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

[DJBonoBobo]

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:



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:


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

And here is the same without treatments:

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:

2. I removed the "cloud":

3. I removed the risers and put the desk flat:

4. I removed the absorbers in front of the window:

5. I removed the green absorbers in the corners:

6. I removed the side wall absorbers:

7. And finally disconnected both subwoofers and deactived the built in DSP:

And here again most of it in one picture:

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

Group delay before (blue)/after (red) treatments

Waterfalls:

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

 

[youngho]

Awesome! Great data. I do wonder whether the AVAA might have had more effect further up the frequency range if the subs and EQ had been turned off before. Did you perceive any subjective difference/benefit from the cloud?

The Archimedes project suggested that floor (or in your case desk) reflections could have timbral and spatial effects, consistent with your measurements >1 kHz removal of comb filter effects, as well as comment re: imaging.

 

[LearningToSmile]

Nice write-up. Those AVAAs are interesting, I wasn't aware of them and they seem to do a good job. The price is a bit steep, though.

 

[DJBonoBobo]

Awesome! Great data. I do wonder whether the AVAA might have had more effect further up the frequency range if the subs and EQ had been turned off before.

Thanks. Maybe, but certainly not much in my room. The AVAA can be effective from 15 Hz up to 150 Hz, but it depends very much on the circumstances what the actual effect is. You can have very different results with different positions. In my room i found them most effective at the back wall only adressing the SBIR from there and almost completely removing it. I bought them before i bought the subs hoping the AVAAs could help with the 70-100Hz gap, but they never really did in my room. So i had to add the subs later.

Did you perceive any subjective difference/benefit from the cloud?

I did not really try.

Nice write-up. Those AVAAs are interesting, I wasn't aware of them and they seem to do a good job. The price is a bit steep, though.

Thanks. They work and they are quite unique, but they don´t do magic. Sound&Recording has also made measurements with the Neumann KH310 with and without AVAA and they came to a similar conclusion, i think: https://www.soundandrecording.de/equipment/psi-avaa-c20-aktiver-bass-absorber-im-test/

 

[Bamboszek]

It's interesting how much desk tilt affects FR.
Did you maybe tried angles other than 10°?
Acoustic improvements are clear, but how is ergonomics?
Keyboard and mouse shouldn't slip, but I imagine lots of other things will simply roll.
Another thing that possible could affect FR is big mouse mat. Something like that - https://dreammachines.pl/en/dmpadxxl
3mm of rubber and fabric isn't much, but maybe highest frequencies?

 

[DJBonoBobo]

It's interesting how much desk tilt affects FR.
Did you maybe tried angles other than 10°?

The angle itself is not important, but it has to be enough so the reflections are deflected from the listening position. It depends on the relation between speaker position, desk size and ear level. 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.

Acoustic improvements are clear, but how is ergonomics?
Keyboard and mouse shouldn't slip, but I imagine lots of other things will simply roll.

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 and rotate the desk 90 degrees so the window is on the side. I only listen to headphones during work.

Another thing that possible could affect FR is big mouse mat. Something like that - https://dreammachines.pl/en/dmpadxxl
3mm of rubber and fabric isn't much, but maybe highest frequencies?

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.

 

[youngho]

Thanks. Maybe, but certainly not much in my room. The AVAA can be effective from 15 Hz up to 150 Hz, but it depends very much on the circumstances what the actual effect is. You can have very different results with different positions. In my room i found them most effective at the back wall only adressing the SBIR from there and almost completely removing it. I bought them before i bought the subs hoping the AVAAs could help with the 70-100Hz gap, but they never really did in my room. So i had to add the subs later.

Thanks. They work and they are quite unique, but they don´t do magic. Sound&Recording has also made measurements with the Neumann KH310 with and without AVAA and they came to a similar conclusion, i think: https://www.soundandrecording.de/equipment/psi-avaa-c20-aktiver-bass-absorber-im-test/

Thanks for that link. Their results were even more impressive than yours. For those low bass frequencies <50 Hz, the effect is pretty close to magic for me.

 

[DJBonoBobo]

I would like to add one more thing.
I have only described my experiences here and shown the measurements, but have not reported my subjective experiences. This is because I have little time to listen to music with it at all, but also because I am unsure how good the result actually is. Unfortunately, I lack a reference, as I don't know anyone who has a better system than I do, nor have I ever been in a real recording studio.
I will say, however, that while the sound is certainly quite good, I am not really satisfied to this day.
I suspect that on the one hand I have reached a limit of what is possible in such a room, but that on the other hand I have never tried certain other measures.
Example: The stereo image is quite good, but very fragile. Depending on the recording or if I move a bit I am constantly unsure how I am sitting "correctly". Not only the imaging, but also the frequency response are relatively fragile and very dependent on how I am sitting, how the screen is set, whether the table is perfectly symmetrical, etc.
Perhaps these are simply the limits of stereo in this kind of nearfield bedroom setup. Or maybe I'm doing all sorts of things wrong. For example, I have never used diffusers or absorbers with scatterplates. Maybe the result would be much better - i don´t know.
My point is that I can't or won't really recommend that anyone do exactly as I did.

 

[smcc]

I would like to add one more thing.
I have only described my experiences here and shown the measurements, but have not reported my subjective experiences. This is because I have little time to listen to music with it at all, but also because I am unsure how good the result actually is. Unfortunately, I lack a reference, as I don't know anyone who has a better system than I do, nor have I ever been in a real recording studio.
I will say, however, that while the sound is certainly quite good, I am not really satisfied to this day.
I suspect that on the one hand I have reached a limit of what is possible in such a room, but that on the other hand I have never tried certain other measures.
Example: The stereo image is quite good, but very fragile. Depending on the recording or if I move a bit I am constantly unsure how I am sitting "correctly". Not only the imaging, but also the frequency response are relatively fragile and very dependent on how I am sitting, how the screen is set, whether the table is perfectly symmetrical, etc.
Perhaps these are simply the limits of stereo in this kind of nearfield bedroom setup. Or maybe I'm doing all sorts of things wrong. For example, I have never used diffusers or absorbers with scatterplates. Maybe the result would be much better - i don´t know.
My point is that I can't or won't really recommend that anyone do exactly as I did.

Cool setup...but from the photo I think you're outside the equilateral triangle and that's why you're not getting a good stereo image...the acoustic axis should end up pointing about 30cm behind your head (imo), but certainly not in front of your ears...looks to me like they're pointing at about 30cm in front of your head; that's not going to be good...easy test, try pushing your desk right up against the radiator....other thing is to make sure they're at the right angle and height, I spent ages getting this right and it was worth it (laser levels, protractors, bubble levels, double check using compass/level on iphone with a square case, (u need the square case; yes i'm a bit mad) ...they're unforgiving on the vertical axis, best a bit below, never above (acoustic axis is between mid and tweeter, not tweeter in case u don't know)...

 

[oivavoi]

I will say, however, that while the sound is certainly quite good, I am not really satisfied to this day.
I suspect that on the one hand I have reached a limit of what is possible in such a room, but that on the other hand I have never tried certain other measures.
Example: The stereo image is quite good, but very fragile. Depending on the recording or if I move a bit I am constantly unsure how I am sitting "correctly". Not only the imaging, but also the frequency response are relatively fragile and very dependent on how I am sitting, how the screen is set, whether the table is perfectly symmetrical, etc.

I would think that this is due to the limited and very controlled dispersion of the Neumanns, combined with the fact that you have killed many of the side reflections with absorption. I could be wrong (I often am!), but that's my hunch. What you could try with your existing setup is to switch out absorbers with good diffusers (EDIT: or just try out with some bookshelves?). I would guess that this would make a difference. Another approach is to use speakers with wide dispersion which are nevertheless well-behaved when it comes to constant directivity. The BMR speakers from Philharmonitor/ @Dennis Murphy come to mind. Difficult to say in advance how it would sound, but it would certainly be very different from the Neumanns!

And yeah, awesome setup and documentation by the way. Really impressive, and it's a service to the community to document it like you do!

 

[DJBonoBobo]

Cool setup...but from the photo I think you're outside the equilateral triangle and that's why you're not getting a good stereo image...the acoustic axis should end up pointing about 30cm behind your head (imo), but certainly not in front of your ears...looks to me like they're pointing at about 30cm in front of your head; that's not going to be good...easy test, try pushing your desk right up against the radiator....other thing is to make sure they're at the right angle and height, I spent ages getting this right and it was worth it (laser levels, protractors, bubble levels, double check using compass/level on iphone with a square case, (u need the square case; yes i'm a bit mad) ...they're unforgiving on the vertical axis, best a bit below, never above (acoustic axis is between mid and tweeter, not tweeter in case u don't know)...

That´s not it, i am similarly obsessed with this stuff and use different laser meters, angle meters, smartphone sensors (with case indeed) and so on. Every millimeter is important. The room is not perfectly symmetrical, though, walls are a bit crooked. Vertically i am always at the exact height. I agree Neumanns are unforgiving vertically. Usually my forehead is a bit closer to the speakers than the distance between speakers, maybe around 20cm. I experience that i depends very much on the recording which distance sounds most "correct". Some recordings sound better when I'm closer to them. Some are better when I sit further back.

 

[DJBonoBobo]

I would think that this is due to the limited and very controlled dispersion of the Neumanns, combined with the fact that you have killed many of the side reflections with absorption. I could be wrong (I often am!), but that's my hunch. What you could try with your existing setup is to switch out absorbers with good diffusers (EDIT: or just try out with some bookshelves?). I would guess that this would make a difference. Another approach is to use speakers with wide dispersion which are nevertheless well-behaved when it comes to constant directivity. The BMR speakers from Philharmonitor/ @Dennis Murphy come to mind. Difficult to say in advance how it would sound, but it would certainly be very different from the Neumanns!

And yeah, awesome setup and documentation by the way. Really impressive, and it's a service to the community to document it like you do!

Thank you. I think i will try diffusers or absorbers with scatter plates in the next room after moving. Problem is they are much more heavy and bulky than a piece of basotect and it is much less easy to simply "try them out". And i was never confident enough what kind of diffusor i should buy for such a small room/short distances.
There is this endless debate what to do with side walls (absorbtion vs. diffusion vs. reflection). Only thing i know is that i can´t allow blank walls because i´ll get horrendous flutter echo. I got rid of uncontrolled things like bookshelves a few years ago, and i think (but also could be wrong) everything was worse when i had them. Some people recommend killing everything in a small room and just use thicker absorbtion to make sure it is broadband (not only treble). Some people even have evidence that reflection from side walls is beneficial, but how do they manage the flutter echo? Some people say diffusors are not efficient or only the half-circle-type. Some say EPS is useless. Some say scatter plates are no real diffusors and condemn them...
So, i really don´t know what to believe when it comes to room treatment besides killing reflections and reducing reverberation. If i decide on one type of product i can´t simply compare it to others.

I have also never seen a proper comparison test of different acoustic modules anywhere. Considering how huge the impact is, I wonder why this gets so little attention.

 

[oivavoi]

Thank you. I think i will try diffusers or absorbers with scatter plates in the next room after moving. Problem is they are much more heavy and bulky than a piece of basotect and it is much less easy to simply "try them out". And i was never confident enough what kind of diffusor i should buy for such a small room/short distances.
There is this endless debate what to do with side walls (absorbtion vs. diffusion vs. reflection). Only thing i know is that i can´t allow blank walls because i´ll get horrendous flutter echo. I got rid of uncontrolled things like bookshelves a few years ago, and i think (but also could be wrong) everything was worse when i had them. Some people recommend killing everything in a small room and just use thicker absorbtion to make sure it is broadband (not only treble). Some people even have evidence that reflection from side walls is beneficial, but how do they manage the flutter echo? Some people say diffusors are not efficient or only the half-circle-type. Some say EPS is useless. Some say scatter plates are no real diffusors and condemn them...
So, i really don´t know what to believe when it comes to room treatment besides killing reflections and reducing reverberation. If i decide on one type of product i can´t simply compare it to others.

I have also never seen a proper comparison test of different acoustic modules anywhere. Considering how huge the impact is, I wonder why this gets so little attention.

I agree that this is not easy! I don't think there's any fixed rules here... Some authorities like Toole and Geddes are skeptical of the utility of acoustic remedies. I think Toole shows in his book that diffusors need to be laughably deep to actually work as stated (if I remember correctly). Geddes agrees with him, even though he disagrees on the utility of early lateral refections, but his solution is then loudspeakers with narrow directivity away from room boundaries. But then, what does one do in a narrow room? No clear-cut solutions!

I will only say that the whole issue of reflections depend a lot on the loudspeakers being used. My hunch would be that a wide-dispersion speaker like the BMR speakers from Dennis Murphy will work better with lateral reflections than the Neumanns, given that what they send to the sides is more similar to the direct sound.

Another point is that our brains don't work like measurement mics. So what your brain perceives may not be the same as what shows up on a frequency plot. I agree with you that flutter echo is horrible and must be avoided at all cost. I have personally found that my brain "accepts" non-perfect and uncontrolled acoustic remedies which can deal with flutter echo effectively, like book shelves or a light wall carpet on one or both walls. When opposing wall surfaces are somewhat different, it usually makes flutter echo go away IME. Even though this obviously is not broadband and uneven with regards to frequency etc, it nevertheless tones down the room signature somewhat and removes flutter echo. But it doesn't make the room as dead as full broadband absorption. So that works for me. I have never tried or experienced a room with diffusion though, I would be very curious to do that...

But yeah, it's difficult to try these out and compare A to B. So all the more valuable that guys like you experiment and document it for the rest of us

 

[ernestcarl]

I will say, however, that while the sound is certainly quite good, I am not really satisfied to this day.

I would tend to agree on the hypothesis that it may be the reduction of certain beneficial reflections too much that's limiting your satisfaction. I find it even likely the case in my room where I have mainly 4" thick acoustic foam absorbers scattered around in the walls. Which is why, far often than not, I prefer to have some kind of upmixing set in place to artificially bring back some semblance of this synthetic, room-induced sense of envelopment -- but the advantage here is it is also controllable with DSP, so I can vary the strength/amount I want without having to physically move acoustic panels around.

*try adding in a pair of KH80s as optional surrounds you can experiment or A/B with.

 

[DJBonoBobo]

Which is why, far often than not, I prefer to have some kind of upmixing set in place to artificially bring back some semblance of this synthetic, room-induced sense of envelopment -- but the advantage here is it is also controllable with DSP, so I can vary the strength/amount I want without having to physically move acoustic panels around.

*try adding in a pair of KH80s as optional surrounds you can experiment or A/B with.

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?

 

[oivavoi]

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?

I think general consensus (sort of-ish) is that upmixing is not very easy to get right manually. It needs fairly advanced DSP algorithms, and some algorithms seem to do it better than others. You want the right amount of ambience content from the signal delivered to the surrounds, not too little not too much. Old Lexicon/Logic 7 processors were apparently superb in this regard (I have one lying in the basement for a multichannel project I failed to get going), and Auro 3D gets very good reviews these days. Are many other options also. I don't know much about this, but I assume there must be some software/programs which allows it do it from your PC? There are some dedicated threads for this topic here on the forum, I believe

 

[DJBonoBobo]

I think general consensus (sort of-ish) is that upmixing is not very easy to get right manually. It needs fairly advanced DSP algorithms, and some algorithms seem to do it better than others. You want the right amount of ambience content from the signal delivered to the surrounds, not too little not too much. Old Lexicon/Logic 7 processors were apparently superb in this regard (I have one lying in the basement for a multichannel project I failed to get going), and Auro 3D gets very good reviews these days. Are many other options also. I don't know much about this, but I assume there must be some software/programs which allows it do it from your PC? There are some dedicated threads for this topic here on the forum, I believe

I will try and search for it. I would not try converting stereo to surround, though, only adding a bit of something to get an even better stereo effect. It seems a bit overkill to use a dedicated processor for this, but i don't know.

 

[youngho]

I agree that this is not easy! I don't think there's any fixed rules here... Some authorities like Toole and Geddes are skeptical of the utility of acoustic remedies. I think Toole shows in his book that diffusors need to be laughably deep to actually work as stated (if I remember correctly). Geddes agrees with him, even though he disagrees on the utility of early lateral refections, but his solution is then loudspeakers with narrow directivity away from room boundaries. But then, what does one do in a narrow room? No clear-cut solutions!

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.

 

[youngho]

Thank you. I think i will try diffusers or absorbers with scatter plates in the next room after moving. Problem is they are much more heavy and bulky than a piece of basotect and it is much less easy to simply "try them out". And i was never confident enough what kind of diffusor i should buy for such a small room/short distances.
There is this endless debate what to do with side walls (absorbtion vs. diffusion vs. reflection). Only thing i know is that i can´t allow blank walls because i´ll get horrendous flutter echo. I got rid of uncontrolled things like bookshelves a few years ago, and i think (but also could be wrong) everything was worse when i had them. Some people recommend killing everything in a small room and just use thicker absorbtion to make sure it is broadband (not only treble). Some people even have evidence that reflection from side walls is beneficial, but how do they manage the flutter echo? Some people say diffusors are not efficient or only the half-circle-type. Some say EPS is useless. Some say scatter plates are no real diffusors and condemn them...
So, i really don´t know what to believe when it comes to room treatment besides killing reflections and reducing reverberation. If i decide on one type of product i can´t simply compare it to others.

I have also never seen a proper comparison test of different acoustic modules anywhere. Considering how huge the impact is, I wonder why this gets so little attention.

Even if it's not really the correct terminology, I find it helpful to consider purely spatial dispersion (geometric diffusers) as scattering, wider spectrum temporal and spatial dispersion as diffusion (mathematical diffusers like QRD, primitive root, etc), and limited spectrum diffusion products like BAD/TAD/FAST or many MLS products like those from Vicoustic/Artnovion as hybrid, referred to by Cox/D'Antonio as diffsorption. True diffusion typically requires placement at a distance at least 3 times the lowest wavelength treated in order to cause coloration from phase anomalies, so an 20cm or 8" deep QRD (down to about 300 Hz) should be at least 3m or 9' away. Hybrid and geometric can be used much closer, but geometric diffusers become less effective when used in a pattern. Hybrid products can be considered as tuned absorbers (https://www.realacoustixllc.com/blog-3/2016/12/1/the-gud-the-bad-and-the-fast). There's no reason that a scatter plate or BAD template couldn't be placed in front of the Basotect.

Flutter echo is typically excited when sound travels back and forth perpendicularly between two parallel bare surfaces. This is not a problem when the sound source is not located between between the two parallel bare surfaces. The lateral reflections from speakers that some people find to be beneficial occur on the side walls at a point between the speaker and the listener.

Although RT is limited in utility, 0.2-0.4 seems to be a typical range that most find reasonable to spend time in and listen to music. Too dry or nearly can become unpleasant...

 

[edechamps]

A few years ago I got intrigued by this AVAA product. It looks great on paper, but unfortunately it didn't work for me. I tried 4 AVAAs in various positions in my medium-sized room. Measurements showed a very tiny difference at best - definitely not worth the expense and hassle. I returned them. Using multiple subwoofers makes more sense IMHO as that has been proven to actually work in practice.