Seek help with REW & Graphs

[chander]

Dear FMs,

I am trying to play with REW, speaker placement & equalisation with my Genelec G3s & 7040A subwoofer. My knowledge & understanding here is extremely limited & even though I can take measurements looking at youtube videos; I am not really sure what I am looking at.

Please bear with me - I took some measurements at the listening position & I have sadly lost that graph - but after a bit of fiddling with the phase of the sub (automatically crossed at 85HZ) & dip switches alone - leaving all things the same - I got the graph in Green. Playing with the placement - I got the graph in red. Please have a look.

To my eyes & ears - the "red" graph and the resulting sound - seems better. However I am not entirely sure - what I am looking at - can someone take out the time to explain OR if needed - if I can provide more information if guided?

I know there are many posts on this; however, as I am completely illiterate in this part of the tech, I was hoping for some direct advice on my specific situation?

****I have not yet incorporated the RME in the system, as I wasn't sure where to apply the EQ. -to me this graph "RED graph - seems pretty linear between 35-800Hz & after that it doesn't look too shabby either, but I am not entirely sure. Looking forward to some great opinions.

Thanks!

Thanks!

 

[Phew]

Well what you are looking at is frequency response taken by the Microphone. If you are liking what you are hearing then whats the point in EQ, unless its the other way around. Don't think much help can be offered unless one knows how you like your music or get to hear your system. Its like you cooking a dish, sharing the image, saying you like it but you want their help in making it better if at all they find it lacking, which is not possible unless they get to taste it, then again the catch here is what they like might not be to your liking. So you will have to rely on your own ears unless 'how others like music over how you like music' is what you are going for.

 

[chander]

Well what you are looking at is frequency response taken by the Microphone. If you are liking what you are hearing then whats the point in EQ, unless its the other way around. Don't think much help can be offered unless one knows how you like your music or get to hear your system. Its like you cooking a dish, sharing the image, saying you like it but you want their help in making it better if at all they find it lacking, which is not possible unless they get to taste it, then again the catch here is what they like might not be to your liking. So you will have to rely on your own ears unless 'how others like music over how you like music' is what you are going for.

Thanks for writing @Phew - I can see how my queries can be confusing - so let me reiterate.

1 - I wish to know what I am looking at in terms of FR. I can see a few bumps and everything above 800HZ being lower than the 85DB that it was all tested at. What could be causing the 800Hz+ to go down?
2 - Can these bumps be fixed without introducing the EQ - in my case RME ADI 2 DAC FS?
3 - Can the FR below 800HZ be called linear - barring those 2 bumps?
4 - How can I make the entire FR - 30 - 20K sit around that 85Db line? With or without EQ.

I am liking the sound of the system & other than educating myself - there is nothing really to it. However I was liking the sound before I made the adjustments too. Am I liking it more? Maybe - but that could be bias - looking at before and after graphs. So the aim to get a linear response across the FR is as much for learning & to see what happens to the sound.

I am not looking for a magic solution to get the perfect sound I am just trying to understand - what can one do to get a linear response - looking at the graphs provided.

I hope this makes things clearer?

***This is what Genelec website shows in free field -

 

[Decadent_Spectre]

Firstly the smoothing and window size you are using is used by people who want pretty graphs and feel satisfied that the graph is pretty/flat. If you want real useful information the window size should be no more than 20db (prefer 10-15db) and the smoothing should be no smoothing, some people use 1/48th. Using more smoothing makes it prettier/flatter and easier to read.

Secondly, don't compare to the Genelec graph since it is free field, in room you will have all sorts of things affecting the response. Based on the response it would seem that maybe the speakers are off axis from the listening position or the speakers are near a wall/corner.

Thirdly, don't ignore the time based graphs.

IF you wish to continue to use 1/3rd smoothing and a large window and want a flatter/prettier graph then you can use a low shelf filter around 2K. I don't know if your RME has this filter. I recommend proper DSP, for cheap the Behringer DCX2496, for better research it. If you wish to go deep into the rabbit hole then Audiolense/Acourate. If you want automated Trinnov/Dirac. I suggest pro audio DSP if you want the best. It won't be as involved/flexible as Audiolense/Acourate but it will sound the best IMO.

You probably shouldn't use DSP to "fix" all the "issues" (peaks/dips). It will look good but won't sound good. Use DSP to flavor to preference, this is the most important part of my post.

I wish to point out I don't endorse objectivity or a flat response. I highly recommend you use DSP to flavor the sound to preference.

 

[prateekatasniya]

Thanks for writing @Phew - I can see how my queries can be confusing - so let me reiterate.

1 - I wish to know what I am looking at in terms of FR. I can see a few bumps and everything above 800HZ being lower than the 85DB that it was all tested at. What could be causing the 800Hz+ to go down?
2 - Can these bumps be fixed without introducing the EQ - in my case RME ADI 2 DAC FS?
3 - Can the FR below 800HZ be called linear - barring those 2 bumps?
4 - How can I make the entire FR - 30 - 20K sit around that 85Db line? With or without EQ.

I am liking the sound of the system & other than educating myself - there is nothing really to it. However I was liking the sound before I made the adjustments too. Am I liking it more? Maybe - but that could be bias - looking at before and after graphs. So the aim to get a linear response across the FR is as much for learning & to see what happens to the sound.

I am not looking for a magic solution to get the perfect sound I am just trying to understand - what can one do to get a linear response - looking at the graphs provided.

I hope this makes things clearer?

***This is what Genelec website shows in free field -

To truly optimize the acoustics of a room, it is crucial to understand that a flat frequency response is not necessarily the most desirable outcome. In fact, a slight sloping of the frequency response can greatly enhance the overall auditory experience. As an expert in the field, I can assure you that your graph accurately reflects this principle.

It is also important to note that smoothing is an appropriate tool for achieving this optimal response, as it allows for a more accurate representation of the acoustics within the space but it's recommended to smooth at either 1/12th or 1/6th value which better represents human hearing. However, it is important to recognize that above 500hz, the frequency response cannot be fixed entirely as it affects the phase response unless you use something like dirac.
As a starting point, I recommend fixing the two peaks at around 43Hz and 110Hz

Regards.

 

[chander]

Thanks @prateekatasniya @Decadent_Spectre - for what you suggested -
@1/6 & 1/12 resp.- my preferred graph - currently looks like this -

 

[chander]

As a starting point, I recommend fixing the two peaks at around 43Hz and 110Hz

where should I start - EQ or something else?

 

[prateekatasniya]

Thanks @prateekatasniya @Decadent_Spectre - for what you suggested -
@1/6 & 1/12 resp.- my preferred graph - currently looks like this -

View attachment 75895View attachment 75896

Reverse the phase on the subwoofer.. this seems to be speakers and sub cancelling each other..
Flip the phase switch on the subwoofer and then it will be working perfectly. Phase to be changed by 180°.

 

[chander]

Reverse the phase on the subwoofer.. this seems to be speakers and sub cancelling each other..
Flip the phase switch on the subwoofer and then it will be working perfectly. Phase to be changed by 180°.

quick question -

Phase to be changed by 180° -

you mean it is at 90 currently - so I get it to 270?

 

[prateekatasniya]

quick question -

you mean it is at 90 currently - so I get it to 270?

Correct..
Change is and take one more measurement and share it..
With correct phase alignment the spl at the crossover frequency will be highest..
I.e you can flip switches ( on Genelec subwoofer) and try multiple combinations.. the combination which gives the max SPL is the correct setting.
also try to increase the bass levels by 3db and check how it sounds.