Hi everyone,
I'm working on a 2-way passive speaker build using the JBL 8PW8 8” woofer and I'm running into some trouble designing the right enclosure. I'm simulating everything in WinISD, and would love some guidance from the DIY audio community.
In typical reflex alignments (e.g., 45–50L tuned to 50–60 Hz), I'm seeing severe cone excursion at moderate power (30–50W), especially in the 40–50 Hz range, well beyond Xmax.
To mitigate this, I tried:
This significantly improves cone excursion control (stays well under Xlim), and even makes the port extremely short or almost unnecessary. Mechanically, the woofer is much safer.
But a new problem appears:
Any help, examples, or tuning advice would be amazing. I’d like to keep this build educational and as clean as possible—something I can trust and possibly upgrade later with a dedicated sub.
Thanks so much in advance!
I'm working on a 2-way passive speaker build using the JBL 8PW8 8” woofer and I'm running into some trouble designing the right enclosure. I'm simulating everything in WinISD, and would love some guidance from the DIY audio community.
Woofer specs:
- Fs: 81.4 Hz
- Qts: 0.76
- Xmax: 3.2 mm
- Xlim: 8 mm (from datasheet)
- Sensitivity: ~93 dB (1W/1m)
Design goals:
- A natural and smooth frequency response (flat if possible)
- No DSP or subsonic filtering
- Avoiding over-excursion in the bass region
- Medium-sized cabinet (ideally under 50L)
- Simple, passive design I can build and learn from
The issue:
In typical reflex alignments (e.g., 45–50L tuned to 50–60 Hz), I'm seeing severe cone excursion at moderate power (30–50W), especially in the 40–50 Hz range, well beyond Xmax.
To mitigate this, I tried:
- Increasing Fb to 90–100 Hz
- Keeping box volume at around 50 L
This significantly improves cone excursion control (stays well under Xlim), and even makes the port extremely short or almost unnecessary. Mechanically, the woofer is much safer.
But a new problem appears:
- The SPL curve now shows a sharp peak near 100 Hz, followed by a dip and slow roll-off.
- The response is no longer flat or natural, and I worry it might sound “boomy” or boxy.
My questions:
- Is it valid to tune Fb > Fs with this kind of woofer, especially considering it doesn’t reproduce much below 70 Hz anyway?
- Is there a known “sweet spot” for tuning high-Qts midwoofers like this?
- Would going sealed (~12L) be a better compromise? I simulated one and excursion is perfect, but there's little usable output below 100 Hz.
- Should I accept the SPL ripple and tame it with EQ? Or is this a sign that the design is mismatched?
- Has anyone here worked with this woofer or similar pro midbass drivers in home reflex enclosures?
Any help, examples, or tuning advice would be amazing. I’d like to keep this build educational and as clean as possible—something I can trust and possibly upgrade later with a dedicated sub.
Thanks so much in advance!
Hello and welcome to diyAudio. Feel free to use the appropriate forum to ask your questions, as this is the introduction area.
