For the sake of completeness, I took some new measurements of the main panels. Horizontal off-axis looks smooth to me(violet trace is the reverse notch which is broad, deep and symmetrical, signs for good phase tracking in the crossover) and vertical is also reasonable(the most off-axis is about 30 degrees).
There are, however, some things that worry me:
1. the response on the back of the baffle has a huge dip around 3-4 kHz(not shown in the graphs) due to the asymetrical response of the small 3" drivers. Because the back wall reflection are quite strong, this might be well significant for the depth perception. One way to address would be to reverse some of the drivers - or add new ones - to face the back side and "fill" the hole.
2. the dipole tweeter Neo3 does not show true dipole behavior because the baffle is to wide and has some 5cm wings. That leads to a higher than should be dispersion in the highs. One solution to this is John's NaO Note (I think) with the dipole on a very narrow baffle. Another could be a waveguide on the tweeter.
3. since we're on absolute phase
both bass/mids and mids/highs crossovers are LR2 requiring electrical phase inversion. I kept the bass with normal polarity and reverse the electrical phase on the mids. I could do it the other way round and invert the polarity on the bass. Would you expect audible differences ?
Horizontal&reverse notch:
Vertical:
There are, however, some things that worry me:
1. the response on the back of the baffle has a huge dip around 3-4 kHz(not shown in the graphs) due to the asymetrical response of the small 3" drivers. Because the back wall reflection are quite strong, this might be well significant for the depth perception. One way to address would be to reverse some of the drivers - or add new ones - to face the back side and "fill" the hole.
2. the dipole tweeter Neo3 does not show true dipole behavior because the baffle is to wide and has some 5cm wings. That leads to a higher than should be dispersion in the highs. One solution to this is John's NaO Note (I think) with the dipole on a very narrow baffle. Another could be a waveguide on the tweeter.
3. since we're on absolute phase
both bass/mids and mids/highs crossovers are LR2 requiring electrical phase inversion. I kept the bass with normal polarity and reverse the electrical phase on the mids. I could do it the other way round and invert the polarity on the bass. Would you expect audible differences ?Horizontal&reverse notch:
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Vertical:
An externally hosted image should be here but it was not working when we last tested it.
I would have gone also lower, but one single Neo3PDR in dipole does not have much bottom end (rising response). It can be shaped, but then you sacrifice sensitivity of the midrange array which I feel is responsible for much of the way the speakers sound as they do. Furthermore, the 3" drivers do allow a high crossover point (they're fullrange after all). In the end, by tapering the array and actually crossing the tweeter to only 2 of his immediate neighbors 3" fullranges at 4khZ seems a good compromise.
An intersting option for both crossing lower and getting a more narrow dispersion of the tweeter would be a waveguide.
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I think to concentrate on one aspect of your audio system is a mistake.
The quality of reproduction required to get a focussed sound stage is best achieved with a holistic approach to the system.
For example. You could spend an age perfecting your speakers only to find that the weak link was the fact that you had not bothered with decent supports for the rest of your equipment.
Once I spent a long time building a modified AR turntable, and then found that I was getting more accoustic feedback thru my pre-amp that was on a wooden cabinet!
You probably know what are the various techniques that are used by people to improve their audio systems. Make sure you are implementing as many of them as you can!
Some DIY aspects that I concider with my home system are
RF rejection and grounding
Equipment supports - Source - Electronics and Speakers
Cabling
Electronic mods - Mostly re-capping, op amps and simple mods.
All these and more, will make a positive difference, and get you closer to your goal.
Regards Xoc1
You concepts about absolute and relativeness seems to be absolutely relative.
Anyway enjoy with anything you might consider relative or absolutely OK...
Phase tracking at 4khz... Piece of wishfull tracking...
Tongue in cheek or would you care to enlighten us?
I'm pretty new to this audio deal, but I'm finding that relative phase is quite important. I'm using the same tweeter as the OP, at about 3.5k if I recall........
A LR24 xo at 3.5k to get a flat response on my listening axis (about 20 deg) would give me pretty measurements, at that axis, but sounded.......meh. Time alignment, electrical filter slope, and careful placement of the xo frequencies to bring close phase tracking? A whole new speaker......
Thanks for the graphs. My guess is that the extra energy circa 500-100Hz and the lack of rearward energy near 3K isn't helping. If you have any way to EQ out that midrange bump, you should try it. It's not much of a bump, but your ears are pretty sensitive in that range and there is a lot of energy in that octave in recorded music. Making it a dip may even help. Worth a quick test if you can.
The FR on the back is going to be harder.
The FR on the back is going to be harder.
Imho, early reflections side effects typical of "kitchen made" ( and friends...
) measurements. Whishfull windowing is of little help to avoid them . Such measurements in my experience are pretty useless under 1khz.Any way what all this has to do with depthhhh....
...that is a condensation of what I think i have read over a long period of time. Start with Haas effect... much has been written both here on DiyAudio and in journal papers on the perception of two channel sound.
@ someone else - ribbons work very well in many instances for producing the proper cues, as do ESLs...
_-_-bear
I see no reason why you shouldn't have a hand in controlling how much of the back wave is reflected rather than leaving it up to the room. I find that imaging can improve with reduced reflections.
Or their narrowing dispersion compared to a dome may reduce the room influence.
How did you come to this conclusion?since we're on absolute phase
Is there any effect on the imaging when you switch between 2nd order and 4th order on the mid/tweeter crossover? I'd imagine the reduced overlap might be advantageous in that frequency region. Only guessing here.
I agree as I have found more variations in perceived depth with source/amps than with speakers.
Must be that...
... And then we might also investigate the sicoacoustics of the guys who believe that speakers are always OK vs the perception of those who find that electronics don't matter a lot...
Imho, early reflections side effects typical of "kitchen made" ( and friends...
Any way what all this has to do with depthhhh....
OK, so: yes, you are right, the measurements are done "in kitchen" - this time. But I doublechecked them several times outdoor in the past, and, while the small scale bumps are indeed reflections, the 1/3 octave or so average is relatively accurate also in the range <1kHz. I believe the previous comment was about the higher wideband energy in the 500-1kHz that is, the low Q "bump", which is real, rather than the small bumps, which are reflections.
And yes, there might be some relationship between tonal balance and depth perception, because the spectral composition of a sound is a depth clue and needs to be right (an instrument/ voice sounds different from different distances)
Happier now ?
Sorry, I was not to clear on that. What I am talking about is: crossover between bass and mids is active LR2. LR2 outputs are 180 degree out of phase which needs to be brought back in phase by reverting one of the outputs - either mids or bass.
What I meant is that i kept the bass with normal polarity (impulse response going up positive ) and mids with reverse electrical polarity (impulse going down, negative). The question was if someone thinks that doing it the other way round would make a difference - i.e. if absolute phase is audible
I can't test that easily: while the bass/mids crossover is active, the mids/highs crosover is passive. I might give it a try in the future tho, as higher -order would allow ths tweeter to be crossed lower.
There's one big factor in distance perception that has not been mentioned yet, and that's the direct-to-reverberant ratio of the sound. A very high ratio may be identified by your brain as a cue that the source is close (no matter what's in the recording). This measure has been shown to be very important to distance perception in rooms.
I had never considered this as an important factor, until recently. At home I have dipoles positioned 2,5 meters from the rear wall in a fairly reverberant room. The depth perception with classical recordings for example is excellent. However, when I listened to the same recordings on Keyser's system (highly directional waveguide system and absorbed first reflections), I did not experience the same depth perception. I've listened to it on numerous occasions and in a different room with no absorbers, and different electronics. It's one of the best systems I've ever heard, but this was the only thing I found it lacked somewhat.
If possible, you should try to avoid early reflections (< 10 ms). If you want to have a better depth perception however, you'll somehow have to raise the reverberant sound in the room (but don't ask me how, it all depends on your situation). The strange thing is that the reverberant sound does not seem add a "fixed" amount of depth. You can still clearly hear depth differences between recordings.
I had never considered this as an important factor, until recently. At home I have dipoles positioned 2,5 meters from the rear wall in a fairly reverberant room. The depth perception with classical recordings for example is excellent. However, when I listened to the same recordings on Keyser's system (highly directional waveguide system and absorbed first reflections), I did not experience the same depth perception. I've listened to it on numerous occasions and in a different room with no absorbers, and different electronics. It's one of the best systems I've ever heard, but this was the only thing I found it lacked somewhat.
If possible, you should try to avoid early reflections (< 10 ms). If you want to have a better depth perception however, you'll somehow have to raise the reverberant sound in the room (but don't ask me how, it all depends on your situation). The strange thing is that the reverberant sound does not seem add a "fixed" amount of depth. You can still clearly hear depth differences between recordings.
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That goes a bit in the direction Linkwitz suggested here, where he is excited by the front wall : ORION++
He also stresses the importance of a "correct" tonal balance front/back - that is, the reverberant field which by default exists in a dipole speaker needs to be properly balance (currently not my case, I have a deep notch in the back response)
I think I will need to place my speakers further off from the wall and do some tests in positioning.
: ORION++He also stresses the importance of a "correct" tonal balance front/back - that is, the reverberant field which by default exists in a dipole speaker needs to be properly balance (currently not my case, I have a deep notch in the back response)
I think I will need to place my speakers further off from the wall and do some tests in positioning.
For the purpose of this discussion, I think it's reasonable to say no.
Maybe it's I that should have been more clear. A combination of physical effects...the differing and varying acoustic phase of the drivers, any inter-driver delay, as well as correcting the differing responses may add up to more phase difference than an LR2 on its own. Maybe electrically in phase is correct...and maybe neither is correct.
I see what you mean. Measurements showed that 180 out of phase is correct in the 200Hz LR2 crossover - there is a good healthy notch if you put it electrically in phase
Physical driver offset is negligible compared to wavelength (at 200Hz, that would be 1.7 m) and phase shifts due to drivers/baffle roll-off are actually corrected by shelving it back to flat. So again, my next steps will be:
- try further away from walls/ less early reflections
- experiment with tonal balance by removing the "warmth" in the 500-1000 Hz
- fix the backwards notch by either crossing tweeter lower or adding a "filler" driver on the back
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