Need help with room and speaker setup, big dip from 250-80hz

[tboooe]

I have a very small and odd room. The room itself is 9' wide by 10' long with 9' ceilings. The wall directly behind my head is only 3' tall, above that it opens up to my family room and kitchen. I have the speakers firing down the 10' length. The speakers (Sonus Faber Guaneri Evolution monitors) are toed in directly at my head, 3' from the front wall, and 1.5" from the sidewalls. I have bass traps in the corners, absorption at the 1st reflection points and ceiling, and a mix of absorption and diffusion on the front wall. My listening chair is right up against the short back wall.

 

I just did a quick measurement of my room using a cheap RS SPL meter and some test tones. It seems I am -6db at 630hz and 250-80hz. Any advice what I can do to help alleviate these dips? As you can tell by my room dimensions I do not have a lot of flexibility. Thank you.

[mansr]

Moving the listening position forward from the rear wall, even by a foot, might make for an improvement. Since you have an SPL meter, you can easily measure a few positions without making any actual changes.

[20hertz]

Cancellations are easily identified. Having your speaker 1 metre from the wall will cancel out 86 hertz. Move the speaker out 3 meters and you lose 29 hertz.

The 250hz dip could be ceiling or floor.

Measure your speakers hard up against the back wall and move out a little if the boundary gain is too much.

And move forward a lot, sit in an equal triangle with your speakers and listen to them like they are headphones instead of listening to your room.

 

Check the Genelec website for all the physics and measurements.

[tboooe]

Cancellations are easily identified. Having your speaker 1 metre from the wall will cancel out 86 hertz. Move the speaker out 3 meters and you lose 29 hertz.

The 250hz dip could be ceiling or floor.

Measure your speakers hard up against the back wall and move out a little if the boundary gain is too much.

And move forward a lot, sit in an equal triangle with your speakers and listen to them like they are headphones instead of listening to your room.

 

Check the Genelec website for all the physics and measurements.

 

OK I moved my meter around the room and the only locations where I got rid of the biggest dips at 80 and 160 (-10db), was literally right in front of the speaker or at floor level right at the back wall behind the listening chair. So according to your advice I should move my speaker closer to the wall behind them?

[wanta911]

OK I moved my meter around the room and the only locations where I got rid of the biggest dips at 80 and 160 (-10db), was literally right in front of the speaker or at floor level right at the back wall behind the listening chair. So according to your advice I should move my speaker closer to the wall behind them?

 

As long as your speakers are in some kind of "room", including rooms bigger than yours, there will a dip/null/cancellation. As 20hertz points out, moving your speakers will alter the frequency where these null/s occur. Closer to the wall behind them will move them to higher frequencies and moving them out will do the opposite. Unfortunately there are not too many of us that can have their speakers 2.5 to 3 metres out from the wall, which would be ideal, so there has to be a compromise.

 

A dip is usually more audibly noticeable at lower frequencies, so moving it to a higher frequency can often be a good compromise solution.

 

Here's a website that gives a rough guide to frequency cancellation changes with different speaker/front wall distances:

 

mh-audio.nl - Acoustic

 

Edit: also moving your LP from the rear wall as mansr suggested is also a good idea, so if you move your your speakers closer to the front wall you may have the opportunity to do this?

[baddog]

BTW, as I am sure you are aware, the Radio Shack meter is far from a precious instrument. Regardless, if you are going to do measurements with it, you should apply the corrections noted in the first post on this thread at AVS.

 

No correction for the reading at 630Hz.

 

For the other readings, corrections are required.

 

Also some good general tips on taking measurements in that posting that are worth a read given your use of the Radio Shack SPL meter.

[wgscott]

Do a free trial of Dirac. Any half-way decent USB mic will give you approximate data, and you can also see if the room correction solves the problem. Get a good mic if you actually wind up purchasing Dirac.

[semente]

I have a very small and odd room. The room itself is 9' wide by 10' long with 9' ceilings. The wall directly behind my head is only 3' tall, above that it opens up to my family room and kitchen. I have the speakers firing down the 10' length. The speakers (Sonus Faber Guaneri Evolution monitors) are toed in directly at my head, 3' from the front wall, and 1.5" from the sidewalls. I have bass traps in the corners, absorption at the 1st reflection points and ceiling, and a mix of absorption and diffusion on the front wall. My listening chair is right up against the short back wall.

 

I just did a quick measurement of my room using a cheap RS SPL meter and some test tones. It seems I am -6db at 630hz and 250-80hz. Any advice what I can do to help alleviate these dips? As you can tell by my room dimensions I do not have a lot of flexibility. Thank you.

 

The proportions of your room are quite close to those of a cube which make it the worse case possible...

 

Could you draw a rough sketch of your room and setup?

How far are you sitting from the speakers and what's the distance between them?

Where is the listening spot positioned in relation to front and back walls?

 

R

[rodrigaj]

I have a question. When you speak of moving speakers, say 1 meter from the rear wall, do you measure from the front, driver side of the speaker, or from the rear of the speaker?

[wanta911]

I have a question. When you speak of moving speakers, say 1 meter from the rear wall, do you measure from the front, driver side of the speaker, or from the rear of the speaker?

 

Well I guess people will do it different ways, so if it's not specified clarification would be required. The calculation in the link I posted above measures from the front of the speaker.

[tboooe]

Thanks guys.

 

I can definitely move the speakers closer to the front wall but I also read that the distances from the front wall and side walls should not be the same? Right now the speakers are 3 ft from the front wall and 1.5 ft from the side walls. How close can these two dimensions be?

 

Also, do you guys think adding absorption on the front wall between the speakers will help? Right now I have a combo panel that acts more as a diffuser.

 

In terms of my listening position, the speakers are 5.5 ft apart and I sit 6.5 ft away. My seating position is right up against the 3 ft wall.

[Solstice380]

I think the GIK Acoustics web site has a nice little calculator app that will show you what frequencies the room modes are at. With your room being close to a cube, as noted, you'll see a lot of room modes close together which would give humps. Keep looking on the sound panel mfrs. websites and you'll come across some other calculators. I've got one on my old laptop (stashed somewhere or I'd tell you the name) that lets you also input speaker characteristics and get back some optimum listening positions. Check RealTraps, etc. I think that some of them will even do a free room analysis and make recommendations before you buy.

 

I think 1 1/2 feet from each side wall is a little much. And then you might try not using so much toe in. You may end up with the best experience by listening near field like your speakers really are big headphones to get away from the room modes. You don't have to crank the volume so much, also.

 

Whichever way you go, treatment of almost ALL rooms is necessary. Then you can start to evaluate your equipment.

[rodrigaj]

Well I guess people will do it different ways, so if it's not specified clarification would be required. The calculation in the link I posted above measures from the front of the speaker.

 

That makes sense and is the way I always measured - afterall, that is where the drivers are.

 

One of the reasons I sold my ProAcs was because of the port in the rear. I always found that I had to move them way into the room and away from the rear wall. ProAc has since moved there ports to the bottom facing the floor which introduces a different set of problems but is better than the rear.

[semente]

Thanks guys.

 

I can definitely move the speakers closer to the front wall but I also read that the distances from the front wall and side walls should not be the same? Right now the speakers are 3 ft from the front wall and 1.5 ft from the side walls. How close can these two dimensions be?

 

Also, do you guys think adding absorption on the front wall between the speakers will help? Right now I have a combo panel that acts more as a diffuser.

 

In terms of my listening position, the speakers are 5.5 ft apart and I sit 6.5 ft away. My seating position is right up against the 3 ft wall.

 

Sitting against a wall increases room interference.

I'd try moving the listener/speakers triangle forward and take measurements at 2 or 3 different positions.

You are sitting quite close to the speakers and shouldn't be getting much reflected sound.

Avoid multiple or equal distances between the speakers and front + side walls as well as woofer to floor.

 

R

[tboooe]

First of all, thank you all for the input. I spent a few hours moving my speakers around my music room, trying to move the speakers closer to the front wall, closer together, adjusting the toe, etc. I was able to get varying degrees of success but I still had massive nulls throughout the frequency range 80-250hz. I finally tried moving the speakers further out into the room. My reasoning was that I had good bass response below 80hz so I could lose a bit but hopefully still be within ,3db of flat. I also moved my speakers further apart so that I was listening in an equilateral configuration. The results were better than expected. From 20-1000hz, I was within ,3db of 70db. My only small null was at 800hz where the response was -6db down.

 

Again thank you all for the input.

[17629]

Did you notice a difference in sound quality?

[mayhem13]

-6db at 800hz......right in the critical vocal range.....problem solved huh........

 

Gotta love this place.

[tboooe]

-6db at 800hz......right in the critical vocal range.....problem solved huh........

 

Gotta love this place.

 

Hey it's better than what I had before which was a null from 80-250. As you know this hobby is all about compromises at least it is for normal people like me who do not have dedicated listening rooms designed by acoustic engineers to have a ruler flat freq response. I am open to recommendations like what the other helpful people on this thread contributed. What do you suggest? Also curious to know what your room response is.

[Fitzcaraldo215]

I have a very small and odd room. The room itself is 9' wide by 10' long with 9' ceilings. The wall directly behind my head is only 3' tall, above that it opens up to my family room and kitchen. I have the speakers firing down the 10' length. The speakers (Sonus Faber Guaneri Evolution monitors) are toed in directly at my head, 3' from the front wall, and 1.5" from the sidewalls. I have bass traps in the corners, absorption at the 1st reflection points and ceiling, and a mix of absorption and diffusion on the front wall. My listening chair is right up against the short back wall.

 

I just did a quick measurement of my room using a cheap RS SPL meter and some test tones. It seems I am -6db at 630hz and 250-80hz. Any advice what I can do to help alleviate these dips? As you can tell by my room dimensions I do not have a lot of flexibility. Thank you.

 

I could be wrong, but the 80-250 Hz depression might be mostly a result of floor bounce cancellation. What you have is a typical symptom of that. But, that might be in addition to room reflections from other surfaces, too. Floor bounce is also partly the result of the speaker's design and position of the woofers in the enclosure itself.

 

But, if it is indeed floor bounce, passive treatments on the side walls or carpeting will not do much to alleviate it in that frequency range. Repositioning speakers or your listening position will likely be of more help. But, positioning is critical and it still might not be totally effective. BTW, Passive treatments in the deeper bass are generally ineffective, unless they are huge. Off the shelf bass traps, even expensive ones like ASC Tube Traps, do not do much for the deep bass below 100 Hz.

 

The best fix is Room EQ, provided no more than 8-10 dB of boost is required. Even so, some response dips are not nearly as bad sonically as peaks if you need even more boost than that. Try Dirac if you can. It is fairly easy to use and not outrageously expensive, and a decent mike is $75-$100. I think something like Dirac is ultimately better, more effective and less expensive than passive treatments, which are extremely difficult to configure accurately to achieve something approaching a similar effect. You will also spend enormously more time tweaking and measuring passive treatments.

 

I suspect you will consider Dirac a bargain, equivalent to having new and better speakers in a better room. Too good to be true? Invest in a mike, try it and find out for yourself. The 30-day trial is free if you do not like it.

 

The mike can also be used with REW, but you can easily get seduced by a tool like that into thinking it is telling more than it really can accurately. It might be a case of "false precision", unless you become more conversant with the complexity of room acoustics. A little bit of knowledge is a dangerous thing. The tool measures like it is supposed to, but it does not interpret the measurements or tell you exactly what to do to fix problems.

[tboooe]

I just remeasured my room but instead of standing next to my listening chair I stood behind it in the other side of the short 3' wall. The -6b drop at 800Hz went away. So now I am measuring within 3db from 20-1000Hz.

 

As for Dirac, I've thought about that but before I can consider that I will need to upgrade my audio pc. Right now I am using an old Atom 525 which won't have the horse power for Dirac. Its definitely on my list of things to try though. What I also need to investigate is how Dirac can work with my current 2pc set up using Audiophile Optimizer, Fidelizer, and Jplay.

[semente]

I agree with Fitzcaraldo215, you really should consider getting yourself a mic and a USB mic-pre.

 

R

[17629]

Hey it's better than what I had before which was a null from 80-250. As you know this hobby is all about compromises at least it is for normal people like me who do not have dedicated listening rooms designed by acoustic engineers to have a ruler flat freq response. I am open to recommendations like what the other helpful people on this thread contributed. What do you suggest? Also curious to know what your room response is.

 

 

You don't need to explain yourself to some clown who's never heard your system. If you say you fixed your system, then you fixed it.