Continue to marvel at No-Room

[Tim Link]

After BACCH I have zero interest in hearing the room. Side wall reflections as a means to widen the sound stage seems down right primitive

I think there is something important to having sound hit your ears from various angles, and this is something that can't be quite properly simulated with just crosstalk reduction and two speakers. There's the option to do what Ralph Glasgal does and add ambience channels. I've not heard a full ambience channel setup. I have heard a well treated room with two channel stereo. When all strong reflections are adequately broken into smaller reflections of more varied timing, the room starts to lose it's noticeable acoustic signature, causing the sound of the recording venue to perceptually take over and create an enveloping effect that I found quite intriguing.

I have played with adding extra channels, such as 4 channel stereo, and playing with delays and attenuation of outer channels to add stereo width and spaceousness. There really is something to it, but it's a compromise between a fuller sound, and purer sound. 2 channel with crosstalk reduction and an anechoic space is about as pure as you'll get on a 2 channel recording. It gives a wide and deep soundstage, and can feel immersive, but in a different way than when sound is really coming at you from a variety of different directions. If you want to hear the "voice of God" coming from a particular direction, you'll need an actual sound source there. I think I got that from David Greisinger. Phantom images are not without artifacts, and that makes them intriguing. I think the novelty of them is part of the magic. It's amazing to hear something in a direction where you know there isn't actually a sound source, and the HRTF isn't quite matching your ears correctly. Similarly, the real 3D world I see all around me isn't as intriguing as an apparent 3D world emerging from a flat stereoscopic image, with it's various odd effects that aren't quite congruent with reality, but kick the 3D perception into gear anyway. The media adds to the message.

Potentially recordings could be made that are synthetic representations of real spaces, with hundreds of sound sources and reflections each with a vector location associated with them. That could then be played over head tracking headphones or I. E. M. that have been calibrated to your own HRTF. In theory, a setup like that could do everything right to create a highly realistic immersive experience, allowing you to even move around in the music venue at will. For now, we have to pick our compromises, and enjoy the weird and wonderful side effects.

 

[Justdafactsmaam]

I think there is something important to having sound hit your ears from various angles, and this is something that can't be quite properly simulated with just crosstalk reduction and two speakers.

The BACCH system is capable of near perfect accurate spatial recreation of an original acoustic event. But it’s content dependent.

The system allows you to record what you are hearing through the in ear microphones used to create the custom filters. You can do a direct A/B comparison. It’s near perfect.

Of course, as it is with any playback system the sense of spatiality is dependent on the recording too.

 

[RayDunzl]

Ok, tried to dig up some old REW measurements for the speakers I'm running right now.
Here is outdoors off a deck at 4m distance. Meant to be best quasi-anechoic tuning feasible to make for a backyard guy like me.

SPL and phase, then a waterfall. No gating.

That's the first (I think) phase measurement of speakers at distance I've seen that is flat, and not wrapped or unwrapped and totally sloping down.

My MartinLogans do nearly as well, in-room, at 10 feet through the range of the panel. The crossover to the 12" woofer is 180Hz


No measurement tricks here either, just a default measre:

DRC was applied to flatten the humps, but it doesn't affect the panel phase much.

The hole at 48Hz is an out-of-phase problem (when both speakers are playing mono) caused by the asymmetrical rear of the room.

I don't notice it. Playing a bass guitar through the stereo doesn't sound off. Didn't know it was there till measured.

The room is not "treated". A pair of JBL LSR 308 located adjacent to the ML make a wrapped mess with their phase.

 

[gnarly]

Once we hear our terrible rooms, we can't unhear them. the in and out is a great way to evaluate progress in the room

Amen !

You can also use measurements to gauge progress

Another amen!

The system allows you to record what you are hearing through the in ear microphones used to create the custom filters.

A fe BACCH questions if i may...
All i can find offered on their website is a plugin........no products with in-ear microphones???

What is the area that is works for, iow how tight is the defined listening area? Seems like it has to be very tight?

Oh, latency? How much, does it vary according to settings?

Very cool but not exactly convenient getting those mics in place lol. I wish my speakers were easily transportable for some outdoor measurements.

Yeah, wouldn't have much value if hard to set up.
Fortunately, it wasn't my first attempt, and it's able to have one tripod guy wire section unhooked from its ground anchor, which allow the whole mast to pivot down to laying on the ground. A permanent 4 ch XLR snake quickly connect the mics which slip into holders. Stand back up and reclip guy wire. Connect another 4 ch snake to carry signal indoors to soundcard. Whole thing done under 10min easy.
Work indoors measuring outdoors, other than when needing to turn the spinorama

That's the first (I think) phase measurement of speakers at distance I've seen that is flat, and not wrapped or unwrapped and totally sloping down.

My MartinLogans do nearly as well, in-room, at 10 feet through the range of the panel. The crossover to the 12" woofer is 180Hz

Yeah, the only way I can avoid phase wraps is when there is direct line of flight without any strong reflections...hence outdoors off a deck.

I've seen and admired your ML in-room traces. I take it you have some relatively clean lines of flight?
That and a speaker without any xovers, other than to the 12".

 

[Sal1950]

Oh heck yes,

Beautiful view - location. Congrats

 

[Chromatischism]

I have played with adding extra channels, such as 4 channel stereo, and playing with delays and attenuation of outer channels to add stereo width and spaceousness. There really is something to it, but it's a compromise between a fuller sound, and purer sound.

This is it. You'll notice the same thing if you play with Auro3D. There's a trade-off between bigger and less pure, or a precise, focused stereo reproduction, albeit smaller. There's a sweet spot right in the middle but you're well aware of the trade-offs.

I tend to find the more pure and clear is preferable for most music. And I also feel the same about IEMs.

 

[Justdafactsmaam]

A fe BACCH questions if i may...
All i can find offered on their website is a plugin........no products with in-ear microphones???

BACCH4Mac | Theoretica Applied Physics

The ultimate audiophile 3D audio playback system for Mac. Bringing BACCH® 3D Sound to Mac-based computer audio.

www.theoretica.us

What is the area that is works for, iow how tight is the defined listening area? Seems like it has to be very tight?

It is a single user system. It’s as tight as the radiation pattern of the speakers dictate. It has head tracking. My speakers are extremely directional. With the head tracking I do not feel the least bit constrained

Oh, latency? How much, does it vary according to settings?

It’s undetectable

 

[gnarly]

Beautiful view - location. Congrats

Thank you sir

 

[LIΟN]

interesting! Good work. I also know your efforts as I've done near semi-acoustic settings outdoors and in large spaces.
Do you have any spare speakers?
If you have one, try placing it near the back 110 degrees for your LEV stimulation. That would be fun too.
If you have more spare speakers, you can adjust the intensity of the reflection directly by varying the distance, or you can mix some speakers with very little reverberation to find fun in Early Reflection after approximately 40ms.

 

[gnarly]

BACCH4Mac | Theoretica Applied Physics

The ultimate audiophile 3D audio playback system for Mac. Bringing BACCH® 3D Sound to Mac-based computer audio.

www.theoretica.us

It is a single user system. It’s as tight as the radiation pattern of the speakers dictate. It has head tracking. My speakers are extremely directional. With the head tracking I do not feel the least bit constrained

It’s undetectable

Thanks.
I'd love to play with BACCH, as I like all things audio.
That said, the idea of sound so singularly confined , that it requires head tracking is hard for me to get over though.
Heck, I've grown out of wanting stereo sweet spot listening. I need to be able to stand, move, dance with my honey, listen from down the hall..
...listen outdoors per this thread!

My speakers are pretty directional too, with a 90 degree horizonal and 60 degree vertical pattern. Being rather large, they hold horizontal pattern down to about 300Hz (pattern defined as holding to -6dB).
Best indoor solution for me so far, has been three of them in LCR, using matrixing ala Gershon and other to derive the channels. This gives a tighter central image than stereo, than stays solid over a much wider side to side listening area, but comes at the expense of a slightly reduced overall soundfield width.
It's a clarity and solid central image, vs envelopment tradeoff.

With BACCH, it seems it's more about spatial enhancement than clarity. Am i misinterpreting?

Latency ...I asked about it to understand what kind of processing/filtering it uses. Curious whether it uses just IIR, or FIR too.

 

[mglobe]

Oh heck yes, EQ for sure. Total FIR based at that, other than an IIR system high-pass.
You saw the phase flat at zero degrees across the spectrum i hope ?........no way in hell that happens on a 5-way without FIR.

Here's the measurement setup. Second mic down is set for on-axis for the main which sits completely above the railing, when on top of sub.
That on-ax mic is probably about 16 ft off the ground.
Between the 4 mics that can be placed anywhere vertically on the mast, and a spinorama for horizontal rotations, a lot of off-axis measurements can be grabbed pretty quickly. More than I can interpret sometimes !
Sub can play through the pickets...subs don't care.

The sub tuning is not done off the deck. It's done ground plane on a driveway. Then I bring it out on the deck, to mate with main.
It will measure clean on the deck, other than longer decays from house wall behind deck and ground bounce.

View attachment 377673

That's commitment! ...or something else. ;-) Seriously, I'm impressed

 

[RayDunzl]

That and a speaker without any xovers, other than to the 12".

It has something...

Low pass to the woofer.

Maybe some "tuning" for the panel.

 

[Sal1950]

I'd love to play with BACCH, as I like all things audio.
That said, the idea of sound so singularly confined , that it requires head tracking is hard for me to get over though.

There is a version called u-BACCH that doesn't require head tracking, it's available as a $1,000 plug-in for
the D & D 8c speakers. I haven't heard it but the guys at TAS seemed to like it in the 8c reviews, but then
they like everything a advertiser sells.

With BACCH, it seems it's more about spatial enhancement than clarity.

For sure its about spatial enhancement.
Maybe one day it will be included on AVR's so it can be compared against the other free spatial enhancement
software like Dolby, DTS, and Auro.

 

[audiofooled]

That's the first (I think) phase measurement of speakers at distance I've seen that is flat, and not wrapped or unwrapped and totally sloping down.

Quite rarely seen, I agree. Here's mine, about the same distance, normal living room:

Some fine speakers your Martin Logans, BTW.

 

[Justdafactsmaam]

Thanks.
I'd love to play with BACCH, as I like all things audio.
That said, the idea of sound so singularly confined , that it requires head tracking is hard for me to get over though.

The head tracking IMO is actually rather freeing. Without it I have never been able to move my head freely. But it’s not a get up and dance system.

Heck, I've grown out of wanting stereo sweet spot listening. I need to be able to stand, move, dance with my honey, listen from down the hall..
...listen outdoors per this thread!

You can still do that. You just lose the benefits of the BACCH

My speakers are pretty directional too, with a 90 degree horizonal and 60 degree vertical pattern. Being rather large, they hold horizontal pattern down to about 300Hz (pattern defined as holding to -6dB).
Best indoor solution for me so far, has been three of them in LCR, using matrixing ala Gershon and other to derive the channels. This gives a tighter central image than stereo, than stays solid over a much wider side to side listening area, but comes at the expense of a slightly reduced overall soundfield width.
It's a clarity and solid central image, vs envelopment tradeoff.

With BACCH, it seems it's more about spatial enhancement than clarity. Am i misinterpreting?

With the BACCH it’s about removing conflicting spatial cues from the cross talk. The unbounded soundstage and imaging is the most obvious improvement but it fixes other problems you wouldn’t realize were problems until you hear them fixed. You will get improved clarity and a huge reduction in listener fatigue since your brain will no longer be grappling with conflicting data. And of course with the additional optimal room correction SP you get improved tonality and clarity that is also tracked rather than based on stagnant room averages.

 

[Tim Link]

The BACCH system is capable of near perfect accurate spatial recreation of an original acoustic event. But it’s content dependent.

The system allows you to record what you are hearing through the in ear microphones used to create the custom filters. You can do a direct A/B comparison. It’s near perfect.

Of course, as it is with any playback system the sense of spatiality is dependent on the recording too.

I suspect it would do very well on a recording that you made with mics in your ears. If BACCH then cancels the repeat HRTF function from the sound crossing your ears again, and cancels the crosstalk, and removes room reflections, then you should hear pretty much what you would have heard on location. However, if you start moving your head around it's going to start to get off a little, because there's no information in the recording for how it should sound with your head pointed in different directions.

This is a similar problem to looking at a stereoscopic image while moving your head a little side to side. The expected parallax effects don't happen, and that looks really weird. To make the parallax happen correctly the image has to be active, and basically model the real scene with 3D modeling - like virtual reality. A recording would have to do the same. So it might include hundreds of sound objects, but just two playback channels could potentially recreate their virtual space for us perceptually, even as we moved ourselves around.

The audio version could be easier than the visual, because visually there's another problem, eye focus and depth of field. The VR headset has to watch your eyes to see where they are trying to converge, and change the focal settings accordingly, and blur stuff that should be out of focus. There's no audio correlation to that. If we could swivel our ears around like cats do, creating a virtual sonic space with just two channels would require tracking both our head position and the rotation of our ears.

 

[Justdafactsmaam]

I suspect it would do very well on a recording that you made with mics in your ears.

Way beyond very well. Pretty close to perfect

If BACCH then cancels the repeat HRTF function from the sound crossing your ears again, and cancels the crosstalk, and removes room reflections, then you should hear pretty much what you would have heard on location.

It doesn’t remove the room reflections. The user has to do that with room treatments and selection of speakers

However, if you start moving your head around it's going to start to get off a little, because there's no information in the recording for how it should sound with your head pointed in different directions.

That’s fixed with the head tracking

This is a similar problem to looking at a stereoscopic image while moving your head a little side to side. The expected parallax effects don't happen, and that looks really weird. To make the parallax happen correctly the image has to be active, and basically model the real scene with 3D modeling - like virtual reality.

Yup. Head tracking

A recording would have to do the same. So it might include hundreds of sound objects, but just two playback channels could potentially recreate their virtual space for us perceptually, even as we moved ourselves around.

No the recording doesn’t have to do anything just the filter. Head tracking

 

[Tim Link]

Way beyond very well. Pretty close to perfect

It doesn’t remove the room reflections. The user has to do that with room treatments and selection of speakers

That’s fixed with the head tracking

Yup. Head tracking

No the recording doesn’t have to do anything just the filter. Head tracking

I think we agree on most everything except I'm making the point that the head tracking will only keep the HRTF corrected for the sound entering your ear from the speaker. It cannot correct for the fact that your head is now oriented differently in the recorded acoustic space because the information isn't available to make that correction.

I agree it's good enough for any listening purpose I have. Although, I've never heard a full VR sound simulation, so it might be another level of revelation even beyond good crosstalk reduction.

One way this could be done on old recordings would be for software to determine the stereo left to right location of each sound in the recording, and separate the sounds out by their locations and apply the appropriate HRTF to each sound. That seems like it'd require some very heavy processing. This could, however, be done ahead of time, essentially up-mixing the 2 channel recording into maybe 20 channels or so, which are then downmixed back to 2 channels during playback, but with HRTF control still over all 20 in real time.

 

[gnarly]

The head tracking IMO is actually rather freeing. Without it I have never been able to move my head freely. But it’s not a get up and dance system.

You can still do that. You just lose the benefits of the BACCH

With the BACCH it’s about removing conflicting spatial cues from the cross talk. The unbounded soundstage and imaging is the most obvious improvement but it fixes other problems you wouldn’t realize were problems until you hear them fixed. You will get improved clarity and a huge reduction in listener fatigue since your brain will no longer be grappling with conflicting data. And of course with the additional optimal room correction SP you get improved tonality and clarity that is also tracked rather than based on stagnant room averages.

Thanks for answering my questions. I 've studied BACCH a bit more and would love to experience it.

That said, i'm pretty sure it can't be my cup of tea, due to my widely varying listening habits. Becuase I'm all over the place....the idea of head-tracking is curiosity at best.

 

[dasdoing]

I wonder why the Bose ideas (901) have been abandoned by the "excite the room" crowd.