Drum Room Construction

[beeros05]

Basic construction Finished

i will do a Sound check in 3-4 hours!

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[beeros05]

Paintjob

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Elastic Sealant

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[Bawoo]

Looks nice. How'd the sound check go?

[beeros05]

How'd the sound check go?

My family told me that after the installation of the floor the results were much much better, so the floor actually works. I haven't heard the results myself yet.

[beeros05]

Finished carpeting

Assembling the kit, I think there is enough space for 3 persons to jam..!

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[Bawoo]

Mmmm, drum kit. Glad the work is helping. I'd love a more scientific sound check result! But dude, you need a new snare head!

[beeros05]

I'd love a more scientific sound check result!

What you mean by "scientific"

But dude, you need a new snare head!

That's not my snare man, mine is the one in the last pic! But you cant see the head, which is almost new.

[Soundman2020]

What you mean by "scientific"

I reckon that he means you need to use a sound level meter to find out how much isolation you are getting! Objective numbers, not subjective opinions.

And if you are getting "enough" isolation, then it's time to figure out your acoustic treatment! What isolation does basically, is to stop the sound getting out of the room. So if the sound can't get out, that means it stays IN! And if it stays in, then that means that the room sounds really bad. So now you have to measure the room response, and install the right treatment for whatever problems the room has: The best way to measure it, is to download "REW", which is free acoustic analysis software that is easy to use. So run a test with that (using a good loudspeaker, microphone and audio interface!), and post the resulting graphs here, so we can analyze them and tell you what you need to do to treat that room. One of the issues will most likely be the MAM resonance of the floor module that you built, but hopefully you damped that enough when you built it. But the major problems will be the modal response, which is simply due to the dimensions of the room: Hopefully, those can be treated to a certain extent with bass trapping, but you might also need something else. Once you post the graphs from REW, we'll be able to tell you what you need.

- Stuart -

[beeros05]

I reckon that he means you need to use a sound level meter to find out how much isolation you are getting! Objective numbers, not subjective opinions.
And if you are getting "enough" isolation, then it's time to figure out your acoustic treatment! What isolation does basically, is to stop the sound getting out of the room. So if the sound can't get out, that means it stays IN! And if it stays in, then that means that the room sounds really bad.

Ok got that but i have not installed doors yet and i do not know when i will do that 'cause i am out of budget. The "best" i can do right know is to use some left over gypsum-boards and make 2 "doors" from those. One interior and one exteriors, 3ply boards and in between them i can hang some blankets, rockwool etc for dampening. Thats the only thing i can do right now.

So now you have to measure the room response, and install the right treatment for whatever problems the room has: The best way to measure it, is to download "REW", which is free acoustic analysis software that is easy to use. So run a test with that (using a good loudspeaker, microphone and audio interface!), and post the resulting graphs here, so we can analyze them and tell you what you need to do to treat that room. One of the issues will most likely be the MAM resonance of the floor module that you built, but hopefully you damped that enough when you built it. But the major problems will be the modal response, which is simply due to the dimensions of the room: Hopefully, those can be treated to a certain extent with bass trapping, but you might also need something else. Once you post the graphs from REW, we'll be able to tell you what you need.

OK bro, i hope this is a user friendly program. I have a friend who will help, he has a very good audio interface, good mic but loudspeaker i dont know...can we use active monitor instead of a loudspeaker?

Thanx,

Spiros

[Soundman2020]

can we use active monitor instead of a loudspeaker?

Sure! As long as it has fairly flat response that covers the range of frequencies that are important to you, that's all that really matters.

- Stuart -

[beeros05]

We did the measurements roughly 'cause my friend saw and used the program at the same time.
He proposed me to do the measurements again in a couple of days 'cause he needs some time to check the program in detail.
He also proposed me that in the next measurement we should use a condenser omnidirectional mic.

Specs:
KRK Rokit 6 Active Studio Monitor
AKG C3000B Condenser Cardioid Mic
NI Audio Kontrol 1 Audio Interface

These are the results:

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[beeros05]

Is there anyone that could tell me what these graphs mean and if the gear that we used is ok?

[Soundman2020]

It means you have a problem and need some acoustic treatment!!!

Yes, you should really use an omni mic, and yes your friend needs some more time to learn the software a bit better, and calibrate it correctly, but even so, even though those graphs are probably not very accurate, the problems are still quite obvious.

I'm assuming that you did the test with no treatment in the room, correct? Just the bare walls, floor and ceiling, with no acoustic treatment? That's what it looks like from the graphs. You seem to have some major modal issues and bass build-up in there, but that is normal for a small room with no treatment. Most of that can be improved greatly with proper treatment.

So, ask your friend to take some more readings in a few days, once he has figured out the software a bit, calibrated it, and found a better mic, and ask him to post graphs that show only the bottom half of the spectrum, from 20 Hz to 1 kHz. Most of your problems will be in the bottom half, so lets concentrate on that first. What I'd particularly want to see first is a more detailed and more accurate waterfall plot, as that will reveal a lot about the modal behavior.

The bad news is that your room has serious acoustic issues. The good news is that this situation is normal and expected for a room like that, and the best news is that it can be treated with acoustic materials.


- Stuart -

[beeros05]

I'm assuming that you did the test with no treatment in the room, correct? Just the bare walls, floor and ceiling, with no acoustic treatment?

Yes, no treatment at all. I have not even installed doors! I have some left over gypsum-boards and i will use them by making 3 layer "covers". One inside one outside

The bad news is that your room has serious acoustic issues. The good news is that this situation is normal and expected for a room like that, and the best news is that it can be treated with acoustic materials.

I was expecting an answer like that to be honest. It is pretty logical. He presented me an "experiment" today. He started producing signals in certain frequencies and he told me to move around the room, stoop and stand up in different areas etc. With this experiment, what he explained me had to do with the "static acoustic waves", i don't know if this is the correct term in English, but now i understand why i can't hear my bass drums clearly when i play.

I know it is early now to talk about the treatment of the room since we do not have a proper mic, calibrated software etc, but i have some general ideas and i would like to hear some opinions.

PANELS:
I already have wood-bars 60cm long and i have enough to make 16 small panels 60x60cm. All panels i have seen so far are not that small, they are 1.20mx0.60m. I assume small panels would not be a problem since we are also talking about a small room. I think it is better also to have small panels, i don't know why, it just seems to me correct.

BASS TRAPS:
i was thinking of Super-chunk bass traps. The height is 2.05m. Instead of trapping the whole corner i thought to make 2 bass traps 95cm tall each one and leave a 15cm gap in between them for lamp installation. Is it ok to do so? Will this gap affect my bass trapping efficiency?

I found today beside garbage, plies of melamine wood from closets. Freshly thrown away and in good condition. I took some pieces to make triangulated cover and base of the Super-chunk bass traps. I think i saved lots of €€€.

[Soundman2020]

It is pretty logical. He presented me an "experiment" today. He started producing signals in certain frequencies and he told me to move around the room, stoop and stand up in different areas etc. With this experiment, what he explained me had to do with the "static acoustic waves", i don't know if this is the correct term in English,

Exactly. In English, those are called "standing waves" or "modes", and they are a direct result of the dimensions of the room. Certain frequencies, where the wave fits in perfectly between two walls, or four walls, or all six walls, will set up pressure conditions in the room where the tone will not be heard at all at some locations, and heard twice as loud at other locations. The dimensions of the room determine what those frequencies will be, and how they will be arranged across the spectrum. That's why I originally asked you if you could change the dimensions a bit, to get a more even spread of those waves. But you said that it wasn't possible to do that.

Since we are talking about room size, what are the final dimensions of your room, now that the inner leaf is completed? Since the room is empty right now, with no treatment, it is the perfect time to measure the room accurately, and post the dimensions here. Based on that we can predict what some of the problems will be, and confirm the prediction with the measurements that your friend will make.

but now i understand why i can't hear my bass drums clearly when i play.

Yup. Either your kick drum or your ears are located in a null for one of the important fundamentals of the note that it is tuned to. And since these are very low frequencies, with very long wavelengths, moving your drum kit and seat around is probably not going to help much. You have to damp those modes heavily, in order to start hearing your kick again.

I know it is early now to talk about the treatment of the room since we do not have a proper mic, calibrated software etc,

Well, we can still give you a general idea of what to do, since this is a small room, and it will have the same general problems that all small rooms have. The measurements will help to pinpoint specific frequencies that might need special treatment, but what you will need without any doubt, is a LOT of bass trapping in that room. Very deep, very large bass traps.

PANELS:
I already have wood-bars 60cm long and i have enough to make 16 small panels 60x60cm. All panels i have seen so far are not that small, they are 1.20mx0.60m.

What type of panel are you talking about here? There are many devices in acoustics that can be called "panels", so maybe you could be more specific? Are you talking about panel traps (also called "membrane traps")? Are you talking about absorption panels? Are you talking about diffuser panels? If you don't know the word in English, then maybe you can post some photos of the type of panel you have in mind.

I assume small panels would not be a problem since we are also talking about a small room. I think it is better also to have small panels, i don't know why, it just seems to me correct.

Actually, it's the other way around. Small rooms need LOTS of treatment, and LARGE treatment. The smaller the room, the more treatment it needs.

BASS TRAPS:
i was thinking of Super-chunk bass traps. The height is 2.05m. Instead of trapping the whole corner i thought to make 2 bass traps 95cm tall each one and leave a 15cm gap in between them for lamp installation. Is it ok to do so? Will this gap affect my bass trapping efficiency?

You could do that, yes. No problem. But then your lamps would be half way up the wall, only about 1 m above the floor! That's a strange place to put lights... There's no acoustic problem with that, but it might not be fun to have the lights shining directly in your eyes while you are sitting down, playing your drums. Maybe a better option would be to put some light rails on the ceiling, above the drums, and put a few adjustable lights in there, so you can direct them where you need them most?

I found today beside garbage, plies of melamine wood from closets. Freshly thrown away and in good condition. I took some pieces to make triangulated cover and base of the Super-chunk bass traps.

Are you talking about putting the melamine across the front of your superchunks? If so, I'd wait a bit before doing that: you might need it, or you might not. Once the superchunks and all the other treatment is in place, then you can get your friend to test the room again, and see if you need it.

What type of absorption can you get in Greece? Can you get Owens Corning 703? If so, then that would be great: buy lots of it! If not, then can you get some other type of semi-rigid fiberglass or mineral wool panels, similar to 703?

- Stuart -