Help improving my speakers' sound?

[tccalvin]

Hey there, audio people.

I've been using a pair of Kali LP-6 for 5 years or so and I'm looking to make a roadmap of little things that I can do to improve their sound in my room. Forgive me since I'm not an expert on room correction.

The challenge is that I'm working with limited space inside a decently sized room (roughly 3.5mx3.5m, give or take). Here's a simplified drawing of it with my current setup:

The green area is the "usable" space, which is roughly a 2mx1m rectangle. I can't really move the "red" furniture (bed+closet) and the walls are uneven (some portions are occupied by furniture, some are made of uneven stone...) so there's limited opportunity for padding, although it's still doable to some extent.

The desk area (orange rectangle) is what is most customizable. Stuff can be moved around and/or replaced as needed, and the wall there (the 2m portion) is quite flat.

As you can see, the current setup is a very near-field one to hopefully minimize the impact of late bass reflections and keep a decent stereo image thanks to the equilateral triangle.

The speakers are equalized with internal DSP thanks to the dip-switches on the back, and they are set to their "on a desk, closest to the wall" preset. Still, the frequency response is not ideal. I don't yet have a measurement mic, but I can tell by ear (using sweeps) that there are some big, narrow bumps around 150Hz, 200Hz and some broader bumps on higher frequencies.

There is a (video) computer monitor between the speakers and the space it takes up is not insignificant. I wonder if it might affect the stereo image.

Things I can probably do without too much trouble:

- Further corrective EQ with measurement mic (dip-switches and/or REW)
- Re-arrange and/or replace stuff in the "usable" area
- Add (some) padding
- Place the speakers on some high quality stands
- Add a sub

Any help is appreciated.

As always, thank you for your patience.

 

[scorlee]

If anomalies occur at a fixed frequency, could it be a problem with the equalizer? or compatibility issues with the hardware being used together.

 

[scorlee]

Especially when there is impedance and power mismatch.

 

[Elkerton]

Have you tried placing the speakers at the quarter point of the wall, which looks like it would be a little further apart? That would help control the standing waves in the room a little and might lower the bumps. Physically, given your constraints, that is my only suggestion. Parametric equalization would be my next suggestion.

 

[tccalvin]

Have you tried placing the speakers at the quarter point of the wall, which looks like it would be a little further apart? That would help control the standing waves in the room a little and might lower the bumps. Physically, given your constraints, that is my only suggestion. Parametric equalization would be my next suggestion.

Thank you guys for the suggestions.

Right now, if we look at the "top" wall from left to right, they are placed at roughly at the 2/4 point of the wall and 3/4 point of the wall. Maybe you mean placing them at the 1/4 and 3/4 points?

It's not impossible, but that would mean sacrificing the equilateral triangle. Since I can only sit at a max distance of around 1m - 1.2m from the top wall, that's also roughly the max distance that the speakers can sit at relative to each other.

 

[Keith_W]

Placing speakers on tables or desks have a few problems:

1. The desk/table has its own resonant frequency. It absorbs vibrations from speakers and may re-radiate it at another frequency. You want a sturdy table to avoid this.
2. Tables cause "table bounce" - very early reflections. This changes the frequency response and directivity of the speaker. Speakers should be pushed to the edge of the table or elevated.

To understand whether your monitor is interfering with your stereo image or not, you need to measure the angle between the on-axis sound of your speaker to the edge of your monitor:

Let's say ϴ = 30 degrees. Now you find the polar plot of your speaker (here is a random one from the internet):

And you draw a straight line at 30deg. Anything outside will be blocked by your monitor.

 

[tccalvin]

Placing speakers on tables or desks have a few problems:

1. The desk/table has its own resonant frequency. It absorbs vibrations from speakers and may re-radiate it at another frequency. You want a sturdy table to avoid this.
2. Tables cause "table bounce" - very early reflections. This changes the frequency response and directivity of the speaker. Speakers should be pushed to the edge of the table or elevated.

To understand whether your monitor is interfering with your stereo image or not, you need to measure the angle between the on-axis sound of your speaker to the edge of your monitor:

View attachment 468309

Let's say ϴ = 30 degrees. Now you find the polar plot of your speaker (here is a random one from the internet):

View attachment 468311

And you draw a straight line at 30deg. Anything outside will be blocked by your monitor.

Thanks again for the feedback.

Swapping desk and placing the speakers on stands is something that is definitely feasible (I have a couple of Gravity SP 3202 stands).

In the current setup, the monitor is placed slightly behind the speakers (the drawing is pretty accurate in that regard) so I'm guessing the angle is >90°, going by the diagram you posted.

This is the LP-6 directivity measurement from Amir's review:

Looks like current placement should be fine for soundstage, at least horizontally. Am I reading the graph correctly?

 

[Keith_W]

Should be OK. As you can see, below about 500Hz your monitor blocks some sound. The effect should be pretty minor, but I would still prefer the speakers to be in front of the monitor.

 

[DVDdoug]

- Further corrective EQ with measurement mic (dip-switches and/or REW)

The DIP switches may help and I assume you've experimented and know what they can do but they probably aren't precise/narrow enough for room modes.

EQ (especially "precise" parametric EQ) can help a LOT with the bumps but it can't do much for dips where the standing waves are canceling. (Bumps tend to be more annoying.)

- Re-arrange and/or replace stuff in the "usable" area

That's unlikely to make a difference with low frequencies (long wavelengths).

Moving the speakers or listening position will make a difference but of course there are "practical" limitations/considerations.

- Add (some) padding

Bass traps have to be very thick and cover significant wall area. Or there are thin "membrane" traps but you still need to cover a significant proportion of the wall area. Regular acoustic treatment doesn't do much for the bass. Too much "regular" treatment can foul-up the frequency balance by absorbing the mid & high frequencies while leaving the lower frequencies.

- Place the speakers on some high quality stands

That won't make much difference either, except to the extent that it allows you to re-position the speakers. The "quality" of the stands shouldn't matter.

- Add a sub

Overall, that's probably a good idea given your baby woofers. But it may not even be operating at 150Hz and it could make room problems worse with the bass coming from only one location (although you usually have more flexibility with placement), and you may discover more low-frequency room modes that are too low to be excited with your current speakers.

 

[Looneybomber]

I don’t know your use case or profession but your setup is the same as a small recording studio with speakers, desk, and monitor(s) close to you. Do what recording studios do - add absorption on sidewalls, behind the speakers (to reduce SBIR dip in the midbass), ceiling, and possibly desk if there’s room.

Here’s a short video to provide some info.