Determining Room Frequency Response...

[Sparky4444]

Hello Everyone..First time poster here..

...So I've taken on the task of improving my home studio room in my basement...I've done some measuring using Room Eq Wizard and my Radio Shack SPL meter...My speakers are Dynaudio BM5A's...

..Anyways...The point I am struggling with is this -- Unless you know frequency characteristic of your source signal, i.e, your speakers, how can you really pinpoint your room's frequency responses?? Unless your speakers can produce perfectly flat output referenced from an anechoic chamber, what's the point?? Your speakers could be putting out more 8kHz relative to 800Hz at the source...Take measurements of your room and what are you measuring, the room or the speaker??

...I took these speakers outside and measure the sine wave sweep...Big hump at 8kHz, everytime...Big hump at 8kHz everywhere I measure inside....These speakers, in my logic, are pushing more 8kHz and area relative to the rest of the spectrum...So now I am on a wild goose chase to treat 8kHz in my room??? My room might just be perfectly fine at 8kHz...

...not looking for help to treat my room...Looking for some help with the science of this...

cheers!
Curtis

[John Sayers]

Curtis - your testing is they way to do it - so get another set of speakers that don't have an 8Khz peak.

much easier than changing the room.

[Sparky4444]

Thanks for you reply John...

I got a response back from a TC Dynaudio tech...he thinks the strong surge at 8kHz is odd...He couldn't find me a freq analysis of the BM5A's (strange) but he did send me the BM6A's that he says should be similiar...There is about a +3dB emphasis from 4kHz upwards...According to Dynaudio, the BM5A v2's had some revisions to its top end...I'm thinking that the Bm5A's are sharper in the high end, probably more so than the BM6A's and that's why they modified the BM5A's..I mean if there are good to begin with, why change them??

I probably can still trim down about 2-3dB of high end in my room by finishing up the basics I've been working on as far as ceiling treatment goes...But I figure these BM5A's are a high endy sounding speaker and combining a slightly bright room with these is giving me the results I'm measuring...
...

[Soundman2020]

I probably can still trim down about 2-3dB of high end in my room by finishing up the basics I've been working on as far as ceiling treatment goes

Well, that will help the room sound (resonant field), but it wont help the direct field: Your ears will still be mostly hearing the direct sound coming straight out of the speakers, and only partly hearing the "resonant" field trailing behind that, hopefully at least 10 dB down. The point is, if your ears are hearing an overly bright sound due to a faulty (or badly designed) speaker, then no amount of treatment in the room can fix that, and you will tend to subconsciously "fix" that in the mix, compensating by cutting the highs slightly in that range, meaning that your mixes will not translate well: they will sound slightly dull in all other places and on all other speakers.

My suggestion would be to either get the speakers repaired, or to swap them for speakers that do have flat response.

But before you do that, are you 100% CERTAIN that your speakers are the cause of the high-mid boost? Is it possible that it could be an issue with your measurement mic, for example? Or with your DAW interface? Or something else in the signal chain? Or even the test tone itself? Maybe you could repeat the tests with a totally different setup: different DAW, different mic, different interface, different pink noise sample, different everything.

Also, did you check the switches on the back of the speakers? The BM5A has several switches on the rear panel for adjusting EQ: are you 100% certain they are all set for flat response?

If all that checks out OK and the problem us still there, then I'd be seriously thinking of turfing those speakers (helllooooo e-bay!) and getting something that does have flat response.


- Stuart -

[Sparky4444]

I probably can still trim down about 2-3dB of high end in my room by finishing up the basics I've been working on as far as ceiling treatment goes

Well, that will help the room sound (resonant field), but it wont help the direct field: Your ears will still be mostly hearing the direct sound coming straight out of the speakers, and only partly hearing the "resonant" field trailing behind that, hopefully at least 10 dB down. The point is, if your ears are hearing an overly bright sound due to a faulty (or badly designed) speaker, then no amount of treatment in the room can fix that, and you will tend to subconsciously "fix" that in the mix, compensating by cutting the highs slightly in that range, meaning that your mixes will not translate well: they will sound slightly dull in all other places and on all other speakers.

Very true...I need to use my control room as my recording room as well -- for vocals, acoustic, no real drums -- so improving the room acoustics is important. I do perceive stronger emphasis in my room at those higher frequencies with other sources. I only added about 1/3 of the ceiling treatment I need to and I have already seen measureable attenuation around 4kHz, so it will be interesting how things measure up when I am done.

My suggestion would be to either get the speakers repaired, or to swap them for speakers that do have flat response.

But before you do that, are you 100% CERTAIN that your speakers are the cause of the high-mid boost? Is it possible that it could be an issue with your measurement mic, for example? Or with your DAW interface? Or something else in the signal chain? Or even the test tone itself? Maybe you could repeat the tests with a totally different setup: different DAW, different mic, different interface, different pink noise sample, different everything.

I have used the Radio Shack meter, as well as a Rode NT3 for the measurements..same thing...Audio interface is M-audio Ultra so I doubt that is the problem..The program is RoomEq Wizard...But I am thinking I will pick up a Behringer ECM8000 and try running the test through my main DAW computer with my RME Multiface...I just can see any of those variables giving this hyped response in that high end area...

Also, did you check the switches on the back of the speakers? The BM5A has several switches on the rear panel for adjusting EQ: are you 100% certain they are all set for flat response?

If all that checks out OK and the problem us still there, then I'd be seriously thinking of turfing those speakers (helllooooo e-bay!) and getting something that does have flat response.
- Stuart -

..oh yeah...certain of that...I really don't see what the difference is using on-board eq'ing on these powered speakers as opposed to slapping a high end filter at the main buss output...As long as my room is well understoond response wise, I should be able to compensate. I am going to take my BM5A's back to the store I bought them and do side by side comparison with others -- especially the BM6A...My ears are a lot better tuned now compared to when I bought them a couple of years ago...

..Although some of this is frustrating, I must say it is kinda fun doing all this experimenting...Great learning process...

[neionsk]

Is there a good tool to measure the low end frequency response in my room? I would like to do a little treating because the low end is not as tight as I'd like it to be. Plus I have 7' ceilings. Thank you. Ps: not too expensive.


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[gullfo]

imho, a speaker and power amp capable of driving 20-250hz would be good. a Behringer ECM8000 mic and decent boom mic stand, a decent ADC for your PC or laptop to drive the signals to the amp and receive the mic feed, and the Room EQ wizard will all work pretty well for doing room measurements and analysis.