[Housteau]

When I finally and properly treated and dialed in my room for the best it had to offer acoustically, my system was already there and close to it's ideal locations.  I think that for many of us this is a fairly normal way of doing things.  But, I had been wondering if it is the best way to go about doing this?  For one thing you end up measuring and dealing with bass issues that are also being caused by the system placement within the room, the integration of the system itself (as in possibly the mains with subs), as well as the physical dimensions of the room.  Now my room ended up just fine and I like the results, but if I had to do it all over again with a new room I was thinking that there might be a better way to go.

I was thinking that it might be better to deal with the room first by itself and get all of it's dimensional bass issues sorted out before trying to integrate any system into it.  In this way you would have benchmark measurements just for the room.  Then, when the time came to set the system up you would be pretty certain that any future bass issues were now being caused by either the system itself, its placement, or integration.  Does this make sense?

What is the best way to go about this?  You will need to take measurements along the way to see and track your progress and so a speaker, or sub in that room would be necessary.  The microphone position could be approximated around where the listening position(s) are thought to be.  Is it best to measure a room at this stage from a single mono source to eliminate phase additions and cancellations?  Should this single mono speaker (or subwoofer) be first placed to maximize the best smooth response in the untreated room and then work from there.  Should measurements be taken from more that one speaker position?  How can we identify and separate out a true room boundary issue from that of a speaker (source) and room combination issue since a bass driver needs to be there somewhere to take measurements with?  Does it even matter?

Just for fun I have another question that has been bothering me.  There are many different ways to treat a room for bass problems.  Are certain methods more musically sound then others?  What I mean is, just going for a straight measureable improvement might not be the last word in creating a space that has good musical bass, or is it?  I remember reading somewhere that straight absorptive techniques can give great numbers, but can harm the ultimate musicality of a room.  Some state that membrane traps offer the best results for musical bass.  Is it just a numbers game for frequency response, or are other considerations there as well, such as possible phase and timing issues?  I don't know and that is why I wanted to pose these questions here.       

[Ethan Winer]

Great questions.

The first step is to establish loudspeaker placements and the listening position. This article shows the best way to do that:

How to set up a room

The "38 percent rule" is just a starting point, though it works well enough that people without the means to measure can just do what's shown and continue on to room treatment. If you are able to measure, that lets you fine tune the placements for the flattest bass response.

Bass response should be measured with all speakers active, or at least the two mains plus a subwoofer if you have one. It's a good idea to measure each speaker separately too, but that's more to find problems that might be missed otherwise. The reason I recommend playing all speakers when measuring is because that's how bass instruments are usually played. The quote below from my Audio Expert book explains in more detail.

As for "musical" bass, I think the ideal is to aim for a flat response. You'll never achieve perfection in any home-sized room! But it's still the ideal response IMO. Note that this has nothing to do with the type of bass traps used. Tuned traps can be useful in some situations, mostly to target very low frequencies. But for most rooms, conventional "porous" bass traps are the best solution because they're broadband.

--Ethan

Earlier I mentioned playing the sweep tone through all the speakers at once. With most pop music, and a lot of other music and all LP records, the bass is centered to sound equally through both speakers. So to learn the true response at low frequencies for music you listen to, you should do the same and play the sweep through both the left and right speakers at the same time. If you use a subwoofer, that should also be engaged for the same reason. However, it's useful to also test each speaker separately. This will quickly reveal unusual problems such as a blown midrange driver, or a severe peak or null that affects only one speaker.

[Housteau]

Thank you Ethan.  It looks like I was over thinking the whole thing and from what you wrote it is pretty straight forward.  I guess it doesn't much matter where the bass issues come from, since they will all have to be delta with in pretty the same ways anyway.

[InfernoSTi]

The "other" way to do it is to figure out how many bass traps you can live with and then add one or two more!  As Ethan says, you can't ever really get perfect so it is often a matter of putting in as much as you can. 

I really like to have bass in the four corners (upper and lower) of the room, a combo of diffusion and absorption on the front and side walls, and absorption on the back wall.  Kind of the "live" walls being from the middle of the room forward and the "dead" walls being from the middle of the room back.  I'm sure this is a personal preference. 

Also, if you don't put bass traps in your three-way upper corners (ceiling and two walls), put something over the corner (even heavy card stock taped up).

Oh, and I do measure using REW and a calibrated measuring mic...I was just offering suggestions in case you didn't start with measurements.

Best,
John

[JLM]

Best place to start - headphones.

If that doesn't work for you (I used them in noisy college dorm rooms and worked great), start with proper room dimensions. 

Then isolate the room completely, paying attention to details (like insulating a house or sealing a leaky pail, 99% sealed is not effective).

Use nearfield setup (takes as much of the room out of the equation as possible).

And read Floyd E. Toole's 'Sound Reproduction'.  Toole worked for the Canadian National Research Council for years before heading up room research for Harmon International.  In the book he explains how bass waves differ from mid/treble sound rays and why bass in every room acts like a shallow bath tub (think of moving your hand back and forth along the length of the water, making waves that interfere with each other).  That behavior is exactly what bass is doing in your room (acoustic tube).  Different frequencies behave differently and no location in the room is 'safe'.  The only way to stop/nullify it is with multiple subs (2 or more, search AC for 'swarm').  If 4 subs and an extra amp doesn't fit into your plans consider this innovative product:

http://www.spatialcomputer.com/page9/page10/page10.html

[bpape]

I would agree to get the system and listening position in the best starting position - then treat the room based on what remaining problems there are to address.

Hey - if you're going to build a race car, might as well start with a Porsche instead of a Beetle....

Bryan

[Housteau]

Thank you everyone for your input.  When I was working with my room I pretty much did what most of you are suggesting.  The photos in my Gallery will give you a decent idea of my room.

My questions here were more theoretical in a way.  I should have mentioned this from the beginning, but I was thinking of someone that was literally starting from the beginning in every way.  For example, if I was starting completely over it would have to be for a very good reason.  I don't see myself relocating for work or anything else.  So, if I had to start over it would be because of a very nasty disaster of some sort, such as a fire.  If I ever had to go through something horrible like that I really do not know what sort of speakers I would go with.  I love what I have now, My VMPS system, but sadly Brian Cheney is gone now and we no longer have that connection to him, or his work.  So what would I go with, monopoles, stay with dipoles, bipoles, omnis?  I honestly do not know.

However, the room would be a constant as no matter what sort of speaker I went with, unlike the higher frequency considerations, the treatment of bass issues would be universal.  My thoughts were of someone first building the ideal room around those bass issues without having a system integrated into it first.  That is why I had asked about measuring the room from a single source, such as a borrowed subwoofer from a friend.  I was thinking that with a listening room like that more than just a bit roughed in it would be easier to start to set up different kinds speaker systems and mostly just have the higher frequency room issues to dial in while comparing them and deciding what one likes.

[JerryM]

Post copious amounts of pictures as you go.

[JLM]

Starting with a blank slate:

1st, the bigger the room the better (less room induced sound)
2nd, proper proportions/shape (most information available and what our ears are used to are rectangles)
3rd, recommend nearfield setup (takes as much of the room out as possible)
4th, use a swarm of subwoofers (search here a Audio Circle, read Floyd E. Toole's 'Sound Reproduction')
5th, isolate completely (sealing 99% of pail still makes for a leaky pail)
6th, minimize noise in the room (ventilation - use lined/insulated ductwork, electrical - dedicated circuiting, no dimmers)
7th, tweak with absorption/diffusion as needed (shouldn't be needed if you've followed steps 1 - 4)

[Hipper]

I'm just a listener that's slowly getting to grips with small room problems so my views don't carry much weight, but I must admit my first thought was, I think, similar to Housteau's, namely if you start with a completely empty room of known dimensions and construction (and its construction would hopefully include any isolation work), there seems to be sufficient knowledge to calculate the problem bass areas and therefore these can be dealt with first. After that, install music playback equipment and measure to confirm or finalise bass response and complete with solutions for the higher frequencies.

Is that wrong then, or not really possible?

[North Star]

Great questions.

The first step is to establish loudspeaker placements and the listening position. This article shows the best way to do that:

How to set up a room

The "38 percent rule" is just a starting point, though it works well enough that people without the means to measure can just do what's shown and continue on to room treatment. If you are able to measure, that lets you fine tune the placements for the flattest bass response.

Bass response should be measured with all speakers active, or at least the two mains plus a subwoofer if you have one. It's a good idea to measure each speaker separately too, but that's more to find problems that might be missed otherwise. The reason I recommend playing all speakers when measuring is because that's how bass instruments are usually played. The quote below from my Audio Expert book explains in more detail.

As for "musical" bass, I think the ideal is to aim for a flat response. You'll never achieve perfection in any home-sized room! But it's still the ideal response IMO. Note that this has nothing to do with the type of bass traps used. Tuned traps can be useful in some situations, mostly to target very low frequencies. But for most rooms, conventional "porous" bass traps are the best solution because they're broadband.

--Ethan

Very nice to see you here Ethan! 

Cheers,
Bob

[Ethan Winer]

Very nice to see you here Ethan! 

Thanks Bob, I've been here for almost ten years!

--Ethan

[North Star]

Thanks Bob, I've been here for almost ten years!

--Ethan

Ten years! ...AudioCircle has been around for that long!

[Ethan Winer]

measure to confirm or finalise bass response and complete with solutions for the higher frequencies.

That is exactly correct. It's not even necessary to measure in most cases. If you follow the standard methods for bass traps and reflection absorbers, you'll surely hear a huge improvement and know you did it correctly.

--Ethan

[North Star]

Ethan, 55 acoustic panels and bass traps in your room, wow!