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Home » Audio Discussions » A big room with good acoustics before treatment, and some other audio tips. (9 posts, 1 page)

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12-08-2016

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xandcg

Rio de Janeiro, BR.
Posts 218
Joined on 09-07-2014

Post #:	1
Post ID:	22875
Reply to:	22875

A big room with good acoustics before treatment, and some other audio tips.

Hello,

Can you give me some ideas for a good room? Also, audio related ideas are always welcome too.

The initial plan is a room with 5m H x 10m W x 14m D (about 16,5ft H x 33ft W x 46ft D). Solid floor, probably porcelain tile (chess floor style), and solid brick walls, probably with one more layer (external) of concrete brick, with the eventually needed isolation material between them.

The biggest doubt is about what kind of ceiling would work better for audio: concave, flat, cathedral, or what? What angle etc?

The bar at the end should have a mezzanine, then it will not be all open. It will have external columns and will be higher than the rest of the room.

This is a figurative drawer of what I am planning to do when I will able to do, but I tried to keep the dimensions more or less correctly:

It is in the very early stage and still will take a while before I start to do anything (I am also slow to make these kind of decisions), but the idea is to have 7 ways loudspeakers. A 5 ways ~>120 Hz module, like Cessaro Omega, plus a pair of full size >50 Hz exponential horns, and sub-woofers. The sub-woofers will probably be big tapped horns.

I aim to have the >50 Hz horn made of reinforced concrete slabs. I do not know if it may work well sound-wise but I am also thinking about a internal finishing of (polished) epoxy or metallic epoxy.

I will not build the loudspeakers myself, and if I find the right person at the proper time, I want to follow the ALE path from >50 Hz, or eventually GOTO.

The listening position is desired to be about 4,5m (about 15ft) from the front of the upper-bass horn.

The electronics but amplifiers should be located in a separated acoustic isolated room.

Thank you in advance for your suggestions!

Think for yourself, do not be sheep.

02-19-2017

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xandcg

Rio de Janeiro, BR.
Posts 218
Joined on 09-07-2014

Post #:	2
Post ID:	22983
Reply to:	22875

Smaller room.

I did an update for a smaller room (4 m H x 8 m W x 12,5 m D). I do not have idea if something like this would work properly:

Think for yourself, do not be sheep.

02-21-2017

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zztop7
Edmonds, WA
Posts 40
Joined on 11-02-2012

Post #:	3
Post ID:	23002
Reply to:	22983

Concrete speakers/woofers

If you do go forward with the concrete speakers/woofers, I will chime in with some concrete mix specifications.You will want experimental batches of the concrete mix done before the actual production mix.
zz.

02-21-2017

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Romy the Cat

Boston, MA
Posts 10,184
Joined on 05-28-2004

Post #:	4
Post ID:	23003
Reply to:	22983

Looks good.

Xandcg, I did not see this thread below. I would not comment on 5x10x14 vs. 4x8x12 rooms, the answer is obvious, What I will comment that the scenario you propose is very close to ultimate configuration for Macondo-like acoustic system. A few this you need to consider, presuming that you mapping is in accurate proportion. Your listening position is too far for the space between the R and L channels. So, you might want to consider to switch the amps and >120Hx horns and have the MF channels to be wider. Also, do consider to add ULF channel, a sealed box operating at transitional slope.

"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche

02-21-2017

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xandcg

Rio de Janeiro, BR.
Posts 218
Joined on 09-07-2014

Post #:	5
Post ID:	23006
Reply to:	23002

One more research to be made.

@zztop

Thank you, it is a good idea, but now you make me add a new research on my audio research queue. :-D

If somehow I find out what are the right material characteristics for a >50 Hz horn, I may try contact my old University¹, to try to grab some researcher with serious concrete knowledge² who can bring the right mix to archive as close as possible that characteristics using concrete, and maybe some finishing like metallic epoxy or whatever.

I have a friend in Germany who is a audio engineer, specialized in acoustics. She is not home/hornaudio minded, she used to do research on large multi channel applications, but eventually she know someone... I would just need to find her before, there is a couple of years we do not talk.

¹It would ba a very different college but I still have contacts in there;
² I think it would not be that difficult.

Think for yourself, do not be sheep.

02-21-2017

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zztop7
Edmonds, WA
Posts 40
Joined on 11-02-2012

Post #:	6
Post ID:	23007
Reply to:	23006

Concrete

Once you have all these contacts come-up with a concrete mix, let me see it if you would like my opinion. I will let you know if I agree or disagree & possible improvements.
IMPORTANT: Is this an existing room? Is this room "on-grade"? Do not forget concrete weighs 150F#/cubic foot /// 5,300 pounds per cubic meter. Nothing better than collapsing your house.
Best to you,zz.

02-21-2017

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xandcg

Rio de Janeiro, BR.
Posts 218
Joined on 09-07-2014

Post #:	7
Post ID:	23008
Reply to:	23003

I see.

Xandcg, I did not see this thread below. I would not comment on 5x10x14 vs. 4x8x12 rooms, the answer is obvious, What I will comment that the scenario you propose is very close to ultimate configuration for Macondo-like acoustic system. A few this you need to consider, presuming that you mapping is in accurate proportion. Your listening position is too far for the space between the R and L channels. So, you might want to consider to switch the amps and >120Hx horns and have the MF channels to be wider. Also, do consider to add ULF channel, a sealed box operating at transitional slope.

I would not call the proportions accurate, I did¹ them using the rocketsciencecanada.com but I added-in some "fat" to have some error margin related to the total used space.

I understand what you say about the >120 Hz modules. I did that one using about 2.1 m between them. I did not have a real reason to use this exactly number, I used it just as some start point. I will reconfigure it later with about 2.5 m but I feel I would need to add more toe-in.

The tapped horns decision was not written on a rock. This is a temporarily choice while I still think I can find a way to driver them with SET, I indeed would prefer sealed ones.

If at some moment I find out it would not be realistic to drive the tapped horns with SET, or it eventually would need about the same power to drive sealed ones, I will make the switch.

PS. I live close to the Audiopax HQ, I never had in there and I do not know them, but eventually a ULF only Audiopax M100 (100W, but a some more using KT120) could be a reasonable sounding alternative, if it really have a close SET sound.

PS.2 . I found your post about the ultimate configuration. When I was thinking on how still have full straight 50 Hz horns in a reasonable smaller space than the first plan, and I had the current idea, I was certain I saw something like that before. Now I know where it was. :-D

¹except the tapped horns size what apparently can be almost anything, and so I just "invented" those dimensions.

Thank you!

Think for yourself, do not be sheep.

02-21-2017

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xandcg

Rio de Janeiro, BR.
Posts 218
Joined on 09-07-2014

Post #:	8
Post ID:	23009
Reply to:	23007

Yes.

zztop7 wrote:
Once you have all these contacts come-up with a concrete mix, let me see it if you would like my opinion. I will let you know if I agree or disagree & possible improvements.
IMPORTANT: Is this an existing room? Is this room "on-grade"? Do not forget concrete weighs 150F#/cubic foot /// 5,300 pounds per cubic meter. Nothing better than collapsing your house.
Best to you,zz.

Thank you and sorry, of course your opinion would be valuable, and probably I would not need to do all that journey.

I just didn't take it into account because my default behaviour when I face a subject I do not domain and can not domain in a feasible time is: think in someone who I know already domain the subject, ever if partially, or may know someone - usually I go back to the University. I do it automatically.

It is a long time project, and it was a reason I was reluctant to post about it here for now. I need to solve some business issues¹ before I can begin to execute any major plan in my life, what necessarily include moving on from my country - what is the easiest part. With almost everything in this audio project involving high import duties, I would be crazy to do it now and them take almost everything back, more or less, from their origin.

Now, directly answering your questions, the room will be made on purpose, standalone out of the house (wherever it will be). The idea is indeed, if necessary and applicable, have some acoustic "improvements" already integrated in the structure. I am certain the horns and amplifiers would take mode time to be ready to delivery than to the room be built.

What is really concerning me is the fact Portugal is very prone to earthquakes², not I am afraid of it, I was indeed living in there in 2009 when a 6.0 degree (Ritcher) happened. I concerned of somehow those >120 Hz modules fall, specially if they remember to fall on top of the amplifiers...

¹ I depend of some government acts, and it is a complete mess here (Brazil) right now. The things are really totally out of control.

² https://en.wikipedia.org/wiki/1755_Lisbon_earthquake

Think for yourself, do not be sheep.

02-24-2017

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xandcg

Rio de Janeiro, BR.
Posts 218
Joined on 09-07-2014

Post #:	9
Post ID:	23032
Reply to:	23009

Updating...

Here is the update as recommended by RomyTheCat, the listening position is about 4 m from the upper-bass (I think it may work depending on how the >50 Hz mouth end up) and I also become creative with the bar. :-)

Do someone eventually know what would be the right properties for upper-bass horns and up?

I will try to find a material with those properties at the chemical/petrochemical market, but it should take a while because I will need to rely on some busy friends.

Cheers!

Think for yourself, do not be sheep.

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