Suggestions on room treatment

[Thomas_A]

You need perforated masonry above 10 cm rock-wool panels as a base behind the speakers. Then add 6 cm wedged foam. You will get broadband absorption to about 100 Hz, it depends on the c-c spacing and size of the holes.

 

[Rantenti]

I can quite accurately reproduce my LP, though whenever I hear the sound different, I would move my head slightly in all directions so find the sweet spot again.

When I get back to my room later, I'll recalibrate the speakers on the Neumann control app, adjusting only for the lower resonating time in my room now with the panels. I have just found that, without the panels, telling the app about how much furniture/ carpet I have in my room which changes the estimated resonating time does change the sound in a range from "dull" to "clangy".

I guess with the panels (I'll look at some more appropriate materials later), the sound should be more correct, taking out the environmental factors as much as possible, but I need to tell the speakers about the change in my room so that the speakers can behave differently to produce the new "correct" sound as preset and intended by Neumann.

Thanks for all the advice!

 

[Thomas_A]

For a quick trial before I buy the more expensive acoustic panels, I placed some cheap 2-inch thick acoustic foam panels covering the wall behind the speakers. The sound became very dull while the bass didn't boom much anymore. I guess it's because the treble is also sucked out by the panels.

Should I remedy it with the KH80's DSP like adjusting room resonant time (I guess the speakers will then lengthen the decay time) and pushing up the treble? or is the cheap foam material the problem? Thanks.

The sound will become less "lively" and more silent when it should be silent, i.e. more dynamic. One impression is that it becomes more dull; you need to measure to know the impact. Better however is to create more broadband absorption as I described in a previous post.

 

[abdo123]

You need perforated masonry above 10 cm rock-wool panels as a base behind the speakers. Then add 6 cm wedged foam. You will get broadband absorption to about 100 Hz, it depends on the c-c spacing and size of the holes.

We're not trying to make an anechoic chamber here.

 

[Thomas_A]

We're not trying to make an anechoic chamber here.

Haha I know, but no, you will not get anechoic with just two panels, one behind each speakers. I made such panels once and they work well without being expensive, hard to make or extremely deep. 16 cm total depth (6 inch) is manageable.

 

[Thomas_A]

I can quite accurately reproduce my LP, though whenever I hear the sound different, I would move my head slightly in all directions so find the sweet spot again.

When I get back to my room later, I'll recalibrate the speakers on the Neumann control app, adjusting only for the lower resonating time in my room now with the panels. I have just found that, without the panels, telling the app about how much furniture/ carpet I have in my room which changes the estimated resonating time does change the sound in a range from "dull" to "clangy".

I guess with the panels (I'll look at some more appropriate materials later), the sound should be more correct, taking out the environmental factors as much as possible, but I need to tell the speakers about the change in my room so that the speakers can behave differently to produce the new "correct" sound as preset and intended by Neumann.

Thanks for all the advice!

Experimenting with foam behind/around the speakers as starter is very enlightening, IMO. You should however start with some default speaker settings or speakers with linear frequency response in the listening window. Experiment some more (my suggestion, build a broadband panel). Finally, make careful nessecary adjustments on the speaker/amp side (PEQ and such).

 

[abdo123]

Haha I know, but no, you will not get anechoic with just two panels, one behind each speakers. I made such panels once and they work well without being expensive, hard to make or extremely deep. 16 cm total depth (6 inch) is manageable.

From my experience wedged foam absorbs High frequencies VERY aggressively to the point that it might further color the room than actually help fixing it.

 

[Thomas_A]

I mean you don't want to aggressively absorb high frequencies like that regardless of how many panels you will end up adding.

He's better off with a diffraction plate on top. 6 inch means that the effective frequency of the panel will be close to ~550Hz, while most issues in rooms are below that not above it.

Behind the speakers will in principle only decrease those fr that either become omni (hence needing better absorption down to 100 Hz), and second, making sure that any sound coming from that side will be from the speakers only. It increases clarity, dynamics while retaining a good listening environment. A perforated panel can be made to act to 100 Hz (600 Hz for foam use only). Of course limited in effectiveness due to small size but anyhow much better than just a wall.

 

[Thomas_A]

From my experience wedged foam absorbs High frequencies VERY aggressively to the point that it might further color the room than actually help fixing it.

That is why you need a base panel with perforated masonry.

 

[abdo123]

Behind the speakers will in principle only decrease those fr that either become omni (hence needing better absorption down to 100 Hz), and second, making sure that any sound coming from that side will be from the speakers only. It increases clarity, dynamics while retaining a good listening environment. A perforated panel can be made to act to 100 Hz (600 Hz for foam use only). Of course limited in effectiveness due to small size but anyhow much better than just a wall.

That is why you need a base panel with perforated masonry.

I'm not really sure to be honest, in my experience, second reflections (>10ms) should be maintained instead of aggressively neutralized as they don't pollute transients and give the room 'air' and 'ambiance'.

 

[Thomas_A]

I'm not really sure to be honest, in my experience, second reflections (>10ms) should be maintained instead of aggressively neutralized as they don't pollute transients and give the room 'air' and 'ambiance'.

I agree for the rest of the room, completely. Panels behind the speakers are however not harmful for the room ambiance, as long as you don't cover the whole wall. Keeping hard surfaces in the center is ok, but as always, this varies from one case to another.

 

[Rantenti]

I think second reflections especially the treble were over-aggressively attenuated when I covered the whole wall behind the speakers with the acoustic panels I got (which were similar to wedge shaped ones), so the sound got even more imbalanced.

My small room size is a real limitation. Space behind speakers are scarce and the speakers need cooling space too, but I'll see what I can do. In addition, I think getting small bass traps for the corners of room should do no harm and should be easy to place.

 

[Rantenti]

I can't believe it's a already a few months since I opened this thread. I got most of the problems improved and today I was finally successful in moving the sound image to the centre!

What I did for the excessive bass "rumbling" was to strategically put some stuffed animals and acoutic panels against the bare walls and rearrange my books in my bookshelves. Books and stuffed animals seem to present a more natural (i.e. less dead) listening environment than using all acoustic panels. Opening the wooden door at a certain angle also compensated for the asymmetry of the room and diminished the bass rumble. The door proved to be a very good tool.

Then I toed in the speakers a bit, the sound improved, but the image was persistently slightly left of centre no matter even though I measure the toe in accurate within 1mm using distance to the back wall. This frustrated me for a long time until today. I found the back wall was not entirely flat! Bingo! If I measured the toe in using the distance of each corner of the speaker to the back wall, it would result in an asymmetrical toe in. I compensated for this today, and now I got a perfectly central image!

Thanks for all your ideas! I learnt a lot.

 

[DJBonoBobo]