The Mini-Traps

The Mini-Traps

Designer: Chris Frechette

Project Time: 1-8 hours
Project Complexity: Hobbyist
Project Cost: $100-$500

Design Goals
The main goal of this speaker design was to have a small, lightweight speaker system that could be at home anywhere from a small coffeehouse acoustic performance to a rowdy tailgate. The PRV Audio 8MR400-NDY 8″ midrange is super lightweight and the response was very well suited to where I needed this to run. For the highs, I chose PRV’s D290Py-B polyimide diaphragm compression driver mated to a WG11-25 60° x 60° horn. For the bass, I went with the PRV 12W700 12″ woofer.

Enclosure Design
The satellites are 0.39 cu. ft. sealed trapezoid boxes that yield an F3 of 104 Hz. I undersized the cabinet a bit from optimum, in order to keep the cone under control when used with higher power setups. The boxes were built using 1/2″ material to keep weight down. Each baffle was recessed 1/2″ from the front, which could allow for a grill or to keep the drivers safe when stacking.

Each sub is a 2.4 cu. ft. cabinet tuned to 43 Hz, which happens to produce an F3 of 43 Hz. I ported this in the rear using a 4″ diameter port tube that was 4-3/8″ long. This was also built using 1/2″ material and I added bracing to keep the cabinet dead but still lightweight.

I wanted this design to be very simple and flexible. I just used a 3rd order high pass combined with a fixed L-pad for the highs. I added a 100 uF capacitor in the sub cabinet to keep the lows out of the mids. The satellite cabinet can be used by itself full-range. The subwoofer is run full-range.

This speaker system achieves everything I wanted it to do, and with ease. The high efficiency allows it to be driven by a small T-amp. It is also a great little PA system for small acoustic acts or one-man bands. Excellent vocal clarity, crisp midrange, and good bass slam are hallmarks of this system.

About The Designer
As a lifelong musician, Chris Frechette has been manipulating audio for many years. His background includes live sound, dedicated two channel, Home Theater systems, and a passion for audio done right. He enjoys working with his hands, woodworking, and home brewing.

Project Parts List

PRV Audio 8MR400-NDY 8″ Neodymium Midrange Speaker 8 Ohm

PRV Audio WG 11-25 60×60 ABS Waveguide 1-3/8″-18

PRV Audio D290Py-B 1″ Polyimide Horn Driver 8 Ohm 2/3-Bolt

PRV Audio 12W700 12″ High Power PA Woofer 8 Ohm

Penn-Elcom M1538 Speaker Mounting Top Hat Plastic For 1-3/8″

Dayton Audio SCT-48 Speaker Connecting Tube

Dayton Audio DMPC-4.0 4.0uF 250V Polypropylene Capacitor

Dayton Audio DMPC-12 12uF 250V Polypropylene Capacitor

Jantzen 0.27mH 18 AWG Air Core Inductor

100uF 100V Non-Polarized Capacitor

Dayton Audio DNR-6.0 6 Ohm 10W Precision Audio Grade Resistor

Dayton Audio DNR-3.3 3.3 Ohm 10W Precision Audio Grade Resistor

Neutrik NL4MPR Speakon 4 Pole Round Chassis Mount

Speaker cabinet port tube, 4” ID x 4-3/8” L

1 comment

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  1. 1

    I’ve been really interested in building this setup for myself. Any chance of getting a little more detail on the build, as far as crossover schematics and cabinet dimensions? Any help would be greatly appreciated. Thank you.

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