Measuring, room responses using REW..

[elangoas]

You can now clearly see that you have ringing issues is the 40 - ~ 150 Hz range. Increase the time scale so that the hills don't get squashed (nose against glass) and you will see how bad. ~ 300 ms or less is what you would want . You can see 40 - ~ 80 squashing ringing beyond 450ms in your plot

I lost the file by mistake.. Anyways will measure it again & re-do it..

You could try positioning your subs to get rid of this ringing (I recollect from other threads that was one of your intentions).

Sure..I have a 3 seater sofa (5 feet wide) against the back wall.. So took 5 measurements at different positions (evenly spaced out)..

LP1 (Listening Position) is the left corner, while LP5 is the right corner of the seat..

Bet 20Hz - 40Hz remains unchanged, surprising..

Bet 40Hz - 120Hz, peak & dips have changed..

Don't know much, but LP5 looks better compared to rest..

If you want to hear how it would sound without that boom before you start moving heavy subs, download and trial a room correction software, or Roon maybe. You should hear tuneful bass after that. A probably unnecessary warning, it will seem underwhelming initially, because it is quality not quantity.

My AVR has Audyssey XT32..Not sure how much it will control the peaks..

Do see also if you have this boom with your subs not hooked up. Probably yes, it is a bane of small rooms

Sure.. Will check this too..

 

[elangoas]

Do see also if you have this boom with your subs not hooked up. Probably yes, it is a bane of small rooms

Measured all the 5 speakers (Left, center, right, surr left & surr right)..

The front & center speaker are placed along the width of the room (14 feet wide).. They have the peaks & dips in common (same as sub response)..

But the surr Left is mounted on left wall & surr right on right wall of LP.. These don't have the peaks & dips where the front speakers have..

Will try moving subs near surrounds and check if the response is better..

 

[sound_cycle]

My AVR has Audyssey XT32..Not sure how much it will control the peaks

Do you use a pc a source ?

Ciao
GR

 

[elangoas]

Do you use a pc a source ?

Yes..Both for movies & music..

 

[sound_cycle]

Yes..Both for movies & music..

Problem solved I'd think. You run your drc program here. Your AVR need not handle the task.

Ciao
GR

 

[elangoas]

Problem solved I'd think. You run your drc program here. Your AVR need not handle the task.

Ok.. But, i have XT32 on the AVR and have an android app (Multi EQ-paid) for the same to tweak it further (which am not aware of)..

Am just hoping if re-positioning subs will help smoothen the response below 150Hz and any DIY bass traps to contain it..

 

[elangoas]

Here is my room layout..

Room mode calculator (suggested by FM sdurani in other thread)

 

[sound_cycle]

Ok.. But, i have XT32 on the AVR and have an android app (Multi EQ-paid) for the same to tweak it further (which am not aware of)..

Am just hoping if re-positioning subs will help smoothen the response below 150Hz and any DIY bass traps to contain it..

I am not familiar with either of the methods you mention.

DIY bass traps (about 4") will do nothing. Do remember mod sidvee had posted of a gikaudio thingy that did on another thread.

I am not sure if you can manage to control a broad range of frequencies with positioning alone. Esp given that the room is not exclusively for audio which probably constrains positioning. But I don't need a sub for my listening and have not given it any time or thought.

IMHO s/w is easier and far more painless. And kinda guaranteed to work.
You could trial them, some are free.

ciao
gr

 

[jls001]

@GR, may I request you to write a concise tutorial on how to use measurement mic with something like REW, and how to create the room correction EQ curve that can be plugged into a player like foobar? I have tried this at home and failed rather miserably despite reading all the relevant REW threads

The corrected response killed/deadened my sound and I had no choice but to go uncorrected. It would be very nice to have a step by step write-up from someone who has successfully done this at home.

 

[elangoas]

DIY bass traps (about 4") will do nothing.Do remember mod sidvee had posted of a gikaudio thingy that did on another thread.

Right.. So treating room with bass traps looks impractical.. Which leaves the option of EQ, in my case XT32..

I am not sure if you can manage to control a broad range of frequencies with positioning alone. Esp given that the room is not exclusively for audio which probably constrains positioning.

Am just wondering how to take measurements after Audyssey on what has been done to the response..

But I don't need a sub for my listening and have not given it any time or thought.

Got it..If my room response improves, then you have a case..

IMHO s/w is easier and far more painless. And kinda guaranteed to work. You could trial them, some are free.

Sure..I will try the possibilities & options that i have now..If nothing helps, will try them..

 

[sound_cycle]

@GR, may I request you to write a concise tutorial on how to use measurement mic with something like REW, and how to create the room correction EQ curve that can be plugged into a player like foobar? I have tried this at home and failed rather miserably despite reading all the relevant REW threads

The corrected response killed/deadened my sound and I had no choice but to go uncorrected. It would be very nice to have a step by step write-up from someone who has successfully done this at home.

Joshua you vastly overestimate my abilities.

I had no success with REW, and threw in the towel and went another (Dirac) route.

The advantages are many, importantly. It is not PEQ, uses multiple measurements (9 around the listening position) figures out what is changing between the positions and then correcting for them. The secret sauce is that works in the time domain and preserves phase. And while expensive it was ridiculously easy to implement. see also https://www.minidsp.com/forum/minid...ence-between-rew-and-dirac?limitstart=0#19107


For REW there are several decent guides. I have linked a couple below

Digital Room Correction for Less Than $100

https://community.roonlabs.com/t/a-guide-how-to-do-room-correction-and-use-it-in-roon/23800

@elangoas: if you want this discussion to go to another thread, will do so thanks

ciao
gr

 

[Hari Iyer]

@GR, may I request you to write a concise tutorial on how to use measurement mic with something like REW, and how to create the room correction EQ curve that can be plugged into a player like foobar? I have tried this at home and failed rather miserably despite reading all the relevant REW threads

The corrected response killed/deadened my sound and I had no choice but to go uncorrected. It would be very nice to have a step by step write-up from someone who has successfully done this at home.

The earlier version of foobar allowed txt file import which you can enter for the correct EQ. But the current foobar version does not recognise txt files.

I would rather suggest you to do room EQ with REW and enter this EQ in a 20 band parametric Equaliser. This allows precise EQ. You can also enter filter Q in the parametric Equalizer. You will need to download the plugin for this and route your laptop soundcard using the microphone Linein and headphone output. There are controls in the Parametric EQ that can be used to do this.

If you check the minimum phase group delay plot, the frequency that are having a peak in the group delay cannot be EQed much as it's Probably a room mode that will require treatment. For all other frequencies the response can be EQed.

 

[sound_cycle]

You could try positioning your subs to get rid of this ringing (I recollect from other threads that was one of your intentions).

And ofc it has been discussed on hfv before http://www.hifivision.com/diy/20482-sub-setups-using-dr-earl-geddes-method.html

ciao
gr

 

[elangoas]

@elangoas: if you want this discussion to go to another thread, will do so thanks

Sorry @sound_cycle, i didn't mean it.. Was just saying very generic..

Few things i inferred from room modes calculator, don't know if it is correct..

Along the width of the room, there is a null at 40Hz, which is where (one) my listening position is..

Length mode, peak at walls (50hz, 103Hz, 154Hz)..My listening position is against back wall.. So i guess, that is the reason there is a max peak of 20dB between freq..

I tried re-positioning the subs in the room to see which position offers the smoothest response at one of my listening position..

Pink trace is when the subs were placed 1/4 and 3/4 along the room width & approx center of length (5.5 feet) of my room..

Blue trace is when the subs were places on the left & corner of the room..

For both the above traces, the mic position was the same against my back wall..

I think the response may or may not get better in further re-positioning..But haven't checked the waterfall yet..

 

[elangoas]

In order to compare both the graphs, they should both be smoothed evenly, both 1/12 or 1/6, i recommend a 1/12 smoothing for subwoofer measurements.

Sure.. Will keep the smoothing same for measurements..

It is also better to have a near field response of the subwoofer, this would even help identify if the dip from 60hz to 80hz is the response of the Subwoofer, or if this has been introduced due to reflections in the room.

Will take near field measurements.. 1 feet from sub should be enough?..

In case the near field response of the subwoofer, has a dip from 60hz to 80hz, the placement will not help much.

Ok..

In most cases the challenging part, is keeping phase in sync throughout the spectrum. Time delay starts to mess things up, and would also suggest to remove distances fed in AVR, in CM's or Meter's when you take measurements, also try keeping the Sub phases to zero.

Sub phase is zero always, since it was recommended for Audyssyey calibration..

Do you mean, i should reset all speaker levels on AVr to "0" and then take REW measurements?..

What matters most than the response is the phase, when you Eq or Delay the speakers, it is challenging to have good acoustical phase along with corrections done by Eq or P-EQ.

Mini-DSP has FIR filters, in one of their products(dont remember the exact model numbers), you can have a look at them too, they are superior than IIR filters IMHO.

Thought i have done some googling on this topic, i could digest only few terms.. Hope to catch-up soon..

The AVR has Audyssey XT32, i have read that it takes care of delay & phase alignment between subs..

 

[sud98]

Did you mean this product from minidsp?

https://www.minidsp.com/products/ht-series/nanoavr-hd

 

[elangoas]

Did you mean this product from minidsp?

I think he was referring to miniDSP 2 x 4 - https://www.minidsp.com/products/minidsp-in-a-box/minidsp-2x4

 

[Hari Iyer]

Sorry @sound_cycle, i didn't mean it.. Was just saying very generic..

Few things i inferred from room modes calculator, don't know if it is correct..

Along the width of the room, there is a null at 40Hz, which is where (one) my listening position is..

Length mode, peak at walls (50hz, 103Hz, 154Hz)..My listening position is against back wall.. So i guess, that is the reason there is a max peak of 20dB between freq..

I tried re-positioning the subs in the room to see which position offers the smoothest response at one of my listening position..

Pink trace is when the subs were placed 1/4 and 3/4 along the room width & approx center of length (5.5 feet) of my room..

Blue trace is when the subs were places on the left & corner of the room..

For both the above traces, the mic position was the same against my back wall..

I think the response may or may not get better in further re-positioning..But haven't checked the waterfall yet..

Can you post same image using log scale instead of linear scale.

 

[Hari Iyer]

One more point to consider is if the phase of the main front speakers are in sync with the subwoofer phase. If they aren't then integration will be poor irrespective of what the REW graphs says. Since you are considering the subwoofer in isolation without considering the front mains, things will go for a toss when combined. Suggest you consider holistic approach instead of piece meal approach.

 

[elangoas]

Can you post same image using log scale instead of linear scale.

Sure.. Will try.. Hope this is aval in settings..

One more point to consider is if the phase of the main front speakers are in sync with the subwoofer phase. If they aren't then integration will be poor irrespective of what the REW graphs says.

I don't know much abt Audyssey technically..But have read, the phase is taken care..

Since you are considering the subwoofer in isolation without considering the front mains, things will go for a toss when combined. Suggest you consider holistic approach instead of piece meal approach.

I use a 120Hz crossover between mains & subwoofer.. So thought to first flatten the response until the crossover point by moving subs as much as possible and then look at mains + subs.. Is it a wrong approach?..