Help with REW results and next steps.

[Charlie Harper]

Hello,

My first post here, but a long time reader of SOS.

I’m having trouble interpreting REW results and what to do with them.

I tried my best to do things right but I’m not sure.So I would appreciate if somebody could help me.

I built some absorbers for the corners 40x40 from floor to ceiling. And some broadband panels for side and back walls 120 x 60 x 20 cm.Each of these walls has two of them.Ceiling has no treatment.

My room is not rectangular.I attached a drawing so you can have an idea of how it looks.

Attached also some amroc mode calculations for the modes of non-rectangular rooms.

My room dimensions are roughly 3.78 x 3.42 x 2.82 m although I have a dropped ceiling.True ceiling height is about 3.10 m.

Positioning:
I followed the 38% rule and my speakers are as close as possible to the front wall.They are separated by 1.42m but the distance of each one to my ears is about 1.10m.

Measurements:
Soundcard Calibrated.
Done with calibrated mic from sonarworks at 0 degrees.
I measured L and R independently, but I used different positions for each,approximately where each of my ears would be.For L and R together I measured in the midpoint between ears along the 38% line.

Thank you.



Thank you.

[Sam Spoons]

I'm sure somebody with much more knowledge WRT this stuff than me will be along shortly but my advice would be to forget about calculations and measurements. I'm assuming you have a project studio and this is a hobby, so forgive me if I'm wrong (and go and employ a professional audio consultant...) but interpreting the calcs and the REW measurements is a complex job and unlikely to be something you can do based on a few forum posts. I'd simply play some well recorded music and compare how the room sounds to before you fitted the treatment. I'm 99% sure it will sound way better than the bare room so I'd* take that and just get on with making music.

* I did the same thing a few years ago and £300 worth of DIY treatment made the room a lovely place to play and record music, Abbey Road it ain't but it's close to as good as a small basement is ever going to be. just remember that 90% of the improvement comes from the first 3 or 4 panels at the mirror points.

[Charlie Harper]

Hello,

Thanks for the reply.

The room sounds subjectively better and objectively measures better after the treatment I have.

But, I’m always looking to improve it to make it more accurate for mixing.There are some nulls there that result in lack of bass at the listening position and must be addressed.Those ones cannot forget and move on.

There are plenty of experts on this forum that maybe can help me a bit

[Sam Spoons]

[Drew Stephenson]

In a room of that size, you're always going to have some bass nulls unless you put in a lot more trapping. Hugh Robjohns shared a thread not that long ago with his latest studio rebuild and his bass traps are about 1m across the front face in three corners for example

It looks from the images as if you've got broadband trapping on the left side of the desk but a large window on the right? If so that might explain the much more peaky response higher up the frequency range on the RH side.

We're definitely going to need some better pictures though - the images have had the axes cropped off and they're really small, my eyes aren't what they used to be!

[EDIT] Here's the link to Hugh's studio article where you can see just how much space is dedicated to bass trapping: https://www.soundonsound.com/techniques ... sound-good

[Charlie Harper]

Hello Drew,

Thank you for your reply.

Sorry about the pics.I was trying to fix that with different hosting services but couldn’t.

Below new links and hopefully they work.
















free download hosting

[Drew Stephenson]

Thanks Charlie, much clearer now!

[Hugh Robjohns]

The room sounds subjectively better and objectively measures better after the treatment I have.

We'll count that as a win, then.

But, I’m always looking to improve it to make it more accurate for mixing.

Fair enough... but practical and budgetary limitations mean it's never going to be perfect... and chasing perfection will just drive you mad. Good enough is good enough!

There are some nulls there that result in lack of bass at the listening position and must be addressed.

Not unusual... and the only solution is a lot more genuinely effective bass trapping. While I can see you have corner traps, they don't look big enough to tackle the really low end.

As you appear to have a single significant null around 60Hz, you could use tuned bass traps just to tackle that specific frequency in the most efficient way. Tuned traps are generally smaller than broad-spectrum traps which will be relevant to your space.

But fundamentally, if you want to sort out that middle-of-room bass null you are going to need a lot more bass trapping.

[Charlie Harper]

Hello Hugh,

Thanks for your insights.

Was actually after seeing the article about your room that gave me hope that with enough determination, I could address the issues on mine.

I was experimenting with one subwoofer and it actually improved considerably the null, but at the cost of increasing the amplitude and ringing of the lowest mode, but didn’t know where to go from there.

[Hugh Robjohns]

Nulls are caused by a cancellation where LF reflects off one or more walls and interacts with the direct wave. So the only way to prevent that cancellation is to kill the reflection — which means proper bass traps in the right places.

A subwoofer in the right place might appear to 'fill in' the null, but it will inevitably cause new problems from other reflections of its own direct sound elsewhere in the room — exactly as you have found.

[Charlie Harper]

Thank you.

I needed to get to the bottom of that

[RichardT]

Hi Charlie, I would second what's been said above.

Particularly, your current trapping won't deal with the really low end, where you have a massive suck-out at around 60 Hz.

I agree with Hugh that the best solution to that problem is going to be some tuned trapping. Getting broadband trapping to work at those frequencies is going to require something very substantial.

I've used tuned traps from GIK to deal with a resonance in the 50Hz area and they have been very successful. If you describe your setup to GIK they will happily give you advice.

These traps have an absorption peak at the centre frequency, with significant absorption spanning about an octave.

It can be tempting to use Sonarworks to even out the frequency response, but all these problems have effects in the time domain (blurring or smearing of the sound) which means you're better off correcting them at source. The same with sub-woofers, as you've found!

[Charlie Harper]

Hi Richard,

Thank you very much.

Will definitely contact GIK.

[Philbo King]

Since you have a dropped ceiling, consider putting 80 cm or so of regular fiberglass bats above the ceiling for additional bass trapping, maybe.

[Charlie Harper]

Hi Philbo,

Maybe dropped ceiling is not the correct term in English, because it looks like it’s made of one piece only.Sorry if somehow it mislead.



If I could I would do it because it’s an excellent idea and plus would be out of sight.

Thank you.