Dangers of over treating a room till it is dead

tuga

. . .
Wammer
Aug 17, 2007
11,946
4,629
173
Oxfordshire, UK
AKA
Ric
HiFi Trade?
  1. No
The idea is the speaker goes at the listening position and you play something like pink noise and then move the microphone around possible locations for the speaker to look for an even bass response. The speaker then goes in this position. As I said it's a common concept for subwoofer placement although usually done by ear. The idea behind it is tied to room mode behaviour and an assumed reciprocal behaviour such that what you hear at the speaker position when the speaker is at the listening position mimics what is heard for the reverse arrangement.

Thinking about it I wonder what REW's room simulator shows if this is tried. I'll have a look some time.
I see now . It makes sense if you have a predetermined listening spot (e.g. when adding a subwoofer).

I prefer to optimise the location of both speakers and listening spot.

 
  • Upvote
Reactions: Bokke

ChemMan

ChemMan
Wammer
Aug 8, 2018
2,511
1,545
148
Brussels
AKA
Steve
HiFi Trade?
  1. No
Do measure from the listening spot, then move the mic around the speaker, then move the speaker to the position where the mic was producing the flattest response, and remeasure from the listening spot and compare?
You put your speaker in the listening spot and take the mic and move it around where you had the speaker and find the flattest response.

I've hooked up the mic and have been playing with the SPL meter just to get a feel for it all.  According to my hand held SPL meter and the app on the phone, my close to silent room measures about 37 on both of those, but REW shows 50.  I've tried both the 90 degree calibration file, the regular one and NO calibration. Additionally, when a loud noise occurs, I  coughed near the MIC  a red "OVER" comes on the meter.

The dealer also said, I should get a white noise and pink noise audio file used for measurements.  Should i get these or just use music?

 
Last edited by a moderator:
  • Upvote
Reactions: Bokke and tuga

tuga

. . .
Wammer
Aug 17, 2007
11,946
4,629
173
Oxfordshire, UK
AKA
Ric
HiFi Trade?
  1. No
You put your speaker in the listening spot and take the mic and move it around where you had the speaker and find the flattest response.

I've hooked up the mic and have been playing with the SPL meter just to get a feel for it all.  According to my hand held SPL meter and the app on the phone, my close to silent room measures about 37 on both of those, but REW shows 50.  I've tried both the 90 degree calibration file, the regular one and NO calibration. Additionally, when a loud noise occurs, I  coughed near the MIC  a red "OVER" comes on the meter.

The dealer also said, I should get a white noise and pink noise audio file used for measurements.  Should i get these or just use music?
The downside of that method is that your listening spot (where you’ve placed the speaker) may not be the best spot.

If you look at the measurements I made in 2011 moving the sweet spot makes as much difference as moving the speakers.

 

ChemMan

ChemMan
Wammer
Aug 8, 2018
2,511
1,545
148
Brussels
AKA
Steve
HiFi Trade?
  1. No
I've hooked up the mic and have been playing with the SPL meter just to get a feel for it all.  According to my hand held SPL meter and the app on the phone, my close to silent room measures about 37 on both of those, but REW shows 50.  I've tried both the 90 degree calibration file, the regular one and NO calibration. Additionally, when a loud noise occurs, I  coughed near the MIC  a red "OVER" comes on the meter.
Will this be a problem or is this normal operating behaviour/ @tuga @MartinC

 

MartinC

Wammer
Wammer
Jul 29, 2005
8,786
4,979
158
HiFi Trade?
  1. No
I prefer to optimise the location of both speakers and listening spot.
Where there is freedom to do so this is definitely the right approach. Pretty much whenever I get involved in any discussion about speaker or subwoofer position this is the first point I raise, as it's so often missed.

 
  • Upvote
Reactions: Bokke

MartinC

Wammer
Wammer
Jul 29, 2005
8,786
4,979
158
HiFi Trade?
  1. No
What microphone do you have or are getting @ChemMan? If it's a UMIK-1 just use the pink noise option in REW. If you're using a microphone you definitely want to use a signal like this, not music. 

 

Bokke

Well-Known Wammer
Wammer
Aug 18, 2018
1,392
884
148
HiFi Trade?
  1. No
I see now . It makes sense if you have a predetermined listening spot (e.g. when adding a subwoofer).

I prefer to optimise the location of both speakers and listening spot.
Very difficult in most UK homes. Even harder for home cinema 

 

ChemMan

ChemMan
Wammer
Aug 8, 2018
2,511
1,545
148
Brussels
AKA
Steve
HiFi Trade?
  1. No
What microphone do you have or are getting @ChemMan? If it's a UMIK-1 just use the pink noise option in REW. If you're using a microphone you definitely want to use a signal like this, not music. 
I have the UMIK-1.   

Here's what I got on the first try using Bluetooth to send the audio signal to my Node from REW.

But I'm sure I've done something wrong as the measurement window shows I'm suing a log sweep. If I click on Pink Noise while not measuring it gives me the standard pink noise fuzz, but then in measurement it reverts to the sweep.

View attachment 93278

View attachment 93279

 
  • Upvote
Reactions: Bokke

MartinC

Wammer
Wammer
Jul 29, 2005
8,786
4,979
158
HiFi Trade?
  1. No
As I believe you said your dealer suggested, you need to use the Real Time Analyser (RTA) for what you have in mind rather than making a measurement.

 
  • Upvote
Reactions: tuga

ChemMan

ChemMan
Wammer
Aug 8, 2018
2,511
1,545
148
Brussels
AKA
Steve
HiFi Trade?
  1. No
As I believe you said your dealer suggested, you need to use the Real Time Analyser (RTA) for what you have in mind rather than making a measurement.
RTA. RIght.  The measurement I took above is from the listening position. I felt it was important for me to understand how it all works before I attempt the speaker placement analysis. By the looks of the graph, my room is a mess.

 

MartinC

Wammer
Wammer
Jul 29, 2005
8,786
4,979
158
HiFi Trade?
  1. No
RTA. RIght.  The measurement I took above is from the listening position. I felt it was important for me to understand how it all works before I attempt the speaker placement analysis. By the looks of the graph, my room is a mess.
Ah, right sorry. Pink noise is for the RTA but if you're trying the swapping positions thing. If you're doing proper measurements then what you did looks sensible beyond that I'd increase the minimum frequency of your sweeps to avoid the risk of causing damage. It doesn't look like it's worth going below 30 Hz from your first measurement, unless you know your speakers go lower?

 

MartinC

Wammer
Wammer
Jul 29, 2005
8,786
4,979
158
HiFi Trade?
  1. No
If you're just looking at bass it doesn't matter but if you're curious to see the full response I'd make to top frequency 20 kHz too actually.

 

Nopiano

Wammer Plus
Wammer Plus
Jul 19, 2016
7,555
4,701
183
Monmouthshire, Wales
AKA
Nick
HiFi Trade?
  1. No
By the looks of the graph, my room is a mess.
Following with interest.  I guess we need a few more tries to see how representative this is, but the trend isn’t bad, surely?  The peaks at 40+, 50+ and 70+ Hz may be what you’re hearing as boominess. 

Did you run the dimensions of the room through Amroc or similar, to see where the expected modes are?

 

ChemMan

ChemMan
Wammer
Aug 8, 2018
2,511
1,545
148
Brussels
AKA
Steve
HiFi Trade?
  1. No
If you're just looking at bass it doesn't matter but if you're curious to see the full response I'd make to top frequency 20 kHz too actually.
Following with interest.  I guess we need a few more tries to see how representative this is, but the trend isn’t bad, surely?  The peaks at 40+, 50+ and 70+ Hz may be what you’re hearing as boominess. 

Did you run the dimensions of the room through Amroc or similar, to see where the expected modes are?
I'm trying to do a million things at once really. I really need to do two main things.  Figure out he software I'm not finding it all that easy. And then, just try and solve listening position by measurement and find out what the bass problems are and come up with a strategy.

We've just moved and so like all family life things are chaotic at the moment. And my frustration level is high.

The RTA is going to be useless for me. I fooled around a little with it and it's just too hard to understand.  It can put the bloody mic in a desk drawer, in a closet in the garage cellar and not get a flat line.

Amroc, Never heard of it, and can't add yet another variable to this.  I've got the mic until Tuesday morning.

 
  • Upvote
Reactions: Bokke

Nopiano

Wammer Plus
Wammer Plus
Jul 19, 2016
7,555
4,701
183
Monmouthshire, Wales
AKA
Nick
HiFi Trade?
  1. No
Last edited by a moderator:

ChemMan

ChemMan
Wammer
Aug 8, 2018
2,511
1,545
148
Brussels
AKA
Steve
HiFi Trade?
  1. No
Sorry, Steve, I thought you’d seen and used it before. Here it is, with some of your dimensions as I had a quick look a couple of nights ago.  

https://amcoustics.com/tools/amroc?l=850&w=520&h=269&r60=0.6

 I can imagine the frustration.  Was just wanting to show a genuine interest. 
 
It's really fine Nick, and I appreciate the support and advice, as I won't get through this without the help of the forum, Like anything new, there is a learning curve and always being pretty booksmart, I figured it be easier. Wrong.  

 
  • Like
Reactions: Nopiano

MartinC

Wammer
Wammer
Jul 29, 2005
8,786
4,979
158
HiFi Trade?
  1. No
By the looks of the graph, my room is a mess.
I missed this before. As I tried to warn you, you were basically bound to find things looked worse than you'd hoped. Basically everyone finds the same so don't be disheartened. This is why EQ to help improve things is generally very beneficial. You'll often see people declare that their rooms magically have perfect bass-response but I've yet to come across anyone who has made a measurement and drawn the same conclusion.

For info. the Room Simulator option towards the top right of REW is an easy to use but I'd say more helpful tool similar to the amroc one posted above.

 

MartinC

Wammer
Wammer
Jul 29, 2005
8,786
4,979
158
HiFi Trade?
  1. No
Figure out he software I'm not finding it all that easy.
You seem to be doing pretty well to me! You'd be amazed the length of some forum exchanges I've had with people just to get them to the stage of taking a single measurement. 

Very much view this as a process where you'll gradually learn more as you gain experience, rather than as a one hour task where you'll be 'done' and then never touch it again.

 

Bokke

Well-Known Wammer
Wammer
Aug 18, 2018
1,392
884
148
HiFi Trade?
  1. No
I'm trying to do a million things at once really. I really need to do two main things.  Figure out he software I'm not finding it all that easy. And then, just try and solve listening position by measurement and find out what the bass problems are and come up with a strategy.

We've just moved and so like all family life things are chaotic at the moment. And my frustration level is high.

The RTA is going to be useless for me. I fooled around a little with it and it's just too hard to understand.  It can put the bloody mic in a desk drawer, in a closet in the garage cellar and not get a flat line.

Amroc, Never heard of it, and can't add yet another variable to this.  I've got the mic until Tuesday morning.
I know how you feel. I don't want to tell you what to do but maybe take a break from it and come back to it later tonight. I've always found that helps me. Brain can't think when stressed 

 

ChemMan

ChemMan
Wammer
Aug 8, 2018
2,511
1,545
148
Brussels
AKA
Steve
HiFi Trade?
  1. No
I know how you feel. I don't want to tell you what to do but maybe take a break from it and come back to it later tonight. I've always found that helps me. Brain can't think when stressed 
thanks.  :notworthy:  That's the plan.  I'm just going to be a dad and husband for awhile and get back to it when the house it is quiet in the evening.