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The Room Measurement Thread

L

Lefty

Trade: Amar Sood Photo
I recently acquired a UMIK-1 room measurement microphone as I thought it would be fun to measure my in-room speaker response. I am hoping others will follow suit so we can be geeks together :)

So here is the measured in room response of my PMC TwoTwo 6 Active Studio Monitors: (I will measure the Neumann KH310 and my desktop Yamaha HS50m over the coming days)

Can someone help me interpret this? It looks like the -3dB point is 30Hz (!) relative to 1KHz. Am I reading that right? If so, that's pretty impressive for a 6.5 inch driver.

Other than that
  • The low end looks a little strong (and lumpy) relative to the rest of the response.
  • There is a suckout between 100Hz - 400Hz
  • Are those peaks at 60Hz, 95Hz, 150Hz, 225Hz room modes?

I've currently got the speakers placed only 20cm from the rear wall. This is unusual for my room as most other speakers need around 45cm of space behind them. However, the PMCs don't seem to suffer any of the usual downfalls (loss of image depth and projection into the room) from close to wall siting. I guessed that they had been designed this way.

Perhaps I could pull them a little further out to balance the bottom end with the rest of the spectrum...

15542171008_9821f55065_b.jpg


Anyone else fancy having a go?

Lefty
 
Ok, this is so easy and I couldn't wait. Here's the response from my humble little Yamaha HS50m. (The Neumanns will take a little longer as I have to get around to setting those up again)

By comparison, the -3dB point for the bass is 57Hz (relative to the level at 1KHz)

15542938540_11ba71c853_b.jpg


Lefty
 
15542679547_889902d965_o.jpg


Two different systems, two different rooms. Both taken from the listening position with both speakers driven. Green trace AS passive pre/303/La Scalas, red trace 34/306/Tannoy 15" Monitor Golds. The thing that surprises me is how superficially similar they look, they sound entirely different! The measurements were taken with the grilles in place on both speakers, which has a noticeable impact in the treble, so I should possibly redo them at some point. I'm pretty sure that explains the La Scalas nose-dive from around 15k.
 
Lefty, I'm surprised that your two traces are so different. Looking at the first one I'd have guessed you have room nodes as you asked, but they're not repeated in the second trace.

:confused:

By the way, I've found that the "reverb" trace was more interesting in terms of what sounded wrong in my room.
 
To start interpreting the data a little better you need to see what they look liked without the room influence, have a look at the mini dsp website, they have some tutorials on gated measurements. That won't get you a picture down low (dependant on gate length) but is a start.

We're both of those speaker traces from the same room with the speakers in the same position? There seems to be no consistencies between them in terms of room interaction.

Stefan
 
Tony L said:
15542679547_889902d965_o.jpg


Two different systems, two different rooms. Both taken from the listening position with both speakers driven ... The thing that surprises me is how superficially similar they look, they sound entirely different!
Click to expand...
I suspect your mic calibration or measurement is off. The coincidence is almost impossible with different rooms and different loudspeaker systems.
 
Space is the Place said:
Do you have a window behind the speakers Lefty, and or a void in the floor? might explain the suckout in 100 to 400Hz range.
Click to expand...

Yes! There is a window behind the speakers. Although it is covered by a wooden blind and (un-drawn) curtains. Didn't realise this could result in a suckout between 100 - 400Hz. Interesting...

Lefty
 
Vital said:
Lefty, I'm surprised that your two traces are so different. Looking at the first one I'd have guessed you have room nodes as you asked, but they're not repeated in the second trace.
Click to expand...

Different locations. The Yamaha HS50m are located on my desk either side of my computer monitor.

Be interesting to measure to measure them in the same location.

Lefty
 
if you are using two speakers to do the measurements you will get constructive a destructive interference. This is at its worse when using single tones for measurements.

Room modes are complicated due to furniture and other issues.

Measuring a room with one microphone doesn't replicate the human head with two easr and a chunk of skull between them.

It's good fun having a go at measurement, but what its relevance to everyday listening is another matter.

Correction is always a bit of a fudge. To do the job "perfectly" is not possible unless you are prepared you sit in one chair on your own. The obvious way out of this is listen in your garden, but then you will find the music rather dead sounding. Some reverb and room effects are helpful.

Beware the "experts".
 
I'm no expert - but I'd repeat that dealing with reverb (boomy bass) is more important than achieving a flat FR. YMMV!
 
m0fPm6k.jpg


Ergo IX driven by NCore NC400 and BKElec monolith DF average of listening position (head height, moved sideways and measured every 30 cm on listening position sofa)

(NOTE - I measured all the way down rather than 'just' from 40hz upwards)

:)
 
mudlark said:
if you are using two speakers to do the measurements you will get constructive a destructive interference. This is at its worse when using single tones for measurements.

Room modes are complicated due to furniture and other issues.

Measuring a room with one microphone doesn't replicate the human head with two easr and a chunk of skull between them.

It's good fun having a go at measurement, but what its relevance to everyday listening is another matter.

Correction is always a bit of a fudge. To do the job "perfectly" is not possible unless you are prepared you sit in one chair on your own. The obvious way out of this is listen in your garden, but then you will find the music rather dead sounding. Some reverb and room effects are helpful.

Beware the "experts".
Click to expand...

You measure one channel at a time, and the Dirac software allows for a weighted
measurement , Lefty you would have to measure both speakers in the same position, although some of the bass peaks correlate.
KR Keith.
 
SteveS1 said:
Looks a bit disruptive Lefty, are you going to have a go at correcting it?
Click to expand...

I'm not sure yet. I'll probably have a go using passive techniques first (changing position, moving furniture etc), but may also try borrowing a room correction gizmo thingy at some point as well to see if it's worth investing in.

Can anyone here relate their experiences with 'active' room correction?

Lefty

Edit - cross posted with YNWOAN. Interesting - what kit did you use and how did you go about it?
 
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