Recording Recording / Practice Booth Acoustics

[Mark Hancock]

Just out of interest, I did a quick test of the acoustic response of my practice/recording booth. I recorded some brown noise first as a direct input, and then through a speaker/mic setup. The images below show the difference.

As you can see, there looks to be quite a difference, but I really don't know what it means. I'd be really interested to hear from anyone whos knows anything about this stuff...

• is this just to be expected from a booth?
• is there anything that could improve it?
• should I just leave it be?
• is it likely to also be the mic?

The booth is already fully lined with acoustic tiles and corner bass traps. I don't think it sounds really terrible in there. For practicing it sounds quite dead, but I use a Jazzlabs deflector, so that's OK. My recordings sound a little harsh IMO (or maybe that's just my tone ).

Of course, I practice long tones every day, but a little extra help from the room wouldn't go amiss...

 

[TimboSax]

I'm by no means an expert, but that looks pretty good. You're feeding in a flat signal, and getting a fairly flat signal out. There's a fall off below 100Hz, which I would suggest is due to a high pass filter, probably on the mic. My mics have a switchable high pass (which allows everything above 100Hz through, and attenuates below 100Hz, they are sometimes called rumble filters and are particularly useful to reduce handling noise or vibrations transmitted through the mic stand etc). There's a slight hump at around 300Hz and another at 5K, but they don't seem particularly large.

Remember in this case you have a number of variables that all have an effect:
- the room acoustic treatment
- the characteristics of the speakers
- the characteristics of the mic
- the positioning of the speakers and the mic

When you're recording, the speakers come out of the equation. You say that you have pretty much acoustically deadened the space, and so there should be reduced reflections from the walls and corners, hence there aren't any significantly noticeable peaks in the frequency response caused by standing waves at certain points (nodes). These can cause dead spots/sweet spots. I remember being in a mastering studio, listening to a mix, and it wasn't properly treated, Sitting in one position gave a fantastic sound, sitting 10 inches to the left the sound was completely different because of acoustic reflections causing frequency humps.

What I would do is repeat what you've done and move the mic around to different locations, just to see if you still get a flat response or if the response changes in any way. That tells you more about your treatment.

There are plugins that can measure the frequency response (similarly to the way that you have done), and then apply a sort of "reverse eq" to flatten out the frequency curve. Some of them also allow you to mimic the frequency curve of well known speakers/headphones. My ears are a bit shot from standing too close to the drummer , and so I don't hear a significant difference, but you might find them interesting. A well regarded one is:

SoundID Reference - Speaker & Headphone Calibration

Create with full confidence in sound with speaker & headphone calibration software SoundID Reference. Already trusted by over 140'000 studios globally.

www.sonarworks.com

 

[Mark Hancock]

I'm by no means an expert, but that looks pretty good. You're feeding in a flat signal, and getting a fairly flat signal out. There's a fall off below 100Hz, which I would suggest is due to a high pass filter, probably on the mic. My mics have a switchable high pass (which allows everything above 100Hz through, and attenuates below 100Hz, they are sometimes called rumble filters and are particularly useful to reduce handling noise or vibrations transmitted through the mic stand etc). There's a slight hump at around 300Hz and another at 5K, but they don't seem particularly large.

Remember in this case you have a number of variables that all have an effect:
- the room acoustic treatment
- the characteristics of the speakers
- the characteristics of the mic
- the positioning of the speakers and the mic

When you're recording, the speakers come out of the equation. You say that you have pretty much acoustically deadened the space, and so there should be reduced reflections from the walls and corners, hence there aren't any significantly noticeable peaks in the frequency response caused by standing waves at certain points (nodes). These can cause dead spots/sweet spots. I remember being in a mastering studio, listening to a mix, and it wasn't properly treated, Sitting in one position gave a fantastic sound, sitting 10 inches to the left the sound was completely different because of acoustic reflections causing frequency humps.

What I would do is repeat what you've done and move the mic around to different locations, just to see if you still get a flat response or if the response changes in any way. That tells you more about your treatment.

There are plugins that can measure the frequency response (similarly to the way that you have done), and then apply a sort of "reverse eq" to flatten out the frequency curve. Some of them also allow you to mimic the frequency curve of well known speakers/headphones. My ears are a bit shot from standing too close to the drummer , and so I don't hear a significant difference, but you might find them interesting. A well regarded one is:

SoundID Reference - Speaker & Headphone Calibration

Create with full confidence in sound with speaker & headphone calibration software SoundID Reference. Already trusted by over 140'000 studios globally.

www.sonarworks.com

Thanks for the response Timbo. There's plenty there to think about... and a side project for the weekend!

 

[Dibbs]

That looks pretty good to me. To really see what the room is doing you'd have to calibrate the mic/amp/speaker chain and remove their effects. You could do what Wharfedale used to do years ago and put mic and speaker atop telegraph poles.