Hello,
I am not going to say I am an expert in any way. Some of this can get expensive because subwoofers are not cheap. I have found that trying to control sound at the lower levels can be the toughest thing to control. I have also found out over the years there are equipment audiophiles (likes to tinker with equipment to change the sound), music audiophiles (only wants to listen to good music), and a combo of both. I am both. Take on one sub at a time with the sub crawl. Best of all it’s free except for your time. Read up on the papers and forums to try their ideas. Again it should be free. Finally buy a Mini DSP or crossover to help you remove the humps or nodes. Just remember our biggest issue is the room. You might want to invest in some bass traps and / or diffusers. The node or hump you are talking about is not the frequency that bass traps fix. They are usually above that. I’m speaking in general. This can be frustrating especially if you are not an equipment audiophile. Finally you can hire a guy if you have the means. Usually it’s $100 per hour in the Chicagoland area. MC may not have patience but he did tell you what to do which you gave someone else credit for the DBA. Basically the more subs you have the less volume they play so those waves don’t have to travel as far which reduces humps and nodes. Try the first one next to you listening position pointing forward toward the front speakers. Then one in opposite corners of the room back to front. Think about it like dropping a stone in a pond at one end. The waves remain big and travel all the way across the pond and back again. Now two people drop stones at opposite ends. The waves get smaller when the meet. As you drop more stones the waves get smaller or canceled out. I hope this helped simplify the understanding of controlling bass. |
@hilde45
Just a friendly reminder.
Use your ears.
Just because something measures well doesn’t mean you’ll like it. This is the reason I say it is best to use your mic and play around with Low Pass to see what it does. You may find that you want a +3 db in that range -for your ears- or you may find you prefer a -4 db.
It is your system so use your ears; what sounds good to you may not to someone else and I feel we lose that thought process with all the tech talk in the community.
Saying that something measures well is different than saying it sounds good.
Your ears are different than mine than his than hers. We all can’t use the same pair of glasses either. |
MC may not have patience but he did tell you what to do which you gave someone else credit for the DBA. Proper credit where credit is due. MC learned to build his DBA (distributed bass array) from Duke LeJeune. Check MC's posts. Duke has been designing, selling and discussing distributed bass arrays since at least 2014. He credits Earl Geddes, and states he is using Mr. Geddes ideas with his permission. Search posts from @audiokinesis. Like in this thread: https://forum.audiogon.com/discussions/best-subwoofer-for-quad-2805-under-5k/post?postid=21366#2136604-06-2014 2:05am
Ime when it comes to low bass, the elephant in the room is the room. No matter how flat the subwoofer starts out, the room will superimpose its effects. We can change the room-imposed peak-and-dip pattern by moving the sub and/or moving our listening position, but we cannot make it go away. It is impossible to find a location for a single sub that provides approximately flat response in the sweet spot, much less elsewhere in the room.
Distributed multiple subs offers an elegant solution, each sub being in a different location and therefore generating a different peak-and-dip pattern, but the sum of several such dissimilar patterns will be vastly smoother than any one alone. Instead of a few big peaks and dips that are quite audible, we end up with more, smaller, closer-spaced peaks and dips, and the subjective improvement is even greater than we might expect because (at low frequencies) the ear/brain system will average out peaks and dips that are within about 1/3 octave of each other.
While it’s possible to equalize a single sub to be flat at the microphone location, its response will be far from flat at other locations within the room. A distributed multisub system significantly reduces the spatial variation in response, such that the difference from one location to another is greatly reduced. If further EQ is needed, it is likely addressing gentle global problems, rather than acute local ones.
As a general rule of thumb, two subs have about half as much variation in in-room response as a single sub, and four subs have about half as much in-room response variation as two subs (assuming they’re spread around somewhat). Smooth bass = fast bass, because it is the excess energy in peaks that makes a subwoofer sound slow (the ear/brain system having poor time-domain resolution at low frequencies, it is the frequency response that dominates our perception). Also, smooth bass = powerful bass, because we’re likely to set the average level of the subwoofer lower than it should be if the response has distracting peaks that stick out like sore thumbs.
Dipoles have smoother in-room upper bass than monopoles do, so the discrepancy between two dipole mains and a single monopole sub is greater than what we get with conventional main speakers. If you read accounts of people who have tried subs with dipole speakers, it seems like most people who try a single sub eventually give up because they can hear the discrepancy. Most people who try two subs keep them, because they don’t hear much discrepancy. Three or four subs would be better still, and they can be small subs.
I spent several years trying to design a super subwoofer that was "fast enough" to keep up with Quads and Maggies while offering good extension and impact. I tried sealed, transmission line, dipole, isobaric, aperiodic, and more. Then a conversation with Earl Geddes changed everything, and I’m now an advocate of distributed multiple subs, in particular for use with dipole mains. I’m using his ideas with his permission.
Imo, ime, ymmv, etc.
Duke
dealer/manufacturer |
You can of course do it with a test signal like white noise and a meter. That’s how I did it with 1 sub. Learned you can’t just trust your ears in this case to get it right. More subs and more controls means more complexity. That’s when automation like minidsp comes in handy to cut to the chase. Live and learn …. that’s a good thing. |
I thought the Ohm blog article I linked to by John Strohbeen above was interesting. Something of a different take on optimizing sub placement for audio as opposed to home theater with more of a focus on timing of the sound waves from the subs relative to mains and listening position and how that affects what you hear than what I’ve heard from bass array proponents elsewhere where the main goal is to produce smoother bass response throughout the room including main listening position. JS’s conclusions on placement based on that seem simpler and different from other bass array proponents including Duke at @audiokinesis. 1 sub, center forward. 2 subs as stands for mains. 3 or more to the rear and set to lower SPL. Would love to hear AK’s take on that? It seems more focused on optimizing the bass more thoroughly specifically at the listeners location. |
