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  • AviaTrix sealed MTM Question

    Concerning internal box volume:
    I know that Curt has cautioned that the Aviatrix sealed MTM is "volume specific".
    He said; "The AviaTrix Sealed design will utilize a crossover topology that is rather enclosure volume specific. This allowed me to put the design in an otherwise too small box, and still obtain reasonable low end extension.".
    I am crunching numbers for a custom build and any way I look at it, I would have to reduce the box volume by about 8% to utilize the Aviatrix kit(which I already have).
    My question is, by reducing volume by this amount, would "performance loss" be primarily confined to bottom end extension?
    These enclosures will be paired with stereo powered subs with a fixed low-pass centered on 80 Hz., so I am willing to "give up" some low-end response.
    But I would not want to do anything that would effect the overall sound, so if that would be the case, I will re-think this project.

    Thanks in advance for any responses.

  • #2
    Re: AviaTrix sealed MTM Question

    The "volume specific" bit is that he's used a trick to enable good bass in a too-small box. Look at the XO
    http://speakerdesignworks.com/AviaTrix_5.html

    See those two caps with the notation "delete in MLTL?" That's what he's talking about. A pair of parallel 500 uf caps yields a 1000uf capacitance. In series with the woofers, they pass high frequencies, but flatten and extend bass response. You can make the box smaller, with a fairly minor loss mostly in the bass flatness and extension, but I'd consider some alternatives, first.

    You've got an "8%" issue. That's 1.2L change in volume. Assuming Curt's dimensions, 3/4" MDF and including the brace, but with no allowance for driver volume, I get 14.94L internal volume. Make the large (20x11.5) panels from 1/2" MDF and you're at 16.46L. Add an extra brace to make up for stiffness lost due to thinner panels and your at 16.24L, about 8% high. It will matter which panel length you shorten; 10.75" deep or 18.6" tall brings you back to 15L. Don't change baffle width (6.5") if you can help it.

    How will you integrate the custom build into the room? Your question sounds like someone trying to fit a speaker into a specific space. You may not realize that the room placement relative to walls and large furniture has a far greater affect on sound quality than 8% internal volume.

    Fortunately, Curt's very thorough, and so he's included an XO option for near-wall placement; see the note on the tweeter circuit. But there are other issues with mounting locations, so tell us more!

    Have fun,
    Frank

    Comment


    • #3
      Re: AviaTrix sealed MTM Question

      Originally posted by fbov View Post
      The "volume specific" bit is that he's used a trick to enable good bass in a too-small box. Look at the XO
      http://speakerdesignworks.com/AviaTrix_5.html

      See those two caps with the notation "delete in MLTL?" That's what he's talking about. A pair of parallel 500 uf caps yields a 1000uf capacitance. In series with the woofers, they pass high frequencies, but flatten and extend bass response. You can make the box smaller, with a fairly minor loss mostly in the bass flatness and extension, but I'd consider some alternatives, first.

      You've got an "8%" issue. That's 1.2L change in volume. Assuming Curt's dimensions, 3/4" MDF and including the brace, but with no allowance for driver volume, I get 14.94L internal volume. Make the large (20x11.5) panels from 1/2" MDF and you're at 16.46L. Add an extra brace to make up for stiffness lost due to thinner panels and your at 16.24L, about 8% high. It will matter which panel length you shorten; 10.75" deep or 18.6" tall brings you back to 15L. Don't change baffle width (6.5") if you can help it.

      How will you integrate the custom build into the room? Your question sounds like someone trying to fit a speaker into a specific space. You may not realize that the room placement relative to walls and large furniture has a far greater affect on sound quality than 8% internal volume.

      Fortunately, Curt's very thorough, and so he's included an XO option for near-wall placement; see the note on the tweeter circuit. But there are other issues with mounting locations, so tell us more!

      Have fun,
      Frank
      Yes, I was contemplating installing the Aviatrixs in custom built-in shelving, but have rethought this and I am going to build the MTTL's and giving them a proper placement.
      But in case someone else needs a slightly smaller TMT sealed, I'll relate what I was thinking. The spaces I was looking at very closely resembled the PE .60Ft3 knock-down boxes;
      http://www.parts-express.com/pe/show...umber=300-7050
      These are the 1/2" birch units that are on sale for $40. With the braces "Swiss-cheesed", they work out to 13.8L Not ideal, but servicable according to your input.
      Me-I'm only a passing hobbyist, but have been enjoying this hobby for a long time. Suffice to say, my first system I purchased at the Grand opening of the second Circuit store in Washington DC(after Richmond). It was 1970 and I saved all summer and bought a Sansui Receiver, a pair of AR-6's and one of those AR turn-tables where the tone-arm moved transversely across the platter. LOL
      My DIY history started with a pair of Wayne J's Dayton Home Theater 2-ways, which I love and still use. Then I did a 5.1 Tritrix system. TL fronts, ported center and sealed MTM's for surrounds. The sealed surrounds never really did it for me and were hard to place due to their size and weight and were replaced with a 10 year old pair of Def. Tech. Bi-polar Floor-standers(BP7004's).
      So that is where I'm at now, The Tritrix TL's up front and the Def. Techs as surrounds. But it is now time to move the Trixs to the shop and go with something new up frt. I thought about another pair DT towers, but I want MTM frt.s and DT MTM's are seriously expensive and I'm not sure the bi-pole frt.s are right for this room.
      It's my understanding the Aviatrix's tweeters are a little more forward than the Tritrix's and that I could expect a little more mid-bass, especially with MTTL's. The two areas where the tritrix leaves me wanting a little more.
      One mistake I won't be making is burrying the X-overs, like I did in the Tritrixs, in case I want to make some adjustments in tweeter attenuation.
      One thing that Curt does is offer so much info on his builds that is a huge help for Noobie-types like me. He's awesome.
      It shouldn't take long to build the Aviatrix's(I'm retired and I bought the MDF today)and I'll post the results here
      I'm going to do something different as far as the cosmetics are concearned. I don't want to give it away, but the look of my DT towers has grown on me.
      Thanks for your interest.

      Comment


      • #4
        Re: AviaTrix sealed MTM Question

        My friend had a nice Sansui receiver back in the early 70's. An excellent unit...large, analog FM dial, I always thought "that's what a stereo receiver should look like." He had the Sansui speakers, but when I built my Speakerlab S2's, he got the parts kit/plans for some S'lab 7's because he was so impressed with just the 2-way S2's. I'd already had plenty of listening experience with the 7, and since he could afford the extra $$, he went with the 7's. I made the cabinets for those and he/we enjoyed that combo for years. The Sansui had plenty of clean power and were a terrific match for the 4-way 7's. The AR's were one of the more well thought-out speakers of that era, too. I came here over 13 years ago and Wayne J.'s website was the first one I was directed to. I had been trying textbook-formula XO's and pre-mades, but obviously, they were NOT working well. I built Wayne's DBP 2-way, with the 5.25" classic woofer, a BR-1 little brother. That one build convinced me I had a lot ot learn about XO design and implementation, plus it completely knocked the c-r-a-p out of the speakers I had built on my own with textbook/pre-made methods. I went on to build other Wayne J. designs, including the DHT, his version of the BR-1 with the same drivers but different XO, and the one I built the most of, the Lyra. The Lyra turned out to be well-suited for rebuilds of old commercial speakers, so I re-purposed a lot of Advent, Polk, Infinity, Fisher, Pioneer, Kenwood, etc. with the Lyra. It helped hone my cabinet-building skills further, in addition to all those enclosures I made for the different Speakerlab models friends and family wanted after they heard my S2's. Looking forward to seeing your project come together and the aesthetics you've chosen.


        John A.
        "Children play with b-a-l-l-s and sticks, men race, and real men race motorcycles"-John Surtees
        Emotiva UPA-2, USP-1, ERC-1 CD
        Yamaha KX-390 HX-Pro
        Pioneer TX-9500 II
        Yamaha YP-211 w/Grado GF3E+
        Statement Monitors
        Vintage system: Yamaha CR-420, Technics SL-PG100, Pioneer CT-F8282, Akai X-1800, Morel(T)/Vifa(W) DIY 2-way in .5 ft3
        Photos: http://custom.smugmug.com/Electronic...#4114714_cGTBx
        Blogs: http://techtalk.parts-express.com/blog.php?u=2003

        Comment


        • #5
          Re: AviaTrix sealed MTM Question

          Two comments. If you have MLTLs now, certainly replacing them with Ariatrix MLTLs is a better option than sealed, Just keep in mind that with those big caps in the sealed XO, you'd have more bass from sealed Aviatrix than from sealed Tritrix.

          I still use my AR turntable, but it's a pivoting S-shape, not a transversing tone arm. Those were B&O back then, as I recall, and way beyond a high-school kid's budget.

          Have fun,
          Frank

          Comment


          • #6
            Re: AviaTrix sealed MTM Question

            Originally posted by johnastockman View Post
            My friend had a nice Sansui receiver back in the early 70's. An excellent unit...large, analog FM dial, I always thought "that's what a stereo receiver should look like." He had the Sansui speakers, but when I built my Speakerlab S2's, he got the parts kit/plans for some S'lab 7's because he was so impressed with just the 2-way S2's. I'd already had plenty of listening experience with the 7, and since he could afford the extra $$, he went with the 7's. I made the cabinets for those and he/we enjoyed that combo for years. The Sansui had plenty of clean power and were a terrific match for the 4-way 7's. The AR's were one of the more well thought-out speakers of that era, too. I came here over 13 years ago and Wayne J.'s website was the first one I was directed to. I had been trying textbook-formula XO's and pre-mades, but obviously, they were NOT working well. I built Wayne's DBP 2-way, with the 5.25" classic woofer, a BR-1 little brother. That one build convinced me I had a lot ot learn about XO design and implementation, plus it completely knocked the c-r-a-p out of the speakers I had built on my own with textbook/pre-made methods. I went on to build other Wayne J. designs, including the DHT, his version of the BR-1 with the same drivers but different XO, and the one I built the most of, the Lyra. The Lyra turned out to be well-suited for rebuilds of old commercial speakers, so I re-purposed a lot of Advent, Polk, Infinity, Fisher, Pioneer, Kenwood, etc. with the Lyra. It helped hone my cabinet-building skills further, in addition to all those enclosures I made for the different Speakerlab models friends and family wanted after they heard my S2's. Looking forward to seeing your project come together and the aesthetics you've chosen.


            John A.
            I have read posts here where Wanye J's designs have been slammed as "out-dated" and lacking support. Well, I have gone though a number of store-bought loudspeakers since I built those, while the little DHT 2-ways have never left my side. He didn't allow any options in the design, so what "support" is needed? Especially in light of how nice the Dayton 1" titanium tweeters sound with his X-over. Way under-rated design and tweeter.
            My two life-long passions have been Audio equipment and motorcycles and now that I think about it, there is a strong comparision in the way the Japanese products came into my consciousness.
            In 1970, a high school buddy came back from "Nam" with a Akai system(sold as Roberts in the States at first) that just blew me away, especially the tape deck. Up Until then, my experience with electronics had been confined to my parents Magnavox console, my Airline(Wards)electric guitar and a Realistic transistor radio. I had been eyeing the Heath Kit stuff, wondering if I could actually build a receiver when Circuit City opened(called Dixie HiFi at the time) and I bought the Sansui receiver and AR 2-ways. The fancy AR turntable I bought used(Lord knows where it came from, but at 18, I wasn't encumbered by a conscious). So it really wasn't the big Japanese brands of today that jump-started my addiction.
            The motorcycle addiction-When I was a kid, my sister's boyfriend offed me a ride on the back of his Triumph Bonneville. As I climbed over the seat, my bare leg touched against the hot pipe and gave me my first motorcycle "badge of honor"( I still have the scar, my body is a road map of my MC histories). My mom was watching and I knew if I cried she wouldn't let me go for a ride. So holding back tears, I went for my first ride and became determined that that when I got my license, that I would get a motorcycle.
            My dream bike was a Norton Commando S, but I wanted a BSA Victor 441 until a neighbor let me try and start his. I didn't have enough arse to push the kicker though, so I had resigned myself to a Gold Star 250.
            But all that changed one evening, when, hanging out at the local Drive-in, something happened that changed my life. The Drive-in sat on the top of a hill with a light at the bottom of the main drag. I heard some strange noise, turned in time to see this "rinngy-dingy", smoking bike leave to light and wheelie though the first three gears up that hill. Everyone turned and stared in amazement. It was the first of the Japanese superbikes, the Kawaski 500cc Mach III and I never really thought about European metal again.
            My same Army buddy had bought a Yamaha Big Bear(305?) and that was what I lusted after, but when my folks finally agreed to buy me a motorcycle for Graduation, they wisely set a limit of 175cc. Happy to have anything with two wheels, I ended up with a new red Bridgestone 175 scrambler. Although it was quick, the less said about that model, the better. Suffice to say, it's probably a good thing that Bridgestone decided to focus on tires
            So like the stereo equipment, it wasn't one of the "Big Four" that got me rolling, but a Japanese brand that is still around, just not on everyone's lips.
            P.S. I remember that first Circuit City store well. There was no showroom, just a warehouse with boxes stacked on industrial shelving. So began a long love/hate relationship with CC.
            Last edited by motomech; 07-18-2013, 01:02 PM.

            Comment


            • #7
              Re: AviaTrix sealed MTM Question

              I just built a Aviatrix center and I thought I would experiment with the remaining two woofers from the kit. I had a pair of Wayne J's Home Theater speakers that I wasn't using, so I bought another tweeter and the MT X-over components and did a pair of Aviatrices in the Home Theater boxes.
              Now, these boxes are smaller than what Curt recommends, 1.8-1.9 Ft.3, rather than the 2.3-2.6 Ft.3(and the driver center spacing is somewhat closer as well), but what the heck, I stuffed them well and and installed the drivers just to try them out.
              Click image for larger version

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              WOW! They are right there with the center. If there is any drop-off on the bass end, it can't be much.
              No disrespect to Wayne J, but these mini-Aviatrices blow the 10 year old Home Theaters out of the water. I guess time marches on.
              I had built the center with the RS28A to match my mains, but for these MT's I used the RS28F. Side by side, it's hard to hear much difference, but if anything, I think the soft domes sound a little "sweeter".
              I can only summize that there is some flexibility in the Aviatrices box volume.
              Not surprising, given what a brilliant design these are in other respects.

              Comment


              • #8
                Re: AviaTrix sealed MTM Question

                they sound great in the designers listening room.
                " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

                Quote Originally Posted by hongrn. Oct 2014
                Do you realize that being an American is like winning the biggest jackpot ever??

                http://www.midwestaudioclub.com/spot...owell-simpson/
                http://s413.photobucket.com/albums/pp216/arlis/

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