Taming room modes - 50, 144, 249, 468Hz room mode?

[Fitzcaraldo215]

but I thought it was better to correct the room modes as much as possible first?

 

You will not have much success with that via passive treatments if they are below about 100 Hz. Off the shelf absorbers and bass traps are not very effective down there and they need to be huge, probably deadening other frequencies that need no correction. Check their specs. DSP EQ is much more effective and targeted at the specific narrow band frequencies that are typical of room modes.

 

Custom Helmholz resonators might work, but they are a huge pain to fabricate. Plus, their action is fixed at one frequency, so you cannot rearrange the room which might shift the frequency of the mode. Some active treatment solutions also exist, but they get expensive.

 

Bottom line - you need to figure out your Dirac problem. It works great for me and many others.

[jmdesignz2]

I'll try removing and reinstalling Dirac

[jmdesignz2]

You will not have much success with that via passive treatments if they are below about 100 Hz. Off the shelf absorbers and bass traps are not very effective down there and they need to be huge, probably deadening other frequencies that need no correction. Check their specs. DSP EQ is much more effective and targeted at the specific narrow band frequencies that are typical of room modes.

 

Custom Helmholz resonators might work, but they are a huge pain to fabricate. Plus, their action is fixed at one frequency, so you cannot rearrange the room which might shift the frequency of the mode. Some active treatment solutions also exist, but they get expensive.

 

Bottom line - you need to figure out your Dirac problem. It works great for me and many others.

 

Thanks

I tried re-installing and no luck. I submitted a help request from Dirac...just now

[dallasjustice]

50hz is probably a length mode. It is almost impossible to find room treatments to deal with that. Other than attempting to use room treatments your options are:

1. DSP; eg. acourate, audiolense or dirac. All of them are really good. I have a preference but its not that big of a deal in your application.

2. Multi-channel system with active crossovers and subwoofers placed in a "source/sink" arrangement on the front and backwalls. This will eliminate all length modes with little or no EQ needed. The downside is that its pretty complicated to setup and can be costly.

3. AVVA active traps. I've seen Bob Katz's posts about these. He measured a 1db improvement. I've seen other measure a 2db improvement at very low frequencies. For the price, it seems like a bad investment given number 2 above.

 

 

Btw, it looks like your speakers have a crossover at 2.5khz. You could use a little target based correction to smooth that transition out. You may or may not like it. But its worth a try.

 

Also, decay times are very much subjective. Some people like a dry listening environment due to the types of music they listen to and others don't. Some acousticians think that 300ms in the rt60 is a good target at all frequencies above the transition. I think that's reasonable for most situations. But there's better ways to measure that. I know Acourate uses a much more technical way to measure decay which seems to fit better with my perception. It's a German acoustics standard; I can't seem to remember it's name.

 

Overall, Acourate will give you the most bang for your buck and will keep you busy for many years. :-) One of the good things about DSP is that you can change your system whenever you want and it will only costs you time. :-)

 

Michael.

[tboooe]

OP, I would first spend a lot of time messing around with different speaker positions to try and get as flat a response in your room before messing around with DSP. Your freq response appears to be saddle shaped +-5db. From everything I have read, a perceptually flat freq response is downward sloping . For example, Bob Katz suggest flat until 1000hz, then sloping to -6db to 20khz. I personally use a target curve that is flat from 20-150hz, sloping -4db to 1000hz, then sloping -5db to 20hkz.

 

Having just gone through this process myself I was amazed at how much better my system sounded with just getting the best speaker placement possible in my room. Using REW and the Umik makes doing must easier. Once you do this, getting bass traps in the corners and absorption panels at the 1st reflection points further help. Only then would I turn to DSP. I started out with REW which worked remarkably well. I have since moved to Acourate since it offers more options, especially in the time domain which REW does not. Also, remember you cannot fix nulls with DSP so do whatever you can with speaker positioning and room treatments to get rid of as many possible.

[miguelito]

You might want to play with the free trial of Dirac (and buy it if you like what it does).

 

What you are starting with doesn't look that bad to me.

Yeah, pretty clean to start with.

[jmdesignz2]

OP, I would first spend a lot of time messing around with different speaker positions to try and get as flat a response in your room before messing around with DSP. Your freq response appears to be saddle shaped +-5db. From everything I have read, a perceptually flat freq response is downward sloping . For example, Bob Katz suggest flat until 1000hz, then sloping to -6db to 20khz. I personally use a target curve that is flat from 20-150hz, sloping -4db to 1000hz, then sloping -5db to 20hkz.

 

Having just gone through this process myself I was amazed at how much better my system sounded with just getting the best speaker placement possible in my room. Using REW and the Umik makes doing must easier. Once you do this, getting bass traps in the corners and absorption panels at the 1st reflection points further help. Only then would I turn to DSP. I started out with REW which worked remarkably well. I have since moved to Acourate since it offers more options, especially in the time domain which REW does not. Also, remember you cannot fix nulls with DSP so do whatever you can with speaker positioning and room treatments to get rid of as many possible.

 

Thanks - I think perhaps one issue could be the 2nd sub left channel is about centered on the left wall?

 

I got an answer back from Dirac -

they said the remove Dirac Live Calibration v 1.2 and install v 1.1 and

restart and recreate a new filter

to use with Dirac Audio Processor v 1.2

 

Will see what happens

[tboooe]

Thanks - I think perhaps one issue could be the 2nd sub left channel is about centered on the left wall?

 

What i really dont understand is the hump you have between 3-10Khz. Are you sitting near anything reflective? Do you find your system too bright at all?

 

Here is what my freq response looks like after using REW. I have a bit of an issue between 60-100hz that I cant seem to fix no matter what I do but otherwise I am very happy.

[jmdesignz2]

What i really dont understand is the hump you have between 3-10Khz. Are you sitting near anything reflective? Do you find your system too bright at all?

 

Here is what my freq response looks like after using REW. I have a bit of an issue between 60-100hz that I cant seem to fix no matter what I do but otherwise I am very happy.

[ATTACH=CONFIG]31189[/ATTACH]

 

Are your curves smoothed with the psychoacoustic setting?

 

I don't find my system bright at all. In fact it seems very good in the midrange to upper frequency. Lots of atmosphere. Sometimes you can get a sense of musicians moving their head, body and arms.

[tboooe]

Are your curves smoothed with the psychoacoustic setting?

 

I don't find my system bright at all. In fact it seems very good in the midrange to upper frequency. Lots of atmosphere. Sometimes you can get a sense of musicians moving their head, body and arms.

Yes, thats with psychoacoustic smoothing.

 

At the end of the day as long as you enjoy your system!

[Ralf11]

I thought it was:

 

"At the end of the day as long as you enjoy tweaking with your system!"

[tboooe]

I thought it was:

 

"At the end of the day as long as you enjoy tweaking with your system!"

 

+1000! True audiophile! Honestly, I think I like tweaking my system more than actually listening to it!

[jmdesignz2]

+1000! True audiophile! Honestly, I think I like tweaking my system more than actually listening to it!

 

Well - removed 1.2 and installed 1.1 - ran analysis and created filters - Still does not work. Dirac Processor shows 1 channel out when I select LIO8 as the output device.

 

It shows 2 channels out when I choose the laptop integrated speakers though...

 

[jmdesignz2]

Well - removed 1.2 and installed 1.1 - ran analysis and created filters - Still does not work. Dirac Processor shows 1 channel out when I select LIO8 as the output device.

 

It shows 2 channels out when I choose the laptop integrated speakers though...

 

[ATTACH=CONFIG]31212[/ATTACH]

 

shows one channel out when I choose LIO8 output from Dirac Processor... Argh - I sent Dirac an updated request for help

 

[wgscott]

Maybe it delivers 8 parallel mono tracks.

[jmdesignz2]

Maybe it delivers 8 parallel mono tracks.

 

sorry I don't understand?

 

My LIO8 shows as having 20 channels out in Dirac calibration which is odd as it is supposed to have only 8 channels.

I tried to optimize all 20 but of course Dirac cal gave errors since some channels did not have signal.

waiting on additional response from Dirac

[jmdesignz2]

Dirac replied that they found a compatibility issue with the metric halos. Suggested finding something to route the signal from the Dirac process to the dac.

[sphinxsix]

I actually helped recently to set up a fullrange speaker system in a room that was much too small for it (and with too 'live' acoustics). Playing test tones showed a peak around 70-80Hz. Correction of -9db, at 74Hz with Q around 6 in JRiver parametric equalizer worked wonderfully. I'm very demanding as for bass quality and smooth response and I was very satisfied with the result. Took less than an hour to get things done.

[DuckToller]

Sphinxsix,

if ever you cross the Loire valley, you are welcome and invited to manage my setup.

Not without reward.

Just pm me then.

;~)

Cheers, Tom

[sphinxsix]

Sphinxsix,

if ever you cross the Loire valley, you are welcome and invited to manage my setup.

Not without reward.

Just pm me then.

;~)

Cheers, Tom

I used to visist this area many times years ago. Anyway I wouldn't have been able to help back then - didn't have necessary experience with audio (later I used to be a dealer so I did quite lots of audio gear set ups for my customers so maybe the whole thing is a bit easier for me than for some). And right now I'm not thinking about visiting France but you know - one never knows. Anyway - merci pour l'invitation.

[twist222]

Dirac replied that they found a compatibility issue with the metric halos. Suggested finding something to route the signal from the Dirac process to the dac.

 

Strange? Did Dirac give you any details about this "compatibility issue" l have used Amara Sympony with IRC on my Metric Halo ULN8 at it works OK.

Did Dirac detail if the compatibility is a measurement or playback compatibility issue ?

Are you feeding a mic pre into the LIO8 for measuring ? Because the ULN8 has mic pre's I measure and record through the ULN 8. Abviously this is one difference between our setup's. The other being that I use Amaras version of Dirac.

If Dirac provides some information on the "compatibility issue" BJ over at Metric Halo is very helpful at resolving issues.

 

The reason I mention all this is if you can get it working Dirac will give you a fairly easy way to see what sort of improvements you will achieve with EQ. If you like what it does you can then work out if you need to explore other options.

 

Regards

Mark

[jmdesignz2]

Strange? Did Dirac give you any details about this "compatibility issue" l have used Amara Sympony with IRC on my Metric Halo ULN8 at it works OK.

Did Dirac detail if the compatibility is a measurement or playback compatibility issue ?

Are you feeding a mic pre into the LIO8 for measuring ? Because the ULN8 has mic pre's I measure and record through the ULN 8. Abviously this is one difference between our setup's. The other being that I use Amaras version of Dirac.

If Dirac provides some information on the "compatibility issue" BJ over at Metric Halo is very helpful at resolving issues.

 

The reason I mention all this is if you can get it working Dirac will give you a fairly easy way to see what sort of improvements you will achieve with EQ. If you like what it does you can then work out if you need to explore other options.

 

Regards

Mark

 

Dirac was not too detailed - the basically said Metric Halo was not compatible