Thiel Owners

Regarding subwoofers for my CS3.7s, I am throwing caution into the wind, along with money  (gulp). I am buying two SS3 subs, and providing all the answers that I was hoping someone here could answer for me. The single SS2.2 I have now is on US Audiomart. But I suspect just adding another SS2.2 would have been the more conservative and equally satisfying route.

FWIW - I think the SS2.2 is a post Jim Thiel alteration , much like the CS1.7 was. Does anybody here know if the SS2.2 has the room boundary compensation.?

Warren- wow. Let us know how this venture unfolds. Are you a closet headbanger?

Correction: I have read that the SS2.2 was introduced when Kathy was still president, so it would be an update of Jim's design. The conversation and questions I am remembering must have come later in the game.

Speaking of boundary compensation (that is correction for SBIR --- Speaker Boundary Interference Response), Thiel smart subs have SBIR correction to compensate for reflections off the front and side walls, but not the rear wall (behind the listener). It turned out I had a major rear-wall SBIR problem that could not be fixed by adding forward facing subs along or near the front wall of any size or quantity. The only cure was a sizeable array of *tuned* bass traps on the rear wall, tuned in my case around 50 Hz (where regular bass traps have very little effect). The key diagnostic for rear-wall SBIR is that the drop-out frequency shifts with distance from the listening position to the rear wall, but not with sub placement along the front wall. Once that problem was fixed, I did go with a 2-sub solution that works very well.

The distance from the LP to the rear wall gives you the quarter-wavelength of the SBIR dropout. From that you can find the dropout’s center frequency. If that frequency is well above your bass range, you can feel safe that you don’t have a rear-wall SBIR problem.

My room dimensions are roughly 15’ (front wall width) by 22’ x 8’3". I wish I had higher ceilings, but otherwise the room sounds great –– after treatment for early reflections, general bass control, and the aforementioned tuned bass traps for SBIR.

I strongly agree with other posters that emphasize the importance of getting your room’s bass response under control before going too far with adding subs. If your bass reverberation times are too long, adding more bass is likely to seriously degrade your sound.

....

I’m likely the guy with the Thiel SI-1 active crossover that @tomthiel mentioned. Although the passive PXO crossovers also do a fine job blending subs with mains, active crossovers also relieve the mains from reproducing low bass. This audibly improves the sound of my 3.7s (for a number of physical reasons): sweeter highs and plays louder w/o distortion. I was looking at Marchand active crossovers just before my SI-1 came up for sale. I wanted a crossover with balanced circuitry, and one of the Marchand variants was the only one I could find, other than the SI-1, that had this feature. In principle, a properly configured Marchand X-over should bring similar benefits, but the SI-1 was designed by Jim Thiel to make configuration a snap, even for non-experts.