Brian Steele

Thanks - that Fi driver does look interesting. I'm working with another driver at the moment, but the Fi's specs suggest 5 or more dB output in the same passband in only a slightly larger TH - nice! I'll pass the info onto the guys on the DIYAudio forum just in case anyone wants to look at it while I'm finishing my current project. It does look VERY promising. Thanks again!

Oof, sounds like a complete rebuild, rather than a simple adjustment. A higher Q will require an adjustment in the horn's geometry to compensate. After having run dozens of TH sims in HornResp, it looks like generally a higher Q = lower throat/mouth ratio to achieve a flat passband. A reduction in Vas might reduce overall size, but this and the change in throat/mouth ratio may not necessarily be good things - the end result might be a sim that looks great - until it's time to actually fit the driver into the box .

To make it a better match for a future project I'm considering. Some background - 1. I've almost finished my POC#2 project - a "small" (4.3 cu.ft. net) 40Hz tapped horn based around a cheap pro audio driver (Fs 39 Hz, Qts=0.31). I haven't put up a page about it yet, but a picture of it under construction can be seen here: http://www.diysubwoofers.org/projects/other/PA310-TH/images/PA310-TH-10.jpg . HornResp predicts efficiency of 93dB@ 40 Hz /1W/1M, over 96dB/1W/1M through the passband, and an upper cutoff above 120 Hz. The design is theoretically displacement-limited to 116dB peak @90W just about 50 Hz in its passband though (and that's assuming that I can use the full 5mm throw of the driver - hardly likely). I can glean a few more dB by going with a slightly larger horn, but if I had access to an inexpensive driver with similar specs and a bit more Xmax... 2. There's a "challenge" on at DIYAUdio at the moment - to build a TH capable of 40 Hz and 125dB peak in its passband, using only one sheet of ply. See http://www.diyaudio.com/forums/subwoofers/170771-single-sheet-th-challenge.html. I'm just curious to see if it's possible to do it with something smaller than a 15", which will give a bit more leeway wrt box geometry.

A little project I'm working on at the moment, that might produce better results with a long excursion driver with Fs around 39~42 Hz....

Is it possible to easily mod the SSA DCON 12 to have a higher resonance frequency, say 39Hz? I know some subs appear to allow this by simple dust cap replacement (replace the stock dust cap with a lighter one).