Chris' Room

Hi, Chris. I'm not Ethan but maybe I can help.

Based on your room's response I'm guessing you could add a subwoofer to extend your low end.

Ethan has suggested a +-10dB response tolerance above 50Hz. Your room seems to adhere to that down to about 72Hz.

It's my impression that you are using 5" speakers or perhaps the location you've put your speakers isn't ideal.

Regardless, pictures would be helpful.

Welcome to the forum.

-m

Or that..

Ya there's always the "I used the wrong mic" syndrome.  I forgot about that one.  

Glad we could get this cleared up.  

As a side note - it would be cool if you leave up that response graph because I want to compare it to my own 5" measurements if you don't mind.  Or email it to me - you can pm your email address if you're comfortable with that.

-m

Looks pretty good. A waterfall graph showing resonances to 300ms and decay plot with 140 and 160ms will also be helpful.

Ok, first - thanks for the measurement of the "wrong" mic. That's helpful when I analyze these graphs - you can never get too much practice and information.

Second, you're using this room, which is small, for mixing and tracking.

I remember in your OP, prior to editing, that you weren't sure what the next step was.

I'll tell you my targets: +- 10dB below Schroeder. I know your room is asymmetrical but you can go to amroc.andymel.eu/ to calculate (roughly) what yours is - probably less than 300Hz.

I'm not sure why people ask for unsmoothed responses below 300Hz; even half of that is caused by boundaries as little as 16" away - barely modal, could be anything, like a desk.

The guy at the bass integration guide is calling for +-3dB 1/3 octave smoothed from 40-300; pretty tough.

Another target is 20dB of decay within 150ms; also not easy.

Regardless, the bottom line for small rooms is approaching the holy grail of anechoic.

Don't think because it's drums you want it "semi-live".

I've been to studios with a drum room. Their live room is half the size of my current apartment complex.

But don't be downhearted - much can be done. You can: gap panels, add more, move speakers, move LP or move out!

Another pointer, which I'm currently observing, is adjust your X and Y resolutions so that your Y axis is always 5dB increments and reduce your X axis so that you're not up to 400Hz.

By using a lower Y resolution, you're artificially presenting a flat response. I know we all want to look good but these graphs are only helpful as long as your room looks bad!

By using a smaller X resolution you're giving more detail in the 30-100Hz range where your problems are most significant. In your waterfall, I'd be hard pressed to identify those resonances.

Indeed, comparing to your decay graph, it looks like there's some inconsistency; though it might just be in presentation.

Just trying to be helpful. Ultimately, the more you can expose your room's weaknesses the more we can help you.

-m

Ok, thanks.

Your next steps are contingent upon your goals.

You want to mix and record.

So I'd say a few things:

1. Is your SPL graph smoothed? It should be unsmoothed - or at most 1/48th octave smoothed - below 300Hz. If you want to smooth your SPL you can do up to 1/3 octave for your full (20-20000, or at least above 300Hz) SPL. Again, this helps us identify specific problems.
2. Disregarding whether your graph is smoothed you clearly have a few problems - none of which seem terrible. In fact, your room seems to be doing alright.
2a. You have some ringing left at around 90Hz.
2b. You have a bit of a null at 60Hz.
3c. A bit of general extra ringing that more absorption, or perhaps gapping your panels, could probably solve.

In order to identify a peak, find the wavelength of the problem frequency and find the correlating dimension in your room. Also look for halves and doubles: For example, the wavelength of 70Hz is 16' - an 8' ceiling also causes peaks and ringing there. 90Hz is a slightly longer dimension. Find it then treat it.
For a null, it's the same thing. The difference is that nulls (nodes) occur at 1/4 wavelength, 3/4 wavelength, 5/4 wavelength etc. If you measure to your back wall then find the 1/4 distance I wouldn't be surprised if you (or your speakers) are sitting in it. I had a similar problem yesterday and I resolved it by moving my LP up.

But, after all, this isn't a graph competition; you want to mix and record.

Well, you're going to have to determine whether what you're room is doing is sufficient for your needs.

Your LP is just one spot. How much residual resonance or aberration from perfect you're willing to tolerate there.

Your recording space is another concern. To record there you should determine what criteria you want to meet and then set out to accomplish that.

The general consensus is at least eliminate early reflections and, if possible, absorb more bass for lower ringing.

This is akin to "getting it right at the source". Time you take now is hours saved later in surgical EQ.

-m

Well, for no smoothing it's good.  I didn't see in your response about the null above 50Hz so I'll drop that.

Ya, gapping is just placing air behind your panels.  It helps lower the effective frequency of the treatment and, in my limited tests, further reduce ringing (although I've yet to really study my results - I just performed the tests this week (which are ongoing)).  Rather than thinking of it as "some air" think it terms of multiples of the thickness of the panel i.e. an 8" panel will receive an 8", 16", 24" or even 32" gap.  4x is the greatest I've heard recommended and, again from my limited testing, you're not necessarily going to get the best effect by throwing up a 1' thick panel 5' into a room to attack ringing at 20Hz.  If all this is above your pay grade then disregard it and just gap 1-4x the thickness of the panel.  Do not gap 1" and say it's not doing anything.  

Broadband treatment comes in a continuum of densities from fluffy to 8lb and beyond; if you're using thinner than 8" then you're better off using dense.  

If you got the budget and skills to build a wall like that then more power to you.  You can also look into QRD diffusers, both well and skyline, which, once the ringing and response are handled, are alternative paths on which to proceed.  

If I heard right, Dark Side of the Moon was recorded in an unusually "dry" environment and I feel that the recording has plenty of soul.  I agree that recording should be a comfortable experience but one has to acknowledge that a studio is a technical place with different needs than your average jam room.  Extra accommodation should be made especially in the case that the room is small or has dimensions not leading to the most ideal acoustics.  

Besides, you can use thin membranes to enhance your treatment's low end effectiveness while reflecting mid and highs.  If appearance and/or vibe is particularly important to you then it's reasonably easy to find posters or perhaps very thin laminate that can be adhered directly onto the absorption itself.  Giant tapestries of Bob Marley come with a free bag of O.G. Vibe when purchased at my local headshop.  

-m

Finding the frequency itself is related to room dimensions and those, in turn, determine where you get primary ringing.

Where you (measurement mic) or your speakers are physically located determine whether you get a peak or a null in your graph.  

If you're halfway or near a boundary then you'll get a peak.  If you're at 1/4 distance then you'll get a null.  This is somewhat of an oversimplification since the acoustic dynamic in any given space is complex but it's still very true and easily confirmable.  Your rear wall is a huge contributor and treating it should always be a priority.

Based on my current measurements you can probably expect that your low frequency null is coming from a longer distance rather than a shorter one.  

It gets complicated but that's what I understand.  

My rigid panels are made up of 2" 703 equivalent with two boards bound together by my frames.  If you're combining materials then don't use glue.  

I think if you look in my "new room, new problems" thread I had posted the best responses I got at that time.  I hope to supersede those results in this new room but I'm still mid-process.  You can follow my current progress, as well as thought processes in my new thread "New Fluffy Panels".

If you care to, you can go to my site (linked in my sig) then click on the Acoustics tab.  From there you can download a pdf I put together (free download) and look at those graphs.  They're not ideal but I would say they're at least "good".  

Heck, though my YouTube channel is going to be primarily focused on music you can subscribe there and help me get to 100 subs!  I'd really appreciate it

While I'm at it I should mention that my Patreon is going live soon.  For a nominal patronage, I'll be happy to offer personal guidance on any of the subjects in which I've become relatively versed including various skillsets in music, home production and how to intimidate thugs.  

Like I said, your graphs are already good.  Ultimately, and like I mention in my book, you're aiming to achieve certain targets.  Many individuals have put forth their own targets.  Those in my pdf are ones that, at that time, I felt were worthy for aiming.  The universal theme is that you want as flat an SPL response as is "manageable" (Ethan's word) and likewise for even, short decay - ringing is a form of decay.  These are targets for rooms smaller than your local megaplex.  If you have access to a megaplex then your targets become slightly different.

Thanks, 

-m