lowerFE Posted June 8, 2015 Report Share Posted June 8, 2015 Are there any sonic issues of making a really "thin" and long cabinet? I'm thinking of building a 60'' x 30'' x 11'' ported sub to be placed behind my sofa. Any problems with that? Thanks Link to comment Share on other sites More sharing options...
tuxedocivic Posted June 8, 2015 Report Share Posted June 8, 2015 Yes, that length is greater than 1/4WL of 80hz and can cause big suck outs in the frequency response. Link to comment Share on other sites More sharing options...
SME Posted June 8, 2015 Report Share Posted June 8, 2015 I reckon you might be able to counteract some of that with some good fiberglass stuffing. If I understand right, the first sub built by Dr. Hsu of Hsu Research was made out of seven feet of sonotube. I'm not very familiar with that product though. Perhaps it was designed for a lower crossover with full range speakers. I don't know. FWIW, the 1/4 wavelength frequency on a 5 foot sub comes to 57 Hz. Link to comment Share on other sites More sharing options...
lowerFE Posted June 8, 2015 Author Report Share Posted June 8, 2015 If my math is right, the Captivator is a 28'' sub (30'' minus 2'' for side panels) would have a 1/4 wavelength frequency of 120Hz, but it has a ruler flat FR to 190Hz. If 1/4 WL causes big suckouts, that's not something EQ can fix. What did JTR do to go around this problem? What about speakers? They serve much higher frequencies than the 1/4 WL frequency of the cabinet. Link to comment Share on other sites More sharing options...
tuxedocivic Posted June 8, 2015 Report Share Posted June 8, 2015 Stuffing soaks up higher frequencies in speaker cabs fairly well. But they're still an issue not to be ignored. Usually making uneven dimensions is a good start. I can't speak to the cap. Eq could fix some. Stuffing some more. Other box dimensions could fill it in. Lots of possibilities. The sonotube probably had a lot of stuff. Not sure how it didn't kill port output, maybe it was sealed. It can be done, it just needs consideration.... Link to comment Share on other sites More sharing options...
SME Posted June 9, 2015 Report Share Posted June 9, 2015 I may be wrong, but I believe that the form-factor of the original Hsu tube subwoofer was specifically chosen because of the ease of integrating the large port required for solid 16 Hz performance in a ported design. I think 11" may be too small. For one thing, you have to account for the box itself when considering internal volume, and 11" doesn't leave you much space on the inside. What size woofer are you looking at using and in what orientation? Link to comment Share on other sites More sharing options...
lowerFE Posted June 9, 2015 Author Report Share Posted June 9, 2015 I'm looking at a front firing Dayton UM15. 11'' is small, but I make that up with a width and height, so the internal volume is still quite high. 60x30x11 is the largest I can do, and it provides over 9 cu ft of internal volume, which is plenty for the UM15. The box size will probably be smaller, maybe around 5.5 cu ft for a 20Hz tune, and I'll boost the lows with a miniDSP. Since this is going behind my sofa, I should be able to get 120dB+ from 20Hz and above, so there is plenty of headroom for me to use EQ. Link to comment Share on other sites More sharing options...
tuxedocivic Posted June 9, 2015 Report Share Posted June 9, 2015 Wait, so the driver will be centered on that 60" dimension? If that's the case then my concern is gone. That makes the 1/4WL 30" long which is higher than to be concerned about. I though the driver was going on the end of this thing. Link to comment Share on other sites More sharing options...
lowerFE Posted June 13, 2015 Author Report Share Posted June 13, 2015 Wait, so the driver will be centered on that 60" dimension? If that's the case then my concern is gone. That makes the 1/4WL 30" long which is higher than to be concerned about. I though the driver was going on the end of this thing. I don't really care where the driver is located on the cabinet. So if the center is the best place, that's where I'm gonna put it Link to comment Share on other sites More sharing options...
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