It’s not egg boxes, foam, or “Auralex” (used by itself).
Generally speaking, sound proofing is expensive, acoustic treatment is not. Sound proofing needs lots of heavy material, and structural support to go with it. You need a pro to do the job, and there’s no cutting corners there. Conversely, acoustic treatment is all about cutting corners, in fact, removing them from the room! It’s easy to DIY. Here’s a simple and highly effective solution.
Basically, the goal with acoustic treatment is to create a room that acts as if there are no walls reflecting the sound. The ideal is “outside”. So as much absorption as you can get in there, while retaining some pleasant reflections via diffusion. You can make a diffuser with a large piece of curved plywood. For more info, Ethan Winer has an excellent article on acoustics on his site.
These will not get you to posh professional level acoustics, but will get you 50% to 80% of the way there, depending on how much work you put in. Just like high end gear, there is a diminishing return the more you spend.
It is simply amazing how much easier it is to mix in a room with this level of treatment.
The control room and the studio
These are the two rooms that every studio should have, assuming you’re recording acoustic instruments.
The control room is the one that needs to have a flat response, achieved as I have already described- basically, absorption.
You can do whatever you like in the studio, to create your signature sound. But generally speaking plenty of diffusion is preferred to avoid big peaks and nulls in the response, and to keep little ones for the character sound. This also retains the room’s natural reverb. So little or no absorption.
Every listening room will need treatment. You know you need it when you find that certain notes, especially bass ones, jump out louder than others. Set up an organ sound on your keyboard, set all eq to flat and play all the notes starting at the lowest the keyboard can make. You’ll find some notes are loud, some are quiet, and it depends on where your ears are. An inch move and they’ll sound different.
Space is expensive, and if you’ve got to live in the place also, compromise is called for. Here are two compromises I’d suggest, if you only have one room available:
1. Use portable bass traps. Store them for tracking, install them for mixing. The other way around for difusers. I reckon you’ll still get around a 50% improvement in room acoustics, which is a lot! And it’ll be cheaper. Assuming the missus doesn’t mind the spare room being full of crap while you’re recording!
2. Commandeer a spare room as a studio only when you need to track. Permanently install attractive looking difusers and run a multicore in there. Shift the bed or WHY for sessions. Then you can have superchunks etc. permanently installed in the control room
Room mode measurement
I think that on a tight budget, measuring room modes is an academic exercise. You can actually gain a lot of improvement by literally putting in as much superchunk as you can without any mode measuring. Maybe later you can measure and look at building absorbers for bass, low mid, hi mid , HF diffusion or whatever you need. After that, it’s expensive, complicated and returns are severely diminished.
But my all means measure before and after so you can pat yourself on the back. 🙂