Blog: Designing The Console Speakers By: John Heisz
Since the console project was primarily about the woodworking, I thought I’d write a short entry here covering how I designed the speaker cabinets.
First, let me tell you about the drivers. They are fullrange (with a whizzer cone) high efficiency 7″ with a neodymium magnet and I bought these after looking through dozens and modeling several. The selection process can take time, but I enjoy doing it. They are from Dayton Audio, the PS180-8:
The unusual thing about this design was that I already had the size of the box, more or less. To match the overall look of the original console this is based on, I really couldn’t change the height (12″) or width (16″) for the boxes. I did have some leeway for the depth, the restriction was on the minimum to fit the computer gear in the centre section. In the end I settled on 12″.
That gives me an internal volume (with 3/4″ sides, top, bottom, back and front) of 26 liters. I’m switching to metric for the volume because that’s what the software uses and also what I’m used to using. I modeled this volume for the speakers I picked out and found it to be too large. So I had the choice of moving the back panel inwards to reduce the volume, or add packing to the inside to reduce it that way. I chose to add padding, since it would also add mass and bracing.
The T/S specs of the driver entered into Unibox:
Unibox is an older spreadsheet I’ve used for many years to design speaker boxes.
The results with an internal volume of 21.7 liters:
The box has no fill and no damping material and has two ports that exit the rear. Ports are 2″ ABS pipe 4-7/16″ long.
This chart shows the projected response:
Important to design the box so that the driver is not exceeding its max excursion (xmax) at the projected maximum power:
That would be the biggest reason why reducing the box volume was necessary.
Another thing to watch for is port velocity:
I used two ports that are fairly small to keep the length short.
And now that the console is finished and had a chance to listen to it? How does it sound? Very good. Remarkably good, actually. The speakers have plenty of low end and my ear ain’t what they used to be, but the midrange and high end sound pretty good too. I consider these drivers to be an excellent choice for this application, or if you want to build a pair of small bookshelf speakers. Shoot for an internal volume of around 20 liters and you can’t go wrong.