Enclosure Effects on Down-Firing SW?

[kentowl]

Hi all. Question regards enclosure around #2 SW.

I'm building a 10' wide granite fireplace surround with built-in AV (my rebuilt Large Advents from the '70s, a Yamaha 8" SW, to-be upgraded center channel, under a 52" Samsung LCD HDTV, powered by Sony DG920) in a 21x22x10 (truncated cathedral ceiling) family room. 7.1 will include 8" surrounds in angled part of ceiling, plus back surrounds in back wall bookshelf (diffuser). With shelves and large opening in back wall, acoustics and power are pretty decent for the jazz and HT we like.

Designer-in-chief now requests no more speaker grills, so #2 SW needs to live in a 12 cubic foot (max) corner bench, with sound exiting from 4" slots at floor (hardwood) level. I plan on down-firing 8"-10" SW, YST-225, YST-315, YST-325 or<?>; and welcome concerns/suggestions about playing SW "in a box".

 

[croseiv]

Well, I'd imagine decreased SPL and SQ by putting it in the "box". You'd also probably get box vibrations...

 

[annunaki]

If the "box" is sealed that the subs will reside in, with only the vents to the listening area, it will act like a very large bandpass enclosure. You could get very undesirable effects from that. i.e. rolled off or peaked response.

 

[kentowl]

Enclosure Effects, Continued

If the "box" is sealed that the subs will reside in, with only the vents to the listening area, it will act like a very large bandpass enclosure. You could get very undesirable effects from that. i.e. rolled off or peaked response.

Thanks for prompt response to a first post. To clarify, one SW sits under an Advent in the fireplace - it's fine. Enclosure is for an added SW, down-firing because without a visible grill I need to use floor-level openings. Peaks were one of my concerns; should have designed the enclosure as a 6th order with a DIY woofer from the start. As is, I left lots of volume and allowed venting from the top as well as very ample slots - over 140 sq. inches. Won't know without experimenting if I can find a horizontal position and angle that "work". I can get three of four sides playing out of openings, but at least one will play "into" the cavity - may need fiberglas to control that. I can also control volume and slot size. If I can't get it to work, we'll have to "negotiate" a better SW position in the room Given this information, would you lean toward the smaller or larger SW?

 

[Shock]

I have a moto.....bigger is better....

In all honesty that box is going to cause some serious problems. I would definetly think you're going to get some rather nasty vibration in that "box".

 

[annunaki]

Thanks for prompt response to a first post. To clarify, one SW sits under an Advent in the fireplace - it's fine. Enclosure is for an added SW, down-firing because without a visible grill I need to use floor-level openings. Peaks were one of my concerns; should have designed the enclosure as a 6th order with a DIY woofer from the start. As is, I left lots of volume and allowed venting from the top as well as very ample slots - over 140 sq. inches. Won't know without experimenting if I can find a horizontal position and angle that "work". I can get three of four sides playing out of openings, but at least one will play "into" the cavity - may need fiberglas to control that. I can also control volume and slot size. If I can't get it to work, we'll have to "negotiate" a better SW position in the room Given this information, would you lean toward the smaller or larger SW?

Larger subwoofers play lower frequencies at a higher output level. This results in more audible low frequency response. I am a bigger is better type of guy unless a smaller driver can do the same job (linear displacement) at a similar price.

I.e. a JL 8W7 vs. a Dayton Reference HF 12" for instance. The 8W7 can do a similar or better job at the same or higher output level while taking up less space. It is also a more linear device resulting in lower distortion playback.