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What makes speakers "disappear " and can it be measured?

I'm laughing at myself now. I just tried Dolby Pro Logic with a stereo signal and just left, right and center speakers hooked up to the receiver. It sounds pretty identical to my matrix setup I described earlier. No need to buy anything. Lol! It actually does a better job! Hard left panned signals are cleanly in the left channel, right in the right, and mono signals are cleanly in the middle. It does the center derivation the way I'd think it should!
 
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“I'm laughing at myself now. I just tried Dolby Pro Logic with a stereo signal and just left, right and center speakers hooked up to the receiver. It sounds pretty identical to my matrix setup I described earlier. No need to buy anything. Lol!”

Yes exactly! That’s what it does.

So I added some thoughts in the BACCH thread.

The problem is that your music was mixed by someone with a face and nose etc.

So even if there is coloration in the center image the mixing engineer has compensated for it.

Now we would need a database of mixing engineers’ HRTF and then apply a compensation based on your own HRTF.

I don’t know what else we can do.
 
“I'm laughing at myself now. I just tried Dolby Pro Logic with a stereo signal and just left, right and center speakers hooked up to the receiver. It sounds pretty identical to my matrix setup I described earlier. No need to buy anything. Lol!”

Yes exactly! That’s what it does.
Well doesn't make life too easy!
 
Well doesn't make life too easy!

So this will be fun reading. I’m not clear on the differences. All I know is Nintendo Switch could not handle anything beyond Pro Logic 2.

Also something different about it that makes it better. It’s actually a current format if you think about it.

I’m wrong about the Nintendo. Apparently the N64, PS2 and GameCube used it.

The newer formats just added channels. But the original is probably enough for our purposes.

I would personally only use the 3 front channels anyway. So that limited frequency single rear channel wouldn’t be used anyway.
 
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And you've got a big TV screen between the speakers and it's still working!
Yes, the TV is definitely not ideal.

There are RPG Modex bass trap panels covered with 1“ fiberglass behind and to the side of the R1s. But still, you can see from the FR without EQ that the room has big problems in the bass. The best results were with the speakers in the corners with significant attenuation of the deep bass.

I had RPG Abfussors made that were finished front and back that I would place in front on the TV when I was listening critically. In theory that should have made a big difference, but they were more trouble than it’s worth, could not hear much difference.

The real game changer was the Audiolense convolution filters. These made a huge difference. Mitch Barnett set them up. One runs on Roon for critical listening and it has latency, and another with very little latency runs on a small PC, this one is used for watching TV.
 
A lot of us have the display problem. As much as I think having controlled dispersion will help with that I realized that sound just goes everywhere.

I have acoustic panels all around the sides of the TV. The entire back of the TV is also covered to absorb back waves. But the front is always going to be an issue.

Maybe one day I’ll take the TV down to listen without it.

Everything in life is a compromise I guess.
 
.1 millisecond precision between drivers corresponds to about 1" of distance at the speed of sound. I have horns that work from 600Hz up to 20kHz so that entire range can come from a point source. But there are still diffraction effects around the mouth of the horn so it's not a perfectly clean time alignment. Once you have multiple drivers you can't get the perfect time alignment at every location so it ends up being a head in a vice situation. Cross talk cancellation is very finicky about precise listening location and speaker setup too. If you aren't doing crosstalk cancellation, you're hearing crosstalk no matter how accurate everything is. If you like that or can hear through it you're good to go. I prefer not hearing it even though the sound can still be very enjoyable with it and just two channel stereo. What causes speakers to disappear is the big question. I have not found that it requires excellent time alignment between drivers or extreme balance precision and speaker placement precision to make it happen, although balance is very important for a balanced sound field. It doesn't seem to require low diffraction cabinets either. And it doesn't even mean the sound is great or that the imaging is great. It just means that for whatever reason the impression becomes that the speakers have nothing to do with generating the sound you are hearing.

So even though I can't say I've achieved perfect phase response and time alignment even at one single location, the potential benefit of these reverse phase multiple speaker arrangements are minimizing of crosstalk at your ears, which reduces comb filtering and thereby improves tonality and imaging. The downside to this is that you have to sit in the exact right spot for the cancellation to work, just like you'd have to sit in the exact right spot for all the drivers to time align at your ears.

If you're not going for crosstalk cancellation but instead going for 3 channel up mix, the benefit is that the center image can remain stable and free of the two channel comb filtering as you move around the room because the center image signal is removed from the left and right speakers and played solely through the center speaker.

No matter how accurately you do it, two channel playback has some inherent issues, so that's the reason for trying out all these methods. It's to find out what they sound like and see if I prefer it or not. Ever since I heard two channel playback with crosstalk eliminated I've not been fully satisfied with traditional two channel playback that allows the sound from both speakers to hit both ears simultaneously with slight time delay when trying to create a center image. A real center image should send one stream of sound to each ear, not two signals with slight time delay and different HRTF, neither of which correspond to a sound coming from straight ahead.

With standard 2 channel playback the only time you won't hear direct comb filtering between the speakers is when the signal is hard panned to the left or right speaker. Those will be the situations where the clarity and coherence will be the highest. With the three channel setup it's the opposite. The greatest imaging clarity is in the center of the sound stage. I think this sounds better and makes more sense. Imagine a camera lens that is blurry in the middle and sharp around the edges of the picture vs a lens that is sharp in the middle and blurry around the edges. Some may prefer the sharper around the edges but for most pictures I don't.

Thank you for your intensive reply to my inquiry, also thank you for your visits to my posts on my project thread. I understand your various points, even though I feel the "degree of SP disappearance" would be greatly dependent on subjective demands and impressions, and it would be also greatly dependent on our room acoustics.

In any way, our interests and experiments/experiences would be highly valuable in deepening our knowledge and providing further preferable options on this issue, I believe.

Very fortunately in my latest setup, the SP disappearance remains unchanged even if I move my head within about 0.7 m (70 cm) from the best listening position, left-and-right, up-and-down, forward-and-backward. This means both I and my wife can enjoy it sitting together side-by-side on our listening sofa.

Thank you again for your comments and discussion in detail.

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These TAD R1s do a pretty good job disappearing. Point source design, 66,000 tap Audiolense convolution filter EQ, extensive room treatments of most 1st reflections

Really nice setup! TAD R1s has been always one of my "dream" speakers; I once auditioned it at quite a nice audio showroom in Tokyo, and I felt the same as you are enjoying now.
 
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So this will be fun reading. I’m not clear on the differences. All I know is Nintendo Switch could not handle anything beyond Pro Logic 2.

Also something different about it that makes it better. It’s actually a current format if you think about it.

I’m wrong about the Nintendo. Apparently the N64, PS2 and GameCube used it.

The newer formats just added channels. But the original is probably enough for our purposes.

I would personally only use the 3 front channels anyway. So that limited frequency single rear channel wouldn’t be used anyway.
That explains the differences between the various Dolby matrixes pretty well. I'm surprised at how well the Pro Logic keeps the channels cleanly separated while neatly extracting the center image signal and moving it to the center speaker. After listening for a while last night and comparing it to standard two channel I'm getting a sense of a very dry, almost too clean sound. When I switch back to stereo it seems a little more open in some ways. It's a tough call because the Dolby definitely improves some things but I get the impression there's a slight cost involved with sound quality. It's either that or it's just technically what happens when the channels are so neatly defined. I'm going to have to listen to tracks that I've mixed with my matrix vs the Dolby ProLogic tonight, if I get a chance. My method creates a lot of interference on side channels. A pure left signal ends up playing in the left speaker, the center speaker, and inverted on the right speaker. On Dolby it just plays in the left speaker, like it technically should.

I think what this does is create a damped room sound. If a centered image is playing on two channel stereo it's playing from two speakers, which are likely causing more room reflections as they are nearer the side walls and, of course, there are two of them. If that signal is moved to a single center speaker then there's going to be less room interaction, making the sound seem more damped. I've read that mono recordings played back on stereo speakers are generally preferred over mono played back on a single speaker, even though the center speaker is technically more correct. Perhaps with this Pro-logic setup I really do need to put in the rear channels and let them add some ambience.
 
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Thank you for your intensive reply to my inquiry, also thank you for your visits to my posts on my project thread. I understand your various points, even though I feel the "degree of SP disappearance" would be greatly dependent on subjective demands and impressions, and it would be also greatly dependent on our room acoustics.

In any way, our interests and experiments/experiences would be highly valuable in deepening our knowledge and providing further preferable options on this issue, I believe.

Very fortunately in my latest setup, the SP disappearance remains unchanged even if I move my head within about 0.7 m (70 cm) from the best listening position, left-and-right, up-and-down, forward-and-backward. This means both I and my wife can enjoy it sitting together side-by-side on our listening sofa.

Thank you again for your comments and discussion in detail.



Really nice setup! TAD R1s has been always one of my "dream" speakers; I once auditioned it at quite a nice audio showroom in Tokyo, and I felt the same as you are enjoying now.
These are great speakers. I had the TAD M1s before these, and frankly they were even better than R1s as they were a 4 way. Unfortunately almost all M1s cracked, TAD gave me a full refund, which I used to buy Magico Q5s. I didn’t like the Q5s at all, sold them and went back to TAD. Andrew Jones is a great engineer and an even better friend. My R1s are biamped using a Pass XVR1 that Andrew set up, and 4 Benchmark AHB2 amps. They sound really great. Incidentally Andrew’s brother was one of the main designers of the AHB2.
 
That explains the differences between the various Dolby matrixes pretty well. I'm surprised at how well the Pro Logic keeps the channels cleanly separated while neatly extracting the center image signal and moving it to the center speaker. After listening for a while last night and comparing it to standard two channel I'm getting a sense of a very dry, almost too clean sound. When I switch back to stereo it seems a little more open in some ways. It's a tough call because the Dolby definitely improves some things but I get the impression there's a slight cost involved with sound quality. It's either that or it's just technically what happens when the channels are so neatly defined. I'm going to have to listen to tracks that I've mixed with my matrix vs the Dolby ProLogic tonight, if I get a chance. My method creates a lot of interference on side channels. A pure left signal ends up playing in the left speaker, the center speaker, and inverted on the right speaker. On Dolby it just plays in the left speaker, like it technically should.

I think what this does is create a damped room sound. If a centered image is playing on two channel stereo it's playing from two speakers, which are likely causing more room reflections as they are nearer the side walls and, of course, there are two of them. If that signal is moved to a single center speaker then there's going to be less room interaction, making the sound seem more damped. I've read that mono recordings played back on stereo speakers are generally preferred over mono played back on a single speaker, even though the center speaker is technically more correct. Perhaps with this Pro-logic setup I really do need to put in the rear channels and let them add some ambience.
Wow I really admire your research and dedication on this.

Now I understand what you meant by inverted phase signals.

So if had to picture this in my head the left only signal would present from the midpoint to the left speaker as opposed to the technically correct left speaker only presentation.

My brain is a little bit fried with a lot of things taking up my thinking space.


However I very curious to learn of your results especially how things pan from left to right in both setups.

Yes I think using a treated room changes some of the listening impressions.

In a lot of senses I think we once we go beyond a studio setup at home we are now dabbling in enhancement territory and things go back to being subjective. It’s like we started with subjective then ASR truths took us into firmly objective territory once there we feel like venturing from a known reference to pick out what we like subjectively.

It sort of reminds me of child development theory where the parent is said to be a stable home base from which a child can explore and when things get tough they can return to the safe place a good parent provides.

ASR objective truth is that good parent.
 
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These TAD R1s do a pretty good job disappearing. Point source design, 66,000 tap Audiolense convolution filter EQ, extensive room treatments of most 1st reflections
Wow, huge speakers relative to the room size, and tucked away towards the wall and corners. Going by the pictures alone, I would have thought it's one of those examples how not to do. Goes to show that dogmas are not always right, and also that room treatment matters more than room size?

Did you get a chance to see which treatment matters how much, or was it all done at once?
 
Wow, huge speakers relative to the room size, and tucked away towards the wall and corners. Going by the pictures alone, I would have thought it's one of those examples how not to do. Goes to show that dogmas are not always right, and also that room treatment matters more than room size?

Did you get a chance to see which treatment matters how much, or was it all done at once?
The R1 cabinet is big but it’s just 2 10” woofers and a 6” coax. The actual drivers are not that close the walls. And the walls are heavily treated so they should not reflect much above 200hz or so. Also the speakers are toed in to minimize reflections.

That said, without DSP it would be impossible to have them where I have them. I tried many locations. In the end I found the corners worked best because it minimized the nulls and yet the peaks can be tamed with DSP. Also, wider is better with the TADs. You want an equilateral triangle if possible.

Imaging from left to right is pinpoint accurate. On some recordings you perceive sound emanating outside the walls or even behind you. And the center image is rock solid with the same timbre as either hard right or left.

The coax of the TAD is good at imaging and it’s reproducing everything over 250hz. But it can be a little bright, especially if they are toed in pointing just in front of the listener. The DSP takes care of this brightness nicely.

I cannot recommend Mitch Barnett of Accurate Sound more. He’s absolutely the best at designing custom convolution filters. He’s written books on this. The R1s are great right out of the box, but properly done DSP takes them to another level.

One trick my speakers have is that Andrew Jones was able to work out settings on a Pass XVR1 so the woofer’s stock passive LPF is bypassed and the LPF is done by the Pass. The allows the woofers to be directly connected to their amplifier. The LPF in the R1 is a bit of a bottleneck with an iron core inductor. The HPF for the coax is stock, but we are also using the Pass HPF to roll of some bass for the coax.

Andrew was able to work all this out so the phases play nice with each other. So this a hybrid biamp. In total it uses 4 AHB2s all in mono. Two per speaker.

Most owners of AHB2s say they sound better in bridged mono. I concur. Also in my case each coax has an AHB2 dedicated to it. That amplifier is not providing any power below 250hz. Also the deep bass had to be attenuated 12 db or so, and therefore the woofers and their amps are operating very efficiently The end result is the dynamics are very much unlimited.
 
The R1 cabinet is big but it’s just 2 10” woofers and a 6” coax. The actual drivers are not that close the walls. And the walls are heavily treated so they should not reflect much above 200hz or so. Also the speakers are toed in to minimize reflections.

That said, without DSP it would be impossible to have them where I have them. I tried many locations. In the end I found the corners worked best because it minimized the nulls and yet the peaks can be tamed with DSP. Also, wider is better with the TADs. You want an equilateral triangle if possible.

Imaging from left to right is pinpoint accurate. On some recordings you perceive sound emanating outside the walls or even behind you. And the center image is rock solid with the same timbre as either hard right or left.

The coax of the TAD is good at imaging and it’s reproducing everything over 250hz. But it can be a little bright, especially if they are toed in pointing just in front of the listener. The DSP takes care of this brightness nicely.

I cannot recommend Mitch Barnett of Accurate Sound more. He’s absolutely the best at designing custom convolution filters. He’s written books on this. The R1s are great right out of the box, but properly done DSP takes them to another level.

One trick my speakers have is that Andrew Jones was able to work out settings on a Pass XVR1 so the woofer’s stock passive LPF is bypassed and the LPF is done by the Pass. The allows the woofers to be directly connected to their amplifier. The LPF in the R1 is a bit of a bottleneck with an iron core inductor. The HPF for the coax is stock, but we are also using the Pass HPF to roll of some bass for the coax.

Andrew was able to work all this out so the phases play nice with each other. So this a hybrid biamp. In total it uses 4 AHB2s all in mono. Two per speaker.

Most owners of AHB2s say they sound better in bridged mono. I concur. Also in my case each coax has an AHB2 dedicated to it. That amplifier is not providing any power below 250hz. Also the deep bass had to be attenuated 12 db or so, and therefore the woofers and their amps are operating very efficiently The end result is the dynamics are very much unlimited.

I can easily guess and understand the pros/merits of driving the SP drivers directly by dedicated amplifiers eliminating all the LCR network and passive attenuators, since I implemented the same in my present setup of stereo 5-way (L&R 10 channels) as summarized here.

I am quite envy for your setup with TAD R1s; I am intensively "dreaming" that I could have TAD R1s in my listening room and implement the similar configurations you are enjoying now...
 
I can easily guess and understand the pros/merits of driving the SP drivers directly by dedicated amplifiers eliminating all the LCR network and passive attenuators, since I implemented the same in my present setup of stereo 5-way (L&R 10 channels) as summarized here.

I am quite envy for your setup with TAD R1s; I am intensively "dreaming" that I could have TAD R1s in my listening room and implement the similar configurations you are enjoying now...
That's a very neat system you've put together. Much more ambitious than mine from a DSP crossover perspective. Initially I was going to use something like the OKTO or the Exasound S88, but Andrew convinced me to implement the crossover in the analogue domain and keep things as analogue as possible. He's a brilliant engineer and he has all the anechoic and electronic measurements for the R1, which he designed, so I was very fortunate to have his support. And I was lucky to find a mint XVR1, of which there are not many. And even more lucky that Andrew found a combination of settings for the XVR1 that got us to where we needed to be so we could keep the coax HPF intact.

Once I set this up, I measured the speakers and the transition from the woofers to the coax was flawless, but the room was still a mess. I tried to find solutions in the analogue domain, using mastering parametric EQs, but it just was not possible. That's when I turned to Mitch Barnett and we measured the room and implemented the convolution filters.

My big surprise is how wide the sweet spot is with the convolution filters. You would think they only work for one location, but the system sounds good pretty much everywhere in the room.
 
That's a very neat system you've put together. Much more ambitious than mine from a DSP crossover perspective. Initially I was going to use something like the OKTO or the Exasound S88, but Andrew convinced me to implement the crossover in the analogue domain and keep things as analogue as possible. He's a brilliant engineer and he has all the anechoic and electronic measurements for the R1, which he designed, so I was very fortunate to have his support. And I was lucky to find a mint XVR1, of which there are not many. And even more lucky that Andrew found a combination of settings for the XVR1 that got us to where we needed to be so we could keep the coax HPF intact.

Once I set this up, I measured the speakers and the transition from the woofers to the coax was flawless, but the room was still a mess. I tried to find solutions in the analogue domain, using mastering parametric EQs, but it just was not possible. That's when I turned to Mitch Barnett and we measured the room and implemented the convolution filters.

My big surprise is how wide the sweet spot is with the convolution filters. You would think they only work for one location, but the system sounds good pretty much everywhere in the room.
If I was doing this over, I probably would get the TAD CR1s and add subwoofers. They are much less money than the R1s. The CR1 is Andrews Jones personal favorite.

If you want a TAD sound for a Pioneer price your best bet is to look for used Pioneer EX speakers. Andrew also designed these and they are very similar to the less expensive TAD speakers that sell for a fortune these days. They have a coax that is similar to what is in the CR1 and R1. The tweeter is beryllium and the midrange is magnesium I believe. I had they while I was waiting for my R1s. A friend of mine now has them in a home theater as they also made a center channel. They are excellent and they come up cheap in the used market every now and then.

Your Yamaha speakers are real classics. I always wanted a pair but back then I couldn't afford them. There aren't many beryllium midrange drivers our there. I believe Yamaha and TAD are the only ones.

The other bargain is the ELAC Navis line that Andrew designed. These are $2000 active 3 ways with a coax mid/tweeter. I bought my son a pair and added a sub. He's in heaven.
 
That's a very neat system you've put together. Much more ambitious than mine from a DSP crossover perspective. Initially I was going to use something like the OKTO or the Exasound S88, but Andrew convinced me to implement the crossover in the analogue domain and keep things as analogue as possible. He's a brilliant engineer and he has all the anechoic and electronic measurements for the R1, which he designed, so I was very fortunate to have his support. And I was lucky to find a mint XVR1, of which there are not many. And even more lucky that Andrew found a combination of settings for the XVR1 that got us to where we needed to be so we could keep the coax HPF intact.

Once I set this up, I measured the speakers and the transition from the woofers to the coax was flawless, but the room was still a mess. I tried to find solutions in the analogue domain, using mastering parametric EQs, but it just was not possible. That's when I turned to Mitch Barnett and we measured the room and implemented the convolution filters.

My big surprise is how wide the sweet spot is with the convolution filters. You would think they only work for one location, but the system sounds good pretty much everywhere in the room.

>My big surprise is how wide the sweet spot is with the convolution filters.

I again can guess and understand this point, since I am experiencing the same with my setup having the latest DSP configurations including the precision time alignment.

BTW, last week at Tokyo International Audio Show, I could intensively auditioned Fyne Audio F1-12S (about 1 hour just for me!) playing my latest "Audio Sampler Playlist" (please refer to here and here). This time F1-12S is/was the only speaker very much attractive/impressive for me among many other SPs I briefly auditioned at the Show.

F1-12S has rather high sensitivity of 96 dB (2.83 Volt @ 1m, nominal impedance 8 Ohm), and I assume it would also well fit my home use with my (our) amplifiers.

I sent my inquiry to the import dealer of F1-12S for possibilities of LCR network bypass options (I mean separate 3 pairs of SP binding posts bypassing LCR networks). This is now my another "dream project".
 
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If I was doing this over, I probably would get the TAD CR1s and add subwoofers. They are much less money than the R1s. The CR1 is Andrews Jones personal favorite.

If you want a TAD sound for a Pioneer price your best bet is to look for used Pioneer EX speakers. Andrew also designed these and they are very similar to the less expensive TAD speakers that sell for a fortune these days. They have a coax that is similar to what is in the CR1 and R1. The tweeter is beryllium and the midrange is magnesium I believe. I had they while I was waiting for my R1s. A friend of mine now has them in a home theater as they also made a center channel. They are excellent and they come up cheap in the used market every now and then.

Your Yamaha speakers are real classics. I always wanted a pair but back then I couldn't afford them. There aren't many beryllium midrange drivers our there. I believe Yamaha and TAD are the only ones.

The other bargain is the ELAC Navis line that Andrew designed. These are $2000 active 3 ways with a coax mid/tweeter. I bought my son a pair and added a sub. He's in heaven.

Thank you for further kind information! You are adding several more in my "dream projects"...
 
Adding more speakers does not necessarily make the speakers "disappear" any better as perceived sound sources for me. Not so far in my experience. With all my multi-channel experiments the speakers somehow give themselves away even though I enjoy the sound quality and I get an impression of sounds coming from behind and all around the speakers. Still, somehow there are coherent cues getting to my brain that allow me to identify the speakers as also being sound sources. On the other hand, cross talk elimination did cause the speakers to disappear for me, so somehow that setup is disrupting the cues that let me identify the speakers as sound sources. So in a nutshell, any setup that confuses our hearing well enough or deprives it of enough cues about the speaker's actual location can cause the speakers to do the ventriloquist act.

One way I've experienced a sonic disappearing act is with a highly directional speaker pointing away from me towards a wall. In that case I perceived the sound source as being a point on the wall because that reflected sound was sufficiently louder than the sound reaching me off-axis directly from the speaker. So this leads to the crazy idea of pointing some highly directional speakers toward the front wall, away from yourself, so that you hear the stereo image projected on the wall and bounced back at you. There could also be absorption between yourself and the speakers to further block any direct sound coming from the speakers to you. This could be a good way for getting sound to seem to come from a big screen TV while opening up entirely new options for speaker placement. They could be off to the sides, firing forward, or even over head from a center fixture, firing in slightly different directions.

We're getting into Bose 802 territory here. I wonder if they do a good disappearing act.

Update: I just did a quick experiment with my cell phone playing music and surrounding it with absorbers, leaving one side open facing the wall on the other side of the room. It works. Turns the wall into a giant cell phone.
 
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