Setting up a subwoofer?

[James Glennon]

Having read a lot on subwoofer placement, the general consensus seems to be that corner placement is best, but I have seen conflicting advice on how far it should be from the corner.

1. Place the subwoofer equidistant from each wall, e.g. 9 inches from side wall, 9 inches from back wall.

2. Do not place the subwoofer the same distance from each wall, but stagger the distance, e.g. 9 inches from side wall, 18 inches from back wall.

Finding the hot spot (where the bass locks into the room) has proved very difficult.

Anybody got any suggestions! I am not a bass freak, but if there is bass on the LP I want to hear it, if there is not I don't!

JG

JG

[dogpile]

The sub design and room will determine the placement. What sub type are you talking about....side firing or down firing woofer?

[MichaelR]

visit Bob Katz's site Digido.com, a fantastic site full of great info.
There is a section on subs there.

Check out the great "honour roll of good sounding cd's"

Michael

[James Glennon]

The sub design and room will determine the placement. What sub type are you talking about....side firing or down firing woofer?

I have a REL Stadium (down firing woofer)!

JG

[John Moschella]

Altho it`s probably what you don`t want to hear, IMO, the only way to seamlessly integrate a sub into a system is to use a real time analyzer, test tones & a decent mike.

I agree completely. The Velodyne DD series does exactly that because is comes with a spectrum analyzer, mic, and has a built in parametric eq.

I don't agree with the corner placement rule. I have found through experimenting with the DD sub that corner placement excites room modes leading to enhanced response a certain frequencies, ie. far from flat and not good for music.

[head_unit]

Put the subwoofer at the listening position (yes, I do mean where your head would be ideally*).

Now stick your head &/or measuring device at the places you might place the sub. By acoustic reciprocity, the result will be the same.

(*I'm thinking that having your downward firing woofer in the middle of the air may not actually affect things all that much. I'll have to ask my friend at Harman what their latest thinking is...)

[James Glennon]

Put the subwoofer at the listening position (yes, I do mean where your head would be ideally*).

Now stick your head &/or measuring device at the places you might place the sub. By acoustic reciprocity, the result will be the same.

(*I'm thinking that having your downward firing woofer in the middle of the air may not actually affect things all that much. I'll have to ask my friend at Harman what their latest thinking is...)

I have been trying the ''place the subwoofer in your seated position and crawl round the room'' method and have been amazed how the bass changes when you move round the room. Some positions are a no-go aesthetically (her indoors), but this has been the best 'non technical' suggestion I have seen.


JG

[Clay]

One option is to put the sub where you want it and then adjust the phase and volume to your taste. A bit simple but can rock the house.

[bdiament]

Having read a lot on subwoofer placement, the general consensus seems to be that corner placement is best...

Hi James,

Corner placement is "best" if you want to maximally excite every resonant mode in your listening room.

Better to try and achieve the best blend with your main speakers, not just in level but in time as well. A misadjusted or misplaced sub might have the right amount of bass quantity but if the bass is not in time with the mids and treble it can sound sluggish and actually impede the performance of the main speakers.

Using measurement devices is a good idea but steady state tones will help you get the level right, not the timing.
I would definitely experiment with keeping the sub somewhere near your main speakers. (A continuously variable phase control is a big help but not all subs have these.)

And have fun too! Must remember that.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

[therockman]

One option is to put the sub where you want it and then adjust the phase and volume to your taste. A bit simple but can rock the house.



This is what I have done. I placed my sub where I thought it seemlessly integrated with the DECOR of the room, then I worked to do the audio adjustments afterward. It has served me well.

[-=Rudy=-]

I agree with Barry regarding the timing issue. Before I rearranged my living room, my sub was maybe three feet closer than my main speakers to the listening position, and it did not sound right. Right now, it is just about on plane with the front of my speakers, and it just sort of "locks in" now.

Even on my cheapo surround system in the den--it didn't sound right until I dialed in the correct distances in the receiver for speaker positions. Even so, I had to set the subwoofer a bit differently until I finally got it to lock in.

One thing I noticed about the timing: if you have ever heard that bass is non-directional, you would not get this impression if the timing is off! That's what I was noticing in my living room--I could still tell the right side of the room was bass-heavy. After I moved it, I can only slightly tell that the sub is on the right side of the room. It just seems to be locked in much better now.

[seriousfun]

Two rules about subwoofer placement:

1. If you determine in-advance where to place the subwoofer, it will be the wrong place!

2. If you work for days with the best equipment to find the best-sounding location, it will be in a doorway, a walkway, or some other unnaceptable location.

It's not really hopeless. Properly integrating a subwoofer means you can embrace your room as opposed to fighting it.

If you are to use an analyzer, it should be a time-based system like MLSSA (Maximum Length Sequenc) or TEF. If it is a Real Time Analyzer, it has to be at least 1/12 Octave (any fewer measured bands, as with a more common 1/3 octave analyzer, won't show you the dips and peaks in frequency response that will affect the sound of your subwoofer). That analyzer, plus an assistant to move the subwoofer around while you look like you know what you are doing, will help you find the placement with the flattest response.

Flattest response will usually mean placement where more room modes are excited, hence corner placement (but remember rule #1).

A few inches can make a difference in subwoofer response - different room modes can actually be engaged with a small location change, and time alignment with the main speakers can be changed, but unless you hear a great difference, don't worry about the difference between 9" and 18".

Down, side, up-firing - with fundamental bass frequencies, all else equal, it doesn't matter.

Continuously variable phase controls unfortunately from my experience screw up the phase response above the crossover point (which isn't brickwall) and a 0/180 degree switch will not. Once the subwoofer is time aligned, the phase switch or control should be adjusted where the movement of the subwoofer driver is the same as the main speakers - all moving out with a positive signal, for example, so notes that are in-common (like right around the crossover point) will be reinforced, not cancelled.

The Reciprocity Method works very well, but it's not always perfect. It's worth a try to narrow down potential placement.

Time alignment (getting the front, positive, waveform from the subwoofer reaching your ear at the same time as sounds from main speakers - all sound, irrelevant of frequency, travels at the speed of sound) is your task here. Sometimes if flattest response is obtained by placing the subwoofer substantially further from the listener than a main speaker, a compromise has to be made. Physical alignment is always preferable to digital delay, but again compromise might be the best solution.

[pdenny]

Right now, it is just about on plane with the front of my speakers, and it just sort of "locks in" now.

This has always been my experience. My new Tannoy sub is about 2 feet from my back wall, 2 feet due left of my right front speaker and a couple of feet away from my equipment rack. Imo, corner placement always overwhelms the room and the emanation point becomes obvious.

[shokhead]

[QUOTE=pdenny;2310361]This has always been my experience. My new Tannoy sub is about 2 feet from my back wall, 2 feet due left of my right front speaker and a couple of feet away from my equipment rack. Imo, corner placement always overwhelms the room and the emanation point becomes obvious.[/QUOTE

My experience is if it overwhelms,its not setup right. 99% of subs are in the corner{or close}. Of course i've seen misdirected listeners with the sub behind the chair they are setting in.:D

[James Glennon]

Not having access to measuring equipment, I tried out this method...

''Place your subwoofer at your seated position and then crawl round the room and listen where the bass sounds best and not uneven.''

Originally I had the subwoofer between the speakers but beside the left-hand speaker, lining up with the back of the main speaker. Crossover set at 80Hz and gain set at 4 o'clock.

I now have the subwoofer outside the left-hand speaker and about 6'' behind it. Crossover set to 52Hz and gain set to 2 o'clock.

I have been amazed at the transformation.

1. The bass is very full and tight sounding (no overhang), I can now follow every note being played, whereas before I was getting a lot of re-enforcing/cancelling effects.

2. The sound has great attack and is much more dynamic.

3. This is the piece that has surprised me (am I imagining it), the midrange is now much fuller (not bloomy) and this has enhanced the stereo separation, instruments are much better placed in the soundstage.

I have played record after record trying to catch the system out, records that 'had' too much bass, records that hadn't 'enough' bass but the balance isn't what I was expecting. I even disconnected the subwoofer and just listened to the main speakers and it doesn't have that 'attack' that the subwoofer gives. This was an aspect I wasn't expecting. I was initially just trying to get more bass out of the system but was unhappy and I had been contemplating getting rid of it, but not now.

I will report back in a week or two and see if I still feel the same way about it.

JG

[bdiament]

...Flattest response will usually mean placement where more room modes are excited, hence corner placement (but remember rule #1)...

Hi seriousfun,

I can see it being closest to (nominally) flat at the very bottom but don't see how exciting as many room modes as possible will provide the most neutral results a bit upwards in the frequency spectrum, particularly in the time domain.


...Continuously variable phase controls unfortunately from my experience screw up the phase response ...

I'd think this would depend on the quality of the engineering (and parts) in the continuously variable control.
Still, I agree that physical placement for time alignment would be the first choice.

Also, while not practical in this particular case, having more than one sub often helps even things out considerably.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

[seriousfun]

Hi seriousfun,

I can see it being closest to (nominally) flat at the very bottom but don't see how exciting as many room modes as possible will provide the most neutral results a bit upwards in the frequency spectrum, particularly in the time domain.



My measurements (MLSSA and/or warble/boink tones with SPL meter) and listening show the bottom two octaves to be better supported by more room modes than, for example, one huge un-tameable dip. 20% or-so rooms will stubbornly not follow this.

Typical home-sized rooms (any room under 12,000 CF, at any rate) will have modal problems. Concrete bunkers will have the fewest, since they have no surprise outside resonances to deal with (but who wants to enjoy music in a bunker?).


I'd think this would depend on the quality of the engineering (and parts) in the continuously variable control.
Still, I agree that physical placement for time alignment would be the first choice.

Also, while not practical in this particular case, having more than one sub often helps even things out considerably.



I just didn't find any good variable phase controls, not even on the most expensive subs.


I found it difficult to find a second location for a second sub, in many rooms that had significant modal problems, that would complement the first sub, but once in a while it worked. I stubbornly believe that there is no such thing as stereo bass, but multiple subwoofers often are a vital component, since headroom runs out first in the bottom two octaves.

[Max F]

Corner placement and EQ the peaks down with a parametric EQ. That works for me! I think a big reason that many people like sealed subs is that they tend to work better in the average sized room. The room boom compensate for the drop off in spl at low frequency in a sealed sub. With a ported sub, EQ is essential IMO (assuming that you've set the crossover and phase appropriately).

[-=Rudy=-]

Physical alignment is always preferable to digital delay, but again compromise might be the best solution.

Agreed.

It makes me wonder why the more expensive subs don't have a digital delay built in. (Do any of them?) If you think about it, hardware for 24/96 AD/DA conversion is cheap, and since it is only the bass frequencies, you don't have to worry so much about the effect of the conversion process on the higher frequencies. It would be nice to offer it as an option to put into the circuit, where you could enable it if needed, or disable it if you want the "straight wire" approach.

For a sub, it would probably make sense to let you dial in the delay time, in milliseconds, and give a conversion chart to show the correlation between distance and delay setting needed.

[seriousfun]

A digital delay, a 1/12/octave analyzer and 3-band parametric EQ... The lower two octaves are less-suseptible to problems caused by these additional electronics, so I have often thought about this.

Most HT receivers have delays built-in, and the EQ and analyzer would open cans and cans o' worms, but these features would be welcome.

[James Glennon]

Not having access to measuring equipment, I tried out this method...

''Place your subwoofer at your seated position and then crawl round the room and listen where the bass sounds best and not uneven.''

Originally I had the subwoofer between the speakers but beside the left-hand speaker, lining up with the back of the main speaker. Crossover set at 80Hz and gain set at 4 o'clock.

I now have the subwoofer outside the left-hand speaker and about 6'' behind it. Crossover set to 52Hz and gain set to 2 o'clock.

I have been amazed at the transformation.

1. The bass is very full and tight sounding (no overhang), I can now follow every note being played, whereas before I was getting a lot of re-enforcing/cancelling effects.

2. The sound has great attack and is much more dynamic.

3. This is the piece that has surprised me (am I imagining it), the midrange is now much fuller (not bloomy) and this has enhanced the stereo separation, instruments are much better placed in the soundstage.

I have played record after record trying to catch the system out, records that 'had' too much bass, records that hadn't 'enough' bass but the balance isn't what I was expecting. I even disconnected the subwoofer and just listened to the main speakers and it doesn't have that 'attack' that the subwoofer gives. This was an aspect I wasn't expecting. I was initially just trying to get more bass out of the system but was unhappy and I had been contemplating getting rid of it, but not now.

I will report back in a week or two and see if I still feel the same way about it.

JG

One other thing I forgot to mention is that I can now give the system more volume and enjoy it!

Barry, I sure am having fun!

JG

[bdiament]

...Barry, I sure am having fun!

JG

Hi James,

That's the spirit! Enjoy!
:righton:

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

[Vinyl-Addict]

I now have the subwoofer outside the left-hand speaker and about 6'' behind it. Crossover set to 52Hz and gain set to 2 o'clock.
JG

Wow, 52hz seems awful high. Are your speakers small satelites?

[James Glennon]

Wow, 52hz seems awful high. Are your speakers small satelites?

Acoustic Energy AE1's well out into the room!

JG

[shokhead]

Wow, 52hz seems awful high. Are your speakers small satelites?

Now,its the other way,its low. 52 means his mains should play down to 52 before the sub takes over. Sats would be around 120 at least.