Thanks guys,
Credit goes to Bon for tackling a slightly more complicated job of making folded pipes (
Tama ba Bon? ML Straight Pipe yung Boink AFAIK)...
Sound? Hmmm... It has visceral midbass dynamics, grand piano, upright bass, and violoncello sound very convincing. Maybe this is due to the Karlson slot? Most probably. Midrange is almost tangible.. But still not in the league of the top tier midbass and midhigh compression drivers (in well designed front horns) of course...
troporobo,
The side and top panels do resonate but not by a large margin. There is a long brace at the inside back panel from top to bottom and also at the front (you see it inside the Karlson slot/vent). The recommended brace is 1" x 4", but due to lack of good wood we just used 3/4" x 4". The narra ply I bought was far from perfect, that's why Bon had to make do of what is usable,
pili na mga parte kumbaga... Some parts of the outer surface of the narra ply veneer have blemishes that cannot be patched up with natural/neutral varnish... But I don't want to be overly obsessed over perfect cosmetics/aesthetics, I'm borderline anally retentive as it is already...
BTW, the edges are made of pine. There should be enough polyfill lining behind the driver back chamber, at least an inch to avoid early reflections to the cone and excess backwave turbulence. There is a way to test adequate stuffing density, it's called the "AAA battery test".. I still have to ask a French-Canadian dude who told me about this and what it entails. The critical part though is not to block the "throat" after the chambe with stuffing, as the designer advised. The transition pathlength from back chamber down to the mouth exit is short and not complex. The Kralson slot has a radius of 38.91 degrees.
Wala pa palang platform/feet/spikes ito so I use temporary Lovan spike rests/discs to lift them up the marble floor a bit to avoid the cab resonance feedback creeping up and muddying the midbass. I could try 3/4" wooden platforms to. There is much potential with this design....
The drivers are vintage Coral alnico jobbies.. They are actually more suited to OB or large aperiodic enclosures (leaky cabs), but they still do manage to sound "good" in the Pipe. Check out the OB forum. When funds allow I would try the Supravox 215 RTF64 (NOT the Sigs) in them and use my vintage Fostex cast horn tweeters on top. I'd still keep the Corals, OB's are up next... Bon may have a source of very good quality ply soon, we still have to see
pag na tistis na yung kahoy.
A big thanks to
Bill Woods for sharing his design online for diy'rs....