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Thoughts on plate amplifiers with boost

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  • Thoughts on plate amplifiers with boost

    I recently bought a Young sd 300 with 6db boost at 30hz, I already made the calculations for my subwoofer box but only for receiving 300W, I didn't include the boost. So wrapping up my two questions are: Should I take into consideration the boost while designing my box and if so how do I do it? Is it good to have boost and If it isn't is there a way to remove it (by removing a capacitor)?
    thanks in advance

  • #2
    If you are using WINISD to model your box, go to the filters section, drop down the filter type list and choose peaking 2nd order high pass. Put in the 6db boost and the 30hz boost frequency. Your frequency response graphs will be updated with the boost included. (I am doing this from memory, so I hope I got it right.)

    Likewise, you can add an 80hz low pass filter to see the effects of the filter between the sub and main speakers.

    -Bob
    -Bob

    The PEDS 2.1 mini system
    My A7 Project - another small desktop speaker
    The B3 Hybrid Dipole - thread incomplete and outdated

    Comment


    • #3
      Originally posted by BOBinGA View Post
      If you are using WINISD to model your box, go to the filters section, drop down the filter type list and choose peaking 2nd order high pass. Put in the 6db boost and the 30hz boost frequency. Your frequency response graphs will be updated with the boost included. (I am doing this from memory, so I hope I got it right.)

      Likewise, you can add an 80hz low pass filter to see the effects of the filter between the sub and main speakers.

      -Bob
      Thank you, is it good to have a boost though?

      Comment


      • #4
        Most often a boosted amp works better w/a closed box, and an un-boosted amp with a vented box (but you have to have the boost turned on in your model to get a good sim).

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        • #5
          It depends on the sub design. For a sealed sub, a 6dB boost at 30hz is usually a good first guess and is generally a good idea. For a ported design, it would take more modeling to say if it's the best option. In either case, a 30hz boost is low enough that it is mostly going to affect movie explosions more than most music, so it is often a good thing to have with smaller subs. Could you describe your sub design? That might give us more to go on.
          -Bob

          The PEDS 2.1 mini system
          My A7 Project - another small desktop speaker
          The B3 Hybrid Dipole - thread incomplete and outdated

          Comment


          • #6
            https://www.parts-express.com/dayton...ProductDetails

            my sub is a 12" and I'm planning on building a ported design tuned for 24.7hz/-3db (77L).
            the dimensions of the port are 34cm x 3.5cm, the length is of 76cm.

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            • #7
              Without modeling, I would think you should use the unboosted version of that amp. It is generally not good idea to have the boost above the tuning frequency. With a ported design tuned that low (which looks about right), I would not think any boost would be needed.
              -Bob

              The PEDS 2.1 mini system
              My A7 Project - another small desktop speaker
              The B3 Hybrid Dipole - thread incomplete and outdated

              Comment


              • #8
                If you use Jeff Bagby’s woofer box designer, set the active filter section to a high pass of 30hz with a Q of 2 and this will perfectly emulate the boost and high pass of this amp. Set amp power to 300w.

                You will find the amp puts out significantly less power until the boost rolls in, starting at about 75w on higher frequencies working up to 300 near 30hz, then dropping like a stone.

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                • #9
                  I want my sub to play some lower notes too, so it would probably be better to use the non boosed version, right? The problem is that I already bought the amp and can't change it anymore, do you guys think there is a way to remove the boost? I'm willing to pay a professional if it is needed.

                  Comment


                  • #10
                    PE is good with exchanges as long as your amp is in new condition. Give them a call. However, your use of metric dimensions indicates that you might not be in the USA. Still, an exchange is the best solution if it is possible.
                    -Bob

                    The PEDS 2.1 mini system
                    My A7 Project - another small desktop speaker
                    The B3 Hybrid Dipole - thread incomplete and outdated

                    Comment


                    • #11
                      Originally posted by BOBinGA View Post
                      PE is good with exchanges as long as your amp is in new condition. Give them a call. However, your use of metric dimensions indicates that you might not be in the USA. Still, an exchange is the best solution if it is possible.
                      Unfortunately I don't live in the US, I'm guessing there isn't such a thing where I live. My only option is to modify it, is there a way to do it so I remove the boost?

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                      • #12
                        Do you guys think I should tune it to 30hz or should I tune it lower, even though it won't match the boost?

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                        • #13
                          With +6dB of boost @ 30Hz, I'd halve your box size and build it sealed and stuffed.

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                          • #14
                            Originally posted by Chris Roemer View Post
                            With +6dB of boost @ 30Hz, I'd halve your box size and build it sealed and stuffed.
                            How low does it get? Would it be a good idea to have a ported design? (I really want the extra output)

                            Comment


                            • #15
                              If you want to disable the boost, keep searching the net. I can’t find it right now but there is a thread out there that says how to do it. It has to do with a few caps on the board. This guy talks about adjusting the boost but not turning it off:

                              http://www.audiodevelopers.com/yung-...modifications/

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