That is true, so it will never be perfect, but you can try to come close. Indeed, a point source is the best in this regard. That is why I use a single mid/high horn with coaxial drivers and crossed over at 400-500hz, to come closer to this ideal. I think that the famous Yuichi horns among others, Azura horn, Inlow paper horn etc. are popular partly because of this. I don't think dispersion has a very important role here, only in the crossover region where the drivers output overlap. And I agree that it is debatable to what extent it is perceivable. I did a lot of experimenting and ended up with my hypothesis that aligning mouths is a valid way to go.
Agreed, I solved this by making the mid/high horn the same width as the midbass horn it crosses over to. Regarding disperion in the cross over region, I found it beneficial to toe in the midbass horn more than the mid/high horn, by some degrees. To have the possibility to toe in the horns individually is also a feature of my system.
Yeah toe in is very important thing to have and utilize for best sound.
May I ask how big is your room, and how big of a stereo listening triangle you have, and what is the rough coverage of your speakers?
I'm asking this as I cannot seem to get past ~2.2meter listening distance / stereo triangle, after which the room sound just dominates and good imaging / accuracy is gone. So far I've tested my system at our living room, typical european, and on another house with bigger room and almost double ceiling height, not much difference, more naked walls there. Seems to be feature of direct / reflected sound ratio. System DI about 5db from 200Hz up to ~10db around 10kHz+, roughly 90deg nominal waveguide for compression driver.
I'm trying to zone in if others have similar observation vs. their situation. If I should increase directivity off tweeter or from low mids and up. Perhaps no replacement for acoustic treatment? I would like to extend the good sound image up to 3 meters where the practical listening position is.
May I ask how big is your room, and how big of a stereo listening triangle you have, and what is the rough coverage of your speakers?
I'm asking this as I cannot seem to get past ~2.2meter listening distance / stereo triangle, after which the room sound just dominates and good imaging / accuracy is gone. So far I've tested my system at our living room, typical european, and on another house with bigger room and almost double ceiling height, not much difference, more naked walls there. Seems to be feature of direct / reflected sound ratio. System DI about 5db from 200Hz up to ~10db around 10kHz+, roughly 90deg nominal waveguide for compression driver.
I'm trying to zone in if others have similar observation vs. their situation. If I should increase directivity off tweeter or from low mids and up. Perhaps no replacement for acoustic treatment? I would like to extend the good sound image up to 3 meters where the practical listening position is.
So, what's the best way in Rew or Holmimpulse (in my case) to get all, or most benefit?
Since the microphone picks up what I hear, I perhaps wrongly assume - if measuring the right output, I can align, phase and time?
Or perhaps not?
Perhaps not so much of the phase though? 🙂
Since the microphone picks up what I hear, I perhaps wrongly assume - if measuring the right output, I can align, phase and time?
Or perhaps not?
Perhaps not so much of the phase though? 🙂
Regarding your description of what happens in your room, it is recognizable and the only way forward is room treatment and proper placement and toe in of the speakers . I am a fan of "beamy" speakers due to the pinpoint resolution, but that induces other problems that I solved with diffusers on the back wall to have enough higher order reflections in my room to create the needed spaciousness in the treble region. Otherwise it sounds closed in in the treble. I do not need to have my head in a vise, but the best sound is in the middle regarding the higher freqs. But moving around in the room is no problem, it sounds good everywhere and also outside of the room. But it took full blown room treatment.
The speakers are about 3 meters apart, listening distance around 3,2 meters. I made a separate thread with pictures about my system, which can be viewed here: https://www.diyaudio.com/community/threads/3d-printed-horn-system.377350/
About the measurements, I made some changes (soundwise to the better) so those may be outdated, but it gives you an impression.
According to your profile picture, you have a nice set of horns and probably a good sound already, but optimizing is always possible to a degree. In the end you must live with compromises and the compromise that you can live with is probably different than others. Therefore I think I am not really entitled to give you an advice here, as your milage may vary. For me, room treatment is king and enables you to remove some of the compromises you have to make.
So true on all counts Hdude!
I really am refining something I and visitors already find impressive/dynamic relaxing, accurate etc
It's good fun to tinker and expand understanding etc.
I'll have a go and no doubt work several iterations to try what's best, I'm sure.
Will report back, here or perhaps on my thread as it's purely about my system then.
I really am refining something I and visitors already find impressive/dynamic relaxing, accurate etc
It's good fun to tinker and expand understanding etc.
I'll have a go and no doubt work several iterations to try what's best, I'm sure.
Will report back, here or perhaps on my thread as it's purely about my system then.
Yes! But you will also notice that you stop tinkering when everything is right 😉 until doubt and uncertainty hits again 🙄
I built a full range bass horn several years ago. Yes it sounds like nothing else. The problem is that recorded music is mixed on speakers that basically roll off below 100 Hz. This leads the engineer to add subbass to get the desired sound. Playing through the full range system sounded awful. It was necessary to put in a roll off to get a tight bass sound. The other issue was everything in the room vibrated. I winded myself by standing in the mouth. In my opinion a room is best driven from one point for bass. I used 4 18inch 400w drivers on a manifold. The sensitivity was phenomenal.
I have one thing that isn't yet clear to me: what happens at the transition point from horn to direct radiator?
The graphs from HR show a rapid drop at that point but I can't imagine that the actual response from the speaker as a whole behaves that way.
If HR show a drop at let's say 200hz, how does the response below that look like? Can you model that in HR or some other tool?
The graphs from HR show a rapid drop at that point but I can't imagine that the actual response from the speaker as a whole behaves that way.
If HR show a drop at let's say 200hz, how does the response below that look like? Can you model that in HR or some other tool?
Jean-Michel once wrote about using a LeCleach horn down through the cutoff. I can't find the post just now but IIRC there was talk of the group delay you'd find there, and that it may not be audible if the cutoff is around or below maybe 250Hz.
Also, these are often put in a small closed box at the same time to trim the output and reactance annul, so you might want to forego that. Hornresp will indicate the acoustic loading, but this isn't something you should notice audibly.
Also, these are often put in a small closed box at the same time to trim the output and reactance annul, so you might want to forego that. Hornresp will indicate the acoustic loading, but this isn't something you should notice audibly.
Different length and position horn alignment..
I calculated the time lag for the sound pressure wave (first peak positive) to progress out of each of the respective horn mouths, and adjusted the time delay in my DSP accordingly.
So, instead of first peak positives from each diaphragm reaching my ears at the same time, it's at the point of emergence from the horn mouths and to my ears, that are the same.
It's only a small delay esp for the shortest of the horns.
It's not even a particularly subtle difference in presentation of the sound between the two alignments.
Different alignments never are though..
I've just started playing around with time alignment by ear, around this new alignment base and got a sound I really seem to like.
Time will tell😂
Custom room alignment, but based on a measurement +👂
I calculated the time lag for the sound pressure wave (first peak positive) to progress out of each of the respective horn mouths, and adjusted the time delay in my DSP accordingly.
So, instead of first peak positives from each diaphragm reaching my ears at the same time, it's at the point of emergence from the horn mouths and to my ears, that are the same.
It's only a small delay esp for the shortest of the horns.
It's not even a particularly subtle difference in presentation of the sound between the two alignments.
Different alignments never are though..
I've just started playing around with time alignment by ear, around this new alignment base and got a sound I really seem to like.
Time will tell😂
Custom room alignment, but based on a measurement +👂
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What I'm going to try next is DSP delays creating the same effect as if all the horn mouths were physically inline with each other.
The mid bass horn is nearest me so is the reference point.
Working that one out at the moment.
The mid bass horn is nearest me so is the reference point.
Working that one out at the moment.
Why do you want the horn mouths physically in line? To hear to difference it makes to a time aligned system?
Yes schiirrn.
It's just a test.
Years ago I aligned the mouths physically, but then timed from 1st peak positive reaching the listening spot.
This is different.
The most recent mouth exit alignment I am using now, has had an interesting effect on lowered perceived distortion, esp on thrashy complex music. Compression less, order improved.
It's just a test.
Years ago I aligned the mouths physically, but then timed from 1st peak positive reaching the listening spot.
This is different.
The most recent mouth exit alignment I am using now, has had an interesting effect on lowered perceived distortion, esp on thrashy complex music. Compression less, order improved.
😂 Didn't like it.
Sounded out of step with itself, if that make sense...?
Rockin' out to the 'exit the mouths at the same time' alignment🎶
One refinement was to go to from 96KHz to 192KHz sampling in the DSP engine.
That doubles the delay sample input units and thus allows more precise delay sample setting.
Before, on a couple of the channels I was a bit out one way or the other, I chose the nearest, but now the nearest is much nearer.
Evaluating now.
That doubles the delay sample input units and thus allows more precise delay sample setting.
Before, on a couple of the channels I was a bit out one way or the other, I chose the nearest, but now the nearest is much nearer.
Evaluating now.
I found an article from Joseph Crowe that clarifies some things for me so I'd thought I'd share it here. It's about his 1798 horn loaded bass cabinet and has all the measurement that I was looking for.
This picture answers my question about the transition between direct radiator and horn loaded.
So you get the shelved response from the BR cabinet, then a hump when the horn kicks in and provides additional sensitivity.
https://josephcrowe.com/blogs/news/bass-cabinet-no-1798
This picture answers my question about the transition between direct radiator and horn loaded.
So you get the shelved response from the BR cabinet, then a hump when the horn kicks in and provides additional sensitivity.
https://josephcrowe.com/blogs/news/bass-cabinet-no-1798
@CoolJazz
Thanks for posting that link! I've been looking into Crowe's designs but had not seen No.1798.
It was a good exercise to take advantage of his blog and video with explanations. I modelled in Hornresp with the TD15M to replicate his design and I'm a bit confused because I'm getting different results. Frequency response looks different: doesn't show the drop at 40Hz that he then corrects with the forward vents.
But I also noticed the waveguide profile Hornresp displays is quite different from the schematic Crowe posted - he mentioned he would add another straight section to smoothen the "curve" - but the difference between an exponential flare and what's seen on the schematic seems important. What am I missing?
Thanks for posting that link! I've been looking into Crowe's designs but had not seen No.1798.
It was a good exercise to take advantage of his blog and video with explanations. I modelled in Hornresp with the TD15M to replicate his design and I'm a bit confused because I'm getting different results. Frequency response looks different: doesn't show the drop at 40Hz that he then corrects with the forward vents.
But I also noticed the waveguide profile Hornresp displays is quite different from the schematic Crowe posted - he mentioned he would add another straight section to smoothen the "curve" - but the difference between an exponential flare and what's seen on the schematic seems important. What am I missing?
