Room Acoustics - To Measure?

[Regan Ireland]

SN,

 

I am working on my HiFi setup, and as you can see in the pic, I have a lovely rustic room, however it is mostly Brick and Timber Floors etc. Not ideal. With the horn-loaded CornScalas, they sound beautiful, but I believe have some mid and high range harshness. Expected from horns, but likely exaggerated.

 

Part of me thinks "Okay, big wool rug on that shiny floor, and some dampening at the first reflection points on the sides".

 

Another part of me thinks "Actually measure the room properly before rushing in to make sure you know what you're aiming for"

 

So a couple of questions:

1. Do you think measurement and analysis is required? Or are there some basic rules of thumb that I should follow (I don't want to get stuck in an analysis paralysis measure-fest, but I want the outcome of improving my musical experience

2. If measuring is the way to go, REW seems the ticket. Does anyone have a suitable Mic I could loan in Melbourne to give me a feel for measuring before I jump right in? (There's a six-pack in it :))

 

 

 

[davewantsmoore]

8 hours ago, Regan Ireland said:

1. Do you think measurement and analysis is required?

 

Required is a strong word.   Measurements are often difficult to interpret, especially if there's uncertainty about how they were taken....  and you often need to measure/interpret/measure/interpret/measure.... to get questions answered.

 

8 hours ago, Regan Ireland said:

Or are there some basic rules of thumb that I should follow (I don't want to get stuck in an analysis paralysis measure-fest, but I want the outcome of improving my musical experience

Yes.  Often measurements will just confirm what we can easily assume by looking at a room.

 

Your room doesn't have very many soft things in it.    Will more soft things make the sound nice?   How will you know by looking at a chart?  (it's not simple)

 

It probably will.   You should try it.    To test it, my advice is to go "big" (to get a significant effect - even if ultimately that won't be domestically acceptable), and cheap (don't spend money).     For example... go get all the mattresses and blankets you have in the house, and move them into your listening room.... chuck the blankets on the floor, and the mattresses standing up against the side wall.    Do you like it?

 

[Regan Ireland]

Good call. Time to send the wife away...

[Hipper]

I agree with Dave M to experiment if you can. I would also consider moving the speakers and listening chair around to find what that does.

 

If you can find people who have your speakers it would be worth seeking their advice.

 

I use REW and, for me anyway, it has taken me years to learn to use it reasonably well. There are simpler but less accurate ways to measure. For example, you could get a test tone CD and use your ears, or better, a Sound Pressure Level (SPL) meter. Here's a free download for bass test tones:

 

https://realtraps.com/test-cd.htm

 

This site also has some good advice on REW as well as room treatment.

Edited August 14, 2018 by Hipper

[YNWaN]

I hope the following is of some help:

 

I’ve used REW before and it is both extremely effective and useful. However, how you address the issues it highlights is another matter. Mid to high frequency issues can be addressed with passive solutions like diffraction and absorption panels (you can buy them or make your own). Bass issues are another matter and it is usually these that are the most obvious. Pretty much every room, unless it has a very random shape, will have one major mode where it actively amplifies a band of sound. The bigger the room the lower the frequency - though sometimes big rooms have weird double bumps in my experience. In theory these modes can be counters by bass traps but in reality this just isn’t true - well, it is in a sense, but the boost is often +6dB or even more, and this is a lot at 50Hz. I’ve read about quite a number of custom built rooms (designed by professionals) and even these fail to counter the major room mode of a rectangular shape. Personally, my solution, was to use DSP to counter the predominant room mode (and its lesser echoes). 

[Happy]

The room looks beautiful. Not too sure about the acoustics for the La Scalas though. You will appreciate a lot of acoustic treatments. But they will spoil the look. If you’re not too unhappy with the sound maybe just live with it lol.

 

Or you can try Digital Room Correction on a full scale.

[AudioGeek]

Decide if you want to treat the room and put stuff on the walls etc. Ends up looking like a studio and not a converted garage/warehouse.

 

You could try the blanket/doona/towel/pillow test at the reflection points and see if it makes a difference before proceeding.

[almikel]

On 10/08/2018 at 7:57 AM, Regan Ireland said:

So a couple of questions:

1. Do you think measurement and analysis is required? Or are there some basic rules of thumb that I should follow (I don't want to get stuck in an analysis paralysis measure-fest, but I want the outcome of improving my musical experience

Lovely room - looks quite large also, which is good

IMO measurement and analysis will be of benefit - but as others have said, the analysis and interpretation is the hard part...

...Have you considered having a professional measure it for you?

That way you'll get the interpretation and they will recommend treatments.

IMO this will be a faster way to get results you can hear and measure.

There are lots of smart people on Stereonet who will give good advice based on your own measurements, but it can be a long and excruciating process.

 

Also IMO, every room will benefit from treatment, and that process should start by targeting lower frequencies (say <500Hz)

 

The more rigid surfaces there are (brick/concrete) the more lower bass issues you'll have, as the bass energy is reflected and stays in the room instead of being absorbed/transmitted (lightweight gyprock walls make good bass traps provided they don't rattle).

What are the other boundaries constructed of (ceiling, other walls, what's under the floor)?

 

Even if you get a professional in to measure, I'd still recommend getting a measurement rig at some stage, as adding treatment is an incremental process, and you'll want to check that treatments are "fixing" the issues identified.

A key part of any measurement rig is a decent mic stand with a boom, so you can get the mic into the right spots.

 

On 10/08/2018 at 7:57 AM, Regan Ireland said:

are there some basic rules of thumb that I should follow

there are, but if it's a shared room, you're unlikely to get approval, and you may not want them either...

...IME you would clean up the bass/lower mid range between ~125Hz - 500Hz significantly with large absorption traps straddling corners. By large I mean 1200mm wide, 200 or more deep, floor to ceiling (for vertical corners).

Difficult to make it look good, and takes up significant room real estate, but without even seeing your room, I'd be very confident of a significant improvement of the perceived "in room" sound - especially bass - and improved measurements for reverb/decay times 100 - 500Hz...

 

...but it would be very foolish to jump that far into the deep end of applying treatment based on a single recommendation from a random forum interweb post without better data

 

On 10/08/2018 at 7:57 AM, Regan Ireland said:

2. If measuring is the way to go, REW seems the ticket. 

REW is an amazing tool, and constantly being developed further, and is free.

 

It's highly likely that any professional you engage to measure your room will use REW also.

It would be a reasonable expectation that they provide you the REW files for your own further analysis/review (rather than just JPG images etc).

 

Since you're in Melbourne, I'd recommend @Paul Spencer for someone to engage to measure your room and recommend treatments.

I have no commercial connection to Paul, and others on this forum would likely provide similar support for Paul's services to achieve great "in room" sound.

 

cheers,

Mike

[Paul Spencer]

Thanks for the mention Mike. 

 

This is an issue that we come across fairly often - harsh or bright sound with a question mark over whether it's caused by the speakers, the room or both at the same time. It's actually a four part problem that involves:

 

1. Your music - we often forget that sometimes even live unamplified instruments can sound quite "harsh"

2. Your speakers - they may have a forward character and many horns and compression drivers have sonic issues causing them to sound bright, harsh or forward

3. Your room - if this is the ONLY problem you have, then typically it will be evident

4. Your expectations and preferences

 

How do measurements fit into this picture? Once you understand objectively how your room performs, it provides direction on how to make it better. Once your room is treated and performs well, you can rule it out as the cause of harshness. 

 

If your entire room is bare as shown in the photo, then your speakers don't have a chance to demonstrate their capabilities.

 

REW is quite easy to set up and run but the real challenge is understanding the results and then knowing what to do with them.

[almikel]

6 hours ago, Paul Spencer said:

 

REW is quite easy to set up and run but the real challenge is understanding the results and then knowing what to do with them.

truer words have never been spoken...

...and paraphrasing a Martial Arts teacher I respected a lot, "once you take 1000 measurements, you begin to learn"

I have long way to go...

 

 

 

 

[davewantsmoore]

The "trick" is in the evaluation of ones actions.

 

It is easy to measure a speaker... or to measure it 50 different ways.... and then you take that information make a decision and then "do something".

 

Critical evaluation that "do something" action is not trivial at all.    Subjectively it is as simple "do I like it?"  (Yes/No/Somewhat).

 

Objectively is a deep rabbit hole.   What issues are relevant?  How to excite and measure a speaker to show an issue?   Is a difference "this" big, important or not?   etc. etc.

 

 

There's a lot of work spent doing something, working out that it didn't work very well... and then going back to the start.    Substituting in subjectivity is a minefield, as unless the system is crud, I can put on my favourite record and "it sounds great".   

[almikel]

On 10/09/2018 at 12:18 AM, almikel said:

...and paraphrasing a Martial Arts teacher I respected a lot, "once you take 1000 measurements, you begin to learn"

 

On 10/09/2018 at 11:53 AM, davewantsmoore said:

It is easy to measure a speaker... or to measure it 50 different ways.... and then you take that information make a decision and then "do something".

yes what I should have said is "interpret 1000 measurements, and then you begin to learn"

 

Pretty easy to measure, analyse the measurement, and make a change expecting an improvement, re-measure, and not see the expected change - or sometimes the change is in the wrong direction 'cos you twiddled the knob in the wrong direction (I've done this lots - especially delay adjustments).

 

No question the interpretation and the "doing something" that works based on that interpretation is the hard bit...

 

...parking Speaker Measurements for a sec...

 

All of my focus on room measurement/speaker & LP position/treatment/sub integration has been in the bottom end, and at that end of the scale, IME there's a process you can follow where improvements in the measurements match well with subjective results (ie when the room measures better it sounds better).

 

Sure you can burn 100s (1000s?) of hours doing this - esp moving speakers/subs/LP around and re-measuring, but getting the measurements to a good place will mean the sound is subjectively good also.

 

Of course along that journey the measurements still may be far from ideal (but better than they started) and subjectively you may say "that sounds good enough" and be happy - I don't think that's a rabbit hole - just that you got far enough along a fairly well defined process for achieving good "in room" bass (eg reverb times low enough and consistent, achieved good sub integration for a smooth enough FR, modes sufficiently tamed for a smooth enough FR etc).

cheers,

Mike