Isetta 2.1 Speaker Build

Isetta 2.1 Speaker Build


Project Category:

Project Level:

Project Time:
20+ Hours

Project Cost:
$100 – $500

Project Description:
IMplementation of Paul Carmody’s Isetta 2.1 Enclosure with an added built in amp.

Design Goals:
Make a small box that doesn’t look like something you can buy cheaply in a store. Also, to have fun.

Driver Selection:
1 – Tang-Band W5-1138SMF

2 – Fountek FE85

Enclosure Design:
Solid Santos Mahogany, African Mahogany Veneer, Solid Wenge, and 1/2in MDF were used for the enclosure.

Enclosure Assembly:
Hardwood and veneered MDF so it does require some thought on wood movement. There is a full annotated gallery of the build with some wood working tips here –

Crossover Design:
Staight from Paul Carmody’s Isetta design – (

Really like the sound and the look of the end product. Fun build.

About the Designer:
A woodworker and recovering engineer just getting into making speakers, because… well, it is just fun.

Project Parts List:

3 Ohm 10W Resistor Wire Wound 5% Tolerance
Dayton Audio 0.50mH 18 AWG Perfect Layer Inductor Crossover Coil
100uF 100V Electrolytic Non-Polarized Crossover Capacitor
12uF 100V Electrolytic Non-Polarized Crossover Capacitor
Fountek FE85 3″ Full Range Speaker Driver
Tang Band W5-1138SMF 5-1/4″ Paper Cone Subwoofer Speaker
Acousta-Stuf Polyfill Speaker Cabinet Sound Damping Material 1 lb. Bag


Add yours
  1. 3

    I am a little confused by paul’s design drawing. Maybe you can help. is the interior dimension of the fountek enclosure 3.25 x 2 x 7, or is the dimension intended to be 3.25 x 2 x 8. The former would create a volume of .75 liters, the latter a volume of .85 liters. I can’t tell from the drawing if the top and bottom of the enclosure sits on top of the sides and front/ back, or if it is supposed to be flush with the front of the box. In the photo of the finished box, the top is clearly inset. It’s the same for the volume of the sub enclosure. With an interior height of 7″, the sub volume is 7.4 liters, for an 8″ height, the interior vol is 8.5 liters. Quite a difference. I guess I am asking for the interior dimensions of the enclosure.

    • 4

      Did not get a notice a post was here and just saw this. I went with with 3.25 x 2 x 7 for the volume. Figure the entire box finished dimensions should be 14.5 x 8 x 6.5 for 1/2in material – so subtract 1in from each measurement for rough internal dimensions, Top and bottom, the two sides, front and back.

      Hope this helps you.

    • 9

      I have a 24v 5000mA output DC converter hooked up to it right now. I have also used 19v. I listen to it in my office while I program, the volume level is such I can’t honestly tell the difference. Either way, it can get very loud (when I have it in the back yard) but still sounds good at lower volumes.

      I think it will depend a lot on what works with the Amp board you end up using.

      Good Luck.

    • 10

      I’ve used 19v and 24v can’t really tell the difference as I do not crank it way up. I think it will be more of a requirement/concern based on the board you use the the drivers themselves.

      Good Luck

    • 11

      I have used both 19v and 24v DC converted with the board I have, didn’t notice a difference at the volumes I listen at – they both sound great.

  2. 12

    I am thinking of building this but had a question regarding the filters. Was there a reason for mounting them in the orientation you have?

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