Two subwoofers in smallish HT room?

Eldartford

I also run three subs, your measurements go right along with my findings. My Onkyo M-504 sub amp has large power meters and confirm that very little power is needed to shake my 4,800 cubic ft. room on it's cement slab floor.

I do indeed have all the tools to measure my room in 1db increments and am very lucky that it measures very smooth over-all with no large peaks/dips down to 17hz...I did build the room as a " room with-in a room"... with my sons help.

I guess where we differ is in how we define "Boom". I was born in 1950 so remember sonic boom before it was outlawed over our homes. You can get a 100hz freq to boom within a room...20hz?...naaah, it would take a huge amount of power.

I guess the other place we differ is on how X-over effects room modes. I have done hundreds of tests using many configurations...over-all measurements as a complete system (speakers+sub) can change drasticly with only a change of x-over settings.

At this time my front subs are 25 ft apart and located at around the ceiling/floor null-point, (Supertowers are upside down) and in the corners in other words. What do you think Rives would think of that!...gotta love those measurements and go with what works after all.

Dave

Sogood51...I am now set up with a crossover where I can alter the SW X/O frequency while music is playing by twisting a knob, and my ears and my spectrum analyser tells me what happens.

With a white noise test signal (flat 20-20KHz) I am able to vary the X/O frequency from 50 to almost 200 Hz with no audible or visible spectral change to the sound. This tells me that I have got the SW well matched to the mains. With music, I sometimes vary the X/O frequency.
With "heavy" sound, like organ, choral, or some orchestral, the six big cone drivers in the subs work better than the Maggies, and I crank it up to about 150.

My room resonates at about 60 hz. Always has with any speakers. Rives uses 70 Hz as his example on the web site. If you are lucky enough to have a larger room it will be lower.

Eldartford

Our systems are somewhat similar...planers, three subs with six large drivers. I suspect the difference that I measure and you don't are related to X-over and mains settings.

Sounds like you run the Maggies full-range thus always the same at their location with the only change being at the subs location.

I use fixed points which changes output freq levels at both locations having greater effect on measurement..at least in my findings.

My Duetta Sig's have an in-room rise of 2db at 30hz and then a roll-off to 25hz...the lowest setting on my X-over is 35hz and the blend between the mains (run full-range) with 35hz X-over to the sub is a little much in my room...a new X-over {maybe one of the digitals) with more choice of filter would probably benefit.

At this point, I x-over at 50hz with 6db slope.

Well, I guess I have gone far off topic...sorry

Dave

Sogood51...My SW systems are built into the wall behind the Maggies, and "play through" the screens. So they are not moved around. I pull the Maggies out 4-6 feet when in use.

I do not run the Maggies full range. I think that getting the really LF signal out of the woofer is the main reason to have a SW. My X/O is 24dB slope.

The Behringer DEQ2496 analyser that I bought recently has really helped me understand a lot of things about my system that I previously could only guess at. I recommend it, and a crossover that you can diddle from the listening position. After the RTA shows you what your problems are, turn it loose in AutoEq mode, and be amazed!

A question was raised about using subs of different sizes, but seems to have been dropped.

I was looking for a second Velodyne HGS-10, when an opportunity to buy a local HGS-15 arose. The HGS-15 was delivered by a system integrator who is very familiar with high-end equipment. He recommended I set my pre-amp to send everything below 80 Hz to the sub. Relieving the smaller KEF 102/2s of handling these frequencies really opened them up; I was surprised that the effect was the same with the 104/2s. The sub sits on an Auralex SubDude. I set all speakers, including the sub, to equal SPL, using the C scale of my Radio Shack sound level meter with slow integration. The pre-amp generates white noise for this purpose. The result is seamless open sound without boom or heaviness, and a grand sound stage with precise imaging.

Now the question: Is it worth hooking up the HGS-10 next to the left 104/2, or should I move it downstairs to use with a pair of 102/2s, and someday look for another HGS-15. The room is 14' X 19', with an opening leading to a dressing area and bathroom. The existing setup seems quite free of peaks, and the single HGS-15 is quite able to deliver the goods for movies. Stereo music is about as good as I've heard.

db