I'm in for chasing the last few things I could do better! Any (niche) things I could take a look at and optimize?

[Plompudu]

My Questions and a link to my measurements are at the end of this comment.

I've got a 2nd SVS SB-2000 today for my small, well sealed room (4.5m x 2.7m x 2.5m) - It sounds amazing, but now I'm in for chasing the last few things I could do better just for the fun of understanding new things and doing work that makes fun and I'm likely able to use later on! (finally studying a Master of Science in Audiocommunication and Audiotechnology starting October!!)

I did the following steps to set it up:

1. I've done 7 measurements (MLP +- ~25cm in all directions) per Speaker/Subwoofer.
2. Cross correlation aligned to the MLP measurement
3. Vector Average
4. Time Aligned Subs (+8ms Front Sub) + added a -5dB LSQ at 14.00 Hz with a Q of 1.23
   
   
5. EQed Subwoofers and Mains (mic cal. only going to 10Hz so take the response below with a grain of salt)
   
   
   
   
   
   
   
   
6. Time Aligned Subs to Mains (+17,66ms Subwoofers) using alignment tool
   (SPL of Sub changing depending on Content from 7dB for Music, 10dB Movies, depending on the mood more or less as well):
   
   
   
   
7. Did a Single point measurement at the MLP of L / R / L+R to check if everything worked (FR pretty much as expected)
   Distortion was a bit high at 30Hz so I didn't boost as much for a flatter response (see 5. Step Response)
8. Checked the Impulse Response and Phase (var. smoothing) of the single point measurements
   IR of L+R+Subs highlighted:
   
   
   
   
   
9. Then I looked at the RT60 (1/6 oct, yes I need more midbass / midrange absorption behind my speakers, but I don't really have place for it in my room...) and Decay:
   
   
   
   
   
   
   
   
   
   
   

I'm still playing around with EQing the Mains above the Schröder frequency.

Here are the measurements as a .mdat file - https://drive.google.com/file/d/1m8onZ4NNf28Axyt4z9DE_dtN7oveiyQy/view?usp=sharing

I've got a few questions:

• Is this Impulse response "ideal" in your eyes for in Room usage? If not how would you adjust it further?
• Would you recommend that I look into FIR filtering to correct the Phase further? Any guides/recommendations? (btw I'm using a MiniDSP 2x4HD)
• Would you be concerned about the extremely long decay time below 30Hz?
• Would you treat the Decay between 120-300Hz; any tips? (don't have a lot of room for Panels...)
• Anything else I should take a look at for a "perfect" system using my hardware? (MiniDSP 2x4HD, 2x Swissonic A306, 2x SVS SB-2000, UMIK-I)
• Anything else that I should add/measure?

Thanks in Advance!

 

[Keith_W]

I had a look at your measurements.

Firstly, there is WAAAAAAY too much bass. About 10dB too much. What does it sound like to you? Since you asked about impulse response:

This is the step response of "L" which I presume is left main speakers with both subs. This is a very ugly step response. After the main impulse, there should be no peak which is greater in magnitude than the main. And we generally want the ringing to stop by about 200ms.

If we switch to "Overlays" and turn on/off "Front Sub" and "Rear Sub" you will see the culprit. Even though your measurements were not taken with a tweeter time reference (so precise diagnosis is not possible), I was able to roughly align the subs to the mains. Once again - the subs are WAAAAY too loud.

This is a simulation of what happens when you reduce the sub by 10dB. I took "Front Sub" and reduced its SPL by 10dB, then "Trace Arithmetic A+B"; with A = Front Sub (reduced by 10dB) and B = "Baseline Left". The step now looks much better.

Anyway, to answer the rest of your questions:

- Do I recommend FIR filtering on your MiniDSP? No, it's a waste of time. The MiniDSP has nowhere near enough taps to do anything useful. If you want FIR filtering, you will need A LOT OF TAPS.
- The extremely long decay time below 30Hz is because your subs are too loud. Forget about absorbers for now, get your DSP right first.

 

[boxerfan88]

Agree, bass too hot. Could the +10dB bump be caused by LFE +10dB gain?

 

[boxerfan88]

:- Do I recommend FIR filtering on your MiniDSP? No, it's a waste of time. The MiniDSP has nowhere near enough taps to do anything useful. If you want FIR filtering, you will need A LOT OF TAPS.

Agree with the above. Those devices have limited taps, resulting in poor LF resolution.

I use foobar convolution engine. At 88200sps, I needed about 32000 taps for my room correction filter to work with decent LF resolution.

 

[Plompudu]

I had a look at your measurements.

View attachment 476094

Firstly, there is WAAAAAAY too much bass. About 10dB too much. What does it sound like to you?

Agree, bass too hot. Could the +10dB bump be caused by LFE +10dB gain?

Yup, it's cause I mainly use this System for watching shows or movies.
Most of the time do I keep it at +10dB for music as well, else I use mainly the ~6dB of Harman.

https://professional.dolby.com/siteassets/cinema-products---documents/dolby-atmos-specifications.pdf

Since you asked about impulse response:

View attachment 476097

This is the step response of "L" which I presume is left main speakers with both subs. This is a very ugly step response. After the main impulse, there should be no peak which is greater in magnitude than the main. And we generally want the ringing to stop by about 200ms.

Thanks for pointing me towards it! I honestly haven't looked at the step response so far outside of the one in Erin's measurement of my Speakers:

https://www.erinsaudiocorner.com/loudspeakers/thomann_swissonic_a306/

I've now gone and corrected the response for the LFE Channel (inverted phase of both and EQed them more separately before aligning them) and got the following results:

https://drive.google.com/file/d/1PTzMyBxHrd7JY8dFwnNdH-B-MdZcYM1U/view?usp=sharing

What do you think about these?
Haven't yet got the time to integrate them properly to the mains cause I'm still playing around with correcting them beforehand.

Anyway, to answer the rest of your questions:

- Do I recommend FIR filtering on your MiniDSP? No, it's a waste of time. The MiniDSP has nowhere near enough taps to do anything useful. If you want FIR filtering, you will need A LOT OF TAPS.
- The extremely long decay time below 30Hz is because your subs are too loud. Forget about absorbers for now, get your DSP right first.

I'm using the system sometimes just with my TV or Phone connected so I'm not able to use more Taps sometimes...
But will definitely look into it for when I'm using my PC as the source, thanks!

 

[Keith_W]

There isn't much to say about your measurements. Pretty impressive that you managed to get your bass flat to 5Hz.

The step response should be used to study the integration of different drivers, and also different speakers. You can also use it to look at ringing. These are measurements of your subs only, so these measurements can not be used to see whether your subs integrate with your main speakers. And even if you want to look at the step response of your main speakers, it's irrelevant since you haven't bypassed the XO in your mains and you're not using an active DSP XO. About the only thing I can say from looking at your step response is that there is a LOT of ringing, and all this ringing is because you are playing your subs too loud.

I get that some people want their systems to sound a certain way. A lot of bass ringing will give the impression of powerful bass, since explosions go BOOOOOOOOOOOOM instead of BOOM. It might sound okay for HT but for music, I would want a lot less. That much ringing will make the bass sound disconnected, slow, and bass heavy. Ultimately, it's your system. You can decide if you prefer it this way or not.

FYI, this is the step response of the L/R speakers and subs of my system showing the first 30ms (left) and zoomed out to show the first 500ms (right). The first 30ms is useful to see whether there is any pre-ringing (there is some, but it's very slight) and how well all the drivers have been integrated. You can see that my step response is very sharp and there are no funny looking waves, which means that I have time aligned all my drivers properly (my system has an active DSP controlled XO, so it's relevant for me. It's not relevant for you). You also want to see that the left speaker is identical to the right.

The zoomed out view shows the post-ringing after the initial impulse. You can see that mine dies down to almost nothing after about 300ms, and there are no secondary peaks that are louder than the main peak. Ideally, each peak should also decay in volume but mine doesn't do that. You can also see that L/R speakers and subs are almost carbon copies of each other. This is from symmetrical placement of speakers and subs in the room.