We have an old WW2 bunker in which we play with meters of concrete around us,
How did you get so lucky? That's amazing!
So: clearly, isolation just is not an issue for you guys, at all! No sound gets out, and no sound gets in.
This is one of those few cases where it really is true that your only problem is treatment! A lot of people come here thinking that they don't need isolation, but pretty much always they do. But not you guys! Lucky...
The height of the room is 3,1m.
Damn! It just gets better and better! That's a darn nice height for a ceiling in a drum room...
on the opposite of the entrance is a riser for the drums mainly. Its as wide as the room, 1,6m deep and 40cm high.
Why??? You don't need it. It reduces the ceiling height above you to 2.7 m, which is mediocre, and it serves no useful purpose anyway. Drum risers are used to isolate the drums from the floor, but you guys do not need isolation: I'm assuming the floor is also thick concrete, and there's nothing better than that for a studio floor. I would dump the riser. if you REALLY do want a riser "just because", then you can build a really good one in much less than a third of that height: 12cm is more than enough.
The drums have to be on the riser or at least near that wall as the room will remain mainly a rehearsal room.
If you insist on keeping that riser, you'll never get a good drum sound in your recordings. Drums need height above them and space around them to sound good. Jamming them up against a ceiling and a wall for no good reasons isn't useful. It places the overhead mics too close to the ceiling, where they catch the reflections coming back from above that interfere with the sound coming up from below, leaving a pattern of major nulls and peaks in the frequency response pattern that they pick up. Get the drums down from there, on to the floor, with just a nice rug underneath, and you'll find that they sound a lot better just in normal playing, and also record a lot better.
Currently mainly all walls are covered by 2 cm thick "eggcrate" acousitc foam.
So it must sound pretty "honky" and "cavey" in there? A bit "boomy" too? Cymbals sounding totally "dead", snare lifeless and limp with no "snap" at all, the kick drum booming all over the place, with toms thudding and clonking through everything else, uncomfortably?
On the concrete floor is old 2 cm thick carpet.
So it sounds even worse than I thought!
The carpet has to go. Here's what carpet does to your room acrostics:
thick-pile-carpet-absorption-chart.png
It totally kills the highs, does selectively nasty things to to the mids, and does not touch the lows at all: That's exactly the opposite of what you need. Get rid of it. In fact, yours is even worse than that graph shows, since yours is thicker....
the ceiling is "covered" with fabric for cosmetic reasons that I dont
Neither do i! It doesn't look very "cosmetic" to me... !!!
Above is air and then at 3,1m uncovered concrete.
Basically, your room is upside-down, acoustically! Just flip it over, and you'll be fine!!
Seriously, the floor should be hard, solid, rigid and reflective, and the ceiling should be absorptive, and/or diffusive. That's the best way to get a room sounding good for recording, rehearsing, playing, mixing, whatever. There are very good acoustic and psycho-acoustic reasons for this, and I can go into those in detail if you'd like to know, but if you just want to know "what works and what doesn't", then the basics are simple: Hard floor, soft/diffusive ceiling, because our ears and brains like it, and so do microphones, when placed correctly.
We plan to do "enhanced" demo tape quality or better drums if possible, understanding the limits of the room.
The room does NOT have to be the limit! In your case, that is. Most home studios are limited by the room dimensions, especially the height, and the need for isolation, but that simply does not apply to you. You are blessed with a fantastic room, where you could get some really great recordings of drums and pretty much anything else. The room does not have to limit
anything for you guys. The limits will only be in the treatment design for the room, how far you want to go to get it sounding incredible, and how much you are willing to spend to make it so...
But at the moment everything we record is flat and punchless and even our good cymbals sound like cooking equipment banged on.
Yup. Absolutely what I would expect from the room the way it is now.
The DW Collectors Drums I saved my ass of for should be ok aswell.
In that room, they should shine! If the room is treated properly.
We have a limited budget of 300€ right now and then can add more stuff in the coming months to make more gradual improvements.
300 won't take you far, but it's a start. If you could keep on adding the same every month for several months, then you could make that room sit up and do wonderful things for you. You could, conceivably, make it good enough that you could rent it out for recording: if you do it right, you could have bands lining up at the door with wads of cash in their hands, to record in your place. If I had a place like that, I'd be laughing all the way to the bank each month...
1) Cover the ceiling with 10 cm of mineral or glas wool and then add a layer of the acoustic foam from one of the walls. All neatly packed ofc so no fibres can escape.
Yes, but not the entire ceiling done like that! Just the places that need it. Some places will need more depth, others less. Some will need to be kept a bit reflective, others a bit diffusive. But the underlying (or rather "overlying" here, since it is the ceiling!) base will be absorption. If you can get Owens Corning 703 where you live, then that's the stuff. If you can also get 701 and 705, then happy days are here....
2) Get rid of the acoustic foam on 1 wall (left or right, I tend to the wall between D and B at the moment) to have some high frequencies not absorbed, increase thickness of the insulation with mineral wool or more foam on the opposite wall
It would be better to "checkboard" the treatment across both walls, such that where one wall has an area of treatment on it, the opposite wall is bare (or has contrasting treatment). Make your devices large, about a meter or so wide and a couple of meters high. Place them strategically, at modal peaks and nulls, to help deal with those.
3) Add bass traps in the possible corners (B,C,D,E).
Your room has seventeen corners: those are just four of them that you mention. Use some of the others!
Think about it...
Would you keep the (wood construction, no filling, covered with carpet) drum riser?
No. That should be the first to go. Depending on how it is built, it is very likely acting as a resonant system, possibly with several resonant frequencies, that are doing strange things to the response.
but more or less isolates the drum from the concrete floor.
Why do you need to isolate it? The floor is massive, it is concrete, it is damped on the other side by the entire Planet Earth..... Why do you want to isolate the drums from that? Just put down a nice large rug of some type to keep the drum kit in place so it doesn't "walk" around as it is played, and to control some of the high frequency reflections coming back up again. That's all you need, if you have the fantastic concrete floor already....
Would you use (build) movable absorbers to place in front of the set when recording?
Yes. Gobos would be very useful in there, as they could be used to change the acoustic response of the room in certain locations, and even to separate instruments from each other to a certain extent, if you wanted to record an entire band all at once. Very much worthwhile. Build them on wheels, make them massive and reflective on one side, and absorptive on the other (or maybe make one or two of them diffusive, for more control and flexibility).
I have to say I'm a bit envious of that space you have! It has really good potential, and could be made to sound very nice. It is larger than the majority of home studios, in all dimensions, and most of all the height is just ... I ran out of words!
- Stuart -
