Hi Guys,
Quickly after reading about Ikea selling Sonos compatible loudspeakers, I watched a couple of teardown videos and I've found the following project:
https://makezine.com/2019/08/16/hacking-the-sonos-ikea-symfonisk-into-a-high-quality-speaker-amp/I couldn't find any topic here on this amazing forum, so I thought it would be nice to share this with you.
I took a little while before I could find the time to go to Ikea, but last Monday I gathered all my courage, drove there and bought a couple of Symfonisk Bookshelf speakers. I have to admit that I turned it on before taking it apart, sorry Dave, but it seemed like a smart thing to do before voiding my warranty.
Anyway, I opened one of my home-brew bookshelf speaker boxes, disconnected both tweeter and woofer drivers from the internal filter. I hooked both of them up to two separate cables, routed the cables out through the reflex port and connected them to the Symfonisk PCB. Yes, this board is bi-amped, and uses a digital cross over filter.
So I played a couple of music fragments through that single speaker and it didn't sound half-bad. Then I ran the Sonos TruePlay calibration sequence and listened some more, but I don't recall if that made a big difference. I found the sound a little 'bassy', but al together not bad.
But then I hooked up the other - non modified - bookshelf speaker to my original Sonos Connect:Amp and played the same music fragments. Even though I have always been very happy with these speakers and this Sonos combination, I was really surprise how much poorer the sound it produced was, compared to the Symfonisk modified speaker. The latter was so much richer. Perhaps a bit too rich, perhaps still a bit too 'bassy', but overall more pleasant to listen to, at least to my taste.
The guy who wrote the article in the aforementioned link says that TruePlay re-tunes the digital cross-over filter, but has no evidence for that. I doubt that it does, but the TruePlay does use a digital equalizer and that could compensate a slightly misaligned cross-over filter, I suppose.
Anyway, I'm trying to bring this project to the next level and I happen to own a Rohde & Schwarz UPL and I started out tonight by plotting impedance graphs of the original Symfonisk drivers. This device is Sonos made, and Sonos develops their own drivers in-house, so not much information can be found on those. Below the plots:
[ Specified attachment is not available ]
The next step is to do the same measurements on the Scanspeak drivers, look up the datasheets and compare them to the Sonos drivers. After that I'm planning on finding a way of plugging the UPL generator output into the Sonos network and checking out what this cross-over filter does. Preferably on a virgin Symfonisk, so I can repeat it after running TruePlay again, to see what changes.
Does anybody else have any suggestions for this project?