The lack of time alignment was something that did not particularly bother me and pushing the tweeter forward helped 6 SYSTEM TUNING 35

37 remove of those reflections because acoustical dampening ascetically did not work with the rest of the design. 6 SYSTEM TUNING 36

38 7 Final Performance Documentation Below are all the plots that were taken after the system was tuned and were to show the performance of the speaker. The response shown below were taken at 96K from an Apogee Duet and an earthworks tuning microphone at 85 db SPL at 20 inches. Full System Plots Frequency Response Integrated Frequency Response 7 FINAL PERFORMANCE DOCUMENTATION 37

39 Harmonic Distortion Minimum Phase 7 FINAL PERFORMANCE DOCUMENTATION 38

40 Horizontal Off Axis Response Vertical Off Axis Response 7 FINAL PERFORMANCE DOCUMENTATION 39

41 Step Response Impulse Response 7 FINAL PERFORMANCE DOCUMENTATION 40

42 Waterfall Plot - Full Waterfall Plot - High Frequency 7 FINAL PERFORMANCE DOCUMENTATION 41

43 Woofer Plots Frequency Response Harmonic Distortion 7 FINAL PERFORMANCE DOCUMENTATION 42

44 Minimum Phase Horizontal Off Axis Response 7 FINAL PERFORMANCE DOCUMENTATION 43

45 Step Response Impulse Response 7 FINAL PERFORMANCE DOCUMENTATION 44

46 Midrange Plots Frequency Response Harmonic Distortion 7 FINAL PERFORMANCE DOCUMENTATION 45

47 Minimum Phase Horizontal Off Axis Response 7 FINAL PERFORMANCE DOCUMENTATION 46

48 Step Response Impulse Response 7 FINAL PERFORMANCE DOCUMENTATION 47

49 Tweeter Plots Frequency Response Minimum Phase 7 FINAL PERFORMANCE DOCUMENTATION 48

50 Horizontal Off Axis Response Step Response 7 FINAL PERFORMANCE DOCUMENTATION 49

51 Impulse Response 7 FINAL PERFORMANCE DOCUMENTATION 50

52 8 Bibliography Dayton Audio. DA in Aluminum Cone Woofer Specification Sheet. Dayton Audio. Dayton Audio. DS in Designer Series Woofer Specification Sheet. Dayton Audio. Dayton Audio. PM in Neo Wideband Midbass Driver Specification Sheet. Dayton Audio. Dayton Audio. PS in Point Source Full-Range Neo Driver Specification Sheet. Dayton Audio. Dayton Audio. RS in Reference Woofer 8 Ohm Specification Sheet. Dayton Audio. Dayton Audio. RS150P-4 6in Reference Paper Woofer 4 Ohm Specification Sheet. Dayton Audio. Dayton Audio. RS in Reference Woofer Specification Sheet. Dayton Audio. Dayton Audio. RS28A in Aluminum Dome Tweeter 4 Ohm Specification Sheet. Dayton Audio. Dayton Audio. RS28F in Silk Dome Tweeter 4 Ohm Specification Sheet. Dayton Audio. Dayton Audio. RSS315HF-4 12in Reference Subwoofer Specification Sheet. Dayton Audio. Dayton Audio. ST in Series II Woofer Specification Sheet. Dayton Audio. Dayton Audio. ST in Series II Woofer Specification Sheet. Dayton Audio. Dickason, Vance. The Loudspeaker Design Cookbook. 7th Edition. Audio Amateur Press, Fountek. FW168 Midbass Driver Specification Sheet. Fountek. Fountek. Neo X2.0 Ribbon Tweeter Specification Sheet. Fountek. Fountek. Neo X3.0 Ribbon Tweeter Specification Sheet. Fountek. Fountek. NeoCD3.0 True Ribbon Tweeter Specification Sheet. Fountek. McCarthy, Bob. Sound Systems: Design and Optimization. Focal Press, Moulton, David. Total Recording. Edited by Nick Batzdorf. KIQ Productions, Murphy, John L. Introduction to Loudspeaker Design. Second Print. True Audio, BIBLIOGRAPHY 51

53 Newell, Philip, and Kieth Holland. Loudspeakers for Music Recording and Reproduction. First Edition. Elsevier, Peerless. DA25BG08-06 Specification Sheet. Peerless, September Peerless. HDS-P Specification Sheet. Peerless, September Peerless. SLS Specification Sheet. Peerless, November SB Acoustics. 10in SB29NRX75-6 Specification Sheet. SB Acoustics. SB Acoustics. 10in SB29SWNRX-S75-6 Specification Sheet. SB Acoustics. SB Acoustics. 6in SB17NRXC35-4 Specification Sheet. SB Acoustics. SB Acoustics. SB26ADC-C000-4 Specification Sheet. SB Acoustics. SB Acoustics. SB26STAC-C000-4 Specification Sheet. SB Acoustics. Scan-Speak. Discovery 18W8434G00 Midwoofer Specification Sheet. Scan-Speak. Scan-Speak. Discovery 26W/4534G00 Specification Sheet. Scan-Speak. Scan-Speak. Discovery R2604/ Tweeter Specification Sheet. Scan-Speak. Subjective Evaluation of Loudspeakers. Technical report AES (r2007). Audio Engineering Society, Tang Band. TRW Series S Specification Sheet. Tang Band. THX Reference Level Accessed February 26, thx-technology/thx-reference-level/. Toole, Floyd D. Sound Reproduction. Elsevier, BIBLIOGRAPHY 52