BRF-10S Design notes

Design Goals

1. Design a sealed sub-woofers

2. For both music and Home Theater

3. Minimum enclosure for living room use

4. Subsonic response not required

I chose the RSS265HF-4 for two reasons, the clean, low bass and cabinet size. This was also a rebuild of my first ever design with this driver and a Denovo 2 cubic foot knock down MDF cabinet which I ported. It ended up being tuned to 14 Hz, which was a novice mistake. Even after trying to limit the cone travel caused by explosions during action scenes with a MiniDSP the voice coil would still hit the magnet. So with a few more years of experience I decided to switch to a sealed cabinet and built two.

I built two 25 liter enclosures out 3/4 inch Baltic birch plywood with the a two layer baffle and back made from 3/4 MDF. I added vertical and horizontal braces modeled after the braces in the Denovo enclosure but used the 3/4 inch Baltic birch instead of MDF. This closely matched the Parts Express recommendations and modeled fine in WinlSD, a 25 liter enclosure tuned to 45.45 Hz with a not too high Qts of 0.836. I wrapped it with beech veneer and finished it with 3 coats of clear shellac just like the rest of the speakers in the living room. The connections use SpeakOns and it has rubber feet. Finally I used the Parts Express Speaker Grill Frame Kit and stuff the enclosure with a pound of PolyFil.

The two BRF-10S sub-woofers are driven by a single Crown XLS 1002 DriveCore 2 Power Amplifier, one on each channel. I am using a MiniDSP 2x4 which doesn't gain match well with the Crown amp and my NAD AVR so I had to put a ART CLEANBoxPro Stereo Balanced/Unbalanced Converter between the MiniDSP and the Ctrown amp. This solved the gain problem and now driving the sub-woofers to clipping is not an issue. I have made one feeble attempt at using MSO to balance the two sub-woofers but I know I have a lot more work ahead of me to get them dialed in.

Simulations

BRF-10S WinISD modeled impedance

BRF-10S WinISD modeled Frequency Response

MLP measurement

BRF-10S Total Frequency Response

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