Measures to Reduce the Boomyness of speakers

[mahiruha]

Hi all,

Pratim (member pratimbayal) and myself are the only ones among all of us, to my knowledge, who visisted mahiruha's place and auditioned his system.

I posted a detailed report here http://www.hifivision.com/amplifier...ng-appropiate-tube-amplifier-5.html#post85976 .

What I discovered (as apparent from my above post) was that it was not just bass boom, it was also overall clarity that the system seriously suffered from. My guess is that it was mostly contributed by the room, especially the huge table, the glossy walls etc.

The discussion in that thread continued for a few more posts. If you have time, please read also my next post in that thread http://www.hifivision.com/amplifier...ng-appropiate-tube-amplifier-6.html#post86121 .

Obviously the solution for mahiruha is to move his music system to another room, because not much rearrangement (in terms of physical movements of speakers etc) is possible in that room.

I am personally not in great favor of using an equaliser in this case, but it may identify some of the culprit frequencies.

I suppose if mahiruha has to keep all his stuff in that room, the best one can do is some damage control as the problems cannot be really cured. So experienced people may suggest only damage control solutions keeping in mind that this is a compromise and not an absolute solution of the problem.

Regards.

Hi Asit,
thanks for understanding the problem. You are absolutely right that I am not looking for ultimate audio nirvana just a bit of improvement permissible in the present environment with some elctronic gadget.Actually before taking the plunge with the VPI TT I am just exploring if I can offer it a little bit better environment to live and play music.
Thanks.

 

[mahiruha]

mahiruha, could you try one thing..this may sound crazy. could you walk across the corners behind the speakers and clap. identify thye place you get Maximum Echo.

Ditto about your seating position...as based on direct + reflecting waves yoy can get a boom on the listening position.

If you get an echo around the corners behind your speakers, then ou need to place
1. heavy absorbent like a bookcase or worst a cardboard box with boooks in the corner or even one of those small square pillows on the upper corner (Ceiling and 2 walls). try to see if the sound is less.

2. If you get a boom in your listening space you may need to move back and forth in the room till you get min sound.

3. Try to model your room in this website (its in german). choose any speaker and try to see which frequencies peak and what are in the trough ( you ca adjust the speakers and the listening position by clicking on it and using the up/down/L/R arrows on your keyboard). do see if the result matches with (2) above. you can play around a bit with position of speakers and listening position to get the best curve.

Hi Arj
that's a wonderful tool. That reminds me of using Risk engine to simulate different possible market environments to do portfolio scenario analysis. I love this kind of analysis. Can you please suggest me from the list of speakers which can serve as a good proxy for the Lyirita Harmony one speaker.
Loudspeakers
Thanks.

 

[venkatcr]

3. Try to model your room in this website (its in german).

It has an option to switch to English also. Great link!!

Cheers

 

[Rajiv]

Well it is clearly visible that I can't really move the speakers may be one thing can be done is to remove the jamo speakers from the room

Hi Mahiruha,


You could try the above,and see if it works.

Back during the Flat Earth days of Audio when Ivor Tiefenbrun and Julian Vereker's word was gospel,and their writ ran large over the UK audio press,they recomended that there should not be any other speaker in the room other than the ones playing music,otherwise the drivers in the unconnected speaker would vibrate in sympathy to the sound waves thereby smearing the sound.


You could also try placing the speakers on the floor with spikes,and see if this helps.


Regards
Rajiv

 

[GeorgeO]

I also tend to agree with the earlier posts (Suri, Asit, etc) that the proem probably lies in the room rather than the system. I don't favour blocking the ports, I think a little experimentation may show some results.

George

 

[stevieboy]

thanks for the kind words suri,

it was a real pleasure meeting you! the morning started off quite hilariously with me mistaking 7.50 for 8.50 but its good you came over! viren's system does sound magical and lets you use some really good NOS tubes.

mahiruha,

a platform on spikes and speakers on that might help as rajiv has suggested. that's how my speakers are. on a granite slab and spikes below touching the ground.

now look closely at the screen while a flash my gadget and when you reach the end of the post you won't remember who i am.

 

[santhosh]

Mahiruha,
Like everyone else, even I would think it is the room that is playing havoc here. You have a fantastic Stereo Rig and you are just not doing justice to it by having so much stuff in that room that can ruin your sound.

Don't get me wrong, please move only your Lyrita tube amp, TT and Lyrita Harmony Ones etc to another room (living room or your bedroom). You will be able to enjoy it better in any other room if you set it up properly. You need to sit within the sweetspot to enjoy the beauty of stereo. While playing Pool, you are constantly moving. Even if you sit down for a serious listen, you are sitting nowhere close to where you should be.

Leave the Jamos and other HT stuff in the current room. You can listen to music on your AVR itself while playing pool and move to your other room for serious music listening.

You could also try placing the speakers on the floor with spikes,and see if this helps.

Regards
Rajiv

Rajiv is right. Isolation might help. I had a similar booming issue with my Jamo speakers around 7 years ago. When I checked with my Guru (an old-timer called Imran who inspired and answered all my questions patiently), he suggested I add spikes. Spikes reduced the boominess to some extent. He then suggested I put the speakers(with spikes) on a solid piece of stone (around 3 inches in height). This further reduced the boominess. My Guru had one more trick up his sleeve which was to add some weight(not very heavy) on top of the speaker. I experiment with all these even today though I now have a dedicated sound-treated room. I can tell you these simple tricks work. Ofcourse, check with Viren, he will be able to tell you what will and will not work with his speaker design.

Before you think of behringer, please consider some simple DIY room treatment - Bass Traps for now and maybe sound absorbers later etc.

 

[santhosh]

a platform on spikes and speakers on that might help as rajiv has suggested. that's how my speakers are. on a granite slab and spikes below touching the ground.

Great, even I suggested the same. Let us wait for results.

now look closely at the screen while a flash my gadget and when you reach the end of the post you won't remember who i am.

Even after meeting you, I can't remember how you look. This 007 has some serious hypnotic powers too:lol:

 

[Asit]

Rajiv is right. Isolation might help. I had a similar booming issue with my Jamo speakers around 7 years ago. When I checked with my Guru (an old-timer called Imran who inspired and answered all my questions patiently), he suggested I add spikes. Spikes reduced the boominess to some extent. He then suggested I put the speakers(with spikes) on a solid piece of stone (around 3 inches in height). This further reduced the boominess.

Very interesting, indeed. However, I have a question/comment: I'd not call it strictly isolation. The boominess is caused by a resonance of sorts at certain frequencies, so you want to damp that or transmit that away. I think this is what the spikes are doing. They are transmitting some of the extra energy away through the spikes into the floor. On the other hand, since the contacts with the floor is only through the pointed ends of the spikes, the speakers are actually isolated from any floor vibration. So I think this is the job the spikes are doing: letting a one way traffic. Please do not hesitate to correct me if I said something wrong.

Now in Mahi's case, he has in addition rear ported speakers and he can give only a foot or so of space at the back. Now this problem may not be solvable through the spikes, because reflection/diffraction from back wall cannot be transmitted away through the spikes because those additional sound waves are not directly generated by the speaker drivers (in this case, only one though), they are secondary sound waves.

The above is just an opinion. I do not know enough on the subject to say definitely, but looks very plausible to me. Actually during the time my speaker stands were being fabricated, I had a lot of discussion, especially with Cranky, and with some other people like prem and arj (documented in my amp thread). What I am writing here is an amalgamation of my understanding of those discussions and of course the practical experience with the placement of my Canton speakers for so many years.

BTW, it all depends on the speakers. Some speakers (especially bookshelves) may be designed in a way so that it is not desirable to transmit any of the vibrations away, rather they need boosting of those vibrations through resonant cavities in the stands. In mahi's cae, however, he has floorstanders, and can clarify from Lyrita if spikes would be better.

Stevie, I have one question for you. This is concerning the use of the granite slab. If you used something else, instead of the granite slab, how the sound may have changed. Did you experiment or you were just lucky the first time?

Before you think of behringer, please consider some simple DIY room treatment - Bass Traps for now and maybe sound absorbers later etc.

I agree fully.

Regards.

 

[viren bakhshi]

Hi Mahiruha,

One more piece of information is required to analyze your room acoustically - the dimensions (length, width, and height). I have a suspician that the dimensions are multiples of each other, and that compounds standing wave problems. Also, other than the snooker table, with its fabric on top, do you have any other soft furnishings in the room?

Now that you mention the rectangular, hollow stand for the speakers, maybe the cavity is resonating and adding to your problem. Place the speakers directly on the floor and listen again. The speakers have shallow, hard points on the bottoms, so should couple well to the floor. If they sound better, leave them that way. Don't worry too much about the lowered height of the drivers - you are listening to more of reflected sound anyway.

Hope that helps.

Viren

 

[mahiruha]

Hello guys,
did some analysis on the tool suggested by Mr Arj. The results are very interesting.It is quite evident in the graph that there are lot of reverberation across the frequencies building inside the room because of its big volume and I am guessing that is principally causing the boominess. It is also quite evident the abnormality in the behavior of the waves upto 125hz when comapred to their behavior in free field. Unless I can do something to reduce the reverbaration I guess no system can perform optimally.
Thanks.

since picture didn't come out good the values I have used are
Length 8.3 m
width 5.3 m
Height 3.0 m
curtains 14 m^2
chairs 3
Cabinet shelves 4 m2
Listening position is 6 m away from the speakers
speakers are 1 m away from side walls and front face is roughly 0.6 m away from the rear walls.
http://img194.yfrog.com/i/frequencyanalysis1.jpg/

 

[stevieboy]

Stevie, I have one question for you. This is concerning the use of the granite slab. If you used something else, instead of the granite slab, how the sound may have changed. Did you experiment or you were just lucky the first time?

Regards.

hi asit,

am sure any other material would have pretty much the same effect. of course someone more critical and analytical than me will find differences. i pretty much ignore these things just too lazy. my amps are still sitting on the floor i just wanted a slab to plonk my speakers on hence the granite. there's a layered material stone the name of which i forget right now. looks pinkish... indian slate? that might be better. also i've not bothered to keep the spikes pointing down. the base is on the ground the points are touching the granite. hope this helps!

regards

edit: i heard the pink slate too but to my ears hardly any difference. the speakers direct on the floor had way too much bass for my room. the floor thundered!

 

[Sumit]

Wow!!

Some many advices. I wonder whats going on in Mahi's head. Well, I think I should give in my take too. I shall keep it Plain and simple.

Firstly, you should not use this room for movies and music both. Secondly, take your HT setup and screen to another room. Leave your lyrita and other 2 channel gear in this room with the snooker table. How can you watch a movie with a 12' snooker table in front of you!!! Beats me..

I have a pool table and I have kept in a room adjoining my HT. I am using two wall hung speakers that take care of my music needs. They are powered by speaker 'B' option of my HT.

PS> A temp arrangement to reduce boom can be managed by using pillows behind the speaker. Try different placements. Maybe this could help you.

Cheers!!

 

[santhosh]

Very interesting, indeed. However, I have a question/comment: I'd not call it strictly isolation.............................
Please do not hesitate to correct me if I said something wrong.

I am with you Asit. You have explained it very well.

Now in Mahi's case, he has in addition rear ported speakers and he can give only a foot or so of space at the back. Now this problem may not be solvable through the spikes, because reflection/diffraction from back wall cannot be transmitted away through the spikes because those additional sound waves are not directly generated by the speaker drivers (in this case, only one though), they are secondary sound waves.

Very true Asit, I totally missed the fact that Mahi's speakers were rear-ported. Mahi should try pillows behind the speaker as suggested by Sumit. Also try bolsters(pillows used in Dewans) an the four corners of the room. Arrange them one on top of the other to form a cylinder.

 

[mahiruha]

Hi all,
I managed to do some more analysis and the results are very encouraging at least visually.
http://img684.yfrog.com/img684/2867/idealsetup2.jpg
In this graph I have used Castle howard S3 as proxy for Lyrita Harmony one speaker.
Castle UK - Loudspeaker Manufacturers - Classic Range - Howard S3
I can see that with the introduction of 50 m2 of carpet and 50 m2 of curtain and 72 m2 of cabinets and shelves front area the reverberation curve comes down below the tolerance level and there isn't too much distortion in the sound level frequency curve. Now the question is This snooker table has top area of 72 ft2 is it offering any effective area at all in the entire process?

@Viren: I have done the experiment by removing the bottom boxes and putting the speakrs directly on floor.There is slight improvement but not too much

Let me experiment with the pillows and I will post the findings.

Just now I did a detailed listening of Jamo speakers through Onkyo and Lyrita through Lyrita systems and boom was present in both of them. Now I fully understand If I sit 18 feet away from the speakers unlees the room is very well treated there will be boom and I listen to moderately high volumes. It is quite evident from the curve apart from 50 m2 of carpet , 50m2 of curtain I need to prive 72m2 more of damping area which us almost 650sq ft of damping which is huge.So the boom is definitely here to stay with me.
Thanks.

 

[viren bakhshi]

Hi Mahiruha,

As you are discovering, the problem in your room has to do with excess reverberation. Too many reflections from hard surfaces. About the only way to control these is to add sound absorbing materials to the room.

The felt covering on the snooker table is thin and dense - good only for absorbing high frequencies. The carpet and drapes will help you in the mids and highs.

What you need is a more effective broadband absorber. If you do a full acoustic false ceiling, about 40 sq.m., the reverberation times in the room will fall dramatically. A quick analysis shows the reverberation time dropping from about 7 seconds to 0.8 seconds after the ceiling treatment. You have enough height that a drop in height of 150mm with a suspended ceiling will not be very obvious. And it won't disturb the rest of your room.

Professional acoustical tiles from companies such as Armstrong are readily available. Something to consider.

Regards,
Viren

 

[suri]

Hi Mahiruha,

As you are discovering, the problem in your room has to do with excess reverberation. Too many reflections from hard surfaces. About the only way to control these is to add sound absorbing materials to the room.

The felt covering on the snooker table is thin and dense - good only for absorbing high frequencies. The carpet and drapes will help you in the mids and highs.

What you need is a more effective broadband absorber. If you do a full acoustic false ceiling, about 40 sq.m., the reverberation times in the room will fall dramatically. A quick analysis shows the reverberation time dropping from about 7 seconds to 0.8 seconds after the ceiling treatment. You have enough height that a drop in height of 150mm with a suspended ceiling will not be very obvious. And it won't disturb the rest of your room.

Professional acoustical tiles from companies such as Armstrong are readily available. Something to consider.

Regards,
Viren

elegant solution! - by the way, viren, after hearing your system in stevieboy's home, i am in awe of your genius!

 

[viren bakhshi]

Ah shucks, Suri!

Thanks for the compliment, though.

Viren

 

[arj]

Hi Mahiruha,

The felt covering on the snooker table is thin and dense - good only for absorbing high frequencies. The carpet and drapes will help you in the mids and highs.

Viren

Viren, would this make the high frequency a bit recessed and and give the perception that the midrange/bass is more heavy ?

 

[mahiruha]

Hi Mahiruha,

As you are discovering, the problem in your room has to do with excess reverberation. Too many reflections from hard surfaces. About the only way to control these is to add sound absorbing materials to the room.

The felt covering on the snooker table is thin and dense - good only for absorbing high frequencies. The carpet and drapes will help you in the mids and highs.

What you need is a more effective broadband absorber. If you do a full acoustic false ceiling, about 40 sq.m., the reverberation times in the room will fall dramatically. A quick analysis shows the reverberation time dropping from about 7 seconds to 0.8 seconds after the ceiling treatment. You have enough height that a drop in height of 150mm with a suspended ceiling will not be very obvious. And it won't disturb the rest of your room.

Professional acoustical tiles from companies such as Armstrong are readily available. Something to consider.

Regards,
Viren

Hello viren,
the solution you have suggested sounds very good. If it can drop the reverbaration time from 7 seconds to 0.8 seconds there is nothing like it.
I am fully confident if the reverbaration can be taken care of then other things will automatically fall into place. Are you referring to these tiles.
Sabbia
Appreciate your help.
Thanks.