Bass Advice

[Rob606]

Hello fellow members. I have a fairly common question regarding room treatments for bass issues. I have a pair of Summits in a room that is about 10'wide x 11'long x 9'high. I am struggling with finding a listening position that captures mid bass frequencies without compromising the spacial imaging of the panels. This seems to be the innate struggle with this type of speaker.
So far I have tried placing some foam yoga rollers in the corners (it's ok to lol) - which removed much of the boominess. very pleased with that
- I've relentlessly and patiently tweaked the speaker positions - which has been worth the effort
- added first reflection screens - a discernible improvement.
- diffused the wall behind the speakers with heavy curtains (they block the windows that sit right behind the speakers) - very helpful for the higher frequencies and imaging.
- I have a floor rug and I sit on a large couch about a foot from the back wall.
- I've also used DSP with my DBX Driverack which helped. But, honestly I'd rather not use as it as I don't want anything to alter the signal (trying to keep it purist as much as possible).
Managing the signal are a Krell KRC 2 pre and Kav 250 Amp which sit between the speakers against the front wall.
I know the size and dimensions of the room is a challenge and further treatment is necessary. I just have no idea where to start ie. diffusion or absorption. When I sit closer to the speakers the full band of bass frequencies appear, but I loose the benefit of the electrostat panels.
Thanks in advance to any and all advice!

 

[Rehan Azim Hashmi]

Hello fellow members. I have a fairly common question regarding room treatments for bass issues. I have a pair of Summits in a room that is about 10'wide x 11'long x 9'high. I am struggling with finding a listening position that captures mid bass frequencies without compromising the spacial imaging of the panels. This seems to be the innate struggle with this type of speaker.
So far I have tried placing some foam yoga rollers in the corners (it's ok to lol) - which removed much of the boominess. very pleased with that
- I've relentlessly and patiently tweaked the speaker positions - which has been worth the effort
- added first reflection screens - a discernible improvement.
- diffused the wall behind the speakers with heavy curtains (they block the windows that sit right behind the speakers) - very helpful for the higher frequencies and imaging.
- I have a floor rug and I sit on a large couch about a foot from the back wall.
- I've also used DSP with my DBX Driverack which helped. But, honestly I'd rather not use as it as I don't want anything to alter the signal (trying to keep it purist as much as possible).
Managing the signal are a Krell KRC 2 pre and Kav 250 Amp which sit between the speakers against the front wall.
I know the size and dimensions of the room is a challenge and further treatment is necessary. I just have no idea where to start ie. diffusion or absorption. When I sit closer to the speakers the full band of bass frequencies appear, but I loose the benefit of the electrostat panels.
Thanks in advance to any and all advice!

Prior to experimentation with absorptive and diffusive material get the placement right. Placement helps to remove or minimize boomy bass. And at the same time allow maximum or optimal performance of the panel.

Inside ML Classic ELS 9 instruction manual a formula for inside room speaker optimal or precise placement. If not precise optimal placement, then close to optimal or within one feet radius of ideal or perfect placement in the room. Placement according to this formula helps to minimize the negative impact of room standing waves.

Measure the distance of the wall in front of LP from ground to ceiling in inches. 9 feet x 12 = 108 inches. Multiply by 0.618 Each speaker's front midpoint must be kept 66.74 inches distance from the front wall or wall in front of LP. Now you know the placement of the speaker lengthwise in the room. 5 feet 6.74 inches.

Next calculation for placement from left and right sidewall. Measure total distance in inches between left and right sidewall. 10 feet x 12 = 120 inches. First divide this measurement by 18. Second multiply by 5. The result 33.33 inches is the required distance expressed in inches from each side wall to the front midpoint of each speaker. 2 feet 9 and one-third inches.

The distance between the midpoint of both speakers is 120 - 66.66 = 4 feet 5 and one third inch. This length should be the minimum distance to the center of both ears measured as a perpendicular from the loudspeaker center.

The goal according to acoustic experts is to allow maximum direct sonic radiation from loudspeakers to be heard. This is the ideal or goal achieved in the free field listening or to its simulation in an anechoic chamber. S

Since our listening room is fully or partially enclosed by walls, it is not a free field environment. We use absorptive and diffusive material to absorb and scatter sound waves. Goal is to prevent or minimize room reflections from reaching our ears. Absorption is more powerful than diffusion in this regard. Using both ensures that whatever is not absorbed is scattered and not directly reflected back at the listening position.

Hope this helps.

 

[ttocs]

In a room that small for those speakers the only thing that comes to mind is anti-bass. Use a small subwoofer that covers the range of frequencies that are causing a problem and invert the signal from the subwoofer. A "correction" filter might need to be employed using a miniDSP product, which is probably the easiest way to implement, but this is the simplest way I know of at the moment.

Effectively, the subwoofer would be nulling the frequencies that are building up in the room. The sub would need the same signal as the speakers are getting.

Another way is to use active bass traps, which are subs that are specifically designed for such a purpose. Basically, they do the same as what I am suggesting, but it's more plug and play.

 

[Rehan Azim Hashmi]

In a room that small for those speakers the only thing that comes to mind is anti-bass. Use a small subwoofer that covers the range of frequencies that are causing a problem and invert the signal from the subwoofer. A "correction" filter might need to be employed using a miniDSP product, which is probably the easiest way to implement, but this is the simplest way I know of at the moment.

Effectively, the subwoofer would be nulling the frequencies that are building up in the room. The sub would need the same signal as the speakers are getting.

Another way is to use active bass traps, which are subs that are specifically designed for such a purpose. Basically, they do the same as what I am suggesting, but it's more plug and play.

How will subwoofer null frequencies outside its upper limit produced by Summit?

Typical subwoofers cover the lowest frequency range. Subwoofer positron waves or out of phase waves with main speaker waves would reduce by nulling or annihilating only subwoofer range sound frequencies. Subwoofers cover from 20 hz to max 120-180hz. Frequencies beyond 120-180 hz subwoofer range, extending to summit crossover point of 270 hz need to be reduced by canceling too. Since produced by woofer and may contribute to the booming sound.

Some ML subwoofers have built-in correction. But for the sound to match with Summit, incomplete towers will need room correction or room fit software and equipment. The application of which will help to fit Summit bass precisely inside the room without over extension or aggravation.

If room fit software and hardware is acquired, then there is no need for a superfluous subwoofer.

Purchase of miniDSP adds to expense.

To streamline all the things that may help.

1. Precise room placement through formula and trial and error. Experiment with rake and toe-in.

2. Adjust bass trim controls on the preamp.

3. Summit includes 10 decibels increase decrease in two subwoofer range frequencies namely 25 hz and 50 hz. Adjusting these controls may help to reduce bass boominess and weight.

4. If problems persist, switch to a larger room. If not possible. Then first...
Whichever one of the following two suggestions or alternatives is a more effective solution occluding the other alternative.

5. Anthem STR stereo preamplifier. Includes room correction features.

6. Active bass traps and room treatment.

 

[ttocs]

How will subwoofer null frequencies outside its upper limit produced by Summit?

It won't.

The suggestion was to choose one that covers the frequencies causing problems.

 

[Fidji99]

Hello fellow members. I have a fairly common question regarding room treatments for bass issues. I have a pair of Summits in a room that is about 10'wide x 11'long x 9'high. I am struggling with finding a listening position that captures mid bass frequencies without compromising the spacial imaging of the panels. This seems to be the innate struggle with this type of speaker.
…….
- I've also used DSP with my DBX Driverack which helped. But, honestly I'd rather not use as it as I don't want anything to alter the signal (trying to keep it purist as much as possible).
……..
I know the size and dimensions of the room is a challenge and further treatment is necessary. I just have no idea where to start ie. diffusion or absorption. When I sit closer to the speakers the full band of bass frequencies appear, but I loose the benefit of the electrostat panels.

unfortunately, sometimes there situations, that just can not be solved in any really good way.
1) room dimensions (on top of size) are the problem - almost cube - it makes all the bass (now referring to the range below 250Hz) problematic. Not only for electrostats, but in general.
2) most of the issues are generated just by relative position of drivers and LP
3)It is too small of speakers like Summits.


What now:
a) measure it with REW, use sub placement simulator in REW to see whether you have a chance to get some acceptable response - with this I mean without big dips in LP
b) acoustic treatments will have limited impact - you need 4-6in thick panels (not foam, forget foam) with 4-6in air gap to have any impact on bass region, diffussion, if made properly is about 6-8 in deep minimum and it DOES NOT work less than 5-6 feet distance and covers frequencies 800-1000Hz upwards. So adding more treatments will very likely be detrimental to the sound.
c) realistically, if you insist on keepimg the Summits - DSP and adding the subs is your only option. Forget any “purity” of the signal - you probably have +- 10dB or more of resonances, ringing, dips and all other acoustical problems.

But honestly, I would just go for another speakers - even if you love electrostats. You need something that behaves well off- axis and can be integrated with subs, and has some calibration feature. I have heard very good systems in smallish rooms, that were not prohibitively expensive, so it can be done.

Sorry, if it sounded harsh, is meant as a good advice. Sometimes is better to just take a step back and cut the losses.

 

[JonFo]

I totally agree with @Fidji99 post above. The room is too small for electrostats. I have a media room (in addition to my main HT) that has the exact same dimensions, and I did a write-up of that setup in this thread: https://www.martinloganowners.com/threads/media-room-–-quad-ml-sub-setup.17591/

I'd recommend the KEF R Meta series for a room that size, as the imaging coherence of coaxial drivers is really beneficial at what is almost near-field listening.

But it will definitely require four subs to tame the room resonances. They can be small ones (10"), but make all four the same.

 

[JonFo]

But it will definitely require four subs to tame the room resonances.

More detail on why in this post on a thread about subs and their placement options: https://www.martinloganowners.com/threads/subwoofer-recommendations.19477/post-206516

 

[Rob606]

In a room that small for those speakers the only thing that comes to mind is anti-bass. Use a small subwoofer that covers the range of frequencies that are causing a problem and invert the signal from the subwoofer. A "correction" filter might need to be employed using a miniDSP product, which is probably the easiest way to implement, but this is the simplest way I know of at the moment.

Effectively, the subwoofer would be nulling the frequencies that are building up in the room. The sub would need the same signal as the speakers are getting.

Another way is to use active bass traps, which are subs that are specifically designed for such a purpose. Basically, they do the same as what I am suggesting, but it's more plug and play.

Thank you for your comment

In a room that small for those speakers the only thing that comes to mind is anti-bass. Use a small subwoofer that covers the range of frequencies that are causing a problem and invert the signal from the subwoofer. A "correction" filter might need to be employed using a miniDSP product, which is probably the easiest way to implement, but this is the simplest way I know of at the moment.

Effectively, the subwoofer would be nulling the frequencies that are building up in the room. The sub would need the same signal as the speakers are getting.

Another way is to use active bass traps, which are subs that are specifically designed for such a purpose. Basically, they do the same as what I am suggesting, but it's more plug and play.

Thank you for the advice. Basically I’d be setting the sub out of phase with the frequencies that are building up. Is that right? Never thought of that idea! My amp has a line out that is the exact same signal. I’ll give it a try today.

 

[Rob606]

More detail on why in this post on a thread about subs and their placement options: https://www.martinloganowners.com/threads/subwoofer-recommendations.19477/post-206516

Thank you JonFo. Btw you got me with the Momentus April Fools day.
Mostly because I’ve been imagining something similar to use in my HT for ceiling Atmos speakers. I was going to repurpose my Vista panels by suspending them with a cable or mount them in an enclosure. Kinda just want to hear what it sounds like.

 

[ttocs]

Thank you for your comment

Thank you for the advice. Basically I’d be setting the sub out of phase with the frequencies that are building up. Is that right?

Yes.

 

[Rob606]

Prior to experimentation with absorptive and diffusive material get the placement right. Placement helps to remove or minimize boomy bass. And at the same time allow maximum or optimal performance of the panel.

Inside ML Classic ELS 9 instruction manual a formula for inside room speaker optimal or precise placement. If not precise optimal placement, then close to optimal or within one feet radius of ideal or perfect placement in the room. Placement according to this formula helps to minimize the negative impact of room standing waves.

Measure the distance of the wall in front of LP from ground to ceiling in inches. 9 feet x 12 = 108 inches. Multiply by 0.618 Each speaker's front midpoint must be kept 66.74 inches distance from the front wall or wall in front of LP. Now you know the placement of the speaker lengthwise in the room. 5 feet 6.74 inches.

Next calculation for placement from left and right sidewall. Measure total distance in inches between left and right sidewall. 10 feet x 12 = 120 inches. First divide this measurement by 18. Second multiply by 5. The result 33.33 inches is the required distance expressed in inches from each side wall to the front midpoint of each speaker. 2 feet 9 and one-third inches.

The distance between the midpoint of both speakers is 120 - 66.66 = 4 feet 5 and one third inch. This length should be the minimum distance to the center of both ears measured as a perpendicular from the loudspeaker center.

The goal according to acoustic experts is to allow maximum direct sonic radiation from loudspeakers to be heard. This is the ideal or goal achieved in the free field listening or to its simulation in an anechoic chamber. S

Since our listening room is fully or partially enclosed by walls, it is not a free field environment. We use absorptive and diffusive material to absorb and scatter sound waves. Goal is to prevent or minimize room reflections from reaching our ears. Absorption is more powerful than diffusion in this regard. Using both ensures that whatever is not absorbed is scattered and not directly reflected back at the listening position.

Hope this helps.

Thanks Rehan. I have this same formula actually. It was perfect in helping me find a starting position.

 

[Rob606]

unfortunately, sometimes there situations, that just can not be solved in any really good way.
1) room dimensions (on top of size) are the problem - almost cube - it makes all the bass (now referring to the range below 250Hz) problematic. Not only for electrostats, but in general.
2) most of the issues are generated just by relative position of drivers and LP
3)It is too small of speakers like Summits.


What now:
a) measure it with REW, use sub placement simulator in REW to see whether you have a chance to get some acceptable response - with this I mean without big dips in LP
b) acoustic treatments will have limited impact - you need 4-6in thick panels (not foam, forget foam) with 4-6in air gap to have any impact on bass region, diffussion, if made properly is about 6-8 in deep minimum and it DOES NOT work less than 5-6 feet distance and covers frequencies 800-1000Hz upwards. So adding more treatments will very likely be detrimental to the sound.
c) realistically, if you insist on keepimg the Summits - DSP and adding the subs is your only option. Forget any “purity” of the signal - you probably have +- 10dB or more of resonances, ringing, dips and all other acoustical problems.

But honestly, I would just go for another speakers - even if you love electrostats. You need something that behaves well off- axis and can be integrated with subs, and has some calibration feature. I have heard very good systems in smallish rooms, that were not prohibitively expensive, so it can be done.

Sorry, if it sounded harsh, is meant as a good advice. Sometimes is better to just take a step back and cut the losses.

Thanks for your concise, honest advice Fidjii99 - Didn't sound harsh at all - I've worried the Summits are too big for the room and the dim's are a major, maybe even unsurmountable challenge - but they just sound sooooooooo good lol. I have a pair of VA Beethoven Baby Grand's. They sound wonderful given their size, and did balance the bass out quite well. I did use a sub with them. I'd like to improve their tweeter as they are the prior model. Maybe that would help give them some of the airiness of the ML's. Just haven't heard anything that can do what electrostats can do in the way of soundstage and imaging (At the under $10k price range). Maybe some used Wilson Audio Sophia's or Sasha's? Do you have any recommendations?

- I will follow your advice measuring with REW. I have the app but never used it. I've measured it with the DSP from my DBX Driverack and used their eq recommendation but it seems to loose the fine detail over 400k+. Could this be just the quality of the DBX? I have little experience with Audiophile level DSP units.
- You were adamant about not using foam for panels. Just curious why?

 

[Rob606]

I totally agree with @Fidji99 post above. The room is too small for electrostats. I have a media room (in addition to my main HT) that has the exact same dimensions, and I did a write-up of that setup in this thread: https://www.martinloganowners.com/threads/media-room-–-quad-ml-sub-setup.17591/

I'd recommend the KEF R Meta series for a room that size, as the imaging coherence of coaxial drivers is really beneficial at what is almost near-filed listening.

But it will definitely require four subs to tame the room resonances. They can be small ones (10"), but make all four the same.

Thank you JonFo! I will read over both of your links. I've never critically listened to KEF's - just while wandering through Best Buy's Magnolia shop; which is never a good idea lol.

 

[Rob606]

More detail on why in this post on a thread about subs and their placement options: https://www.martinloganowners.com/threads/subwoofer-recommendations.19477/post-206516

Thanks JonFo! The Harmon link is an insightful read!

 

[Rob606]

In a room that small for those speakers the only thing that comes to mind is anti-bass. Use a small subwoofer that covers the range of frequencies that are causing a problem and invert the signal from the subwoofer. A "correction" filter might need to be employed using a miniDSP product, which is probably the easiest way to implement, but this is the simplest way I know of at the moment.

Effectively, the subwoofer would be nulling the frequencies that are building up in the room. The sub would need the same signal as the speakers are getting.

Another way is to use active bass traps, which are subs that are specifically designed for such a purpose. Basically, they do the same as what I am suggesting, but it's more plug and play.

hello again ttocs. what do you mean by "correction filter"?

 

[Rob606]

Thank you JonFo! I will read over both of your links. I've never critically listened to KEF's - just while wandering through Best Buy's Magnolia shop; which is never a good idea lol.

Hi again Jonathan and thank you. Should the four subs be active bass traps as others have mentioned or would I be using them to fill in? I've never played around with more than 2 subs in a room. I'm just trying to understand the purpose of one in each corner so I can know what I'm listening for.

 

[JonFo]

Thank you JonFo. Btw you got me with the Momentus April Fools day.
Mostly because I’ve been imagining something similar to use in my HT for ceiling Atmos speakers. I was going to repurpose my Vista panels by suspending them with a cable or mount them in an enclosure. Kinda just want to hear what it sounds like.

Ah, the infamous Monoray closed-back ESL system. My SL3XC center is now a closed back, works like a charm, very focused dialog now.

As for suspending speakers for rear or tops, it's been done by our member Robin, just look at the pics on the first post.

But I do not recommend ESLs for tops, wrong dispersion characteristics. An ML in-ceiling, or a KEF R8 Meta as a Dolby Elevation speaker would be my choice in a small room.

 

[JonFo]

Hi again Jonathan and thank you. Should the four subs be active bass traps as others have mentioned or would I be using them to fill in? I've never played around with more than 2 subs in a room. I'm just trying to understand the purpose of one in each corner so I can know what I'm listening for.

When using four in a room shaped like yours (and my Media Room), the subs effectively work to cancel the room modes. It is best to use REW to figure out the best mix of phase settings on each sub, each pair of subs (front vs rear), and then the combo. Once that is as flat as can be made with the sub controls, then run the DRC on the processor. And yes, for a room like that, you need a room corrector, at a minimum, on the subs. So if keeping the current preamp, you can add an active XO and use a miniDSP and run the MultiSub Optimizer (MSO) software, and it should get you good results.

Here is the waterfall plot of my cheap system with four ML Dynamo 300's (7" 'subs'), with Audyssey DRC applied:

Note the rapid decay; most of the room resonance is gone by <200ms, and while the FR is still a bit ragged, the variance is less than 6dB, which, compared to the 20+dB with just a single sub, is a big step forward.

MSO + a miniDSP could make this even flatter, but I kept this setup simple (well, for me, simple )

 

[ttocs]

hello again ttocs. what do you mean by "correction filter"?

If the "anti-sub" doesn't quite fit the range of problem frequencies - maybe the sub covers too wide of a frequency range, you can make a PEQ filter with a miniDSP. It's trial and error, but can work. This way you can tailor the width of the filtering you'd like to have.

But it would help us to understand the issue better if you could measure the response as-is so we know what range(s) of frequencies are the issue. If it's all low, then what @JonFo is recommending would be preferred.

Lots of ways to achieve successful results. Just takes time and money! I consider the time aspect the fun part! . . . along with the learning.