Help designing sono tube with dual 15

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  • Gregg Loewen
    Senior Member
    • Aug 2000
    • 285

    Help designing sono tube with dual 15

    Hi, I currently have a dual 12' shiva sonotube sub and wanted to build a second to add to my system. What do you all recommend for size to match my first tube? I figure to match the second with the first they should have approx. the same tuning points (correct?).

    Here is a link to my first tube:



    I would like both tubes to look similar to each other. I could make the second tube with 30" diameter tube (if needed) but dont really want to if I can avoid it. My first tube is tuned to 22-23 so it should extend to 19-20.

    I am very basic at all of this, and would really like a down and dirty instruction list. This is my DandD list on my first:

    54" length of sonotube.

    2 caps, with 2 layers of MDF (?) caps on each end that are entirely mounted internally. 11" hole on each end for the driver, 8 inch hole for the port. the finish caps are mounted externally so this does not contribute to the volume but the port does not extend to the end of the cap so you will have to add / subtract the cap height to the port length measurement.

    Each 8" port to be 17 " long (plus adding the cap height).

    Does the above make sense? and if so what are your recommendations?

    Thanks a bunch!!

    Gregg
  • Patrick Sun
    Super Senior Member
    • Aug 2000
    • 1380

    #2
    Gregg, my Sunosub I is very similar to your SonoDome, but when I started on my Sunosub II with the Tempest, I realized that I would need 16-20 ft^3 of internal volume (which is just too much for my room), so you might have to go with a 30" wide sonotube. I won't have my modelling software at work, but I could suggest something later tonight. Else, you should consider building 2 Tempest Sonodomes (10 ft^3 internal volume each tuned to 16Hz) and sell the original Sonodome with the dual Shivas.




    PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
    PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs

    Comment

    • Andrew Pratt
      Moderator Emeritus
      • Aug 2000
      • 16507

      #3
      Gregg I edited your message to make the hyperlink work (add the [url][ /url] taggs for it to work) Pats right a dual 15" sub would be massive and maybe overkill...esp when you already have a very capable unit. Have you seen the graph for my single 15? Its flat to 20 and is amazing. If you really want to go dual 15's I wouldnt' use the Tempest but the Stryke driver since its better suited to smaller box's...but it will cost you a lot more.




      Comment

      • Bing Fung
        Ultra Senior Member
        • Aug 2000
        • 6521

        #4
        Cost is not a factor for Gregg :B

        Sorry Gregg, on the TTP I never realized you were wanting to use 2 Tempest drivers. That would require a box in the 18 cubic ft range.

        A single Tempest tuned to 19Hz looks pretty impressive, That's in a 10 cubic ft tube.




        Bing
        Bing

        Comment

        • Patrick Sun
          Super Senior Member
          • Aug 2000
          • 1380

          #5
          I think Gregg should sell me his second Tempest driver (at the cheapo rate, of course) so I can build Sunosub III. :d




          PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
          PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs

          Comment

          • ThomasW
            Moderator Emeritus
            • Aug 2000
            • 10934

            #6
            I currently have a dual 12' shiva sonotube sub and wanted to build a second to add to my system.
            What are you trying to accomplish?

            Mating these two doesn't make good sense, unless the room is HUGE!!!!!! 20'X40' or so.

            Dual 15"s are approx equal to 5 or 6, 12" drivers. So there's nothing to be gained by keeping the dual 12" tube in the same room. And there is actually potential for them to mess each other up.

            For max performance just double the size of the tube discussed in Patrick Sun's thread, and "blessed" by Dan Wiggins. This is optimized for the 15"




            theAudioWorx
            Klone-Audio

            IB subwoofer FAQ page


            "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

            Comment

            • Gregg Loewen
              Senior Member
              • Aug 2000
              • 285

              #7
              Hi, thanks for the info.

              Well, my room is pretty large, it is 34x34 with a 10x10 office in the corner enclosed by french doors. The back of the room opens to a large staircase which goes up to the main level.

              My current sub occasionally (rare) maxes out when at +2-5 about ref levels (calibrated at 85). I thought the second tube would give me a lot more head room. Id rather go into over kill versus having limited volume power.

              My current sub is corner loaded, and I was thinking the new sub would go behind my right main speaker (not corner loaded) so I was thinking this would help balance the 2 out somewhat. ???

              How long is 18 CF of sonotube with a 24" diameter vs a 30" diameter?

              Gregg

              Comment

              • Andrew Pratt
                Moderator Emeritus
                • Aug 2000
                • 16507

                #8
                thats a hugh sub gregg




                Comment

                • ThomasW
                  Moderator Emeritus
                  • Aug 2000
                  • 10934

                  #9
                  Greg,

                  I doubt that you'll have bottoming problems with the dual 15" sub. But.........

                  What might work is placing the subs in opposite corners, Now normally this is the exact opposite of what I'd recommend, but your room is very big.

                  Is the office actually "walled" off?

                  I'd also try putting the subs on a A/B/A+B type of switch. This would allow trying out differing sub positions, and seeing what happens with one or both operating.

                  Some positions they will reinforce each other, and other positions they will cancel each other. So experimentation is necessary for this to work.

                  3.1417 times r^2, times the length(height),divided by 1728=cubic feet

                  So 24" tube 70" long =18.33 cu ft, 30" tube 45" long =18.41 cu ft

                  The actual length will of course be longer, taking into consideration the displacement of the 2 drivers/port/endcaps etc.




                  theAudioWorx
                  Klone-Audio

                  IB subwoofer FAQ page


                  "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

                  Comment

                  • Bing Fung
                    Ultra Senior Member
                    • Aug 2000
                    • 6521

                    #10
                    Gregg, add about another 4" to the total height to account for the caps and to lift the tube 3" off the floor. That's one big tube, however what you could do is design it so it looks like a column in the corner of the room. You could build two of these with one driver per column to create that classic theater look with the marble columns




                    Bing
                    Bing

                    Comment

                    • Patrick Sun
                      Super Senior Member
                      • Aug 2000
                      • 1380

                      #11
                      And then you have to add in some more height to account for the port(s) volume(s), and the driver volume displacement.




                      PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
                      PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs

                      Comment

                      • Tom Vodhanel
                        Junior Member
                        • Sep 2000
                        • 18

                        #12
                        With dual 15" shivas...I'd go with 20-24 cubes, tune in the 19-22hz rnage, and use 600-1200w total.

                        Adding the second larger tube to the existing tube should pose any problems...assuming they are located near one another. Keeping the smaller tube in the room should give you a couple dBs of extra headroom.Once you get into the bass energy you're talking about ...adding a couple dBs is pretty hard and shouldn't be shrugged off immediately. I'd probably start with both tubes going, and then shut down the smaller one, and see if the dual 15 tube can handle the room by itself.

                        The hard part about dual 15s is they're going to want a LOT of port area down low.....dual 10" ports would be nice.


                        TV

                        Comment

                        • Lexman
                          Super Senior Member
                          • Jun 2000
                          • 1777

                          #13
                          Whoa, dual 10" ports ey? Heck Tom, he should be able to set up a small room in there, rofl. That's the largest port recommendation I remember hearing. What was that due to ? Size of enclosure? Size of drivers?

                          I run 2 4" ports, totaling 8 " of port per 12" driver, and it seems way more than adequite. I never hear whoosh, but I definitely hear the bass!

                          Welcome to HTG TV! Hey, that's almost HGTV! lol.

                          Lex

                          Comment

                          • Andrew Pratt
                            Moderator Emeritus
                            • Aug 2000
                            • 16507

                            #14
                            Lex dual 4" vents does not equal a single 8" vent...a single 8" port has twice the area then dual 4" do.




                            Comment

                            • Gregg Loewen
                              Senior Member
                              • Aug 2000
                              • 285

                              #15
                              I have some 6 " and 8 " PVC tubing around. No 10" though. I had to have the 8" shipped in from Portland. Would the 2 8" surfice or should I go with 4 6"?

                              Comment

                              • ThomasW
                                Moderator Emeritus
                                • Aug 2000
                                • 10934

                                #16
                                Big woofers like to see big ports(actually large port surface area). Eliminates port "chuffing", and in general makes life easier for the woofers on the absolute lowest notes.

                                10" ports displace a lot of internal volume averaging 1.5-2 cu ft/port. So in order to use them, the tube size must be increased accordingly. If you're going to target 24cu ft "net internal volume " then the actual internal gross will be closing in on 30 cu ft.

                                After adjusting for the displacement of the ports, 2 woofers, endcaps, etc. you'll be looking at a 30" tube approx 75" tall.

                                You can certainly use multiple smaller ports,

                                If you want a Fb 16Hz, you'll need 24 cu ft "net internal" volume use 3-8" 55.75" long ports. I wouldn't go smaller than 8" ports for this design

                                If you want a Fb 19Hz (same volume as above)then use 3-8" 36.45" ports.

                                With the large driver holes necessary for the 15"s, you can easily "play" with different tunings using PVC couplings to add port length.

                                BTW, the Fb 16Hz graph looks best. This is the tuning Dan Wiggins recommended.

                                Hope you have a big amp




                                theAudioWorx
                                Klone-Audio

                                IB subwoofer FAQ page


                                "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

                                Comment

                                • Patrick Sun
                                  Super Senior Member
                                  • Aug 2000
                                  • 1380

                                  #17
                                  Andrew, stop being mean to Lex, he's using Lex-Math(tm)!

                                  Gregg, if you do something this big, I'd go with the 16Hz tune since you'll have to room for 55" long ports, plus it'll protect the drivers tuning it lower than 19Hz.




                                  PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs
                                  PatCave; HT Pix;Gear;DIY Projects;DVDs; LDs

                                  Comment

                                  • Lexman
                                    Super Senior Member
                                    • Jun 2000
                                    • 1777

                                    #18
                                    Thanks Patrick. These guys can be merciless sometimes! lol. Andrew, :F I knew that icon would come in handy someday, lol.

                                    I would say there is a reason you don't just leave one whole end of a tube open, isn't there? But I am not the DIY expert, that's why we have these other guys.

                                    Lex





                                    <A HREF="http://www.catcables.com" <IMG SRC="http://www.htguide.com/lexman/other/sm_logo.gif"

                                    Comment

                                    • ThomasW
                                      Moderator Emeritus
                                      • Aug 2000
                                      • 10934

                                      #19
                                      Lex

                                      I wonder if you weren't using the 2-4" to equal a single 6". This would be a more appropriate diameter for your subs




                                      theAudioWorx
                                      Klone-Audio

                                      IB subwoofer FAQ page


                                      "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

                                      Comment

                                      • Andrew Pratt
                                        Moderator Emeritus
                                        • Aug 2000
                                        • 16507

                                        #20
                                        Lex what goes around comes around




                                        Comment

                                        • Gregg Loewen
                                          Senior Member
                                          • Aug 2000
                                          • 285

                                          #21
                                          Thanks for the help guys! My questions continue:

                                          1. If I use both tubes together should they have the same approximate tuning?

                                          2. Will the new tube really have 5-6 x the output of my current tube?

                                          3. Really, how much will I complicate things if the 2 tubes are not placed near each other in the room?

                                          4. If the new tube will really have that much more output then how do I sell my current tube?

                                          PS just thinking that if I had posted each question seperately, then I would almost be a full member now

                                          Gregg

                                          Comment

                                          • Pat
                                            Super Senior Member
                                            • Aug 2000
                                            • 1637

                                            #22
                                            Hey, that is twice now that I have seen the "finger" used...both times it was aimed at Andrew:B...




                                            Pat's Page
                                            Pat's Page

                                            Comment

                                            • Lexman
                                              Super Senior Member
                                              • Jun 2000
                                              • 1777

                                              #23
                                              Thomas, that must have been what I was thinking.

                                              Haha Pat, interesting coincidence! Let's all give Andrew the finger, perhaps a seperate thread for that?

                                              Gregg, they are gonna have a field day with #3 I think. I will wait for the troops on that one Then you will become a full member, maybe senior member just fielding all the responses, lol.

                                              Lex





                                              <A HREF="http://www.catcables.com" <IMG SRC="http://www.htguide.com/lexman/other/sm_logo.gif"

                                              Comment

                                              • Bing Fung
                                                Ultra Senior Member
                                                • Aug 2000
                                                • 6521

                                                #24
                                                That's good Lex, I like that smiley... and it was used in perfect context.

                                                Gregg ARE YOU CRAZY MAN 70"+ tube :E
                                                Just trying to envoke a reply that will help you out buddy...




                                                Bing
                                                Bing

                                                Comment

                                                • ThomasW
                                                  Moderator Emeritus
                                                  • Aug 2000
                                                  • 10934

                                                  #25
                                                  1. If I use both tubes together should they have the same approximate tuning?
                                                  Doesn't make much difference. I'd go for the FB 16Hz on the new sub. The "plot" for this looks VERY nice.

                                                  2. Will the new tube really have 5-6 x the output of my current tube?
                                                  No sorry, that isn't how it works. Probably 3+db or so more output (though this isn't trivial). The ability to move more air will be significantly greater, with a big enough amp.

                                                  3. Really, how much will I complicate things if the 2 tubes are not placed near each other in the room?
                                                  Only trial and error will answer that question. Usually the "best" placement is with the subs together. But given the size of the room it's possible you can find separate placement that won't create too many nulls

                                                  4. If the new tube will really have that much more output then how do I sell my current tube?
                                                  Is this a trick question? You offer it for sale

                                                  PS just thinking that if I had posted each question seperately, then I would almost be a full member
                                                  Yes, but you showed how mature you are by not wasting the bandwith. :B




                                                  theAudioWorx
                                                  Klone-Audio

                                                  IB subwoofer FAQ page


                                                  "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

                                                  Comment

                                                  • Tom Vodhanel
                                                    Junior Member
                                                    • Sep 2000
                                                    • 18

                                                    #26
                                                    Here's a generic dual 15shiva plot, something like 24 ft3,tuned to both 16 and 20hz. I'll post the CD(excursion-600w per driver)...and the response curves.

                                                    btw--is there anyway to adjust the freq limits of the graphing? It would be cool to have a 5-80hz window.

                                                    this is the excursion.



                                                    this is the response...I put the cursor at the *meeting* point of the two tunes...about 18.3hz. From 20-30hz(an important HT range)...the 20hz tune has about 2-3dB more output.

                                                    Either of these options is going to kick booty though.




                                                    TV

                                                    Comment

                                                    • Tom Vodhanel
                                                      Junior Member
                                                      • Sep 2000
                                                      • 18

                                                      #27
                                                      >>>Thanks for the help guys! My questions continue:
                                                      1. If I use both tubes together should they have the same approximate tuning?1/6th octave of true extension...which is always nice. Dropping all the way down to 16hz might sound even better to you...but just be aware of the trade-offs.

                                                      a)you lose 2-3dB of sensitivity in the critical 20-30hz range.

                                                      b)cone excursion(and therefore distortion)is higher....although this will only be a worry at HIGH output levels.



                                                      >>>2. Will the new tube really have 5-6 x the output of my current tube?>>3. Really, how much will I complicate things if the 2 tubes are not placed near each other in the room?>>4. If the new tube will really have that much more output then how do I sell my current tube?<<<


                                                      Try locally, shipping costs will be more than the entire thing cost you to build I bet.



                                                      btw---thanks for the welcome Lex...I got your email a while back...been lurking a bit...seems like a nice place.


                                                      TV

                                                      Comment

                                                      • Bing Fung
                                                        Ultra Senior Member
                                                        • Aug 2000
                                                        • 6521

                                                        #28
                                                        Yes Tom, welcome to the HTG!

                                                        Your last graph has answered or brought up an often sought design considerationin my mind.
                                                        Knowing that the crtical range is 20-30Hz, Is it correct to assume thet the more ideal curve is the one that is the flattest in that range? i.e. the red line. That's not to say that the Yellow one is bad, just trading off SPL for lower extension?




                                                        Bing
                                                        Bing

                                                        Comment

                                                        • ThomasW
                                                          Moderator Emeritus
                                                          • Aug 2000
                                                          • 10934

                                                          #29


                                                          Gregg
                                                          Here's the Fb 16Hz(red) vs Fb 18Hz (orange) comparison. In the 24 cu ft tube, with the 3-8" ports as discussed.


                                                          TV
                                                          As far as I know the only way to "adjust" the plot any further is to manually edit it with a graphics program.




                                                          theAudioWorx
                                                          Klone-Audio

                                                          IB subwoofer FAQ page


                                                          "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

                                                          Comment

                                                          • Tom Vodhanel
                                                            Junior Member
                                                            • Sep 2000
                                                            • 18

                                                            #30
                                                            >>>Your last graph has answered or brought up an often sought design considerationin my mind.
                                                            Knowing that the crtical range is 20-30Hz, Is it correct to assume thet the more ideal curve is the one that is the flattest in that range? i.e. the red line. That's not to say that the Yellow one is bad, just trading off SPL for lower extension? <<<



                                                            This is often debated. It probably comes down to personal preferences to some degree. One thing to keep in mind about software sims...is...they are software sims.

                                                            Yes, they will give you a REPRESENTATION of what will probably happen when you put the respective parts together. However, I can assure you...of two things...


                                                            1) the anechoic response curves won't be identical to what a software sim shows.(in my experience...the software sims ALWAYS predict favorably...the lower the freq, the more favorable the prediction is.

                                                            2) the response curves the software sims show you...are based on LOW output levels. Like the posts TW and I just put up.....low level response curves. doubel the wattage, and what happens? 3dB boost across the board. 2x it again, another 3dB boost...2x it again,another 3dBs....hey this is easy!

                                                            But pretty inaccurate.

                                                            Again, the software favorably assumes every aspect of the subwoofer is going to work perfectly(or nearly so) as the input voltage to the amp increases. This isn't how it happens in the real world.

                                                            After software *simming* hundreds and hundreds of subwoofer in the past year or two, and actually building and measuring many dozens of these ....2m/GP(2m ground plane = 1, anechioc)...the one constant in all my testing is that software sims favor always favorably predict the maximum lowend output.

                                                            As Nousaine once said...

                                                            software sims are for show.....2m GP is for go.

                                                            TV

                                                            Comment

                                                            • Gregg Loewen
                                                              Senior Member
                                                              • Aug 2000
                                                              • 285

                                                              #31
                                                              Thanks a bunch guys!!

                                                              I think there may have been a little bit of mis understanding. If I do only use this 1 new tube I will definitely be corner loading it. The ceiling in that part of the room is around 7 feet. So the max size I could do on a 30" diameter tube is about 5'8" plus leg height extra. Using the excel program Andrew emailed me that equates to 22.3 cf.(I could maybe squeeze another 6 inches in height - by maybe making my legs only 3", etc)

                                                              Also, I have ordered a Peavy 1.3 which is stable at 2 ohms and was planning on running one sonotube off of each side of the amp. If this will not give me enough juice I'd have to spring for another amp. (time to sell some more LDs )

                                                              So if I go for a lower tune I will be giving up some volume in the 20-30 range? But the reason I am making the second tube is to gain more in this range. I DONT LISTEN TO ORGAN MUSIC, so Im thinking the 20 hz tune would be better. (??)

                                                              Please tell me again what the trade off in port length is about? I used the Winisd (thanks again Andrew) and plotted my current tube. The program calls for 2 vents each 32" long, but TV had me put in 18" vents. Im not sure why? I could put 3 vents in the new tube but would then have to buy some more PVC.

                                                              Thanks in advance!!

                                                              Gregg

                                                              PS: The how do I sell my current sub was not meant to be a trick question. Shipping will be out- maybe one of the local moose may take a liking to it? I may have to drive to Boston to get a buyer.

                                                              Comment

                                                              • Mike Temple
                                                                Junior Member
                                                                • Sep 2000
                                                                • 18

                                                                #32
                                                                Gregg

                                                                The port length tunes it to a particular frequency as long as the diameter stays the same. In WinIsd just change the tuning frequency and you will see the length of the tube change. Being new, the one thing I've learned is that WinIsd is good, but is pretty simple compared to the programs the big boys are using so it seems that if an expert( and there are quite a few people on this forum who make a living on Bass or have the practical knowledge to be considered experts IMO) can help their advice would be better than just using a sim IMO

                                                                Good luck

                                                                Comment

                                                                • ThomasW
                                                                  Moderator Emeritus
                                                                  • Aug 2000
                                                                  • 10934

                                                                  #33
                                                                  Gregg

                                                                  I believe TV used 10" ports as his reference, not 18"

                                                                  Per you request I modeled with multiple 8"

                                                                  With either of the models you'll get VERY good in room response in the 20-30Hz range. As Dan Wiggins stated the Fb 16Hz will give you more protection for the driver.

                                                                  As for tube size, 36" tube is available if it will fit through the door! Also you can use increased amounts of damping to fool the woofer into thinking the enclosure is larger.

                                                                  So, make the tube as long as possible, but remember, you'll need extra clearance to pivot the tube upright once it's completed




                                                                  theAudioWorx
                                                                  Klone-Audio

                                                                  IB subwoofer FAQ page


                                                                  "Complicated equipment and light reflectors and various other items of hardware are enough, to my mind, to prevent the birdie from coming out." ...... Henri Cartier-Bresson

                                                                  Comment

                                                                  • Gregg Loewen
                                                                    Senior Member
                                                                    • Aug 2000
                                                                    • 285

                                                                    #34
                                                                    Thomas, the 18" Im referring to the the length of each of the 8" diameter ports used in my first tube. TV designed the first tube for me. Let me add he did an awesome job. My question is why he got me to use 18" port lengths instead of 33" port lengths that winisd is recommending. (I know there must be a reason???)

                                                                    Comment

                                                                    • Tom Vodhanel
                                                                      Junior Member
                                                                      • Sep 2000
                                                                      • 18

                                                                      #35
                                                                      >>>Thomas, the 18" Im referring to the the length of each of the 8" diameter ports used in my first tube. TV designed the first tube for me. Let me add he did an awesome job. My question is why he got me to use 18" port lengths instead of 33" port lengths that winisd is recommending. (I know there must be a reason???) <<<


                                                                      The *tuning* of the enclosure will be determined by the effective volume of the enclosure and the resistance in the port. The wider the port, the longer it has to be for a given. The more bass energy you want the port to be able to flow without compression, the bigger it has to be.(the use of flares helps).

                                                                      Dual long throw 12s, are OK with 8" of port.Dual long throw 15s should have 10" minimum, and hopefully 12-15" or unflared port.

                                                                      If you use a 10-12" (id) port for the dual 15s, place an upside down funnel on the ground under the port....this will add about 1-2dB of headroom.


                                                                      TV

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