DIY two-way speakers with Fostex components
In 2023, I was lucky enough to get my hands on a pair of brand new Fostex FW 208N woofers at the annual auction at the ETF (European Triode Festival). Just looking at the chassis gave me the idea of using them to build a pair of self-made speakers. But as is often the case with such DIY projects, the implementation took time.
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The first steps – measurements without housing
At the Frickelfest light, a meeting of DIY audio enthusiasts, I was able to convince Olli to measure the Fostex woofers. Olli, who is known among connoisseurs as "Mr. JBL", has already completed many DIY projects and has a lot of experience in the field. To everyone's surprise, it turned out that the drivers had promising performance even without a housing. Of course, however, the right tweeter was still missing. After some consideration, I chose the Fostex FT66H, a suitable partner for the 208N.
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The project lies dormant – until the last spark ignites
As is often the case with hobby projects, the construction of the loudspeaker was postponed. Everyday life took its toll and several months passed without any progress. But two weeks before the next tinkering festival, I became ambitious. I called Olli and asked him if we could implement the project directly at the festival. Olli was kind enough to draw me a suitable housing with mitered edges, which I could then submit to a carpenter. At this point, a clear recommendation for dabenmo.de - the package arrived on time and perfectly finished directly at the tinkering festival.
The Assembly – Teamwork at the Frickelfest
With Olli at my side, we got straight to work at the tinkering festival. Thanks to his well thought-out planning and precise drawing, everything went smoothly and the housing could be glued together without any problems. The miter cut made the whole thing visually appealing and precise.
After the glue had hardened, we started to complete the assembly. The drawing was perfect and Olli had even factored in tolerances, but we still had to sand the recesses for the tweeter and midrange a little, as Fostex's drawings were not 100% accurate - a big thank you again to Christian for his support! He also helped me in particular with inserting the chassis and the bass reflex tube, which we made from a standard 50 KG tube - and yes, it works perfectly!
The measurements and the crossover
Now things got exciting: Olli brought his special rotating measuring tripod with him, which allowed us to measure the loudspeaker both "on axis" and "off axis". The measurements were then fed into VituixCAD, a simulation program, where Olli was able to simulate the crossover. First, I used a DSP solution to test how well the first concept fit - and in fact, there was already great potential here.
Since I had never built a passive crossover before, I was happy that other participants in the tinkering festival lent me the right components. Using Wago terminals and under the gaze (and comments) of the others, I put the crossover together. After the first listening test, it was clear: the high frequency range was still too aggressive.
Fine-tuning and helpful tips
By trying things out, changing things around and constantly adjusting the crossover, we managed to refine the sound even further. Tips from renowned experts such as Karl-Heinz Fink and Thomas Schick also helped. Although the loudspeaker was not perfect at the end of the tinkering, we had taken the right path so far.
Conclusion and Outlook
To date, the project is not yet completely finished, but this article serves as a motivational boost to finally continue. The idea for a final crossover already exists, it just needs to be implemented. Part 2 of the project will hopefully follow soon.
For all those who want to try their hand at DIY speaker projects: It's a long road, but the joy of experimenting and tinkering with like-minded people makes every minute worthwhile. Stay tuned!