Basic observation for practical DIY loudspeaker seems to be that: speaker tuned with far field measurements doesn't sound the same near field. Conversely, speaker tuned to near field doesn't sound the same in far field.
Well, still I suspect the sound is probably rather fine mostly, with kind of minor differences with the distance. While this is fine for home listening I'm afraid it makes fatigue when working with sound. If the sound keeps on changing depending on where one listens at and the brain is constantly thinking I should EQ this or that. Perhaps professional sound workers can get past this, but I've found this to be the worst distraction in hobby mixing as I can't be sure if I'm listening at right spot, at the same spot as 15 minutes ago, or at the same spot as previous song or previous session was. Sound of even small near field monitors changing constantly depending on where the head is at is a serious distraction for me. Perhaps I'm concentrating on wrong things which makes it so apparent and not a problem for real pros with permanent setups and routine work.
Well, still I suspect the sound is probably rather fine mostly, with kind of minor differences with the distance. While this is fine for home listening I'm afraid it makes fatigue when working with sound. If the sound keeps on changing depending on where one listens at and the brain is constantly thinking I should EQ this or that. Perhaps professional sound workers can get past this, but I've found this to be the worst distraction in hobby mixing as I can't be sure if I'm listening at right spot, at the same spot as 15 minutes ago, or at the same spot as previous song or previous session was. Sound of even small near field monitors changing constantly depending on where the head is at is a serious distraction for me. Perhaps I'm concentrating on wrong things which makes it so apparent and not a problem for real pros with permanent setups and routine work.
Last edited:
Tmuikku,
Feels same as you about the constantly changing sound and i can add to that when there is a (big) mixing desk in front of you it even worsen things...
Eventually you have to be used too it ( and the numbers of monitirs usually availlable help to make an average reference).
Feels same as you about the constantly changing sound and i can add to that when there is a (big) mixing desk in front of you it even worsen things...
Eventually you have to be used too it ( and the numbers of monitirs usually availlable help to make an average reference).
The reasons why I say that it is necessary is because without coupling I will hear the separated drivers. The coupling of the drivers due to 1/wavelength optimal spacing or nearing 1/4wl, makes it a non issue. Maybe this is a larger issue with larger speakers such as mine.
Now you have me questioning the notion lol I don't recall having issue with the Altecs that made me fall in love with horn speakers in the first place 🤔 Then again judging by this picture I was not sitting at 1m....I do recall moving them closer to test out 1m but I cannot say what was on my mind as this was several years ago.
Last edited:
As long as they are stacked vertically, one above the other, I doubt that, as our hearing is generally bad at discriminating the elevation of a sound source.
Such loudspeaker may sound different at 1m and deeper in the room but that doesn't mean it can't be optimized to be listened to at 1m, if that's the requirement.
I really dislike the head in vice reference,...only because I heard that term so many times before owning the large horn, and then after owning the large horn, it hasn't not been my experience. Maybe I am taking the term to literally. Small head movements resulting in radical changes? Not even close, but, it very well could be the large dimensions that make me appreciate the 1/4wl spacing, or at least near, as I am off by an inch or so.
I will experiment more and comment back. When I experimented with raising the XO, my main issue was being able to tell which source covered which frequencies. At that time I had the horn on top of the 15" mid woofer. It is possible that with further optimization, the situation would have improved.
From top to bottom as a two way, the speaker is 46" tall. CTC is
@mabat could it be that the large CTC is playing a factor, that would lead to my previous thoughts about 1/4wl spacing? The close proximity and large vertical size would stress the issue of optimal ctc spacing, I would think.
I am not trying to be argumentative..... we have talked about this topic several pages ago....and my discrimination to elevation, seems to be more sensitive than others seem to experience. I am not claiming to have super powers lol, I just don't want to pretend like I can't hear what I hear. I remember distinctly moving the crossover upwards and the space the horn occupied changed. I also remember it working much better than I thought it would, but non the less, the 200hz sounded much better.
Thank you for your words, I think I should investigate this more. Configured as a 3 way (2way with sub
) I was really impressed with how well things worked (even with the higher cross over) given the large distances. Its just that I kept coming to the conclusion that 200hz sounded much better.I want to try again after I get AudioLense running so that Voicing changes will run much faster, instead the cumbersome manual adjustments.
Last edited:
I think that is reality......that diffraction is kinda a virtual driver in it's own right, with variable summations with the real drivers, based on angles and distance.
The synaudcon article you linked got me thinking that way some time ago....
True. But that's also true in my opinion, for real drivers even if there were no reflections/refractions.
The acoustic definition of near-field vs far-field, is far-field is when phase has settled down between drivers and the entire frequency range obeys the inverse square law, falling 6dB per doubling of distance.
Inside that distance is near-field and a plain old jump ball imo.
Yes, one can tune specifically to a spot in the near-field, but the area that the spot tuning holds up for gets ever so small. It's simply a matter of myopic focussing imo, just like how our eyes work focussing up close. Pure, up close, trig. Baaad idea imo...unless riveted down.
I say get smaller speakers if you want to listen up close.........
To be in the studio definition of near-field....where direct-sound dominates reflected-sound, and also be in the acoustic definition of far-field, where phase has settled down.
Cause what we really need for listening to speakers in the studio "near-field", are speakers small enough to listen to in their acoustic far-field.
Hope that made sense...
One thing i still don't get, if anyone has a good way of explaining....
I can't see how staying in 1/4 WL c2c makes for a summation that is deemed completely coherent and doesn't break apart any.
Seems to me it's just a rule of thumb for when FR magnitude variations are minimized to the point of acceptability. I mean, it's just the phase wheel summation for like signals in play, when focused to a particular distance, right?
Isn't that what the synaudcon article is saying?
Mark i think there is a reason listening point is located at critical distance of a room in studio : from my understanding of what you wrote it satisfy your studio definition of nearfield and acoustic definition of far field...
I always pointed it multiple time in this thread, but Camplo said he wanted to be located in nearfield.
I don't think 1/4 is a rule of thumb. In fact for 2 sources they still sum as one and only up to ctc 1/3 of wavelength:
Fig3: up to 0,33 wl ctc 2 source behave as 1:
http://www.xlrtechs.com/dbkeele.com/PDF/Keele (2007-09 AES Preprint)- Linear Phase Digital Crossover Flters Part 2.pdf
I always pointed it multiple time in this thread, but Camplo said he wanted to be located in nearfield.
I don't think 1/4 is a rule of thumb. In fact for 2 sources they still sum as one and only up to ctc 1/3 of wavelength:
Fig3: up to 0,33 wl ctc 2 source behave as 1:
http://www.xlrtechs.com/dbkeele.com/PDF/Keele (2007-09 AES Preprint)- Linear Phase Digital Crossover Flters Part 2.pdf
Camplo, I haven't heard your speaker or that big of a horn so only speculating. Some head in vice experience from fullrange driver speakers and small studio monitors I have.
mark100, I think basic idea in the 1/4wl c-c is that the sources have max 90deg phase difference at the wavelength no matter which angle and distance the observer is at and in this sense the two can be though as one. The path length difference, or phase difference is much less to most directions and the worst are the exact north and south pole when the other is exactly behind the other. There is whole plane between the two where they are always equidistant and sum constructively all the way up to 20kHz. I'm not sure if there is anything more specific to the rule.
When there is this kind of rule of thumb one can then reason with it to ballpark response between two devices in 3D space. When two sources are within 1/4wl they are roughly one and no need to think further.
Here two point sources 25cm apart, the other is behind the other.
25cm is 1/4 wavelength of 343Hz. If we check the amplitude at 343Hz there it is some net constructive interference of about ~3db. Around 450Hz there is crossing to destructive interference ~120deg or 1/3wl. Max null 180degree difference at ~686Hz. As we see the 1/4wl is on the brink, and just a rule of thumb. We are already 1db down from max around ~220Hz, ~60deg, ~1/6wl.
If we constricted ourselves to a plane between the two sources so that we are always equidistant from both, it doesn't matter what the c-c is a we'd be always equidistant and phase difference would be 0 and in this sense the 1/4wl rule is just a concept that helps thinking a system. A system could be subwoofer and a boundary or two.
What comes to edge diffraction its again bit different, as the sound that emits at the edge backwards is in opposite polarity to direct sound and the bandwidth is kinda narrow. Its also different to each sound source and so on, so we can assume diffraction always messes up a response
Being very close to an object small movement makes big difference in path length differences from any two points on the edge / the transducer, while being far away the difference gets smaller in relation.
Basically, we can now reason from how much sound changes with movement. When everything is within 1/4wl the sound doesn't change that much with some movement even in near field.
mark100, I think basic idea in the 1/4wl c-c is that the sources have max 90deg phase difference at the wavelength no matter which angle and distance the observer is at and in this sense the two can be though as one. The path length difference, or phase difference is much less to most directions and the worst are the exact north and south pole when the other is exactly behind the other. There is whole plane between the two where they are always equidistant and sum constructively all the way up to 20kHz. I'm not sure if there is anything more specific to the rule.
When there is this kind of rule of thumb one can then reason with it to ballpark response between two devices in 3D space. When two sources are within 1/4wl they are roughly one and no need to think further.
Here two point sources 25cm apart, the other is behind the other.
25cm is 1/4 wavelength of 343Hz. If we check the amplitude at 343Hz there it is some net constructive interference of about ~3db. Around 450Hz there is crossing to destructive interference ~120deg or 1/3wl. Max null 180degree difference at ~686Hz. As we see the 1/4wl is on the brink, and just a rule of thumb. We are already 1db down from max around ~220Hz, ~60deg, ~1/6wl.
If we constricted ourselves to a plane between the two sources so that we are always equidistant from both, it doesn't matter what the c-c is a we'd be always equidistant and phase difference would be 0 and in this sense the 1/4wl rule is just a concept that helps thinking a system. A system could be subwoofer and a boundary or two.
What comes to edge diffraction its again bit different, as the sound that emits at the edge backwards is in opposite polarity to direct sound and the bandwidth is kinda narrow. Its also different to each sound source and so on, so we can assume diffraction always messes up a response
Being very close to an object small movement makes big difference in path length differences from any two points on the edge / the transducer, while being far away the difference gets smaller in relation.
Basically, we can now reason from how much sound changes with movement. When everything is within 1/4wl the sound doesn't change that much with some movement even in near field.
Last edited:
Hi Camplo! I tried to search and find it (you are a prolific writer), I was just wondering how you ended up mounting the horn? Did you go with a fancy damping solution, or just bolt it onto a block of wood?
(I have a little more time for myself now, so lining up projects that I want to work on, vice rebuilding the porch and stuff).
(I have a little more time for myself now, so lining up projects that I want to work on, vice rebuilding the porch and stuff).
Being down 3db... thats a trend, attaching that to 1/4WL, I can see how that came to be a rule of thumb. Sorta lika f3 for coupling.
I agree about the 2 appearing as one, and with a large ctc this needs to happen more than not, when listening at 1m
The comment about equidistance. That is something I over looked in claims about ctc.
Ok, let me try again maybe @mabat can see my viewpoint.
For monitoring at close proximity such as 1m, of an asymmetrical presentation, 1/4wl is important, due to the minimizing of phase change, allowing the 2 sources to appear more like 1.
Yes this situation can be optimized without 1/4wl spacing but the sweet spot would be smaller, though it on the vertical plane where our sensitivity to such things are less... there is still an improvement when 1/4wl spacing is achieved
@mark100 I wish you would talk more about your experience with having sub bass come from the same axis as the Tweeter.... the way these guys talk, they would suggest that it would be unperceivable yet you and I seem to know that this is not true
You have your Synergy on top of a sub. Your Synergy plays down low, and you said it was an unexpected but welcome increase in sound quality, did you not?
This should not be true according to some... You should not be able to tell where the sub bass is coming from.
I agree about the 2 appearing as one, and with a large ctc this needs to happen more than not, when listening at 1m
The comment about equidistance. That is something I over looked in claims about ctc.
Ok, let me try again maybe @mabat can see my viewpoint.
For monitoring at close proximity such as 1m, of an asymmetrical presentation, 1/4wl is important, due to the minimizing of phase change, allowing the 2 sources to appear more like 1.
Yes this situation can be optimized without 1/4wl spacing but the sweet spot would be smaller, though it on the vertical plane where our sensitivity to such things are less... there is still an improvement when 1/4wl spacing is achieved
@mark100 I wish you would talk more about your experience with having sub bass come from the same axis as the Tweeter.... the way these guys talk, they would suggest that it would be unperceivable yet you and I seem to know that this is not true
You have your Synergy on top of a sub. Your Synergy plays down low, and you said it was an unexpected but welcome increase in sound quality, did you not?
This should not be true according to some... You should not be able to tell where the sub bass is coming from.
Last edited:
Ever since I sat the horn on top of ppsl I havent thought twice about it lol. I was for enough that the height of ppsl enclosure in combination with the upward angle of the horn sitting in the gap of the slot, points at my head at about 1m. In the future I will figure out something more permanent but I returned the 200 some odd dollars worth of SS marine antenna mounts because if I can get this close to optimal for free without having to augment the horn, why not.
This is basically what I see
Last edited:
120hz and below. I'd say its harder to spot 10khz from my 1" dome tweeter I have downstairs
Room modes hide location, but what if there is no mode there?
Also consider 1m distance
I did say last we talked on this topic that as I moved away from the sub it became much harder if not impossible
Room modes hide location, but what if there is no mode there?
Also consider 1m distance
I did say last we talked on this topic that as I moved away from the sub it became much harder if not impossible
Last edited:
120hz is definitely bass and not sub anymore in my view ( we have an octave difference, it's large). You could be able to spot from there.
With full range i havent find spot 10khz was difficult! But maybe you are less sensible to this ( you seems to not be bothered by things Tmuikku and i seems to be).
With full range i havent find spot 10khz was difficult! But maybe you are less sensible to this ( you seems to not be bothered by things Tmuikku and i seems to be).
Hi krivium. Yep, we've both mentioned the difference in studio near-field and acoustic near-field more than once.
I don't think the studio near field definition and its associated critical distance, where direct-field equals reflected field,
has any bearing at all on the acoustic definition.
Yep, I think that's how most folks see it.
I don't anymore due to articles like the synaudcon mentioned (do check out how the article shows it can be harder / take more distance, to get into the acoustic far field for VHF than for low freg).
And I also measure freq response ripple with multiple drivers' polars, on my syns that are within 1/4WL summation. Like four closely spaced mid drivers.
So i really believe it's simple triangulation of multiple source in the end, to listening/measuring location. And how that distance triangulation falls on the phase wheel, given frequency of interest.
No such thing as summed together never to be apart...kinda like marriage haha
Yep, but isn't that Fig3 is addressing beamwidth, without showing the freq response ripple associated with the beamwidth?
I'll be able to talk about it better when I get that particular speaker back running. I needed to take it down and revert to my 3 syn LCR config.
And I need to add bass-reflex ports. About to begin that now, as weather is warming.
Oh, and I will be building it to stay outdoors on a real strong cart, to make far-field measurements, and outdoor listening experiments. CD will be at standing ear level.
It had a different sound than a typical syn on top a sub. A bit cleaner...bass almost sounded thin....and maybe it was due to less floor coupling.
When I raise the level on the sub drivers section, it sounded really good...as strong as floor subs, but still a bit cleaner.......looking forward to outdoors...
When I experimented with raising the XO, my main issue was being able to tell which source covered which frequencies. At that time I had the horn on top of the 15" mid woofer. It is possible that with further optimization, the situation would have improved.
Could it be that the large CTC is playing a factor, that would lead to my previous thoughts about 1/4wl spacing? The close proximity and large vertical size would stress the issue of optimal ctc spacing, I would think.
I am not trying to be argumentative..... we have talked about this topic several pages ago....and my discrimination to elevation, seems to be more sensitive than others seem to experience. I am not claiming to have super powers lol, I just don't want to pretend like I can't hear what I hear. I remember distinctly moving the crossover upwards and the space the horn occupied changed. I also remember it working much better than I thought it would, but non the less, the 200hz sounded much better.
Configured as a 3 way (2way with sub
No doubt (in my mind) why the pioneers chose a 2/3 back focal point for voicing cinemas.