Based on discussion in the "What equipment have you built recently?" thread, this topic seems to warrant its own thread. Its always fun to gab about stuff you are working on currently as one usually has a lot of excitement about their current project. It also might inspire others. That is after all one of the benefit of diy related forums.
This weekend I was finishing up my Aikido preamp. Its been a really long time (>1 year) since I stuffed the boards, but putting it all together in a chassis with connectors, selection switches and volume control, building the chassis and the PSU all took considerbly more time than expected. Worthwhile it was though.
I didn't fire it up yet as I re-modeled the PSU in PSUDII and decided to change some components in the power supply. I am awaiting a cap to use as a quasi cap input supply (small C, in a cLCLC supply). I added the other LC section, as my original PSU was just LC, and that dropped ripple to a predicted 3mV level and the small c is being added to bring voltage level back up to around 300V. The result is a PSU that has low ripple, good transients and doesn't ring.
Since the Aikido stage is nicely self adjusting, I will like fire up the preamp san small-c to see how it sounds and works. It is easy to add the cap after the fact.
Secondly, my speaker project is coming along. I machined the baffles to countersink the waveguides (PITA!). Next, I need to glue the waveguides to the baffles and then bondo and sand the seams to be seamless. Also, more fiberglass is going to be added to the back of the waveguides for added rigidity and dampening. My local Pepboys had all the necessary supplies as well as various primers and sealers for prepping the baffles for painting.
I've been reading up on TL theory from quarter-wave.com. I got the hair-brain idea to build a closed TL cabinet for the mid. The idea is to absorb the back wave as much as possible so it is not reflected back through the cone. Since, I plan to high pass the MT at somewhere between 200-300hz, the TL is targeted for ~200hz and tapered.
The downside to the TL enclosure is the added size due to all the braces that make the line (folded). So this will add to size, I just need to see how big this will be.
There is a website, I saw recently, of a RAAL/PHL MTM
that uses such a cabinet. That was partially the inspiration, JohnJ of AES was the other.
P.S. contact me if you know how to design such a TL, I'd love some verification since this is new territory for me.