January 4, 2022

A tale of two bandpass subs

Covid lockdown here in Australia has seen many people stuck at home with renewed focus on enjoying their listening rooms. During lockdown, one client approached us looking for a custom sub similar to one he had heard in the past and found impressive. He presented a fairly simple bandpass design, based around a budget 8" driver and a simple and easy to build cabinet. I could see how this design could work for people wanting an easy to build project but I had concerns about applying a bandpass design to other drivers. They tend to be very sensitive to swapping out drivers. I also felt, we could offer something far more impressive. So I presented two options. I'll call them "big thumper" and "little thumper."

Big Thumper was a large 6th order bandpass with a 1kw amp and a Dayton 12" driver. Given this is a music sub with fairly generous allowed dimensions, I was able to maximise sensitivity and achieve 91 dB voltage sensitivity. Lil thumper was a more modest animal, using an old favourite driver - a variant of the Peerless XLS range paired with a 200W amp. This was a smaller and simpler design - 4th order bandpass. That means effectively a sealed box sub with a front chamber attached. This bumps up the sensitivity and filters the distortion. Normally a sealed design would achieve 86 dB at 40 Hz (2.83V) but here with a bandpass design we can get it up to 92 dB.

This client chose to go ahead with the larger design but then another client chose to go ahead with lil thumper.

Lil Thumper - a compact 4th order bandpass sub >


 


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