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Experienced opinions please - 12" sub design with 15" Dayton RSS PR

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  • Experienced opinions please - 12" sub design with 15" Dayton RSS PR

    Hi Everyone,

    I've been fiddling around with BassBox for a while cooking up a subwoofer design for my living room. I think I can get good results with the Datyon RSS315HF 12" sub and RSS-390PR-15 15" passive radiator, but I'd appreciate it if someone who's done PR designs before could check my thought process. BassBox 6 model is attached, (better...more readable version in the second post).

    I currently have an Ultimax 15 sub in the Denovo sealed 3 cuft knockdown kit that's sold on PE. I power it with a Crown XLS 1502 amplifier, running bridged mono (rated at 1550W for 4 Ohm... I'd be shocked if I used half of that power). This setup sounds good, but there are noticeable room nodes where the bass drops out. Additionally, I think there's some low frequency extension stuff I'm just not getting from the sealed setup. Doing some study, It sounds like moving to a dual subwoofer setup and using these passive radiators will address these issues.

    Project Goals:
    - Lower extension than the sealed 15" (should be achievable with PRs... I'm not trying to crack my foundation, just achieve the most bass for the space)
    - Smaller footprint / external volume per box than the 3 cuft Denovo (aiming for Vb = 2 cuft)
    - Operates well on 250W (Crown amp rated to 525W @ 4ohm in dual channel setup)

    Required Protections / filters:
    - I think adding a 20Hz FMOD high pass from Parts Express to each sub is advisable to avoid Xmax limits on the active 12" driver.
    - The crown has 4th order Linkwitz-Riley filters that I can use as a high / low / band pass, but the min freq is 30Hz, which will cut out extension I'm looking for.
    - I use the Marantz receiver to set low-pass crossovers at 80Hz between subwoofer and my Swope tower speakers.

    My thoughts on the attached modeling
    - Normalized response shows fairly flat response, with a ~1dB boost between 50 and 60Hz.
    - F3 of 26hz is a big improvement over the sealed Ultimax's F3 of 40 Hz

    - Customized response showing some improvement with PRs between 20 and 50Hz.
    - The sealed design has more output at higher freq, but I cutoff at 80Hz.
    - Assuming 250W of power (probably how much I use anyway) the PR setup still puts out 106.8 dB at F3, and peaks at 110 dB

    - Cone displacement for the PR is not a problem. Driver Xmax for the 12" sub is exceeded at 17.5 Hz under 250W.
    - This is ~3hz below my planned 20hz rumble filter/FMOD, but I am not sure if that's enough protection.

    - Max Acoustic Power and Max Electric Power don't show any issues.

    - System Impedance seems fine. No dips below 4 ohm (lowest is 4.35ohm @ 23.9 Hz)

    - Phase response isn't concerning until 13.7Hz (shouldn't be an issue)

    - Group delay is at 23 msec around 20 Hz... this is likely not a problem, but I don't have experience here, and see conflicting reports online.


    So... Based on all that, please let me know what you guys think! Is there anything I'm not considering that I should?
    Thanks in advance!
    Attached Files
    Last edited by KEtheredge87; 03-20-2017, 08:38 AM. Reason: Original picture of model wasn't readable when forum uploaded it. Added 2nd post below with Google Drive link.
    Voxel Down Firing with Dayton SA70

  • #2
    My Apologies. I thought that image would expand to something readable on the forum. The full size image can be viewed from my Google Drive account, here:

    https://drive.google.com/file/d/0B4R...ew?usp=sharing

    Thanks for any advice you guys can provide!
    Voxel Down Firing with Dayton SA70

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