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Neumann KH310 in a small room (+subs, MA1, absorbers, AVAA)

oivavoi

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You may be thinking of the depth required for resistive absorption to address bass frequencies. Toole discussing a RPG QRD: "At 7.9 in. (0.3 m) deep and exhibiting useful diffusion down to about 300 Hz, they appear to meet the requirements for wideband diffusers"

Geddes: "It appears then that the best rooms for serious listening would have a large amount of low frequency absorption accompanied by very low amounts of high frequency absorption... the directional source can be pointed in such a way that the first reflection actually arrives at the ear opposite the direct arrival. For the directional source, the secondary (after the first) reflection arrivals are virtually all lateral and behind the listener – a good thing." His solution is to have highly directional (90 degree coverage pattern) speakers toed-in severely to cross significantly in front of the listening position so that the first lateral reflection is actually contralateral and consequently later, not early.

Thanks a lot for clarifying!
 

ernestcarl

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That's interesting, i could try this quite easily with my secondary KH120 and my RME UCX.
How exactly do you upmix? R to R surround and L to L surround, but less dB? How much less? Or a bit of L to R surround and vice versa? Do you add delay to simulate a reflection? Could it be beneficial not to place them in the back but on the sides?

Well, dunno if it's gonna be easy... depends on how one goes about it.

I myself am just using JRiver's native upmixer. I've read some people say it's similar to the old Dolby Pro Logic IIx algorithm, though I cannot be certain. I use it to upmix stereo LR content to 5.1 and 7.1 -- however, minus the center channel as I have no space for it.

My very vague memory of what is does (could be wrong in some of this!):

Copies LR signals in a lower level to the surrounds and inverts the IR of one of these for each surround. I believe the LR correlated signals will cancel each other out. Each surround channel produces a new decorrelated signal -- when both are summed acoustically (measured through a microphone), they (surrounds) also cancel each other out additionally lowering the level.

How it sounds for the side surrounds (20ms delayed) is a little bit different from the rears (30ms delayed). I'm not sure how it does this exactly, but it seems vocal ambience is a little clearer from the rears and instruments a bit more clear to the sides -- or that could purely be from the differences in frequency response and spectral decay characteristic (inevitably malformed by the room) when it finally arrives at my ears.



1635169433943.png


In my sofa setup (2.1/5.1ch), I have the surrounds maybe at a ~110-15 degrees angle from the front central axis.

For my desk setup (2.1/5.1/7.1ch), I have the side surrounds less than 5 degrees directly to the left and right from the desk chair MLP. The rears are maybe ~135 degrees located in the back corners of the room.

You will have to experiment to find out whatever positioning works best...

With regard to the sound levels, I have the surrounds EQ'd and toned down to be similar yet slightly lower than the front mains -- listening to pink noise helps in the matching process here -- but then, I also have additional saved presets in JRiver which allow me to change the focus of the sound:

1635169733973.png


Manual time and phase alignment is a challenge due to my mixing and matching of different speakers (ported and sealed) of different designs. Ultimately, I found it easier if I am able to mix both FIR and IIR EQs and xo with DSP -- since it's also desirable to have the phases from all loudspeakers sum coherently: wherein one is also able to vector average (time and magnitude sum) all channels, including the sub-LFE, with as little cancellation artifacts as possible.

1635201142362.png

edit: adjustments in phase to better match sub-LFE channel by changing the xo slope and freq.

This may be faster/easier to accomplish with the help of more advanced auto-calibration and full bass optimization features found in certain AVR processors.
 
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DJBonoBobo

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Well, dunno if it's gonna be easy... depends on how one goes about it.

I myself am just using JRiver's native upmixer. I've read some people say it's similar to the old Dolby Pro Logic IIx algorithm, though I cannot be certain. I use it to upmix stereo LR content to 5.1 and 7.1 -- however, minus the center channel as I have no space for it.

My very vague memory of what is does (could be wrong in some of this!):

Copies LR signals in a lower level to the surrounds and inverts the IR of one of these for each surround. I believe the LR correlated signals will cancel each other out. Each surround channel produces a new decorrelated signal -- when both are summed acoustically (measured through a microphone), they (surrounds) also cancel each other out additionally lowering the level.

How it sounds for the side surrounds (20ms delayed) is a little bit different from the rears (30ms delayed). I'm not sure how it does this exactly, but it seems vocal ambience is a little clearer from the rears and instruments a bit more clear to the sides -- or that could purely be from the differences in frequency response and spectral decay characteristic (inevitably malformed by the room) when it finally arrives at my ears.



View attachment 161350

In my sofa setup (2.1/5.1ch), I have the surrounds maybe at a ~110-15 degrees angle from the front central axis.

For my desk setup (2.1/5.1/7.1ch), I have the side surrounds less than 5 degrees directly to the left and right from the desk chair MLP. The rears are maybe ~135 degrees located in the back corners of the room.

You will have to experiment to find out whatever positioning works best...

With regard to the sound levels, I have the surrounds EQ'd and toned down to be similar yet slightly lower than the front mains -- listening to pink noise helps in the matching process here -- but then, I also have additional saved presets in JRiver which allow me to change the focus of the sound:

View attachment 161353

Manual time and phase alignment is a challenge due to my mixing and matching of different speakers (ported and sealed) of different designs. Ultimately, I found it easier if I am able to mix both FIR and IIR EQs and xo with DSP -- since it's also desirable to have the phases from all loudspeakers sum coherently: wherein one is also able to vector average (time and magnitude sum) all channels, including the sub-LFE, with as little cancellation artifacts as possible.

View attachment 161359


This may be faster/easier to accomplish with the help of more advanced auto-calibration and full bass optimization features found in certain AVR processors.

Thank you very much for your detailed answer. I will think about it, even if it is unfortunately probably a bit more complicated than I first thought.
 

smcc

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...from what I've read, the reason people don't recommend diffusors for small rooms is that there isn't enough distance for them to work correctly...I do also remember that there are certain types that can…but not readily available, need to build…

…tbh your measurements look great, there’s many studios that wouldn’t look that good in data…hence why i was thinking maybe placement was a bit…tbh, u might just be hearing the limit of a three way…can’t beat coax for imaging…

…i like the 310s for mixing as FR is so linear and distortion is so low, and they have good headroom for tracking unprocessed instuments…but for just listening I’d go with a coax…or a set of sh50s even, not totally accurate, but pure joy…

I wouldn’t go crazy spending any more money on acoustics…think you’re at the point of very diminishing returns…maybe play with moving things around a bit…dabble with some eq…
 
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youngho

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...from what I've read, the reason people don't recommend diffusors for small rooms is that there isn't enough distance for them to work correctly...I do also remember that there are certain types that can…but not readily available, need to build…
I have heard that, as well. https://www.audiosciencereview.com/...om-subs-ma1-absorbers-avaa.27288/#post-950938

Also:
 

sadburai

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very interesting! I think it would be even more interesting, if you showed not only the frequency response for every additional measure (i.e. your Steps 1-7), but also the time domain (e.g. Waterfall Plot or RT60 plots). I guess that the frequency response shows only half of the story to evaluate the effect of each treatment step.
 

ernestcarl

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very interesting! I think it would be even more interesting, if you showed not only the frequency response for every additional measure (i.e. your Steps 1-7), but also the time domain (e.g. Waterfall Plot or RT60 plots). I guess that the frequency response shows only half of the story to evaluate the effect of each treatment step.

It might be informative to include spectral decay plots as well.

Related to what I wrote before i.e. bringing back some lost envelopment cues due to over-absorption by using upmixing DSP.


Here's some graphs showing the effect of upmixing a plain stereo L+R sine swept signal to surround channels:

1635710460013.png 1635710551750.png

The additional surround signal is added after 20ms delay time -- visible as a faint (but brighter) energy line in the horizontal plain in the second wavelet graph.


The decay graph (after upmixing) also slightly appears more smooth/even overall as the surround channels help fill-in many of the dips in the later spectra:

1635710774999.png 1635710780857.png

At the very least JRiver's upmixing process does not seem to be doing any obvious harm or alteration to the direct sound when set up correctly.
 

sadburai

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The angle itself is not important, but it has to be enough so the reflections are deflected from the listening position. [...] I use risers with a fixed height, so i can not really adjust the angle. You can try with a mirror on the desk and see how much you have to tilt it so you don´t see the speaker in it anymore.

Ergonomics is bad. I angle the desk only for listening to music. It is okay for surfing the internet while listening and i still can place a bottle or a cup on it, but i would not use it that way during work. I would not recommend a window behind the screen either. For working, i remove the risers

It is certainly possible to place absorbers on the desk instead of angling it. I don´think a mouse mat will be effective, though. I own a big mouse mat (90 x 40 cm), but it did not really help, i think, but I don´t have measurements of it.

I gave it a try to place absorbers on the table and I think it's much more convenient than to tilt the whole table. According to my measurements, it's sufficient to only treat areas on the desk according to the mirror method. At least it made a big difference, although I didn't try to tilt my desk for comparison.

I didn't have any absorbers at home, so instead I used:

1.) an IKEA TOFTBO floormat for the bath, folded to 5cm height and placed it on the table. It was slightly sloping downwards from the speakers to the edge of the table (mirror method).
2.) A small wooden board (approximately 30x40), angled such that I could not see the speaker from the listening/mic position in the mirror. The board was placed ca. 10cm away from the speaker, so that there is a gap. Otherwise, it's hard to not see the speaker in the mirror from the mic position.

You can still work at the desk relatively conveniently and the treatment can be added/removed within seconds.

Measurements:

Disclaimer: I used an uncalibrated Audyssey Mic, with the SPL dialed in by an Android App. The room is untreated.

The measurements show L+R channels simultaneously, but the effect is very similar for the individual speakers. There is not much difference between the IKEA mat and the angled wood in individual measurements. Both methods reduce the early reflection peaks in the impulse response and flatten the frequency response.

Impulse response:
- brown before treatment with strong reflections from the table after 1ms
- green after treatment with an IKEA mat (L) and an angled piece of wood (R)

Impulsantwort, L+R, Tischerstreflexion,gedämpft.jpg


Frequency response:
- much flatter after treatment (green). 1/48 smoothing
Frequenzgang, L+R, Tischerstreflexion,gedämpft.jpg
.
A mousepad on a flat table doesn't do much however.

Impulsantwort R, Mauspad.jpg
 
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DJBonoBobo

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very interesting! I think it would be even more interesting, if you showed not only the frequency response for every additional measure (i.e. your Steps 1-7), but also the time domain (e.g. Waterfall Plot or RT60 plots). I guess that the frequency response shows only half of the story to evaluate the effect of each treatment step.

You can PM me if you want, and i send you my mdat-file. Too much work for me to post all the graphs ATM.
 

sadburai

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I can't edit my previous post anymore, but I still wanted to upload photos of my make-shift absorber & angled reflector to reduce the early reflections from my table. Super simple but effective. The gap between the angled board and the speaker makes it easier to place the board according to the mirror method such that no reflections arrive at the listening position.

table_absorber.jpg
 

hemiutut

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Hello,
I would like to share my experience of how the Neumann KH310 behaves in a small room and what measures have improved the acoustics for me.
I thought it might be interesting for others, since the KH310 has been reviewed and measured and the predominantly neutral characteristics are well known.
It might also help some who are very interested in small differences between speakers, but perhaps haven't thought much about room acoustics yet.

I'm not looking for advice since I'm moving in a few weeks anyway and will be starting all over again.

My setup at the moment looks like this:
- Neumann KH310
- 2x Neumann KH750
- 2x PSI AVAA active bass absorbers
- RME UCX II

The room is a small bedroom with the dimensions 3.0 x 4.8 meters (14 sqm). There is a bed and a big closet full of clothes, books and other stuff in it. The front view looks like this:

View attachment 158831

There are:
- 2x basotect absorbers at the ceiling ("cloud"), ca. 12cm thick
- 2x basotect absorbers on the side walls, 10cm
- 2x basotect absorbers in front of the window, 10 and ca. 12cm
- 2x green basotect absorbers in the corners, 25cm thick, with another 25 airgap
- 2x green basotect absorbers, 40 cm trangles

The 2 AVAAs are at the back wall. Subs are in the L/R corners (on top of the small wooden boxes and partially behind the absorbers) at 1/4 room heigt.

Listening distance and distance between monitors is 1.55 meters.
Desk is small, 1.0 x 0.5 meters and tilted 10 degrees. I use furniture risers like this:
View attachment 158834

This is the frequency response i get with all measures after calibration with the Neumann MA 1 (single sweep L/R + average): red: left 1/24; green: right 1/24; blue: average with var smoothing

View attachment 158835

And here is the same without treatments:
View attachment 158836

And now the interesting part, i hope. I'll go through the individual measures and show the differences in each case:

Left channel single sweep only for all graphs.

1. I switched off the AVAAs:
View attachment 158837

2. I removed the "cloud":
View attachment 158838
3. I removed the risers and put the desk flat:
View attachment 158839
4. I removed the absorbers in front of the window:
View attachment 158840
5. I removed the green absorbers in the corners:
View attachment 158841
6. I removed the side wall absorbers:
View attachment 158842
7. And finally disconnected both subwoofers and deactived the built in DSP:
View attachment 158843

And here again most of it in one picture:
View attachment 158844

Some additional graphs:
ETC before (blue)/after (red) treatments:
View attachment 158845

Group delay before (blue)/after (red) treatments
View attachment 158846

Waterfalls:
View attachment 158847
View attachment 158848

Some conclusions for me:
- AVAA in my room helps only below 30 Hz
- Tilting the desk was very important for imaging
- Basotect absorbers behind the monitors and in the corners help in upper bass and lower mids, but have no effect below 100Hz
- Cloud in my case may be the least helpful measure.
- Subs were needed to fill the gap between 70 and 100 Hz (1 sub did most of it, btw. second sub didn´t add very much)
- EQ is mandatory in a small room even with neutral speakers, absorbers and PSI AVAA
Do you have the measurements of the TR ( Topt,T20,T30 without and with treatment ?

Written with translator

Greetings
 
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DJBonoBobo

DJBonoBobo

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Do you have the measurements of the TR ( Topt,T20,T30 without and with treatment ?

Yes. Although i have to say i didn´t measure very loudly and i read somewhere the RT60 would not be very useful in a small room. I have no expertise in this, though.

T20 after and before treatment (before means: no absorbers, no avaa, desk straight, but with sub and eq)
RT60_t20_overlay.png


Before:
RT60before.png


After:
RT60after.png
 

Frgirard

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Yes. Although i have to say i didn´t measure very loudly and i read somewhere the RT60 would not be very useful in a small room. I have no expertise in this, though.

T20 after and before treatment (before means: no absorbers, no avaa, desk straight, but with sub and eq)
View attachment 182748

Before:
View attachment 182745

After:
View attachment 182746
REW doesn't measure the rt60. Read the help and what is wrote on the screen.
On the srcreen above I read topt t20 t30. Not rt60.

The rt60 is a property of a room whatever the direction the amplitude is the same, whatever the location the decay is the same.
And I post my authority argument.
 

dasdoing

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Hello,
I would like to share my experience of how the Neumann KH310 behaves in a small room and what measures have improved the acoustics for me.
I thought it might be interesting for others, since the KH310 has been reviewed and measured and the predominantly neutral characteristics are well known.
It might also help some who are very interested in small differences between speakers, but perhaps haven't thought much about room acoustics yet.

I'm not looking for advice since I'm moving in a few weeks anyway and will be starting all over again.

My setup at the moment looks like this:
- Neumann KH310
- 2x Neumann KH750
- 2x PSI AVAA active bass absorbers
- RME UCX II

The room is a small bedroom with the dimensions 3.0 x 4.8 meters (14 sqm). There is a bed and a big closet full of clothes, books and other stuff in it. The front view looks like this:

View attachment 158831

There are:
- 2x basotect absorbers at the ceiling ("cloud"), ca. 12cm thick
- 2x basotect absorbers on the side walls, 10cm
- 2x basotect absorbers in front of the window, 10 and ca. 12cm
- 2x green basotect absorbers in the corners, 25cm thick, with another 25 airgap
- 2x green basotect absorbers, 40 cm trangles

The 2 AVAAs are at the back wall. Subs are in the L/R corners (on top of the small wooden boxes and partially behind the absorbers) at 1/4 room heigt.

Listening distance and distance between monitors is 1.55 meters.
Desk is small, 1.0 x 0.5 meters and tilted 10 degrees. I use furniture risers like this:
View attachment 158834

This is the frequency response i get with all measures after calibration with the Neumann MA 1 (single sweep L/R + average): red: left 1/24; green: right 1/24; blue: average with var smoothing

View attachment 158835

And here is the same without treatments:
View attachment 158836

And now the interesting part, i hope. I'll go through the individual measures and show the differences in each case:

Left channel single sweep only for all graphs.

1. I switched off the AVAAs:
View attachment 158837

2. I removed the "cloud":
View attachment 158838
3. I removed the risers and put the desk flat:
View attachment 158839
4. I removed the absorbers in front of the window:
View attachment 158840
5. I removed the green absorbers in the corners:
View attachment 158841
6. I removed the side wall absorbers:
View attachment 158842
7. And finally disconnected both subwoofers and deactived the built in DSP:
View attachment 158843

And here again most of it in one picture:
View attachment 158844

Some additional graphs:
ETC before (blue)/after (red) treatments:
View attachment 158845

Group delay before (blue)/after (red) treatments
View attachment 158846

Waterfalls:
View attachment 158847
View attachment 158848

Some conclusions for me:
- AVAA in my room helps only below 30 Hz
- Tilting the desk was very important for imaging
- Basotect absorbers behind the monitors and in the corners help in upper bass and lower mids, but have no effect below 100Hz
- Cloud in my case may be the least helpful measure.
- Subs were needed to fill the gap between 70 and 100 Hz (1 sub did most of it, btw. second sub didn´t add very much)
- EQ is mandatory in a small room even with neutral speakers, absorbers and PSI AVAA


very nice data. I will read it all later.
I just moved and was curious about the cloud I had, too.
It will basicly clean up the mids in the spectrogram and has impact on the ETC. I probably wont install one again. I would only use it if my ETC had a big spike over -20dBFS
 

hemiutut

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Yes. Although i have to say i didn´t measure very loudly and i read somewhere the RT60 would not be very useful in a small room. I have no expertise in this, though.

T20 after and before treatment (before means: no absorbers, no avaa, desk straight, but with sub and eq)
View attachment 182748

Before:
View attachment 182745

After:
View attachment 182746
Thank you for your patience in answering.
The RT60 in small rooms (most of us have small rooms and it doesn't matter if they are 12 meters or 50, they are considered small rooms) I had already understood it and I even look at the schroeder frequency,
although with porous velocity treatment you can do a very good job.
Do you know the air flow resistivity in Pa.s/m2 of the panels you have made in basotech ?
made in basotech ?

I use this filler material in my wide band porous treatment (speed) and in Spain it is called wadding.
My panels are 20-30 and 45 cms thick.

boata-guata-tapizar.png


Written with translations

Greetings
 
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DJBonoBobo

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Do you know the air flow resistivity in Pa.s/m2 of the panels you have made in basotech ?
No, i don´t know. The internet says it is something between 8000 and 20000. Some say it is 12000. But it is higher than the flow resistivity of mineral wool and therefore not the best material for bass traps. Basotect is the name of a melamine foam made by BASF.
 

hemiutut

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No, i don´t know. The internet says it is something between 8000 and 20000. Some say it is 12000. But it is higher than the flow resistivity of mineral wool and therefore not the best material for bass traps. Basotect is the name of a melamine foam made by BASF.
I am familiar with Basotect but I don't know its resistivity to air flow, hence my question.
I hope it is not higher than 12000 Pa.s/m2.
I advise you to try again and make them with a material of at least 5000 Pa.s/m2 and with a thickness not less than 20 cms.

I leave you a link where you can appreciate the TR ( Topt ) of my dining room of 21 meters.
There are 3 measures:
Green line of January 2017 with furniture,sofas,curtains,carpet and very little acoustic treatment.

Blue line from October 2020 with much more treatment.

Pink line May 2021 with the maximum treatment that they let me put.
The change to the ear is very noticeable and the measurements confirm it.
RT-Topt-de-3-medidas-hechas-el-2017-2020-y-2021.jpg
 
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DJBonoBobo

DJBonoBobo

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I moved recently and want to install new (better) absorbers in the new room, as soon as i have time. I can post an update about the new room and maybe a comparision between Basotect and mineral wool absorbers some day. Could take a few months, though.
 

hemiutut

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I moved recently and want to install new (better) absorbers in the new room, as soon as i have time. I can post an update about the new room and maybe a comparision between Basotect and mineral wool absorbers some day. Could take a few months, though.
I will look forward to your further comments on the acoustic treatment.

My comment in your thread has been for people to understand that there are many ways to do an acoustic treatment yourself and have very good results vs commercial.
If you are agile in DIY,it is very easy and if you are not you can always find a reputable carpenter.
If you don't want to get your head hot, then use this material (not Basotect for low frequencies) at least joining 2 panels together to obtain a thickness of 20 cm.
https://www.don-audio.com/CARUSO-ISO-BOND-WLG-040-100mm-Akustikvlies-Schallabsorber
WLG 040 >= 5.000 Pa*s/m²

My friends use Knauf TP116 wool or similar in resistivity to the passage of air flow and wadding (the material I use).

Regards
 

mulderX

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I'm wondering witch is the best monitor at the cost of 1500€ each? ( 2000€ the top
 
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