Now that you have explained that the lower trace was 2nd order distortion using a 48dB Bessel 200Hz HP filter, we can see about 1/3 octave down from the crossover frequency, H2 has risen to 18% with about 106dB output, and at 140Hz, 71% with only about 95dB output, ouch.
A 4" direct radiator in a little box can do around 6dB more level at 140Hz with around 10% THD..
Looks like at 300Hz the horn is doing OK, it may reach rock&roll, or even hip hop levels near field without farting out using fourth order filters.
Compared to Butterworth or Linkwitz-Riley, Bessel has the widest, most gradual crossover region. Considering the horn's steep acoustic rolloff is not at all gradual, BW would probably be the better choice to maximize output above the crossover, while minimizing excursion (and distortion) below.
The CEA-2010 tone bursts up to "-4.5db on the gain" (whatever SPL that is) would be interesting to see the higher harmonics generated using the horn below Fc, and their peak levels.
Art
Why are you using a Bessel 48?
Really, why Bessel at all?
Bessel has a handful of variations.....which one are you using?
-10db and -20db???? The woofer will be dominate.....Thd will not measure as high in combination.... But I take it this, is the way its done.
Its random, happens to be the top of menu for filter types.....
isn't that relative to listening level....At 75db average, there will be plenty headroom right ???
Last edited:
Well we agree Fluid: 77dbc when listening to 'typical pop' music (so in K-14) with calibrated monitoring set to -6db ( to allow to have k-20 signal played without having to change the K- reference on monitoring controler/knob).
So where 75db does come from? By choosing this number Camplo is already compromising work to be done by introducing 'de facto' 2db reduction range before even starting to work on material...
Given the initial target is to try to escape loudness war ( and have a level at which we can work long enough and with minimal freq response deviation from Fletcher Munson curves...) i don't see the point.
So where 75db does come from? By choosing this number Camplo is already compromising work to be done by introducing 'de facto' 2db reduction range before even starting to work on material...
Given the initial target is to try to escape loudness war ( and have a level at which we can work long enough and with minimal freq response deviation from Fletcher Munson curves...) i don't see the point.
Last edited:
I'm guessing a round number that wasn't thought to be too loud, not a carefully considered reference level
Ok,
Yes it makes sense. But it won't help with making things understandable within the thread... if it was confusing to me ( which was involved into this) i can see it will be for others too, especially for beginners!
Camplo why do you obsess on 200hz for xover freq? Because from your description it seems to me the issue you face in your listening space at this freq is more room related than driver/loudspeakers. I bet a couple of acoustics panels would help you there and difference between direct radiator/horn would be diminished by huge amount.
Yes it makes sense. But it won't help with making things understandable within the thread... if it was confusing to me ( which was involved into this) i can see it will be for others too, especially for beginners!
Camplo why do you obsess on 200hz for xover freq? Because from your description it seems to me the issue you face in your listening space at this freq is more room related than driver/loudspeakers. I bet a couple of acoustics panels would help you there and difference between direct radiator/horn would be diminished by huge amount.
this is the thread that never ends (sung to the refrain of "This is the song that never ends" )
so can someone clear me up on this whole trend of lowering crossover points...the few experiments of done in this vein always seemed to produce a less than satisfactory result as i've always found that the increase in driver distortion is counter productive.
so can someone clear me up on this whole trend of lowering crossover points...the few experiments of done in this vein always seemed to produce a less than satisfactory result as i've always found that the increase in driver distortion is counter productive.
Well low xover frq. I can't answer for Camplo, but as i'm infected by the disease... i can talk about my view on it:
_ it help to have 1/4 wl ctc condition for driver acoustic 'summing'. With 18",15" and such a 'big' horn it is easy to see why Camplo try to reach 200hz imo.
_ to have most of the 'telephone range' ( speech intelegibility) on one and only driver
_ if a xover ( or multiple) have to be used it is suposedly less impactful outside the speech intelegibility range
I wonder if Camplo is not thinking about passive filtering in the end... and so less steep slope filter use in order to 'blend' drivers.
In my view it is counterproductive: i prefer tîme aligned system and FIR ( high steepness) complementary filters. But it is preference related and speculative as i've not heard Camplo's system, either i'm not sure we listen to same things ( focus on the same things within the reproduced message).
I agree with you about distortion increase ( less headroom), i've had same outcome from my own experiments.
_ it help to have 1/4 wl ctc condition for driver acoustic 'summing'. With 18",15" and such a 'big' horn it is easy to see why Camplo try to reach 200hz imo.
_ to have most of the 'telephone range' ( speech intelegibility) on one and only driver
_ if a xover ( or multiple) have to be used it is suposedly less impactful outside the speech intelegibility range
I wonder if Camplo is not thinking about passive filtering in the end... and so less steep slope filter use in order to 'blend' drivers.
In my view it is counterproductive: i prefer tîme aligned system and FIR ( high steepness) complementary filters. But it is preference related and speculative as i've not heard Camplo's system, either i'm not sure we listen to same things ( focus on the same things within the reproduced message).
I agree with you about distortion increase ( less headroom), i've had same outcome from my own experiments.
At 77db theres enough headroom...
The levels in the graph are on average, higher than whats needed for 85db.
Thanks to dsp, the xo point is never set in stone really. 200hz causes the image to be much more centralized to the horn. My experimentation hasnt been with the drivers in proper configuration. I still think this temp, improper, situation is being used to expose the cracks. I said already that I believed the horn to deliver more directivity at 200hz than the woofer but more experimentation is warranted. A lower xo also is more friendly to close sitting positions, another aspect that puts strain on the tasks at hand.
Which one of you ran out of headroom using a horn/compression driver at 1m? What was they xo point and horn cutoff? Is this rhetorical ☺️
The levels in the graph are on average, higher than whats needed for 85db.
Thanks to dsp, the xo point is never set in stone really. 200hz causes the image to be much more centralized to the horn. My experimentation hasnt been with the drivers in proper configuration. I still think this temp, improper, situation is being used to expose the cracks. I said already that I believed the horn to deliver more directivity at 200hz than the woofer but more experimentation is warranted. A lower xo also is more friendly to close sitting positions, another aspect that puts strain on the tasks at hand.
Which one of you ran out of headroom using a horn/compression driver at 1m? What was they xo point and horn cutoff? Is this rhetorical ☺️
In my experience it isn't rethorical but your sentence is too vague, it misse some important parameters.
I've experienced it in a dj booth we set up for rehearsal but it wasn't at 1m ( more 2m).
How i see things is all drivers have a set of limits. You can play with them, stretch a bit but it quickly compromise the outcome.
This comes down to application and compromises you are willing to make, and given your target, i would stay away from anything that could introduce too much trouble in this freq range: you are close enough to intelegibility range to introduce nasty in my view.
Recently Mabat commented in another thread that horns/waveguide could exhibit resonance at cutoff freq and that the way measurments are presented kind of 'hide' the effect ( well this is how i interpreted it).
If your horn introduce this AND your driver lack of headroom at the same time you are going to compromise on accuracy in a very important range imo.
Have you performed CSD to be sure the horn doesn't exhibit that behavior? ( Sorry the thread is now too long to seek into, maybe you already did it. But i think the 'swell' shape in your freq measurements is clear enough).
I agree at close listening position lower xover point help but you'll start to compromise on something else.
I would he careful about listening impressions of drivers alone. You built a system and often the outcome is not only the sum of parts, something else happen by combining (integration) and it can not be evident when listening only the parts in isolation.
I've experienced it in a dj booth we set up for rehearsal but it wasn't at 1m ( more 2m).
How i see things is all drivers have a set of limits. You can play with them, stretch a bit but it quickly compromise the outcome.
This comes down to application and compromises you are willing to make, and given your target, i would stay away from anything that could introduce too much trouble in this freq range: you are close enough to intelegibility range to introduce nasty in my view.
Recently Mabat commented in another thread that horns/waveguide could exhibit resonance at cutoff freq and that the way measurments are presented kind of 'hide' the effect ( well this is how i interpreted it).
If your horn introduce this AND your driver lack of headroom at the same time you are going to compromise on accuracy in a very important range imo.
Have you performed CSD to be sure the horn doesn't exhibit that behavior? ( Sorry the thread is now too long to seek into, maybe you already did it. But i think the 'swell' shape in your freq measurements is clear enough).
I agree at close listening position lower xover point help but you'll start to compromise on something else.
I would he careful about listening impressions of drivers alone. You built a system and often the outcome is not only the sum of parts, something else happen by combining (integration) and it can not be evident when listening only the parts in isolation.
Last edited:
Playing the devils advocate here//
How can you compare it without proper setup, measurements and crossovers in place? We haven't seen any proper ones yet. At least not in a post here in this thread.
Yes, we've seen preliminary measurements but surely they were not valid for determining "sound quality". The first thing we hear it the frequency curve.
When it is as rough as you show it to be, how is that going to be a valid test? The key here was "sound quality" right? Then get your measurements right and fix that frequency curve. I don't know what you've done so far to do this test, but based on the measurements shown and the info in this thread it can't be a fair comparison. At least, it feels like slapping something together quickly and having a listen. Sorry, but You'd have to do better than that...
Show the frequency curves of both woofer/axi combination you've listened to. One with a 200 Hz crossover and one with a 350 (or something in that area) crossover. Both properly executed. Then maybe you could convince us that one sounds better than the other. The curves "should" be near identical. Without the room's influence at the critical crossover frequencies anyway.
Exactly what did you listen to... axi by itself vs woofer by itself? A quick crossover between woofer and axi for both versions?
//End devils advocate...
How can you compare it without proper setup, measurements and crossovers in place? We haven't seen any proper ones yet. At least not in a post here in this thread.
Yes, we've seen preliminary measurements but surely they were not valid for determining "sound quality". The first thing we hear it the frequency curve.
When it is as rough as you show it to be, how is that going to be a valid test? The key here was "sound quality" right? Then get your measurements right and fix that frequency curve. I don't know what you've done so far to do this test, but based on the measurements shown and the info in this thread it can't be a fair comparison. At least, it feels like slapping something together quickly and having a listen. Sorry, but You'd have to do better than that...
Show the frequency curves of both woofer/axi combination you've listened to. One with a 200 Hz crossover and one with a 350 (or something in that area) crossover. Both properly executed. Then maybe you could convince us that one sounds better than the other. The curves "should" be near identical. Without the room's influence at the critical crossover frequencies anyway.
Exactly what did you listen to... axi by itself vs woofer by itself? A quick crossover between woofer and axi for both versions?
//End devils advocate...
I think with a system this large, sitting so close....its going to make me wonna monitor at lower volumes. At 77db average 97db gives me 20db headroom.....plenty. If it can do that at 115db, it sure can handle 97db....and I'm pretty sure its much cleaner than the last measurement at 110db.
At the end of the day its never set in stone, thanks to dsp. Maybe I'll find a reason to want to cross over at 300hz once it is properly set up. AS you said, how can i be valid in my ideas in the designs current state with one horn pointed at the ceiling from the floor, and the woofers setting upright.... I think there might be a little validity in placing my head at 90 degress from the horn.....It may lend to causing only omni like frequencies to dominate....a good source to try and blend with the lower woofer stationed next to it. I don't really think about it that much as I know that my perception will be much different once set up like it should be....like I said before, take it with a grain of salt!
He actually had the same conversation with me here....part of that formula involved taking measurements outside, so of course Rew has decay and the bunch....The initial measurements I took, I shared the Rew files. One of the advantages of a big horn, I think, is having the resonant note placed low in the room mode territory....like BR, no one can tell the difference between a good vented and sealed design until the rooms rt60 gets very low. The decay isn't grossly out of pocket on the resonate notes and nearby harmonics but they are in the burst decay.
1/3oct Burst decay
wavelet 1/24 res
The FR is like +/- 4db with minimal effort.... +/- 2.5db in some areas and +/- 1.5db from 400hz to 5khz...... How good do you think I should aim for? Of course when it comes time I will let Audiolense do its thing to a target curve....
Oh its definitely that lol, but its what I have time for so.....slow motion is better than no motion...14hr days at work 6 days a wk, and 4 kids and a wife.....are you all single? lol
Those decay measurements will be tighter at lower volume I would think. 200hz makes for much better summation at such a close sitting position and such a close sitting position increase headroom ability allowing 200hz XO. The drawback of sitting so close.....still might be some summation issues....the rooms level will be lower....if you are into that sort of thing.
At the moment I have the Horn and the Bass drivers playing together, just to see what that sounds like 😊😊😊
Last edited:
Take it easy Camplo, hard work may be the ethos of the American Dream, the flipside is a burn-out
The resonances of your horn+Axi2050 are all 'textbook' phenomena.
At the low end these are primarily horn related and >8 Khz the diaphragm dominates.
The wavelet only confirms the previous predictions (based on the K+T test).
And yes, with your setup you can only approach the ideal of 'flat everyting' (within < 1 dB) of the typical MOR direct radiating high-end tower, but - as the Asians have known for decades: you gain a lot in other areas.
A similar linearity should be approachable:
Last edited: