Fireside plans

Fireside – The plans

QCad professional

The plans were made with QCad professional which is an open source Cad program but that must be purchased. Despite the name « professional », the price is only 33€, a very cheap price for a CAD program of this quality !

Making the Fireside plans

For this box I didn’t want the walls to be only 12 mm thick. I usually turn the volume up quite a bit, and I was afraid of vibrations. So 16 mm seemed better for me. The first step was to recalculate the dimensions so that the Bjørn Johannesen’s recommendations were still respected. Here is an excerpt of his recommendations for a Tabaq of larger volume more suited to a 4″ driver :

Larger volume

In this example, the cross section of the line has been increased to 171 cm² and the volume of the last part of the line (the opening) has been increased to 22.8 cm². Stuffing is 84 gram.

Here is the PDF file from Bjørn Johannesen with the description and the simulation of the box with a larger volume. You can find this file in the DIY Audio Forum.

So I adjusted the dimensions to keep the 171 cm² cross section, and the opening of the cross section to 22.8 cm². There is a mistake here I believe, this is not a volume. The length of the port has been kept at 9.7 cm. The speaker has been raised by 5 cm, you can see from the forum that B.J. says it is doable without bad effects on the sound. I find this more aesthetic.

You can download the plans freely, I have only made the drawings, the design is the design of Bjørn Johannesen. However you can not resell the plans, or claim that they are your own (except of course if you are Bjørn Johannesen 🙂)