Bass in small bedroom (effects of PSI AVAA, subwoofer and EQ, also passive absorbtion)

[Absolute]

In essence, important down to around 100 hz and not important below. I experimented with this a while ago when adjusting subs.
When I let my fronts play fullrange, I got a 150-200 ms better decay plot between 40-50 hz (-30 dB) than when I crossed them off at 100 hz with the ~ same frequency response, but I couldn't hear a difference. I could hear a difference further up, so concluded that it was a better trade-off to ignore decay at low frequencies in favor of cleaner mids from the fronts.
Not scientific by any stretch, but it made me more relaxed concerning the audibility of resonances in the deep.

 

[JohnPM]

Note that the papers I linked to are concerned with the audibility of the decay separately from the audibility of the frequency response peak that normally goes along with an extended decay, they took measures to separate the two effects.

 

[Absolute]

That should be a given, the claim I (Floyd Toole actually) made was that we hear frequency response and not decay at low frequencies

 

[QMuse]

When you properly EQ frequency peaks the decay also reduces.

 

[Absolute]

When you properly EQ frequency peaks the decay also reduces.

Example for those who have not tested;

 

[hyperplanar]

OP, have you tried playing with the delay settings on the KH750? Maybe that could help fill in the hole around 70-80 Hz more. Bizarrely enough I found that I had to delay the KH750 KH120s by about 4 ms to maximize the SPL in the crossover region even though the sub is right under my desk.

 

[QMuse]

OP, have you tried playing with the delay settings on the KH750? Maybe that could help fill in the hole around 70-80 Hz more. Bizarrely enough I found that I had to delay my KH750 by about 4 ms to maximize the SPL in the crossover region with my KH120s even though the sub is right under my desk.

Sub delay can easilly be measured with REW. Such low delay would show as a jump in phase response.

 

[hyperplanar]

Sub delay can easilly be measured with REW. Such low delay would show as a jump in phase response.

Indeed, in fact I actually used the alignment tool in REW with a measurement of the sub and the KH120s with a loopback timing reference to arrive at the needed 4 ms delay. I don't think the OP provided any phase response graphs yet.

 

[QMuse]

Indeed, in fact I actually used the alignment tool in REW with a measurement of the sub and the KH120s with a loopback timing reference to arrive at the needed 4 ms delay.

Exactly.

Btw, how comes you didn't flatten that peak at 400Hz?

I don't think the OP provided any phase response graphs yet.

He didn't. He didn't even provide XO frequency between sub and mains.

 

[hyperplanar]

Exactly.

Btw, how comes you didn't flatten that peak at 400Hz?

Ah, this measurement was from when I was first working to integrate the sub, so no EQ was applied yet above 200 Hz. That peak is pretty position dependent so I did a MMM measurement afterwards and came up with a filter to flatten it.

He didn't. He didn't even provide XO frequency between sub and mains.

As far as I can tell from using the Neumann iPad app for a few days, the crossover frequency is fixed at 80 Hz if you choose a specific speaker-- I don't see a way to change it :/

 

[QMuse]

That peak is pretty position dependent so I did a MMM measurement afterwards and came up with a filter to flatten it.

Yup, I guessed that because of funny phase fluctuation at the same point.

 

[Lao Lu]

Great post, as simple as it gets.

I have a small room myself (3.5mX3.5m) and have been struggling to achieve a proper bass, I have built 3 big (120cmX60X40) bass traps that didnt even help the bass, ironically, the only thing that really helped is a huge closet that is in the room (240cmX180X60)
eventually i took the multi-subwoofer approach , with some EQ i got incredible bass I never thought was possible achieving in that room.

have you thought about multi sub option?

How many subs? What size? Sealed, ported?

 

[DJBonoBobo]

Thanks for your interest. The XO frequency is indeed fixed to 80 Hz. Neumann says they want to implement a changeable XO in future versions of the app.

I haven´t tried to play with the delay. I always used the setting based on the distance. I´m not sure if i understand how you (@hyperplanar) found the 4 ms. I don´t know what´s a loopback timing reference, but i think i can´t do it with my UMIK-1. I have a another mic i could probably use, though. Perhaps i will look it up - your phase graph looks definately better than mine. Don´t know if it´s important.

I can provide a few more infos now, maybe i can make additional measurements later (sub alone would be interesting maybe...):

Phase response of the green graph above (left channel (+ Sub), var smoothing, EQ and AVAA active):

Settings in Neumann-app:

Note: I used -6db for sub because i set the analog KH 310 monitors to 94db output (not 100db as suggested by the app).

And the looks of my room (editing for privacy). Circled are the new (better) positions of the AVAA.


Edit: I open the doors of the closet when listening to avoid reflections.

 

[QMuse]

Thanks for your interest. The XO frequency is indeed fixed to 80 Hz. Neumann says they want to implement a changeable XO in future versions of the app.

I haven´t tried to play with the delay. I always used the setting based on the distance. I´m not sure if i understand how you (@hyperplanar) found the 4 ms. I don´t know what´s a loopback timing reference, but i think i can´t do it with my UMIK-1. I have a another mic i could probably use, though. Perhaps i will look it up - your phase graph looks definately better than mine. Don´t know if it´s important.

I can provide a few more infos now, maybe i can make additional measurements later (sub alone would be interesting maybe...):

Phase response of the green graph above (left channel (+ Sub), var smoothing, EQ and AVAA active):
View attachment 56286

Settings in Neumann-app:

View attachment 56287
View attachment 56288
View attachment 56289
Note: I used -6db for sub because i set the analog KH 310 monitors to 94db output (not 100db as suggested by the app).

And the looks of my room (editing for privacy). Circled are the new (better) positions of the AVAA.
View attachment 56290
View attachment 56291
Edit: I open the doors of the closet when listening to avoid reflections.

Can you please apply FDW of 6 cycles to that measurement and re-post it?

And also pls post RTA MMM measurement of all speakers (L+R+sub) playing.

And right channel + sub, as you did for left.

 

[QMuse]

And correction settings for right channel.

 

[QMuse]

Btw, based on what you posted your sub filter #3 is wrong and is making things worse, but let's wait for L+R+sub measurement.

 

[hyperplanar]

I haven´t tried to play with the delay. I always used the setting based on the distance. I´m not sure if i understand how you (@hyperplanar) found the 4 ms. I don´t know what´s a loopback timing reference, but i think i can´t do it with my UMIK-1. I have a another mic i could probably use, though. Perhaps i will look it up - your phase graph looks definately better than mine. Don´t know if it´s important.

I'm sorry I don't think I can explain this very well but I'll try my best! Basically you need a measurement of the sub playing by itself, and a measurement of the mains playing together, where the relative timing of each measurement is preserved. In other words, you don't want REW to be adjusting the timing offset for each measurement. The way I achieved this was by setting up a loopback of REW's output in some unused channels of my RME Babyface Pro and using it for both measurements, but I'm sure there's an easier way to do it.

You can press the Sub and No Sub buttons in the main screen of the iPad app to get each to play separately.

Once you have the two measurements, you can go to the All SPLs tab, then click the gear icon on the top right and press Alignment Tool. There you can simulate different gains and delays for the sub and the monitor to see what will give you the flattest summation.

Also, I separately EQed both the subs and the mains before attempting this in order to minimize the influence of any minimum phase variations caused by the frequency response when trying to figure out the optimum delay. When setting the EQ target for the sub and the mains, you should set the speaker type to speaker driver, then use the LR4 LP and HP at 80 Hz for each.

 

[DJBonoBobo]

@QMuse
Sorry, what does "FDW of 6 cycles" mean?

Correction for right channel is the same as for left.

Right channel (plus sub), same as left above:

R+L+Sub RTA MMM

 

[DJBonoBobo]

@hyperplanar
Thanks for the explanation! Perhaps i´ll try that later as it´s something i haven´t done yet.. At the moment i´m quite satisfied with my results, though. Curious if more optimization is possible.

 

[hyperplanar]

@hyperplanar
Thanks for the explanation! Perhaps i´ll try that later as it´s something i haven´t done yet.. At the moment i´m quite satisfied with my results, though. Curious if more optimization is possible.

Maybe you can post the frequency response of the sub and the mains playing separately (disregarding the timing offset stuff) and we could see at a glance if changing the delay would help with anything.