Distributed Bass Array configuration
hleeid- @mike_in_nc - mike_in_nc, Hope you are paying attention (to the whole thread) because this is typical of what happens every time. A small number of us have experience and knowledge. A whole bunch more talk as if they do. Sift though the chaff to sort out the wheat and you will be fine. |
Some additional independent perspective on sub placement for music from a very experienced and knowledgeable source. For Optimum Sound, How Many Subs, and Where Do You Put ’Em? | News & Views | Ohm Speakers | Custom Audiophile Speakers for Music & Home Theater " At 80 Hz, it is quite difficult to determine the source of sound. However...." |
Hilde 45, Right, of course there is stereo bass. you just can't hear it somewhere below 80 Hz. Sound always has a direction even though in a room it can be confused. Mr McGowan is a snake oil salesman. There are far better experts I care to listen to like Siegfried Linkwitz, Nelson Pass, John Curl, Roger Sanders, Edgar Villchur and groups at Shure, JBL, Harmon Kardin (now Harmon International) and others. I am not an acoustic engineer however I do design and build my own subwoofers and I have been intensely studying the problem since 1978 when I got my first subwoofer system comprised of first one then two RH Labs subs, a Dalquist DQ-LP1 crossover and Kenwood L07-M amplifiers, SOTA in the day. It became obvious pretty fast that one subwoofer would not do. This is 1978 and many here were still in diapers. An expert by the way is anyone who parrots what you want to hear:-) I was using ESLs so it was not a Radio Shack system. I had an efficiency apartment, a single large room almost perfect for Hi Fi. I use to take a break mid day when everyone was at work and blast myself silly. I digress. Even with two subwoofers there were problems. I could always tell the subwoofers were there when I got them up to realistic levels. It also became obvious quickly that the ESLs sounded better when I got the crossover point up above 100. But, the subwoofers became more obvious. In the end I never got that system to the level it could have performed at with the right electronics but, they were not available then. Everybody else thought it was a dynamite system. I had it in my head that it was possible to make a system that was as gratifying aurally as a live concert and that system was not. Back then, because of the difficulty integrating subwoofers they were considered taboo by the high end establishment. But, none of their systems were as gratifying as a live performance either and to my mind low bass was the biggest problem. I sold that system on leaving Miami and took a break from subs for several years. I was in a regular apartment building in Ohio with wood construction and subwoofers would probably have gotten me lynched. I did discover line source loudspeakers during this period in the form of Acoustat 2+2's and with Krell KMA 100s they sounded marvelous, still no deep low end and still not representative of a live performance. The two main issues were bass and imaging. Every system I had ever heard sounded like the audio version of a TV screen. It was not instruments standing in a space. You could hear the third dimension but it did not encompass the instruments and voices, if this makes any sense. You could hear the size of the venue and items were localized side to side. Just like a TV screen, you can see the size of the space but the third dimension is missing. Even today very few systems are capable of creating the third dimension. Does the band really sound as if it is standing in your room, are you sitting in the venue? People talk about 3 dimensional sound, the third dimension. What they really mean is they can hear the size of the venue like you can see it on a TV screen. Creating 3 dimensional sound requires near perfect imaging and bass. Low bass creates that feeling of air around the instruments. To get the effect you have to have both. Most systems have damaged imaging because the frequency response of the main speakers is not exactly the same.  In 1987 I moved back to New England and waiting for me there was a brand new pair of Apogee Divas. The most frustrating speaker I have ever owned. When they were on they were incredible, incredibly fragile and flawed. I destroyed ribbons for 6 years before returning to Acoustat 2+2s. With the Divas I did start up again with subwoofers using the original Velodynes. They were not as good as the old RH labs units. There were no subwoofers on the market I really liked. In 2000 my Krell preamp got taken out by a lightening strike. I used the insurance money to buy a TacT TCS. I used the multiple channels to biamp the Divas and the bass management system gave me the flexibility to build my own subwoofers and for the first time integrate the subwoofers to the point that they disappeared. Digital signal processing allows you to put the subs where they belong, in corners, and get them matched up in time and phase with the main speakers. Lucky me has a brother with a PhD in aquatic acoustics from MIT. After a lot of scotch, long discussions and some computer math. We came up with the four subwoofer array I still use today 20 years later. I am now working on my fourth and hopefully final version of my subwoofers comprised of four enclosures and 8 12" drivers. I use full range ESLs so the crossover will be in and around 120 Hz 4th or 6th order both high and low pass filters. With dynamic loudspeakers that cross out of their woofer below 500 Hz there is no reason to run a crossover this high. 80 Hz is fine but to benefit you have to use a 2 way crossover. Adding a subwoofer in at 40 Hz is IMHO worthless. Very few speakers can project anything under 60 Hz with authority. I always have frequency response specs quoted, " my speaker goes from 25Hz to 50 kHz." Right, at one meter, not to mention that it was already 3 dB down at 25 hz at 1 meter. The idea behind subwoofers is to project with authority frequencies your main speaker can't down to 20 Hz at 3 meters in a real room, flat. And, to relieve the main speakers from having to reproduce these frequencies which seriously distort everything else the main woofer is doing because of the long excursions they require. Subwoofers have to be corrected so that they match the main speakers in phase and time. in order to do this you have to use a digital crossover and correction. It is virtually impossible to do it with an analog crossover and if you think you can do it by ear I have a wonderful piece of property to sell you in Key West. OP, my inclination is to always use stereo subwoofers. Most bass is mixed towards the center anyway. |
