Local speaker guru Ed Maniet is mainly responsible for the surround sound speaker system constructed in the last year by this chapter. This system currently resides in a classroom on the PSU campus, and another of a similar type is currently being considered for a spring/summer chapter project.
The system is driven by 8 to 10 two-way satellite speakers. The document below describes their construction.
This document descibes the design and performance of the louspeakers designed for use as surround channels in the classroom of the New ARL Bldg. These loudspeaker were designed by Edward Maniet Jr. along with Ralph Muelhiesen and Chris Link.
The classroom surround speakers (hereafter abbreviated CSS) are a simple sealed-box, 2-way design. A total of eight CSS were built for use in the classroom. Four other CSS were built for use in other lab projects. Spare drivers were provided for replacing damaged ones. The effective frequency response range of the CSS is 70-20000 Hz. Power handling is about 50 watts. The CSS are not intended for low frequency (ie. bass) output at high levels.
The exterior cabinet dimensions are: 13.5" H x 8.5" W x 7.25" D. The cabinets are made of 3/4" thick particleboard, except for the front panel which is a double layer of particleboard 1.5" thick. An internal shelf brace provides additional stiffness. Standard cup mounted binding posts are located on the rear of the cabinet. The eight cabinets intended for use in the classroom were painted with Stonecraft Travertine Tan. This provided an attractive textured finish. Two other cabinets were painted with Texturelac black lacquer, an extremely durable texture finish. The remaining two cabinets were unfinished at the time of this writting.
The 6.5" woofer is a Vifa P17WJ-00. The woofers were purchased from Just Speakers1. This woofer has the following specs.: Qts=0.35, Qes=0.45, Qms=1.55, Vas=34.7 liters, fs=37 Hz, xmax=4 mm, sen=88 dB 1W 1m, nominal power (IEC 268-5)=70 W.
The tweeter is a 1" aluminum dome with gold flashing. It is a customized variant of the SEAS 25TAC/D . These tweeters were purchased from Zalytron2.
The internal volume of the cabinet is 0.24 cu.ft. The resulting low frequency response is characterised by: Qtc=0.86, fb=91 Hz, f-3=70 Hz. When placed on a wall as intended the bass will be boosted somewhat. There is a contoured piece of foam behind the woofer and the area above the shelf brace is filled with polyester fiber fill for damping.
The crossover between woofer and tweeter is at 2500 Hz. It consists of 1st order lowpass and 2nd order highpass filters. Circuit schematics and response curves are attached to this document. The circuit is built on a piece of pegboard and glued to the bottom of the cabinet. Internal wiring is 16 ga. speaker wire.
Numerous meaurements were taken of the completed system, mostly with the CLIO system. Several response curves are attached to this document including: input impedance, on-axis frequency response and nearfield woofer response at low frequencies.