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Looking for the BASS

For some time I wanted to open a discussion about subwoofer set-up, where audiogon-ers can share their experiences and knowledge on the matter.

My story is about REL subwoofers (the only subwoofers with which I have experience). However, since the physics of low waves does not change when going from REL to VELODYNE to JL Audio, etc., this discussion should definitively NOT BE restricted only to REL subwoofers. Any tips and tricks that might help us improve our set-ups are very welcomed.

Here goes my story:

In august last year we have moved to a new home where I've got to have my own music/study room. The dimensions of the room are (L x W x H) 4.70 x 3.60 x 2.40 (i.e. 15.42 x 11.81 x 7.82). While it is not a very large room I find its dimension more than decent. My system consists of Accuphase electronics (E-550 class A integrated amp, DP-550 cd player and the DG-38 vicing equalizer) and a pair of Focal Micro Utopia Be speaker complemented with a REL Stentor 3 subwoofer. (For more detail see the page of my current system, i.e. Kosh Naranek.)

In the last 6 months I have been moving the system around the room, placing the speaker and woofer agains each of the four walls, then further optimizing the position of the subwoofer. While getting a good stereo image was never a problem, obtaining a smooth bass response was challenging. Depending on the wall against which the speakers were place I was getting either too much or too less bass.

Placing the speakers against the long walls yielded much better results then when placing then against the short ones. This is in agreement with my findings in my previous rooms, though this need not be always the case. As can be seen in the 3rd pic on my Kosh Naranek system, I ended up with the subwoofer between the speakers, about 30-40 cm behind de plane of the speakers and rather close to the left speaker (about 20-25 cm).

** SPEAKER PLACEMENT:

From experience I know that it is best to place my MicroBe about 2.0 - 2.30 meters apart and place the listen chair at approximatively the same distance form the speakers. Thus, given the dimensions of my room, the speakers were placed approximately 1.2-1.6 meters from the back wall and 0.75-1.5 meter form the lateral walls (different room layouts led to different values, of course).

** SUBWOOFER PLACEMENT:

* I start by following the REL procedure - as indicated in the REL manual. With the subwoofer in one of the corners behind the speakers and while playing a track with repetitive strong bass I do the following:

a) adjusts the phase of the subwoofer in order to get the loudest bass,
b) moves the subwoofer away from (or closer to) the corner, again looking for the position that gives the loudest bass
c) adjusting the crossover point and the volume of the subwoofer in order to obtain the smoothest response

While this method yields decent results, one can almost always improve the results obtain with it. This is how I accomplish this:

Using the settings for the crossover and volume determined using the REL procedure, I moved the subwoofer in my listening position. Then, I move around the room looking for the position that has the most even bass response. What I actually do here is: 1) Play an walking bass line, most often the first 3 seconds from track 3 on Norah Jones's "Come away with me" album, i.e. Cold cold heart. I make a loop with my CD player and play the first measure of this track continuously. 2) Walk around the room and look for the place where all notes of the double bass sound equally loud. Once I have found the right place I move the subwoofer there (keeping the sub orientated exactly as it was when placed in the listening position). Further fine tuning can still be done by moving the sub in very small steps of 5 cm or so. Slight movements of the listening chair closer or further from the plane of the speakers can result in additional small improvements. Finally, I should mention/stress that in my room I always had to change the phase setting of the REL (compared to the setting determined when using the REL procedure, even though the REL is still behind the speakers) in order to obtain the most even bass response.

Following this procedure I was able to obtain a very natural and full body bass in my room. At this point, I have run the room set-up procedure of the Accuphase DG-38 voicing equalize. This has improved things even further, much further actually, i.e. by clearing up all bass notes (by removing any bass bloat) and making them sound much faster.

The final result was definitively worth the effort, though moving my large drum kit around the room 5 times (and then setting it up) was a bitch. Moreover, my wife has now the greatest respect for my patience and determination. She knows me for 11 years and had no idea I have this in me ... though, like all women, she wishes I would put this kind of effort into something more useful ... :)

Take home messages:

1) BE PATIENT AND DO NOT GIVE UP EASILY!
2) Subwoofer placement is crucial
3) Electronic correction can make a huge difference BUT apply it only in the last stage and as little as possible

As mentioned in the beginning of this post I look forward to hear your thoughts/experiences on subwoofer set-up procedures.

Best wishes,
Paul
nvp
nvp OP
317 posts
 

Vicdamone, thanks for the contribution. Writing a good long post takes time and often is not appreciated.

Of course, choosing the right type of connection is essential for achieving a seamingless integration between subwoofer and the main speakers. (My sub has both types of connections, i.e. high level and low level. I use the high level one because this is what the manual recommends.) However, while essential, choosing the right type of connection does not guaranty a successful integration.

The main point I am/was making in this thread is that the position of the subwoofer in the room is really essential, viz. interference patterns depends very sensitively on the relative position of the sound sources, i.e. sub and reflecting walls (which need not necessarily be the walls of the room where the sub is). Interference really has nothing to do with the type of correction one uses (low or high level inputs). Also, while not a bad argument, the fact that pro subs most often do not have a high level input is not that relevant (IMO). This can be pure commodity :).

The second point I made in this thread is that electronic equalization is important. Here we fully agree. Most often, even after carefully optimizing the position of the speakers and subwoofer, one still has a few frequencies that are excited (or partially canceled) by the room. Having the ability to tame down or pump up a little very specific modes can make all the difference in the world. (In this regard REL is definitively lacking a very important and essential feature. I believe you were referring to REL in your post, right? Fortunately, I can use my Accuphase DG-38 voicing equalizer to address this issue.) However, I firmly believe that electronic equalization should be done only after optimizing everything else - trying to even out peaks and valleys of 10 dB or more without adjusting the crossover, volume and position of the sub in the room is wrong.

Best wishes,
Paul
vicdamone
850 posts
 
Ahh, the easy way...

["REL Studio III subwoofer
By Larry Greenhill • Posted: Oct 26, 2004 • Published: Oct 1, 2004
Setup
Two Sumiko installers, Patrick Butler and Allan Hager, traveled to my listening room to install the big REL. They had all the desired criteria: youth, intelligence, physical strength, and lengthy experience with and respect for REL subwoofers. Together, they lifted the Studio III off my garage floor, carried it carefully into my house, up the stairs, and into my listening room. Patrick—taller, more fastidiously dressed, more precise in diction—orchestrated the physical installation. Allan—more casually dressed, more poetic—provided a lengthy description of how to accomplish the subwoofer's fine-tuning and room-matching.

The second reason that installing a REL Studio III is no solo task is the degree to which the sub must be tuned to one's listening room. A minimum of two people are needed: one to listen, the other to set the controls on the Studio III's service panel. This Patrick and Allan did. In fact, Sumiko trains dealers across the US to install and tune REL subwoofers; any buyer of a new Studio III would get the same assistance in delivery and setup that I did."]

[{"Finally, I should mention/stress that in my room I always had to change the phase setting of the REL (compared to the setting determined when using the REL procedure, even though the REL is still behind the speakers) in order to obtain the most even bass response.'}]

Just an FYI for everyone using a sub. The phase of recorded material, regardless of the type of media, can change from track to track on the same album. It's most noticeable in popular music were the, "Kick," or Bass Drum has a dominate voice.

If your subwoofer has remote control with a phase button, from your listening position try switching the phase. It's not always noticeable but if that track is out of phase you'll notice the Bass Drum tighten up with the rest of the music. A pain in the butt to be sure but if you're doing some serious listening its worth checking.
atmasphere's avatar
atmasphere
12,171 posts
 
THe lowest note on a Fender bass is 42Hz!

Who are you trying to impress???

Me. (organ pedal tones and synthesizers can go to 16Hz) That is who does most of the listening to my stereo. But I don't have subwoofers, instead I have speakers that go to 20Hz on their own (Classic Audio Loudspeakers T-3). They sit about 8 inches from the wall. I have a room resonance at about 26Hz. Due to the down-firing woofer (in addition to the front firing woofer) it seems to exacerbate the room resonance the least of any speaker I have tried. So the bass is good all the way down.
mrmitch
359 posts
 
Ralph, have to agree with you about the downward firing woofer. I have a pair of Unity Audio Signature 1's from the early 90's that I still love (Bob Grost did it right)that use downwards firing woofers. I dont get near 20 Hz as each woofer is 10" and the internal volume of the speaker isnt that large, but I imagine it goes down to 32 Hz or so. I dont have any huge room resonances excited by the bass, so I've been very happy with the extension and clarity of bass in my system. The speakers are about 2 and a half feet out from the wall, and the fact that they have a front-firing port may help.
nvp OP
317 posts
 
Hey Atmasphere,

Thanks for coming to my aid. Of course, this was my plan all along, i.e. to impress a famous designer by talking about the lowest notes. :)

Leaving jokes aside, what are your opinions regarding subwoofers and subwoofer placement?

Best wishes,
Paul

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