Bitches Brew Open Baffle, by Perry Marshall

Description

Recommendations:

Capacitors: The 80uF capacitance value is first in the tweeter circuit. Splitting that value between two smaller parallel capacitors (39uF) will speed up the response (smaller capacitors are capable of faster discharge) at no additional cost.

The 39uF capacitors will be measured and matched, selecting values that measure on the higher end of the manufacturing range, to obtain values as close to 40uF as possible. Any small variance remaining below 80uF is still well within manufacturer tolerances for a single 80uF. Two measured 39uF may actually result closer to the stated 80uF value than a randomly selected 80uF, due to having been measured and selected.

This should also be supplemented with a small bypass capacitor, which is being provided. The bypass capacitor helps to further improve the speed of dissipation.

Inductors: The design plans call for an aircore inductor on the woofer (6.0 mH) with a DCR near or under 0.75 ohms, which correlates to a 14ga wire inductor (large and heavy). Many builders of this design have substituted with lesser gauge inductors, so a 16ga aircore is also offered. This is the most critical inductor in the design.

16ga and 14ga options are provided for the smaller 0.5mH tweeter inductor. 16ga is adequate.

16ga and 18ga ironcore options are provided for the larger 7.0mH inductor. Super Q inductors represent the highest performing option for iron core inductors and is recommended due to its critical placement in the tweeter circuit. A traditional 18ga iron core option is offered for cost savings, but will result in higher DCR as well as greater potential for distortion in that circuit.

Resistors: We have kept it very simple here. High-Quality resistors are very affordable. We are providing 4pairs of GR-Research 10 watt resistors. We don’t see a need for $30 or even $10  resistors in this design but if you feel that need, email us and we can modify a package for you.

Wiring: The design incorporates 3 large drivers in a 52″ tall front baffle. 20ft of each color is adequate to allow for clean wire management in this visible open design.  If you want extra wire for another project, the 30ft wire option is also provided.  You may purchase the kit without our wire.

We do think our wiring is the best value available. Premium wire without the traditional markups. Both versions are very similar, 16ga solid strand, high-purity OFC, Polyethylene insulator.  The “unbranded” is imported, the “Premium USA” version is not. Wire details are here.