Help me out with acoustic treatment please?

Fiddlesticks_

I've been doing a bit of recording recently after a while away and I've realised that my new(ish) room might need some acoustic attention. One of the main things I've noticed is that A notes on bass and guitar resonate very unpleasantly.

Because it's not a standard square room I don't really know where to start.

Do I start with bass traps and where do I put them if so?

Or will some square panels on the brick wall behind the monitors, on the back wall and directly to the sides of the desk do the job?

Ideally I don't want to spend a massive amount.

I appreciate that it will likely take a bit of trial and error but I just need a decent starting point.

Here's a pretty crude mock up of the space with the back wall and ceiling taken out:



Thanks in advance

Snags

@poopot has been giving me some pointers on this.  If you've got an iPhone there's an app (Impulse AE I believe) that will help you find your problem areas. No Android version I could find. There's also Room Wizard which will work on a proper computer. 

Panels you can DIY with plywood, rockwool (the acoustic type), and some fabric for way less than buying them. 

ChrisRG

I built some panels a while back. Here’s the build thread.

https://www.thefretboard.co.uk/discussion/183659/acoustic-treatment-in-home-studio-let-the-fun-begin/p1

There’s loads of really useful input in the thread from peeps on here who know a shed load more than I do. 

Hope it helps. 

Stuckfast

I can't see your mock up for some reason, but if an open string on bass is resonating then that suggests you have a problem with room modes. The fundamental frequency of the A on a bass guitar is 55Hz, so it's likely you have a strong room mode at 55 or maybe 110 Hz. Either way I'm afraid that is not going to be easy to sort out. If you do it with conventional bass trapping you are going to need a lot of it and it will have to be done right -- many off the shelf "bass traps" do nothing at those frequencies. If that's the only problem frequency (which to be honest is unlikely) you might be able to tackle it using a Helmholtz resonator but that's unlikely to be a cheap option either.

What are the dimensions of the room?

Danny1969

Sounds like there's a problem at 220 / 110 ... basically bass builds up in the corners (all 8 of them) and adds or subtracts to whatever note ... if it's in phase it adds, if it's out then it nulls.  Generally trapping the corners will help but working out whats happening at what frequencies is the best starting point. You do this by comparing a sweep of frequencies picked up by a mic in the room to the original frequency content of the file. That tells you what the actual rooms doing to the sound. 

Fiddlesticks_

@Snags cheers for that, I’ll try them apps out. 

@Stuckfast ;the room is about 6m at the widest and 4m at the longest. It has a couple of boxy spaces as well where the doorway is and next to a built in cupboard. It’s in the loft so has vaulted ceiling.

I’ve edited the original post to fix the image, hopefully it works now.

Stuckfast

Nice mock-up! It's not easy to calculate the exact room modes for a shape like that but it does sound as though it's a modal problem, though I guess it's also possible there's some sort of resonance in the chimney. Either way it looks as though you have plenty of space for acoustic treatment which is good. The best place to put bass trapping is in the corners and you've got a lot of corners, plus a lot of floor space that presumably isn't very useful for anything else because of the low ceiling. So for example you could shove a shit ton of Rockwool RW45 into the area on the right next to the low wall. You'll also want some treatment on the rear walls so that your monitor speakers are firing towards acoustic panels rather than bare walls. It might also be worth experimenting with rotating the setup 90 degrees so that they're firing down the long axis of the room, though it's a bit unpredictable in such an irregular space.

Fiddlesticks_

A bit of the low ceiling space is taken up by amps, and I actually plan on building some furniture (something akin to an Ikea Kallax) into the walls where the ceiling is low, so I suppose it will be worthwhile trying to adapt that design so that it can do a bit of acoustic work. 

So, what kind of product would you suggest for bass trapping? I have some moderate DIY capabilities so making something rudimentary isn’t out of the question if it’s the best option.

Also, I’ve taken some pictures of the actual room to hopefully give a better idea. Ignore the mess, the room is still very much a work in progress!