Mark's Statements Build Thread

Collapse
This topic is closed.
X
X
 
  • Time
  • Show
Clear All
new posts
  • mlammert
    Senior Member
    • Dec 2007
    • 373

    Mark's Statements Build Thread

    Hey everyone,

    I have been drooling over and pestering people long enough on the aspects of building the Statements... So, I am finally ready to start building my own...

    I have never built a set of speakers before; except for maybe a sub box back in my college days... However, I would say that I am an average to above-average wood worker... So, I have decided to take the design of my particular Statements build up a notch...

    I take a very analytical approach to my wood working... Very calculated and very thought out...

    At the writing of this, I am about 98% completed with the calculations and designs of my speakers... In the next few posts I will be showing how I came to my calculations and how I designed all the pieces of the speaker...

    Thanks to all who have helped me thus far and thanks to all who I am sure will help me more with the actual build!!! This is an awesome community...

    Mark
  • mlammert
    Senior Member
    • Dec 2007
    • 373

    #2
    How I Came Up with the New Size and Volume

    Since my new Statements were going to have a different footprint (shape of bottom of speaker) I have to calculate how the new footprint will affect the height needed to get the proper air volume inside the speaker...

    The following are my calculations on how I determined the exact air volume of the original Statements and then used that to figure out the air volume and ultimate shape of my new Statements...

    Please, let me know if anybody sees any glaringly wrong calculations here... Or, if anybody has any questions regarding my logic...

    Here it goes:

    Original Volume for Original Statements Speakers
    All Dimensions Taken from Statements AutoCAD Layout PDF from Curt's Web Site


    Overall Volume of Speaker Cabinet = 53.5 x 10 x 14.5 = 7757.500 cu in

    Volume of Internal Bracing and Midrange Enclosures:

    Shelf Brace = 0.75 x 10 x 14.5 x 1 = 108.750 cu in
    Cut Out in Shelf Brace = 0.75 x 8 x 12.5 x 1 = -75.000 cu in
    Midrange Enclosure Top and Bottom = 0.75 x 6.5 x 14.5 x 4 = 282.750 cu in
    Midrange Enclosure Sides = 0.75 x 5 x 14.5 x 4 = 217.500 cu in
    Midrange Void = 5 x 5 x 14.5 x 2 = 725.000 cu in
    Midrange Side Braces = 0.75 x 1.75 x 16.25 x 4 = 85.313 cu in
    Back Brace = 0.75 x 5 x 10 x 2 = 75.000 cu in

    Overall Volume of Items Inside Speaker Cabinet = 1419.313 cu in

    NOTE: Speaker Volume and Port Volume and Crossover Volume will remain consistent across original speakers and my new speakers so those volumes will not be factored into these calculations

    Overall Air Volume = 7757.5 - 1419.313 = 6338.187 cu in

    New Volume for Mark’s Speakers
    All Figures were Calculated Using Google SketchUp and Rounded to the Thousandth of an Inch


    Volume of Internal Bracing and Midrange Enclosures:
    Plywood Side Stiffeners = 34.877 cu in x 8 = 279.016 cu in
    Top and Bottom Braces = 104.630 cu in x 2 = 209.260 cu in
    Large Vented Braces = 51.376 cu in x 2 = 102.752 cu in
    Small Vented Braces = 27.000 cu in x 2 = 54.000 cu in
    Midrange Braces = 88.776 cu in x 4 = 355.104 cu in
    Midrange Walls = 62.496 cu in x 4 = 249.984 cu in
    Midrange Void = 5 x 5 x 18 x 2 = 900.000 cu in

    Overall Volume of Items Inside Speaker Cabinet = 2150.116 cu in

    Overall Air Volume of Original Speakers = 6338.187 cu in

    Overall Volume of New Speaker = 2150.116 + 6338.187 = 8488.303 cu in

    Internal Bottom of New Speakers = 139.507 sq in
    Side Height of New Speakers = 8488.303cu in / 139.507 sq in = 60.844 in

    We will round this figure up to an even 61 inches for the height of the sides of the speaker cabinet.


    So, that's it... Again, if anybody sees any stupid mistakes or has any questions about how or why I did what I did, please let me know...

    In the next couple posts I will be showing the various parts of the speakers as I designed them in Google SketchUp...

    Thanks,
    Mark

    Comment

    • mlammert
      Senior Member
      • Dec 2007
      • 373

      #3
      Some Preliminary Pictures

      Here are some preliminary renderings of the cabinets...

      From left to right you can see front, angled, and side views...

      The last image is from the back wit the right side panel removed so that you can see the internal construction and bracing...

      The only thing left to design/render is where I am going to put the port... A tube port is kind of out of the question due to the curved back of the speaker...

      Curt was kind enough to calculate a 2.25" x 8" port opening 14" long that should provide the same tuning frequency as the original 3" port...

      So, I am thinking of doing that type of port either out the back towards the bottom of the speaker... Or, possibly do that type of port through the top of the speaker which angles back slightly...

      BTW, I got the idea of the curved back from this web site:


      Mark

      Click image for larger version

Name:	marks_statements_angles.jpg
Views:	1549
Size:	50.1 KB
ID:	851123
      Last edited by theSven; 02 May 2023, 12:28 Tuesday. Reason: Update image location

      Comment

      • TacoD
        Super Senior Member
        • Feb 2004
        • 1078

        #4
        I like your cabinet plans, the curves make it more "friendly". Sonus Faber is able to put the ports in the back, so I see no reason you cannot do the same.

        A bottom port will alter the tuning frequency due to the boundary loading of the floor.

        Comment

        • FroDaddy
          Senior Member
          • Mar 2006
          • 274

          #5
          Your tweeter looks to be centered in relation to the height of the cabinet, or about 30.5in. You'll want your tweeter height to be about the same height as your ears are when sitting down in your room, so if 30.5in is the height then that's good. But typically it is around 38-42in. For me, Curt signed off on having the edge of the RS225 frame being 3/4in from the top of speaker. So you have some room to play with if desired.

          HTH

          Comment

          • mlammert
            Senior Member
            • Dec 2007
            • 373

            #6
            Originally posted by FroDaddy
            Your tweeter looks to be centered in relation to the height of the cabinet, or about 30.5in. You'll want your tweeter height to be about the same height as your ears are when sitting down in your room, so if 30.5in is the height then that's good. But typically it is around 38-42in.
            Hey FroDaddy,

            Thanks for the look over... Just to clarify, the center of my tweeter is exactly 38" from the floor in my speaker design... I don't know how you gauged it so perfectly, but the center of the tweeter is exactly 30.5 inch from the horizontal line which is towards the bottom of the speaker... Then, the horizontal line is 7.5 inches from the floor... Thus, making the tweeter's center 38 inches from the floor... FYI, the horizontal line is a "decorative groove" that will be cut into the wood...

            These types of comments/questions/suggestions are awesome... Thank you so much...

            Mark

            Comment

            • cobblepots
              Senior Member
              • May 2008
              • 102

              #7
              My suggestion for the port is this:

              Put it on the bottom between the lowest shelf and the base. If you cut a circle on the flat side of the board, you can then use a rabbeting bit on the "curved" side to get the flush look. This will make the port go straight into the box as opposed to being at an angle and also not have some of the edges raised off the surface. I don't think that the curve is so great that you can't VERY carefully create a flush recess for the port flange. Someone correct me if I'm wrong but port placement doesn't matter too much just as long as it isn't directly behind a woofer and not next to a wall or baffle.

              Great idea plans though and goodluck!

              Comment

              • Curt C
                Senior Member
                • Feb 2005
                • 791

                #8
                Originally posted by mlammert
                The only thing left to design/render is where I am going to put the port... A tube port is kind of out of the question due to the curved back of the speaker...

                Mark
                I didn't go through all the calculations Mark, but it looks correct at a casaul glance... :T

                Are the very bottom and top compartments in your design dead space? I assumed you would be adding the base as Jim did. I may be able to suggest a better port option once I get my addled brain wrapped around your design...

                C
                Curt's Speaker Design Works

                Comment

                • mlammert
                  Senior Member
                  • Dec 2007
                  • 373

                  #9
                  Hey Curt,

                  Thanks for taking a look at my build thread...

                  Yes, the very top and bottom portions of the speaker are dead space...

                  Basically, I didn't want feet or a platform of any sort at the bottom so I created the dead space at the bottom to lift the tweeter (and other drivers) up to the appropriate ear-level height... I then added the dead space at the top to "balance" the speaker vertically...

                  I decided to slope the top back to give it that little extra something... Purely aesthetic... The top angle is the same angle as the sides...

                  If you have the time to think about the port, that would be awesome!!!

                  All I have to do is nail down a good port design and I am ready to finalize the CAD file and start cutting wood...

                  Thanks,
                  Mark

                  Comment

                  • Curt C
                    Senior Member
                    • Feb 2005
                    • 791

                    #10
                    Ah Ha!

                    Being always the frugal Scot, I hate to see anything wasted. How much extra volume is in each of those compartments?

                    Edit: I see now that its 12 liters if I followed your posts correctly. This is actually a good thing, and I'd suggest you add it to the woofer volume. You see, Jim and I 'cheated' the woofers a bit to keep the overall size of Statements manageable. Since this constraint is not applicable to you, adding the 'extra' 24 liters will result in an f3 3 Hz lower. :B

                    One possibility would be a 2" x 4" flared port in each of what 'was' the dead space compartments. I would think these would fit acceptabley in spite of the curve, and will only have slightly more airspeed than the single 3" x 5" port. The advantage of 2 ports being symetrical acoustic loading of the woofers. If you can make them fit, a pair of 3" x 10" would exhibit lower port airspeeds, and you could probably forgo the large flares.

                    C
                    Curt's Speaker Design Works

                    Comment

                    • mlammert
                      Senior Member
                      • Dec 2007
                      • 373

                      #11
                      Originally posted by Curt C
                      How much extra volume is in each of those compartments?
                      Hey Curt,

                      The speaker is basically shaped like a trapezoid; so...

                      Speaker front is 11.5 inches wide
                      Speaker back is 7 inches wide
                      Speaker sides are 18 inches deep
                      The bottom dead area is 6.75 inches tall (5.25 inches tall internally taking into account the two .75 inch thick braces at the top and bottom of the dead area)

                      941.576 cu in including the two braces
                      732.337 cu in in between the two braces

                      I would have to do some heavy hitting math (at least for me :P ) to figure out the volume of the top dead area since three of its sides are angled...

                      I hope this was the info you were asking for... If not, let me know and I can try again...

                      Thanks,
                      Mark

                      Comment

                      • Curt C
                        Senior Member
                        • Feb 2005
                        • 791

                        #12
                        Lets just call them 24 liters together and call it good :W
                        see my edited post above...

                        C
                        Curt's Speaker Design Works

                        Comment

                        • mlammert
                          Senior Member
                          • Dec 2007
                          • 373

                          #13
                          Hey Curt,

                          Gotcha... I just saw the EDITS to your post...

                          I am sorry but I am REALLY confused now...

                          I get what you mean by adding the dead space to the main speaker volume... And, I did a quick liters to cubic inches conversion and I totally understand how you came to those figures now...

                          Lets just call them 24 liters together and call it good
                          The part that I am confused about (and this is where my speaker building knowledge lacks) is that it seems you are "roughly" adding "approximately" 24 liters to the volume of the speakers and none of the measures seem very "exact"... Don't we have to be exact in the measurements of air volume for everything to sound correct??? You don't seem to be that concerned??? I obviously trust your judgment on this... But, could you please just help me understand why air volume in this case seems to not be an exacting science...

                          And, sorry, I am also a bit confused on your recent suggestion of the different port sizes... I get what you mean by using two ports for proper balancing... That makes sense...

                          But, you threw out two 2"x4" or two 3"x10" ports... Those seem like large differences... Could you explain what those difference do to the sound??? Are they round or rectangular???

                          Sorry for the onslaught of questions... I thought I understood everything and was going good... You kind of threw my a curve ball... But, that is GOOD... That is how you learn and progress forward!!!

                          Thanks,
                          Mark

                          Comment

                          • Dennis H
                            Ultra Senior Member
                            • Aug 2002
                            • 3791

                            #14
                            Don't we have to be exact in the measurements of air volume for everything to sound correct??? You don't seem to be that concerned???
                            Welcome to the real world of speaker building. In an enclosure that big, +/- a liter or two will only change the tuning a fraction of a Hz. So you really don't need to calculate everying to 1/1000 of a cu.in. I think Curt's suggestion can be summarized as bigger enclosures (within reason) are better than smaller ones and you can fine tune the response with the port.

                            Comment

                            • mlammert
                              Senior Member
                              • Dec 2007
                              • 373

                              #15
                              Hey Dennis,

                              Thanks for the explanation of Curt's response... I see what you both mean now...

                              In an enclosure that big, +/- a liter or two will only change the tuning a fraction of a Hz. So you really don't need to calculate everything to 1/1000 of a cu.in.
                              That is crazy... I would have never thought that... That is really cool...

                              Okay, so I am going to take Curt's suggestion and re-build the speaker enclosure so that the two "dead spaces" are no longer "dead" and actually make them part of the cabinet...

                              I will work on the new CAD file and post new pictures soon...

                              After I do that, I guess I am back to the whole issue of ports again...

                              I think Curt's suggestion can be summarized as bigger enclosures (within reason) are better than smaller ones and you can fine tune the response with the port.
                              So, my next question(s) will be:

                              Once I build the speaker to the newly suggested specs, how do I (a) tune the port and (b) know when the port is properly tuned???

                              Thanks again guys... I am learning so much and it is only the first day!!!

                              Mark

                              Comment

                              • Jim Holtz
                                Ultra Senior Member
                                • Mar 2005
                                • 3223

                                #16
                                Hi Mark,

                                Curt is a box tuning master. ;x( Go with his port recommendations and you will be happy.

                                Jim

                                Comment

                                • mlammert
                                  Senior Member
                                  • Dec 2007
                                  • 373

                                  #17
                                  Hey guys,

                                  Attached is a new CAD drawing of my Statements with the "dead areas" now integrated into the speaker cabinet... Took no time at all... I love Google SketchUp...

                                  You will see that I simply used my "vented" braces at the top and bottom instead of using the original solid braces...

                                  I also chamfered the top of the side walls and created a top "lid" for the speakers with chamfered sides as well... Now I have a speaker top with no end grain... Nice... 8)

                                  I guess now I am back to my questions of a couple minutes ago:

                                  Thanks guys; this is exciting!!! :T

                                  Mark

                                  Click image for larger version

Name:	statement_no_dead_space.jpg
Views:	1040
Size:	50.8 KB
ID:	851126
                                  Last edited by theSven; 02 May 2023, 12:29 Tuesday. Reason: Update image location

                                  Comment

                                  • Dennis H
                                    Ultra Senior Member
                                    • Aug 2002
                                    • 3791

                                    #18
                                    That is crazy... I would have never thought that... That is really cool...
                                    A pic is always worth a word or two. Here's a quicky in ISDOnline, 4 boxes all tuned to 27 Hz by adjusting the port -- 100, 110, 120 and 130 liters net volume.

                                    Click image for larger version

Name:	box-size-100-140.gif
Views:	4732
Size:	4.7 KB
ID:	851130
                                    Last edited by theSven; 02 May 2023, 12:19 Tuesday. Reason: Update image location

                                    Comment

                                    • yousuredo2
                                      Senior Member
                                      • Jun 2006
                                      • 206

                                      #19
                                      Nice cabinet design, I Look forward to seeing these completed.
                                      Please take plenty of build pic's.
                                      My System
                                      ~ BenQ w5000 DLP 1080p Projector
                                      ~ Sony Bravia SXRD KDS-60A3000
                                      ~ Onkyo tx sr805
                                      ~ Sony PS.3
                                      ~ Xbox 360
                                      ~ Natalie P's Main L/R
                                      ~ Polk Csi A6 -Center
                                      ~ Polk RTi6 Rears
                                      ~ Behringer ep2500
                                      ~ Behringer Fbq 2496

                                      Comment

                                      • mlammert
                                        Senior Member
                                        • Dec 2007
                                        • 373

                                        #20
                                        Thanks for all the positive and helpful feedback guys...

                                        Dennis -- not being familiar with the graph you produced, I take it that the graph is showing the four boxes and how the large difference in net volume is actually making a very small difference in overall performance... As seen by the very slight variation in where the four plots curve off at the left???

                                        Curt -- if I could ask you -- so if I go with this new enclosure design with the 24 liters added to the net volume as you suggested, what types/sizes/etc ports should I go with???

                                        I didn't realize that my speaker "build" was going to take a curve and go into speaker "design"... I am treading in unfamiliar waters... Which is scary 8O and also cool :P ...

                                        I am really trying to understand everything that you guys are talking about so as many detailed or baby-step instructions you can give to help me understand better would be greatly appreciated...

                                        Thanks again this is very exciting!!!

                                        BTW -- yousuredo -- yes, I plan to take many build pics once I start cutting wood... Hopefully I might even be able to use my home made CNC machine to cut all the parts... That would be the icing on the cake...

                                        Mark

                                        Comment

                                        • Dennis H
                                          Ultra Senior Member
                                          • Aug 2002
                                          • 3791

                                          #21
                                          Dennis -- not being familiar with the graph you produced, I take it that the graph is showing the four boxes and how the large difference in net volume is actually making a very small difference in overall performance...
                                          Yup, you got it. 30% change in box volume and not all that much change in frequency response. So, you can put away your micrometer. Just listen to what guru Curt tells you.

                                          Comment

                                          • mlammert
                                            Senior Member
                                            • Dec 2007
                                            • 373

                                            #22
                                            Awesome... Thanks Dennis...

                                            I will definitely listen to everything Curt has to share!!!

                                            FYI, I am in the process of taking the new speaker design (as shown in post 17) and making dimensional cut diagrams of all the pieces...

                                            I will obviously need these for when I start cutting wood... And, I wasn't for sure if Curt would need them for any port calculations he is willing to do...

                                            Thanks,
                                            Mark

                                            Comment

                                            • mlammert
                                              Senior Member
                                              • Dec 2007
                                              • 373

                                              #23
                                              Hey guys,

                                              Attached is a graphic of the dimensions of the main parts of the speaker and then also a full view of the assembled speaker with overall dimensions...

                                              Let me know if anybody has any questions or comments or sees any problems with this...

                                              I think all that is left is to determine the ports for the speaker... :T

                                              Thanks again for everyone's help so far!!!

                                              Mark

                                              Click image for larger version

Name:	dimentional_speaker_layouts.jpg
Views:	1045
Size:	86.5 KB
ID:	851131
                                              Last edited by theSven; 02 May 2023, 12:29 Tuesday. Reason: Update image location

                                              Comment

                                              • impala454
                                                Ultra Senior Member
                                                • Oct 2007
                                                • 3814

                                                #24
                                                Wow those suckers are going to be enormous! Be sure to share those drawings if you're so inclined
                                                -Chuck

                                                Comment

                                                • dlneubec
                                                  Super Senior Member
                                                  • Jan 2006
                                                  • 1454

                                                  #25
                                                  One thing to consider, is whether you might be creating some possible cabinet resonaces as you narrow it down toward the back, along the open back mid walls. You will have a narrow opening, that tapers to nothing, between the speaker inside walls and outside of the boxes for the open back mids. If this is a ported system, you have air moving along those narrow gaps from the top or bottom woofers, or both, if the port is centered. These narrow gaps could act as ports on their own, causing some odd resonances, which might even effect the peformance of your main port. At first this seems like a non issue, but Roman Bednarek reported resonance problems with a design he had which had this same type of situation, two large volumes separated by a narrow section. It was easily heard and very annoying according to him and he had to scrap the box deisgn and start over.

                                                  Obviously, this was not a problem with the original statements, but you are narrowing them down quite significantly. I'd be concerned about it, if I were you. Maybe you could use pvc pipe for the open back mids. It has 1/4" walls, and since it is rounded, it has a much smaller footpring inside the box and therefore would not have nearly as much potential for creating a "port" inside the box as the square boxes, with 3/4" sides. Food for thought.
                                                  Dan N.

                                                  Comment

                                                  • mlammert
                                                    Senior Member
                                                    • Dec 2007
                                                    • 373

                                                    #26
                                                    Hey Dan,

                                                    Thank you VERY much for pointing this out... Hmm... That is quite the predicament...

                                                    I know I had talked to Curt a few days ago and he is suggesting two ports; one at the top and one at the bottom...

                                                    I uploaded the cabinet dimensions so that Curt could finalize on a diameter and length for me... I know he originally said something about either two 2" x 4" ports or two 3" by 10" ports... Wasn't quite sure how I should proceed yet...

                                                    Dan, your main concern seemed to be air moving in the small narrow cavity when I assume the port is at the top or bottom or middle... But, if/when I go with Curt's plan of two ports (one at top and one at bottom) does this issue go away or lessen, in your opinion???

                                                    And, to Dan and any others, what would some potential pro's and con's be for using the PVC for the mid enclosures??? I thought at one point there was a discussion on some thread about someone trying the mid enclosure with PVC and it didn't work out for some reason... However, I could be totally wrong on that...

                                                    Thanks Dan, I appreciate the warning...

                                                    Anybody else have any comments on this situation???

                                                    Thanks guys,
                                                    Mark

                                                    Comment

                                                    • dlneubec
                                                      Super Senior Member
                                                      • Jan 2006
                                                      • 1454

                                                      #27
                                                      Well, Curt is the guy to give you feedback on this. It is his and Jim's design and they know what they are doing. I just thought that this issue might have been overlooked in your new design. I would think, however, if you are using two ports, one top and one bottom, you could split the cabinets into two separate volumes. That might reduce air movement along the length of the cabinet. I'll search on the PE forum to see if I can find Roman's post about the problem he had.

                                                      As far as the PVC pipe, I used it in my SoundRounds design for the mids and had no problem with it. Being a tube it is naturally very rigid and can have much smaller sidewalls, hence the use of sonotubes for subs. That said, I'm sure Curt and Jim considered PVC in the original design and decided to go with an mdf box instead.
                                                      Dan N.

                                                      Comment

                                                      • dlneubec
                                                        Super Senior Member
                                                        • Jan 2006
                                                        • 1454

                                                        #28
                                                        Here is the PE thread where Roman talks about his similar problem.
                                                        50lbs of mdf trash
                                                        Dan N.

                                                        Comment

                                                        • Curt C
                                                          Senior Member
                                                          • Feb 2005
                                                          • 791

                                                          #29
                                                          Originally posted by mlammert
                                                          I uploaded the cabinet dimensions so that Curt could finalize on a diameter and length for me... I know he originally said something about either two 2" x 4" ports or two 3" by 10" ports... Wasn't quite sure how I should proceed yet...

                                                          Dan, your main concern seemed to be air moving in the small narrow cavity when I assume the port is at the top or bottom or middle... But, if/when I go with Curt's plan of two ports (one at top and one at bottom) does this issue go away or lessen, in your opinion???

                                                          And, to Dan and any others, what would some potential pro's and con's be for using the PVC for the mid enclosures??? I thought at one point there was a discussion on some thread about someone trying the mid enclosure with PVC and it didn't work out for some reason... However, I could be totally wrong on that...

                                                          Mark
                                                          Let me elaborate on my earlier post:
                                                          “One possibility would be a 2" x 4" flared port in each of what 'was' the dead space compartments. I would think these would fit acceptably in spite of the curve, and will only have slightly more airspeed than the single 3" x 5" port. The advantage of 2 ports being symmetrical acoustic loading of the woofers. If you can make them fit, a pair of 3" x 10" would exhibit lower port airspeeds, and you could probably forgo the large flares.”

                                                          The advantage of ‘symmetrical acoustic loading', is each woofer will ‘see’ for the most part, only the port nearest to it, and each end of the cabinet will ‘see’ the same instantaneous air pressure at any given moment. Consequently, there will be little pressure differential around the midrange enclosures and as a consequence little excitement of any cavity resonances created as a result. The open spaces adjacent and between the mid tunnels certainly could be lined / filled with foam / polyfill / whatever to eliminate any chance of resonance.

                                                          The port choice has to do with port airspeed and what will fit on the rear enclosure panel.
                                                          Dual 2” port will work, but in my experience, must be flared to minimize port noise. The twin 3” ports would be the better choice, as the port airflow is half of the 2” ports, and in practice one could get by with little or no port flare. The 3” ports would be my preference if you can make them fit on your baffle. I’m put them in the void between the first and second brace of the top/bottom and equally spaced from the tweeter height on the cabinet. (Equidistant from the woofers.)

                                                          5” PVC is tough to come by, and expensive when you do find it.

                                                          Let me know if I can further confound this conundrum. :B

                                                          C
                                                          Curt's Speaker Design Works

                                                          Comment

                                                          • David_D
                                                            Senior Member
                                                            • Feb 2008
                                                            • 197

                                                            #30
                                                            Hi Mark,
                                                            You are undertaking quite a project. They will be a “Statement” to say the least. I really like your tapered & curved back design.
                                                            One thing I did notice on your layout is that there is better then 2 feet of un-braced side panels across the two mid chambers. You may set your self up for some cabinet resonances in that area. You may want to consider some way to tie the mid chambers to the side walls.
                                                            Looking great!
                                                            -David

                                                            As we try and consider
                                                            We receive all we venture to give

                                                            Comment

                                                            • mlammert
                                                              Senior Member
                                                              • Dec 2007
                                                              • 373

                                                              #31
                                                              Dan, Curt and Dave, thank you guys SO much for your comments!!!

                                                              Curt, I am pretty sure I understand exactly what you are talking about now regarding the ports... Give me a little time and I will mock-up some new drawings with the 3" x 10" ports placed as you described...

                                                              Dan, thanks for that link... I am going to read through that and hopefully with Curt's suggestions and information, it will not be an issue with the new port design...

                                                              David, thank you very much... And, yes, thanks for pointing that out... I am going to re-configure my braces when I add the ports to the drawings and hopefully that will alleviate the issue you pointed out...

                                                              Thanks again guys... My confidence is building back up again... Thank you all SO much!!!

                                                              Mark

                                                              Comment

                                                              • Curt C
                                                                Senior Member
                                                                • Feb 2005
                                                                • 791

                                                                #32
                                                                Originally posted by mlammert
                                                                David, thank you very much... And, yes, thanks for pointing that out... I am going to re-configure my braces when I add the ports to the drawings and hopefully that will alleviate the issue you pointed out...
                                                                A couple of vertical braces on each side tying the mid cabs to the external side panels should be sufficient.

                                                                I assumed you'd left them off the original drawing for clarity. 8)

                                                                C
                                                                Curt's Speaker Design Works

                                                                Comment

                                                                • mlammert
                                                                  Senior Member
                                                                  • Dec 2007
                                                                  • 373

                                                                  #33
                                                                  Hey Curt,

                                                                  Ha ha, no I didn't leave them off for clarity... Slight oversight... ops:

                                                                  Please don't assume anything with my designs or questions... Total "noobie" here who is learning as he goes... :P

                                                                  I am also going to color-code the various parts on the next drawing that I post so that communication about the design can be more straightforward... 8)

                                                                  Thanks again!!!

                                                                  Mark

                                                                  Comment

                                                                  • mlammert
                                                                    Senior Member
                                                                    • Dec 2007
                                                                    • 373

                                                                    #34
                                                                    Hey everyone,

                                                                    Attached you will find a new CAD drawing of the speakers...

                                                                    Couple things to point out:

                                                                    1) I color-coded the various pieces to make discussion easier...

                                                                    2) I added the two 3" x 10" ports and centered them between the tweeter center-line and the top and bottom of the speaker as Curt suggested... Thanks you Curt...

                                                                    3) I added a small vented brace in the center of the speaker behind the tweeter for more bracing in the middle... Thanks David...

                                                                    4) I added additional "stub outs" on the sides of the midrange braces that attach to the sides of the speaker for more bracing in the middle... Thanks David...

                                                                    After reading the post that Dan pointed out... And, Curt's feedback on the port's "symmetrical acoustic loading" and stuffing in the narrow cavity, I am not as worried about any "odd resonances" caused by the narrow midrange enclosure gaps... However, I would still appreciate some feedback on that from people more knowledgeable than me...

                                                                    So at this point, I would kindly ask for some more feedback on the ports and overall structure of the speaker...

                                                                    Thanks again for everyone's help, support and knowledge!!!

                                                                    Thanks,
                                                                    Mark

                                                                    Click image for larger version

Name:	color_coded_speakers.jpg
Views:	1088
Size:	94.2 KB
ID:	851132
                                                                    Last edited by theSven; 02 May 2023, 12:29 Tuesday. Reason: Update image location

                                                                    Comment

                                                                    • Dennis H
                                                                      Ultra Senior Member
                                                                      • Aug 2002
                                                                      • 3791

                                                                      #35
                                                                      After reading the post that Dan pointed out... And, Curt's feedback on the port's "symmetrical acoustic loading" and stuffing in the narrow cavity, I am not as worried about any "odd resonances" caused by the narrow midrange enclosure gaps... However, I would still appreciate some feedback on that from people more knowledgeable than me...
                                                                      Like Curt said earlier, stuff the center part of the enclosure around the mid tunnels with fiberglass or polyfill.

                                                                      Comment

                                                                      • dlneubec
                                                                        Super Senior Member
                                                                        • Jan 2006
                                                                        • 1454

                                                                        #36
                                                                        I agree with the others, the dual ports top and bottom plus stuffing the mid section of the box should resolve any concern you have about internal "port-like" resonances.

                                                                        Those are some very nice looking boxes :T .
                                                                        Dan N.

                                                                        Comment

                                                                        • Curt C
                                                                          Senior Member
                                                                          • Feb 2005
                                                                          • 791

                                                                          #37
                                                                          Originally posted by mlammert
                                                                          So at this point, I would kindly ask for some more feedback on the ports and overall structure of the speaker...
                                                                          IMO,
                                                                          The input of the ports are too close to having a direct path to the back of the woofers. I'd move them out to between the green and yellow braces.

                                                                          Doubling up the thickness of the yellow braces is unnecessary, as it will do little to increase the stiffness of the side panel.

                                                                          Note my crudely altered example below: I'll still suggest the vertical braces will perform better than the extra horizontal brace. This ties the enclosure sides and the mid enclosures together making a very strong center section.

                                                                          Optional: a vertical brace running between the yellow and green braces. This would support the inner 'free' end of the port and allow for a 3/4" flare at each end of the port.

                                                                          C

                                                                          Click image for larger version

Name:	Marks_Statement_enclosure.JPG
Views:	568
Size:	69.0 KB
ID:	851134
                                                                          Last edited by theSven; 02 May 2023, 12:30 Tuesday. Reason: Update image location
                                                                          Curt's Speaker Design Works

                                                                          Comment

                                                                          • mlammert
                                                                            Senior Member
                                                                            • Dec 2007
                                                                            • 373

                                                                            #38
                                                                            Thank for all the great feedback, Curt!!!

                                                                            The input of the ports are too close to having a direct path to the back of the woofers. I'd move them out to between the green and yellow braces.
                                                                            Gotcha... I will move the ports so that they are in between the yellow and green braces... I will reflect this in my next mock-up...

                                                                            Doubling up the thickness of the yellow braces is unnecessary, as it will do little to increase the stiffness of the side panel.
                                                                            I have these doubled up because the light-blue top and bottom parts of the front baffle are separate pieces of wood from the purple part of the baffle... I am planning ahead to my finishing process where the light-blue pieces of the baffle will be one wood species and the purple part of the baffle will be another... I figured the doubled up yellow brace would help in the support the separate baffle pieces...

                                                                            I'll still suggest the vertical braces will perform better than the extra horizontal brace. This ties the enclosure sides and the mid enclosures together making a very strong center section.
                                                                            Sounds good... I will incorporate something like those into my next design... I will probably only be able to do one vertical brace on each side due to how skinny the gap gets towards the back of the cabinet based on the angled sides of the cabinet...

                                                                            A vertical brace running between the yellow and green braces. This would support the inner 'free' end of the port and allow for a 3/4" flare at each end of the port.
                                                                            Makes sense... I can mock that up in my next design as well... Question: Would the vertical brace be flush with the end of the PVC pipe??? Meaning that when I route the 3/4" flare I would be removing some wood and some PVC plastic at the same time??? Or, am I not thinking that through properly???

                                                                            Okay, sounds like I have some design work when I get home tonight...

                                                                            Thanks again for all your feedback and help!!!

                                                                            Mark

                                                                            Comment

                                                                            • mlammert
                                                                              Senior Member
                                                                              • Dec 2007
                                                                              • 373

                                                                              #39
                                                                              Hey guys,

                                                                              Attached is a new design incorporating the suggestions that Curt made...

                                                                              1) The ports have been moved further away from the woofers... I modified the green and yellow braces (wide cross strut) so that I could create and attach a vertical brace at the end of the port...

                                                                              The vertical brace at the end of the port is flush with the end of the PVC... I can change that if I was incorrect in doing so...

                                                                              2) I created yellow vertical braces on the sides of the midrange enclosures that connect the enclosures to the sides of the speaker box...

                                                                              Let me know what you guys think!!!

                                                                              Thanks,
                                                                              Mark

                                                                              Click image for larger version

Name:	new_port_positions.jpg
Views:	565
Size:	88.1 KB
ID:	851141
                                                                              Last edited by theSven; 02 May 2023, 12:30 Tuesday. Reason: Update image location

                                                                              Comment

                                                                              • David_D
                                                                                Senior Member
                                                                                • Feb 2008
                                                                                • 197

                                                                                #40
                                                                                Those look awesome Mark.
                                                                                I am really interested how you attack the curved backs.
                                                                                Let’s make some saw dust!
                                                                                -David

                                                                                As we try and consider
                                                                                We receive all we venture to give

                                                                                Comment

                                                                                • Curt C
                                                                                  Senior Member
                                                                                  • Feb 2005
                                                                                  • 791

                                                                                  #41
                                                                                  Two thumbs up! :T :T
                                                                                  Curt's Speaker Design Works

                                                                                  Comment

                                                                                  • mlammert
                                                                                    Senior Member
                                                                                    • Dec 2007
                                                                                    • 373

                                                                                    #42
                                                                                    AWESOME!!! Thanks Dave and Curt!!!

                                                                                    Very exciting...

                                                                                    Curt, question: Was I correct in making the vertical braces flush with the end of the PVC pipe??? Meaning that when I route the 3/4" flare I would be removing some wood and some PVC plastic at the same time???

                                                                                    Also, is 3/4" flare absolutely necessary or could I make it 1/2"??? Just trying to figure out if I have to buy any router bits...

                                                                                    I was also thinking of using a 1/4" round over on all the internal braces that have holes in them... Is that a standard practice???

                                                                                    Dave, yeah I have some ideas on how I want to tackle the curve of the back... My initial thought is to laminate various strips of MDF together... If I orient them so that the end grain faces the speaker box that will allow me to cut the curve into the various strips using my band saw and then glue them all together and smooth the curve using a belt sander... Also, if I do it this way I can then use the miter saw to cut perfect angles at the top and bottom and also cut out the midrange openings using the miter saw as well...

                                                                                    I will mock-up the actual back curves in SketchUp once I am to that point so that this all makes more sense...

                                                                                    Thanks again guys!!!

                                                                                    Looks like I will be buying some MDF this weekend...

                                                                                    Mark

                                                                                    Comment

                                                                                    • Curt C
                                                                                      Senior Member
                                                                                      • Feb 2005
                                                                                      • 791

                                                                                      #43
                                                                                      Originally posted by mlammert
                                                                                      Curt, question: Was I correct in making the vertical braces flush with the end of the PVC pipe??? Meaning that when I route the 3/4" flare I would be removing some wood and some PVC plastic at the same time???
                                                                                      That should be fine. Alternatively, you could add a backer board to the MDF so the flare is all 'in' the MDF and the end of the pipe is supported more securely.

                                                                                      Originally posted by mlammert
                                                                                      Also, is 3/4" flare absolutely necessary or could I make it 1/2"??? Just trying to figure out if I have to buy any router bits...
                                                                                      That will be fine as well. A 3/4" roundover is pretty handy, but its not indispensable.

                                                                                      Originally posted by mlammert
                                                                                      I was also thinking of using a 1/4" round over on all the internal braces that have holes in them... Is that a standard practice???
                                                                                      Lots of folks do this, or something on that theme. While in most cases I don't think its strictly necessary, it certainly can't hurt.

                                                                                      Originally posted by mlammert
                                                                                      Dave, yeah I have some ideas on how I want to tackle the curve of the back... My initial thought is to laminate various strips of MDF together... If I orient them so that the end grain faces the speaker box that will allow me to cut the curve into the various strips using my band saw and then glue them all together and smooth the curve using a belt sander... Also, if I do it this way I can then use the miter saw to cut perfect angles at the top and bottom and also cut out the midrange openings using the miter saw as well...
                                                                                      Another possibility: You can easily make a jig:
                                                                                      For example, you can lay out your curve on the side of a couple of 8ft 2x8's. Rip appropriate lengths of 1/4" MDF/HDF/masonite. Glue 2 and clamp between the two halves of your jig. When dry, glue the third layer, etc. until you've built up to the thickness you desire. -Smooth curve with little sanding...

                                                                                      C
                                                                                      Curt's Speaker Design Works

                                                                                      Comment

                                                                                      • mlammert
                                                                                        Senior Member
                                                                                        • Dec 2007
                                                                                        • 373

                                                                                        #44
                                                                                        Alternatively, you could add a backer board to the MDF so the flare is all 'in' the MDF and the end of the pipe is supported more securely.
                                                                                        Okay, here is where my inexperience is going to make me ask very particular questions again...

                                                                                        So, does my attached drawing correctly show what you are describing??? And, if so, doesn't the extra 3/4" flare length alter the port tuning since the port is actually a little longer than 10" now??? Or, is it just inaudible at that point??? Or, am I just way off base???

                                                                                        You can easily make a jig...
                                                                                        You read my mind... That is exactly how I was thinking of doing it... Instead of using the band saw to cut all the curves... Make my template and then use a pattern cutting router bit to keep sequentially adding thickness...

                                                                                        Thanks again,
                                                                                        Mark

                                                                                        Click image for larger version

Name:	pvc_mdf_port_diagram.jpg
Views:	546
Size:	8.4 KB
ID:	851147
                                                                                        Last edited by theSven; 02 May 2023, 12:31 Tuesday. Reason: Update image location

                                                                                        Comment

                                                                                        • Curt C
                                                                                          Senior Member
                                                                                          • Feb 2005
                                                                                          • 791

                                                                                          #45
                                                                                          Originally posted by mlammert
                                                                                          Okay, here is where my inexperience is going to make me ask very particular questions again...

                                                                                          So, does my attached drawing correctly show what you are describing??? And, if so, doesn't the extra 3/4" flare length alter the port tuning since the port is actually a little longer than 10" now??? Or, is it just inaudible at that point??? Or, am I just way off base???

                                                                                          You are exactly on point, Mark.

                                                                                          10" is for unflared, or minimally flared ports. The larger the flare, the longer the total port length has to be, but in our case, an inch either way will only affect the tuning by a few tenths of a Hz, so it is not a critical measurement. Call your 'new' port length 10.5" total with the 3/4" roundover 'flares'. :W

                                                                                          C
                                                                                          Curt's Speaker Design Works

                                                                                          Comment

                                                                                          Working...
                                                                                          😀
                                                                                          😂
                                                                                          🥰
                                                                                          😘
                                                                                          🤢
                                                                                          😎
                                                                                          😞
                                                                                          😡
                                                                                          👍
                                                                                          👎
                                                                                          Searching...Please wait.
                                                                                          An unexpected error was returned: 'Your submission could not be processed because you have logged in since the previous page was loaded.

                                                                                          Please push the back button and reload the previous window.'
                                                                                          An unexpected error was returned: 'Your submission could not be processed because the token has expired.

                                                                                          Please push the back button and reload the previous window.'
                                                                                          An internal error has occurred and the module cannot be displayed.
                                                                                          There are no results that meet this criteria.
                                                                                          Search Result for "|||"