Sorry to ask this again, but...

[Rob Babcock]

I can't seem to find the spot I asked before!:confused: I've used my pair of TN 1220's in the right front corner of my room for years, with the 500 W amp fed by a Behringer parametric eq. While this has worked very well, I wonder if placing them on the floor lying down behind my center channel and under my Da-Lite 100" screen would work better.

My thinking would be to build a cradle to hold the subs horizontally; this would be right between my mains and behind the center.

The reason I wonder about this is that some (namely, Russ Herchelman, in many articles in SGHT) have stated that corner placement engages too many room modes as opposed to placing the sub in a null. The long and the short is that he asserts corner placement is bad and that bass is smoother with the subs out of the trihedral corner.

I would like to know what Dr. Hsu thinks of this idea; the cradle wouldn't be too hard to build, but I don't want to go to the trouble if I'm barking up the wrong tree.

Thanks for any help you can offer.

[Lwang]

You can't pick a random spot and assume that it would be a good place to place the sub.

I did 1/3 octave warble tone measurements along the whole side of one wall in 12" increment to find the spot with flattest response (kept the sub at listening position and moved the meter, so freq below 1/2 wavelength of room length was inaccurte). Also did many other measurements with sub upright, sideways, out in the open, rear corner region, movement of seating position +/-12", etc.

I finally came to a point roughly 1/2 way along the length of the room. Then had to consider upright or horizontal placement. The horizontal offered some advantage, including having the port not at that nodal point, and it would become invisible hidden behind my rack. But at that position, the woofer would be closely facing a sofa, so some of the bass might be absorbed by it.

At that position, it minimized excitation, but was also the least efficient place to put the sub, but it seems to be enough for most situations. Plus the driver on the TN bottoms out quite gracefully, so even if its limit is reached, it does not sound like it is ready to explode.

Here is how the sub is situated in my system:

[Rob Babcock]

I agree you shouldn't pick a random spot, but a spot on the midline in front is something I arrived at given the measurements of the room. By measuring the room and calculating the length of the wavelength at each freq proportional to the room you'll understand where the peaks and nulls are and why corner placement can load many room modes at once.

Unfortunately, I also don't have an awful lot of places I can place the subs. Both front corners are open; I've tried every placement option I could using one corner, both, etc. The rear right corner is also open, and I could conceivably place them horizontally behind my listening love seat.

You're method is similar to how I initially placed my subs; they do sound good there, but I'm always open to improvements. So why not just try it, why ask Dr. Hsu? Because he knows a lot more than I do!:) And I don't want to build a "sub rack" if I'm barking up the wrong tree.

BTW, Lwang, do you use any acoustic treatments in your room? I'd kinda like to free the front corners for bass traps and/or Eighth Nerve seams. Parametric eq is great for bass, but I'm ready to improve room treatment at other freqs, too.

Thanks for the advice. I can see that your technique is very thorough and well thought out.

[Lwang]

I don't use room treatment much, except for some ficus tree diffusers behind the main speakers. Since I have magnepan speakers, they don't need much side wall treatment due to their dipole nature.

[Dr_Hsu]

The length of the 1220HOs can be helpful in this case. Assuming that you have space for this, I would suggest laying the 1220HOs down with the ports close to the corners and the woofer ends closer to the center of the front wall. That way, the lowest bass gets the benefit of corner loading, while the upper bass is not corner loaded.