Tapped-TQWT Stuffing - To Stuff or To Line ?

[zobsky]

Currently running my Shiva MK IV Tapped-TQWT in "prototype" mode i.e. sans bracing, stuffing and terminus cover (which technically means I'm running in TQWT mode, rather than Tapped-TQWT mode), and the seal provided by placing the subwoofer on the carpet. I get down to 25 Hz at least but output is obviously compromised by incomplete sealing. (below 30 Hz, the sub appears ready to levitate on account of sound pressure.

Question: I understand it's been recommended to stuff the first half or so Tapped-TQWT to remove some undesirable upper harmonics

To this end:
Can I get away by merely lining the walls, as opposed to stuffing them. I'm concerned that stuffing this enclosure will limit the "tapped action" i.e. the path from the terminus to the throat and back?

[GM]

Maximum damping occurs at the closed end, so with a traditional TL/TQWT where you're willing to accept some HF ripple/deep notch at its 3rd harmonic to get ~max gain LF BW, you just line it about halfway down and adjust it by adding more only at the closed end. Doesn't hurt to line the folds either: DSL DTS-10: AVS Forum

GM

[zobsky]

Thanks, I'll stuff the line over the next few days ( currently involved with bracing and the such)

[Brian Steele]

Originally Posted by zobsky

Question: I understand it's been recommended to stuff the first half or so Tapped-TQWT to remove some undesirable upper harmonics

My experiments with my POC #1 suggest that LIGHTLY stuffing the first 1/3 to 1/2 (starting from the throat, just after the driver) produces the best results, and actually might eliminate the upper "notch", if it's high enough in frequency. See The Subwoofer DIY Page v1.1 - Projects : A "Proof of Concept" tapped pipe - Results (2)

[zobsky]

Just an update. The final result works, and works well. Not as efficient as a full out horn sub when used with a pair efficient speakers (above 95 db/w/m), but gets deep enough below 30 Hz and way more efficient for anything less efficient i.e .the typical 87 - 90 db/w/m design.

Subjectively, I prefer the pyle driver (tighter bass) but the shiva can get louder and handle more power

I'll post measurements when I can

[zobsky]

Originally Posted by zobsky

Just an update. The final result works, and works well. Not as efficient as a full out horn sub when used with a pair efficient speakers (above 95 db/w/m), but gets deep enough below 30 Hz and way more efficient for anything less efficient i.e .the typical 87 - 90 db/w/m design.

Subjectively, I prefer the pyle driver (tighter bass) but the shiva can get louder and handle more power

I'll post measurements when I can

BTW, I lined the first two segments (starting from the driver) with fiberglass batting.