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Next project: 3-way with open baffle

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  • rpb
    replied
    Re: Next project: 3-way with open baffle

    Originally posted by 50 watt head View Post
    It's just another way to help shape the tweeter response/level. A series resistor before the filter is easy to simulate in PCD, and I've found that sometimes it helps eliminate the need for an Lpad.
    The L-pad may make it easier to shape the lower end of the midrange response. I don't like a sharp knee in a response.

    Leave a comment:


  • 50 watt head
    replied
    Re: Next project: 3-way with open baffle

    One suggestion . . . offset both mid and tweet on the baffle, and keep them aligned vertically. The 2" mid will benefit from the baffle offset, just like the tweet.
    Will do -- thanks!

    Leave a comment:


  • Pete Schumacher
    replied
    Re: Next project: 3-way with open baffle

    Originally posted by 50 watt head View Post
    Yep, it's a 3-way design, so it'll be a challenge!

    On the other hand, I can't help but think that other aspects of this project will be less complicated, due to the fact that the woofer can be dealt with separately from the mid/tweeter. The woofer will just be in a simple box, with a simple 2nd-order LP filter. Once that's taken care of, the prototyping could begin by grabbing a random piece of pine 1x8 out of the scrap pile and mounting the mid and tweeter on it. Adjusting driver offsets and alignments and acoustic centers suddenly became really easy And, when one baffle turns out to be a dud, I can grab another scrap and try another alignment. (All of this would be informed and guided by the simulations I've already done in PCD.)

    It just occurred to me just now that this isn't *that* much different from a typical subwoofer and satellite design. What my idea has more or less turned out to be is much like what you would have if you had a subwoofer on each channel, crossed really high (~600 Hz), to a small box-less TM satellite.

    Aesthetically, I'm thinking of finishing the bass bins in black, and using a really nice light-colored hardwood (e.g., quilted maple) for the TM baffles. That would look sharp! I won't have access to my tools for awhile, though, so actually making some sawdust on these will have to wait until later this summer :(
    One suggestion . . . offset both mid and tweet on the baffle, and keep them aligned vertically. The 2" mid will benefit from the baffle offset, just like the tweet.

    Leave a comment:


  • 50 watt head
    replied
    Re: Next project: 3-way with open baffle

    Originally posted by Soundslike View Post
    It looks like this one could be even more challenging..
    Yep, it's a 3-way design, so it'll be a challenge!

    On the other hand, I can't help but think that other aspects of this project will be less complicated, due to the fact that the woofer can be dealt with separately from the mid/tweeter. The woofer will just be in a simple box, with a simple 2nd-order LP filter. Once that's taken care of, the prototyping could begin by grabbing a random piece of pine 1x8 out of the scrap pile and mounting the mid and tweeter on it. Adjusting driver offsets and alignments and acoustic centers suddenly became really easy And, when one baffle turns out to be a dud, I can grab another scrap and try another alignment. (All of this would be informed and guided by the simulations I've already done in PCD.)

    It just occurred to me just now that this isn't *that* much different from a typical subwoofer and satellite design. What my idea has more or less turned out to be is much like what you would have if you had a subwoofer on each channel, crossed really high (~600 Hz), to a small box-less TM satellite.

    Aesthetically, I'm thinking of finishing the bass bins in black, and using a really nice light-colored hardwood (e.g., quilted maple) for the TM baffles. That would look sharp! I won't have access to my tools for awhile, though, so actually making some sawdust on these will have to wait until later this summer :(
    Attached Files

    Leave a comment:


  • Soundslike
    replied
    Re: Next project: 3-way with open baffle

    Wow Phil, barely enough time to catch your breath from the Gila Monsters and you're tackling another design. It looks like this one could be even more challenging. Can't wait to see how it turns out.

    Leave a comment:


  • 50 watt head
    replied
    Re: Next project: 3-way with open baffle

    Originally posted by rpb View Post
    Why do you place the resistor in front of the x-over? It will change other values needed, but I'd put a resistor in series, and one across the terminals.
    It's just another way to help shape the tweeter response/level. A series resistor before the filter is easy to simulate in PCD, and I've found that sometimes it helps eliminate the need for an Lpad.

    Leave a comment:


  • rpb
    replied
    Re: Next project: 3-way with open baffle

    Originally posted by 50 watt head View Post
    OK, here is a preliminary stab at a crossover for

    Peerless 831735 + HiVi BMNa + Vifa BC25SG15

    I've mocked it up for now as a conventional box/baffle, with convenient/ballpark driver offsets, just to get the ball rolling.

    Pete, I modeled around with the ND20, and I after awhile I just found the Vifa easier to work with. Even though it's a large-faceplate tweeter, that hasn't caused any trouble for me yet.

    Wolf, thanks for the tip on the HiVi mid, so far that's been pretty easy to work with, and it came out with less components in the Xover than the tweeter
    Why do you place the resistor in front of the x-over? It will change other values needed, but I'd put a resistor in series, and one across the terminals.

    Leave a comment:


  • 50 watt head
    replied
    Re: Next project: 3-way with open baffle

    Here's another simulation, using the RS180-8 instead of the 831735.

    Crossover is very similar to the circuit I posted above. Looks like an increase of a few dB in sensitivity. The RS180 mounting hole is 5.75" which is identical to the 831735, so the cabinet could be built such that they are physically interchangeable.
    Attached Files

    Leave a comment:


  • greywarden
    replied
    Re: Next project: 3-way with open baffle

    Oh well yeah that makes sense

    Leave a comment:


  • 50 watt head
    replied
    Re: Next project: 3-way with open baffle

    Originally posted by greywarden View Post
    So... what's the benefit of an "open baffle" with sealed-back drivers on the baffle?
    I'm not sure there are any benefits. My considerations behind this idea were partly aesthetic ("it's cool and unique") and partly functional ("why build a box for drivers that are already sealed?").

    Basically, I was planning to build a ported bass bin for the woofer; that's straightforward, nothing special there. Beyond that, the design process would involve nothing more than a simple baffle with the M and T drivers mounted to it. Play around with offsets and alignment from there. Sounds like fun!

    Leave a comment:


  • greywarden
    replied
    Re: Next project: 3-way with open baffle

    So... what's the benefit of an "open baffle" with sealed-back drivers on the baffle?

    Are the woofers going to be open, too?

    I was going to suggest using a cone did, like a small fullrange, and a tiny tweeter like the NDs

    Then situate the peerless woofers in an H-, U-, or W-frame (for lack of a better term, I just woke up).

    Leave a comment:


  • 50 watt head
    replied
    Re: Next project: 3-way with open baffle

    OK, here is a preliminary stab at a crossover for

    Peerless 831735 + HiVi DMNa + Vifa BC25SG15

    I've mocked it up for now as a conventional box/baffle, with convenient/ballpark driver offsets, just to get the ball rolling.

    Pete, I modeled around with the ND20, and I after awhile I just found the Vifa easier to work with. Even though it's a large-faceplate tweeter, that hasn't caused any trouble for me yet.

    Wolf, thanks for the tip on the HiVi mid, so far that's been pretty easy to work with, and it came out with less components in the Xover than the tweeter
    Attached Files
    Last edited by 50 watt head; 06-06-2011, 11:15 PM.

    Leave a comment:


  • Wolf
    replied
    Re: Next project: 3-way with open baffle

    That's right- I don't like it, and never have, no matter who's used it.

    In the way OP stated 'open-back', yes. Dipole- no.

    Later,
    Wolf

    Leave a comment:


  • rpb
    replied
    Re: Next project: 3-way with open baffle


    Keep in mind that a smaller format mid will exacerbate baffle diffraction, especially above the step, where the RS52 will be playing. Pay special attention to that upper baffle, and get some large roundovers up there to smooth things out.
    +1 .... I would attempt this only if you plan to measure the responses.

    Leave a comment:


  • 50 watt head
    replied
    Re: Next project: 3-way with open baffle

    Originally posted by Wolf View Post
    And you mentioned inspiration in seeing another like that, was it these?

    Yep, I recall seeing that pic of yours before, so I'm sure they formed a part of my inspiration.

    Leave a comment:

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