Vifa C17 dappo, built by Greg
Copyright 2013 © Troels Gravesen


Hi Troels,
I am an admirer of your work. I have spent countless hours studying your designs on your web page.
For quite some time I got inspired by your Vifa C17 design. I have build full range single driver speakers before and hi efficiency appeals to me (I was running some of my speakers using a clone of Decaware ZEN - SE EL84). It took me quite some time to score 4 second hand C17WH on the internet. DT300 came just from a shop.
As you can see on the front baffle suffers from serious measurement mistakes. The crossovers are still in an experimental phase outside of the boxes. I have ordered a low resistance ferrite coil (0.095Ohm) for the woofers. At the moment I run the crossovers with air core 0.7Ohm coils, which are certainly not suitable for two C17 wired in parallel.

Even with the present crossover I like the speakers very much. Finally, I can sit down and listen to music. I do not feel the urge to start another project.
At the moment I run the speakers with Aura VA80 (2x40W) and I never go beyond 10o'clock position. I tried to use my Bocama Lafayette  224B (PP on 2 EL84 per channel) but result was not that good - weaker bass. Maybe because of the low impedance of D'Appolito configuration. Maybe I should try again later when when the speakers have been burnt in a bit.
The only critique I have is that sometimes the sibilliances are overstressed. I cannot say whether it is the amplifier or the speakers. I remember that I had a similar problem with the full range speaker using Aura and it was gone when using Zen EL84. Unfortunately Zen has been packed in (as it does not have a proper case and I have now two little kids poking their fingers everywhere). I hope Zen will be resurrected soon so that I can try it as well. Also a Pass Zen is waiting for a new case (same reason as the other Zen). I expect quite a lot from the Pass Zen as it should deal with low impedance of the speakers well.
Finally, please find attached some pictures of the speakers. Feel free to post them on your page.
As you can see after my workplace in the garden has been cleared up the garden is taken up by some other enthusiasts of MDF dust!
Many thanks!
Best regards, Greg