First decent measurement! Tweeters+room acoustics question

[TimWellens]

Hi everyone!
I love this forum,glad I found you guys’n’girls!
I just did my (first decent) measurement,gear used is an Apollo Twin X,RAM Heritage monitor controller.2x Neumann KH310a’s and a UMIK-1.
I did 4 measurements. All measurements are done at listening position with Umik-1 mounted on a MIC-stand at ear hight.

First measurement is Umik-1 in listening position pointing forward (0 degree file loaded) of the L+R Neumann KH310a’s. (L+R stereo). Color code is RED

Second measurement is Umik-1 in listening position pointing forward (0 degree file loaded) and aimed at the LEFT monitor. (LEFT OUTPUT ONLY). Color code is GREEN

Third measurement is Umik-1 in listening position pointing forward (0 degree file loaded) and aimed at the RIGHT monitor. (RIGHT OUTPUT ONLY).Color code is BLUE

Fourth measurement is Umik-1 in listening position pointing towards ceiling (90 degree file loaded) of L+R monitors.
(L+R stereo) for lower frequencies.Color Code is Orange

I’m new to REW and a noob in room acoustics. My walls are treated with acoustic foam panels and I have bass traps in every corner.

I have 2 questions.

1) Some of you maybe have seen my previous thread (J test). I accidently did a J test not meant for playing thru loudspeakers.I failed to read the accompanying red text saying ‘NOT FOR PLAYING THRU LOUDSPEAKERS CAN DESTROY TWEETERS’. (I know very stupid but I got carried away testing the various generators in REW).
Can someone take a look and see if there is any damage done on the tweeters? The J-signal blasted thru the L+R monitors so comparing the left monitor with the right is difficult as both could be affected.
2) As I’m new in this measurement business (love it so far) could somebody help a noob out and tell me how my diagrams are looking? They look kinda not good to me,or is it not so bad after all? It’s a small/medium sized room with acoustic foam plastered on all walls and some foamy bass traps in each corner.There is a window to the left of the room which I stuffed with big pillows so It’s completely covered.
.mdat file included,4 diagrams in total (please see up for details) all with 1/6 smoothing.

Thank you so much x

 

[sm52]

You worry in vain about the damage. Tweeters are fine. From 1.2 kHz to 20 kHz play flat. At the very end, the level drops slightly. The room doesn't echo. Even a bit muffled.
When measuring the right and left sides together, the microphone should be at the same distance from the speakers.

 

[DanDan]

Look at your L or R measurement. View Distortion. Your speakers seem just fine. https://www.avnirvana.com/threads/some-guides-to-rew-and-acoustic-measurement.121/page-2#post-49827

 

[TimWellens]

Thank you so much for your time! The mic was at the same distance from both monitors (1,42 meter triangle monitors-mic,best listening position according Neumann is between 1m and 2,5m) but indeed I think it’s the room…If you look at the left diagram and right diagram separately they look very alike but the combined signal (stereo measurement) shows a dip in the higher frequencies.I read somewhere on the REW forum something about the comb filtering effect when recording stereo signals?
I also think I overdid the foam on the walls,there is acoustic foam almost everywhere on all walls. Is overtreating the room a thing? Hence it sounds dull?
Maybe it’s time to remove at least some of it so the room can ‘breathe’? I’m a producer of Techno/Progressive music,not a movie mancave man (I mean the room is meant for audio production,not home movie theatre)so maybe better too dull than too reflective for accurate mixing of audio tracks in a DAW?

I’m so happy my tweeters are ok.Someone told me this J-test warning is meant more for users of amps+passive speakers but still I was not sure I could trust my monitors.
The Neumann’s KH310A’s are the best investment I ever did for my studio,and the thought of having ruined them is really not good for my mental health

Thank you!

 

[TimWellens]

Look at your L or R measurement. View Distortion. Your speakers seem just fine. https://www.avnirvana.com/threads/some-guides-to-rew-and-acoustic-measurement.121/page-2#post-49827

I looked at the distortion diagram of the L and R output (separate),but I don’t have any reference of how a normal distortion diagram should look like so I gladly take your word for it if you say you don’t see anything wrong
I still have a lot to learn,so thank you for the very informative link! Digging in as we speak.

Thanks for your time and sorry for my English,not my native language.

 

[DanDan]

You are welcome. The Total Harmonic Distortion is in general close to 1%. This depends on Loudness and Frequency, but I have seen a KH310 spec of less than 3% 100Hz to 10KHz. I have the same speakers here www.soundsound.ie They are the best I have heard. Many reviews and Laboratory reports concur.

 

[sm52]

The mic was at the same distance from both monitors

Almost. You need to measure it very accurately. Up to a millimeter.

the combined signal (stereo measurement) shows a dip in the higher frequencies.

Try to do as I wrote.

Is overtreating the room a thing? Hence it sounds dull?

Yes.

Maybe it’s time to remove at least some of it

This should be done in small portions. And check with measurements.

 

[DanDan]

Take a look at your RT60.....i.e. Room Decay. It is short and nicely flat through most of the spectrum. But with very long low frequency decay. This suggests a lack of LF absorption. I think the flat MF and HF suggests a neutral rather than dull short room tone. But with a big boom at LF. Oddly such treatment frequently creates a very clear direct field response. i.e. Speaker to ear, very suppressed Early Reflections. No HF cancelling comb filtering..... Sparkly clear. My KHs have the tweeter turned down, and I use Dirac Live to impose a further more controlled HF roll off. When I move to other speakers in domestic rooms here, there is no substantial change of tone. Mix Translation Nirvana.

 

[TimWellens]

Almost. You need to measure it very accurately. Up to a millimeter.

Try to do as I wrote.

Yes.

This should be done in small portions. And check with measurements.

Take a look at your RT60.....i.e. Room Decay. It is short and nicely flat through most of the spectrum. But with very long low frequency decay. This suggests a lack of LF absorption. I think the flat MF and HF suggests a neutral rather than dull short room tone. But with a big boom at LF. Oddly such treatment frequently creates a very clear direct field response. i.e. Speaker to ear, very suppressed Early Reflections. No HF cancelling comb filtering..... Sparkly clear. My KHs have the tweeter turned down, and I use Dirac Live to impose a further more controlled HF roll off. When I move to other speakers in domestic rooms here, there is no substantial change of tone. Mix Translation Nirvana.

Thank you for your clear explanation
I will do some more measurements and repositioning of the bass traps. Will look around my house to see if I find some bulky/heavy things I can put on the ground in my studio to see how it translates in the LF measurements.
Also,my KH310a’s have switches on their back for Low,mid and highs(still all at their default position). Apart from corrective EQ (maybe in the future),should I tamper with them? My gut feeling says leave them alone and try to put have cases (like boxes of vinyl records) on the ground to the sides.
Thnx!

 

[TimWellens]

Almost. You need to measure it very accurately. Up to a millimeter.

,they are positioned up to a centimeter,didn’t know it has to be as close as a milimeter Time to buy a laser measurement tool then.
My GF thinks I’m crazy because I’m so obsessed with REW/measurements and I think she has a point
Thank you for your time,appreciate it!

 

[sm52]

My GF thinks I’m crazy

Buy her chocolate and flowers.

 

[FargateOne]

My GF thinks I’m crazy because I’m so obsessed with REW/measurements and I think she has a point

your not alone man...

 

[DanDan]

Definitely a Millimetre or better. Sadly a friend damaged his tweeter... the magnet pulled the end stop of the measuring tape. I wouldn't sweat this though. No matter what I do Dirac Live sees a time delay between L and R and imposes a correction. Bypass, ignore. Don't view L+R measurements over say 500Hz. I have my HF switch turned down so that there is not so much difference if I have to not use Dirac.

 

[sm52]

In the first screenshot, the sum of the left and right channels, if aligned well. On the other two, the same amount, but incorrectly aligned. Similar to your measurements.
This suggests that your tweeters are working together and separately as they should. And what we see in your measurements is a matter of measurements.