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First PA system and it got stuck in a garage......overkill?

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  • First PA system and it got stuck in a garage......overkill?

    So I thought I would share a PA system I built.......for my garage. This was my first build so don't rag on me too much people (I hate the grills). I wanted something for my 3 bay garage that I could crank up and listen to with the garage doors open and not be straining anything.

    I chose the following (if I miss something feel free to ask):
    1. Eminence SigmaPro18A2 18" sub-woofers in a 4.5 cubes box tuned to about 42Hz
    2. Eminence Delta10A 10" mid range drivers in a 1.5 cubes box tuned to about 80Hz
    3. Eminence PSD:2013-8 compression drivers mated to Faital Pro Tractrix Horns

    The MTM format could be a complete mistake, I don't really know. I was going for something different and have always been a fan of MTMs when done 'correctly'. I wish I had room on the floor for the subs, but I don't so I have that working against me. They definitely sound better down low for some reason. I'm running a tri-amplified setup through an Ashly Protea 3.6sp DSP. Eventually I would like to get another server cabinet and get a different amplifier for the highs as I am not a fan of the Ashly SRA class-D amplifier that is powering the compression drivers. It could use a little more power and the A/B or class H stuff just sounds better to me, especially on the high frequencies. The Ashly MX-508 analog mixer is only running a HK bluetooth module through channels 1 & 2 to give me actual stereo output. eventually I am going to bridge the subs and change the DSP output to mono for them. I don't really need stereo on the subs and really could use more power. Right now I think my modeling said I could send around 550W @8ohms to each sub and I only have 750W on hand to each through the MFA8000s. If I bridge it mono and run @4ohms I then have 3KW on tap which gives me some headroom for the peaks in the music.

    I don't really know what the point of the post was except to share with my fellow speaker buddies out there my setup. Take a look, enjoy, and comment if you wish.

    Cheers,
    Chris
    Yes those are Ashly MFA8000's.  I might be an Ashly fan boy.....
    "I don't know everything and do not claim to. I continue to learn and that is what makes me human."

  • #2
    I know nothing about pro sound stuff, but I'd say you have a lot out potential output for your size garage. The speakers look to be finished beautifully!

    As far as the subs being on the floor, they look to be pretty close to the ceiling... wouldn't that give you close to the same 'boost' in the lower bass as being on the floor? I'm not 100% sure with that, but when we measure speakers indoor, we try to get midway between the ceiling and floor when we can... I know that's not entirely for the bass reflections, more for higher frequencies, but I think you'd be good with them that close to the ceiling.

    I have a radio shack radio from the 80's with a single 3" speaker as my garage sound system. If I spent a lot of time in my garage, I guess I'd put some better sound in it as well. Have plans for a small Eminence Alpha MTM in the future, but what you've got blows pretty much everything I've seen away. Rock on! ;)

    TomZ
    *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
    *Part 2 *Gluing multiple curved laminations of HDF *Cello's Speaker Project Page

    *Building the "Micro-B 2.1 Plate Amplifier -- Part 1 * Part 2 * Part 3 * Part 4 * * Part 5 'Review' * -- Assembly Instructions PDF

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    • #3
      Originally posted by STIchris722 View Post
      Eventually I would like to get another server cabinet and get a different amplifier for the highs as I am not a fan of the Ashly SRA class-D amplifier that is powering the compression drivers. It could use a little more power and the A/B or class H stuff just sounds better to me, especially on the high frequencies.
      That's a heck of a large system for a 3-car garage, LOL.

      ​Try using a parallel passive filter on the main speakers to flatten their impedance at high frequencies and bring it down to 8 ohms if necessary. It might be possible to do this with a simple cap and resistor. That may improve how they sound with the class D amp.


      Brian Steele
      www.diysubwoofers.org

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      • #4
        MTM is fine, but they should be placed vertically. The subs might sound weaker placed high due to floor bounce. Or they might sound better placed low as that makes harmonic content less obvious. I'd aim them at the wall in any event.
        www.billfitzmaurice.com
        www.billfitzmaurice.info/forum

        Comment


        • #5
          Originally posted by tomzarbo View Post
          I know nothing about pro sound stuff, but I'd say you have a lot out potential output for your size garage. The speakers look to be finished beautifully!

          As far as the subs being on the floor, they look to be pretty close to the ceiling... wouldn't that give you close to the same 'boost' in the lower bass as being on the floor? I'm not 100% sure with that, but when we measure speakers indoor, we try to get midway between the ceiling and floor when we can... I know that's not entirely for the bass reflections, more for higher frequencies, but I think you'd be good with them that close to the ceiling.

          I have a radio shack radio from the 80's with a single 3" speaker as my garage sound system. If I spent a lot of time in my garage, I guess I'd put some better sound in it as well. Have plans for a small Eminence Alpha MTM in the future, but what you've got blows pretty much everything I've seen away. Rock on! ;)

          TomZ

          Thank you for the kind words. I guess I was thinking go big or go home. Like I said it was my first real project. Rock on is right!
          "I don't know everything and do not claim to. I continue to learn and that is what makes me human."

          Comment


          • #6
            Originally posted by billfitzmaurice View Post
            MTM is fine, but they should be placed vertically. The subs might sound weaker placed high due to floor bounce. Or they might sound better placed low as that makes harmonic content less obvious. I'd aim them at the wall in any event.
            Bill -- I never knew that. Thanks for the heads up. I always saw HT center channels and assumed that MTM's were okay horizontal. I also used to have a set of Presonus studio monitors that were MTMs that were to be used Horizontally OR vertically. What's the negative of how they are mounted? Should I rotate the horn and then rotate the speakers?

            Are you saying to turn the subs around backwards? Would I need to change the delay/phase on the DSP?
            "I don't know everything and do not claim to. I continue to learn and that is what makes me human."

            Comment


            • #7
              Originally posted by Brian Steele View Post

              That's a heck of a large system for a 3-car garage, LOL.

              ​Try using a parallel passive filter on the main speakers to flatten their impedance at high frequencies and bring it down to 8 ohms if necessary. It might be possible to do this with a simple cap and resistor. That may improve how they sound with the class D amp.

              Brian -- It definitely sounds bad up close as it's not a nearfield setup (duh right?!?). You have to get some distance from it for it to sound right. It really sounds cool when you get out of the garage with the doors open. The neighbors love me (The police department)!

              What are you talking about with the passive filter? Could you elaborate for me?
              "I don't know everything and do not claim to. I continue to learn and that is what makes me human."

              Comment


              • #8
                Originally posted by STIchris722 View Post
                What are you talking about with the passive filter? Could you elaborate for me?
                ​Some class D amps are not load-invariant - their HF response changes depending on the impedance at high frequencies of the speaker that they're driving. A simple "fix" for this is to flatten the impedance at high frequencies with the use of a parallel filter fitted across the speaker's terminals. One way to find out the right combination of filter components to do this is to measure the impedance of the speaker and use Xsim to come up with a filter design.
                Brian Steele
                www.diysubwoofers.org

                Comment


                • #9
                  Originally posted by STIchris722 View Post
                  I always saw HT center channels and assumed that MTM's were okay horizontal.
                  It's not OK. They do them that way because it's the only way to fit them under a TV. Horizontal placement narrows the dispersion angle by more than 1/2 where the mid basses are less than 1 wavelength CTC, and results in comb filtering where they're more than that.
                  Are you saying to turn the subs around backwards?
                  Yes. That adds acoustical filtering to above bandwidth harmonics.
                  Would I need to change the delay/phase on the DSP?
                  I assume you mean polarity. That's unaffected. Time align might need adjustment, but probably not, considering the wavelengths involved.
                  www.billfitzmaurice.com
                  www.billfitzmaurice.info/forum

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                  • #10
                    I've not used an Ashly Protea, but whenever I move a sub I take the spatial offset with the Mains into consideration.
                    "Not a Speaker Designer - Not even on the Internet"
                    "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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                    • #11
                      Originally posted by Sydney View Post
                      I've not used an Ashly Protea, but whenever I move a sub I take the spatial offset with the Mains into consideration.
                      Sydney -- I have all of the software and microphones to do the analysis, but don't really know what I am doing! I could use some help in that department. I guess it doesn't help that my MTMs are in the wrong orientation too. I am not crazy about the drivers I picked for the subs. I wish I would have went with something different like the Eminence Definimax or one of the B&C drivers. The sigmas seem more like a woofer than a sub-woofer.

                      Chris
                      "I don't know everything and do not claim to. I continue to learn and that is what makes me human."

                      Comment


                      • #12
                        http://blog.presonus.com/index.php/c...our-church-pa/
                        I don't have measurement gear so I sorta do it the old fashion way - Calc the distance differential ( between Sub and Mains ) and convert to a time offset as a starting point and repeated listening with bass signals or low frequency sweeps focusing at the shared bandpass. Tweak until it sounds synced.
                        In a garage it won't take much delay

                        More advanced approaches
                        https://www.prosoundweb.com/channels...ase_alignment/
                        http://bobmccarthy.com/phase-alignme...ulse-response/
                        "Not a Speaker Designer - Not even on the Internet"
                        "If the freedom of speech is taken away, then dumb and silent we may be led, like sheep to the slaughter."

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