I like to build stuff and i like to listen to music. After a few online radios based on ESP32 I wanted to do something bigger. Searching for inspiration online I found several projects for active speakers and initially I settled for Carmody’s Sprite but then I saw his Isetta project and went for that one. Here is the original project: Paul Carmody's DIY Speaker Pages - Isetta
It uses the W5-1138SMF woofer from Tang Band and two full range 3" drivers from Hi-Vi: B3N.
As I don’t have audio equipment (nor the knowledge) to measure parameters I wanted to do something that is already proven by to work. I made the enclosure a little bigger then the original project: 7 liters for the woofer and tuned it to 40Hz using WinISD
. Could not find a 1.5" port so I used a 40mm OD (about 36 on the inside) diameter water pipe and I 3d printed a flange for it.
The cabinet is made from 12mm MDF. I had the panels cu to size but everything else I have done it manually: cutouts, drilling, gluing, sanding, applying filler, sanding, prime, more sanding, paint, sanding and finally some varnish. I also printed the feet.
Initially I wanted to buy a cheap 2.1 amplifier based on some class D amplifier chip like TPA3116, but also wanted Bluetooth. As a board type amp would imply a lot of work to integrate into the speaker so I started to search for a plate amplifier and I found the Arylic Up2Stream Plate AMP 2.1 to have everything I wanted and more. It was more expensive then I wanted to spend but the thing that convinced me was the fact that it has programable DSP onboard. You see, the original Isetta project had filters (crossover filter, BSC filter and a notch filter for cone breakup compensation) made of passive elements which are expensive, needed some work to put together and didn’t offer much flexibility to adjust things. I was more than happy to replace all of this hardware components with a few clicks in the ACPWorkbench tool.
Note that I am not an audiophile so I cannot measure the result but I think I am pretty close to the original project.
I used Xsim and Edge to simulate the response and apply the filters as below:
Baffle step compensation simulation in Edge
Cone breakup filter. Xsim simulation of Isetta’s filter.
A few words on the Arylic Up2Stream Plate AMP 2.1:
- highly integrated: you only need to connect the drivers
- DSP included
- Wi-Fi: many online services but also plays audio from LAN DLNA (browsing is very fast)
- besides the app, it has a very nice web interface (this is not mentioned anywhere online)
- voice guided prompts of the amp status
A couple of pictures of the final product:
I will test the amp features in the following days and maybe I will post a few impresions.