Kvalsvoll

Too dry does not work well. In a larger room, with large horn speakers, it may not be necessary to add any absorption for early reflections, because all early reflected energy is already very low in level. I find it interesting to notice that accuracy and detail up front in the soundstage is not compromised, but rather enhanced by later reflections from the room. If all early reflections are controlled and low in level, it does not seem like a more live room destroys anything. The back of the Room2 has no absorption, part form the last ceiling absorbers. But it is still too dry sounding. The radiation pattern from the speaker focus the sound towards the back of the room, and so it is possible to do something about it by directing some of that sound back towards the listening position.

Moving the lp closer up front is possible, but the distance to the speakers gets smaller and the direct sound to reflected ratio is even greater, and that does not create more space, and the sound stage is still limited to somewhere between the speakers. The distance is closer to an equidistant triangle than what it looks like form the pictures.

I hate to say it, but you are absolutely right. It is possible to improve it, it is already better, but there is a problem with the close walls, it may be difficult because the reflections are too close. I would also like to move the system sideways, so that speakers and listening position is offset from dead center, and how to do that.. The problems with a too small space is what many have to live with, but it can be improved. The Moderate Cinema room is only 4.1m wide, and the sound in that room is quite good, with a large enveloping sound stage.

The Room2 process has different stages, where focus is on fixing one problem at a time: 1. Empty room: Analysis and listening. 2. Decay and boundary interference: Front wall absorption. 3. Early reflections: Ceiling and side wall absorption. 4. Sound stage: Adjust reflections and diffuse sound field to achieve desired sound stage. 5. Adjustments: Analyze and listen, then make adjustments as needed. Step 4 is happening now. The sound stage - placement of instruments and sounds in the 3D perspective, and perceived physical size and room dimension of the recorded event. I know how I want it to be, and it does not sound like that at all after placement of absorption for fixing early reflections and low frequency decay. I want a larger stage, extending far beyond the R/L speakers, with the recorded room extending from the speakers and seamlessly backwards into my room towards the listening position. Instruments and sound shall have physical presence and size, not only a precise location. This is achieved by adjusting the reflection pattern in the room. It is difficult in a small room, controlled directivity speakers makes it possible. This more or less like it is now - a small and "dry" rendering of the recorded event, somewhere between the speakers: This is how I want it to be:

..and that is why the "textbook" crossover does not work, but as you can see, this can be fixed. A "data-bass only exclusive audio secret" - set the delay to get the best possible impulse while retaining correct frequency domain summation. The difference is huge. The bass suddenly becomes defined, precise with a natural and powerful transient attack. The first calibration sounds like there is too much bass, and still lacking in power and impact. I find it interesting when you can actually see a correlation between what is heard and what is measured, like in these spectrograms. It is then possible to use the measurements to set up a system, and get predictable results, without needing "golden ears" to get it right. The timing is not exact through the bass range, but it may be difficult to improve this much further due to room acoustic properties and placement. The big system in the Moderate Cinema measures exact timing, and the bass is also perceived as better - more defined, more precise attack. But that system has much larger bass horns, so there may be other properties that affect the result. The dips in the 200hz-up range must be fixed, and here I can also use spectrograms to try to find out what is going on, but the decay plot will also have useful information. But there are other issues with this room that must be addressed, and after fixing those, the response in this frequency range may have changed.

@SME wanted to see spectrograms. Different analysis for each purpose, and the spectrograms are especially useful for seeing what happens in the very early time range when the signal starts. Here is a good example of what you can see in those: This is the Room2 system with 2x S6-14 subwoofers. Timing between sub system and mains are set by setting subwoofer distance, which the processor interprets as time delay on the mains. Here this is set using the typical method, the frequency response sums up correctly, and the sound is the usual bad-subwoofer-integration-bass. In this spectrogram we see why - the bass is actually delayed from the mains, causing very poor transient performance. By delaying the mains A LOT more, the timing improves, and it still sums up correctly: It is possible that this could be improved even further, but the processor does not have enough time delay available. Here is the spectrogram from the Moderate Cinema, here we see the timing is accurate:

Yes, isn't it - from 80hz.. The room is a bit lively in the lower bass range, but as you can see the decay is still reasonably smooth, there are no huge resonances. This can be improved in different ways, but with 2 subwoofers only the only option is to add more damping, and that will be difficult, so have to live with this. The bass system consist of 2 S6-14 compact horn subwoofers and amplifier with dsp - very small, small 6" driver, limited to 30hz extension, addictive bass quality. Explains the 30hz roll-off. The response is equalized in the dsp, peaks and resonances are attenuated, by looking at the decay/time-response and the frequency response. There is a hole around 60hz, which can not be filled, but the dip is reasonable. The eq improves this system quite a lot, both frequency response and decay improves very much. It could be fine tuned more accurately to get an even smoother frequency response, but that does not necessarily lead to better sound, it is important to look at both time and frequency domain. Sound good now, but those small subwoofers can only do so much, physics still applies. Here is the velocity response, actually improved a bit in the bass: Red: spl Blue: 0 degrees on-axis Brown: 90 degrees sideways Green: Horisontal

Unfortunately those reflection cancellations have to be fixed, and that will not be easy. Some of this is caused by the chair in the lp, but if you look at the graph of the freq resp, one of the measurements is with and the other without this chair, so that does not explain everything. The dip between 1k-2k is the floor, and that one is easy to fix.

It may be better. But the acoustic properties of the wall behind will have greater impact. This is a problem mainly for surround and center speakers, because they are meant for placement against a wall. The problem is worse for wall placement because the distance between the front baffle and the wall is so small that the cancellations and peaks will end up far into the midrange frequency range. For the S1.2 surround speakers the shape of the cabinet gives a smoother transition to the wall boundary, for the C1 center I designed the baffle a little wider.

The room got a new player, I installed a small laptop, in matching white color: Runs Kodi, just like the other player in the Moderate Cinema demo room:

Bass installed. 2 S6-14 subwoofers, how can anyone need more.. Frequency response improves, it is now kind of full range, at least to the unaware: Decay response, compare it to the previous I posted, with the trad hifi-speakers:

Nice effort, and it may improve, but be prepared that it also might get worse. A rectangular box actually has smoother frequency response than a sphere.

The step response can give some usable information for setting the timing, but the shape of it rarely looks nice, so it may be difficult to see what the best setting is.

Of course it does, real bass makes the big difference. Unfortunately the myth that subwoofers are not good for music still lives on, and that is due to bad set-up. Properly configured it will sound better because the overall response has less peaks and nulls, part form the obvious extended bass response.

Now I got it right, the bass sounds good and also measures quite well. Decent bass was possible to achieve with 2 subwoofers placed in front. DSP is necessary, and the delay setting on the mains is what makes it work.

I have tried several other speakers, such as these: They measure like this, decay plot 20ms lines 20ms rise time: The differences between horn and small domes are interesting, they radiate very different. With horns it is easy to achieve a low early reflection level, and since the sound is more focused on the reflective surface at the back of a room, it is also easier to preserve and control the ambient sound from the room. Testing subwoofers in the room today, so far it does not sound better with subs, which means I did not get it right.

A surface will give boundary gain when the frequency gets low enough, below the first cancellation. It will no longer act as a reflection, it has become part of the original sound source. This is why the front wall absorption is 20cm deep, and not 60cm - it absorbs from around 100hz and up, and then the wall supports the low frequency response below that. Further up in frequency, the many reflections from boundaries around the speaker and close to the listening position will sum up and tend to flatten the response. When most - but not all - of those are removed, there is a good possibility that there will be large deviations in the frequency response. Measuring with and without side wall absorption in this room reveals that the side wall absorption does more good than bad in here, so it stays. The room is nearly completed, there are a couple of issues that remains to be looked into. In general, the decay is very good at lower frequencies, but there is potential for improvement in the midrange 200hz-2khz. Fortunately, I have a selection of speakers I can measure and try, so that I can avoid compensating for problems caused by faults in one speaker design. I use decay analysis a lot when working on this, it is a very good tool to see what is going on, and it correlates well with listening impressions.

The table was partly due to design considerations, the old one did not look good in the room now. But it works fine for acoustics - it does no harm to sound, compared to a table with a large reflective surface. It is not large enough to have any significant effect on the floor reflection alone.

Acoustic table installed: http://www.kvalsvoll.com/Designs/acoustictable.htm

As a starter, I present building instructions and drawings for an acoustic absorber: http://www.kvalsvoll.com/Designs/absorber120x120x20.htm

I have posted about the new Room2 in the bass punch threshold thread, and announced that I would start a thread on the building of this room. I plan to present a complete article describing what the acoustic improvements do for the sound, from start to finish, and I also have measurements form all stages of the build process. Here is how the room looked initially, after removing subwoofers and audiophile mains, and some furniture, including the table, which will be replaced: Preview of the process:

Because they still have not installed proper sound monitoring in the studios. That is the only reasonable explanation for this. The sound designers and mixers work with what they hear, and if they can not hear or otherwise experience it, it will only be noise appearing on the spectrum analyzer (if the spectrum analyzer even shows what goes on below 20-30hz.. in a studio I have visited it does not..). If they had ever experienced the difference, every movie would have some serious ulf effects, because they would never pass on this opportunity to create something that gives such a powerful and immense effect, they would disregard the fact that most home systems would not be able to reproduce it. A system that can do this does not need 5 or 6hz extension, but it needs to be set up properly to give the right physical impact of the ulf, and you need extension well below 20hz, with full spl capacity. Compared to what they have in the studios today, even 20hz REAL extension would be a huuuuuge improvement, and we would see a lot more decent soundtracks. To the producers/sound mixers/studio owners out there: No, your sound system is not state of the art for sound reproduction. Ignorance, bad sound reproduction systems and incompetence among the producers are the reasons why we see this today.

Yes, according to above post this really has some heavy bass to challenge the soundbar.

Watched Bølgen today, sounds quite good, never too loud and nice surround presentation. Ended up using the +6dB moderate bass-eq track. I noticed clipping in one scene only, when the wave comes rolling. But I can not stop wondering whether the ulf effects on the wave would be much better if they could actually hear what they were doing in the studio.

@maxmercy, I just checked the DTS vs 7.1 tracks, you definitely do not want the DTS. The DTS is dynamically compressed and all bass is gone, what is left of the upper bass is reduced in level. To me it seems like this DTS track is intended for mobile phone speakers, you know - "..because that's what they have at home." Quiet dialogue scenes are louder, while the wave and action scenes are very reduced in level. This does not help much for dialogue clarity in action scenes, though, because they applied the compressor on the final bus, reducing the dialogue as well as the blasts and sound effects. But I really don't care about that, what is excellent is that they provide a "sound-bar" track - the DTS, and a real sound track - the 7.1, with great sound and excellent dynamics and bass. Only thing missing now is INFORMATION ON THE DISC so that people can manually select the proper 7.1 sound track. I think it is the wave that causes the clipping. I guess the wave was too big even for 24 bit audio, after all, it is only 144dB dynamic range.. When you look at the size of that wave, it makes sense, sort of. And it lasts for a long time. With bass-eq the whole house shakes, like it should. So, look forward to getting this when they eventually release it in other parts of the world, the story itself is different form the standard Hollywood disasters, there are wonderful scenery from the norwegian coastal mountain landscape, and - with bass-eq - house-shaking bass.