Apologies in advance for my n00biness and questions that might seem ridiculous, trying to learn and lots of stuff popping up in my head that i need to clear to be able to move on, so again thanks , any help will be mucho appreciated 🙂
Trying to understand relationship between beamwidth an driver size.,... found some very neat excel format ( thanks Csaba Horvath !! )
from here : http://www.tonestack.net/software/speaker-directivity-simulators.html
That kind of explain i think why the use of larger woofers by Dr. Earl Geddes ( much respect! ).
1- So i was wondering why i never saw any type of " waveguides " for woofers ?? Surely a similar waveguide that is normally used for HF could be used partially for Mids ??
Wouldn't a smaller driver like let's say a 6" have the same type of directivity behavior as a larger one if a waveguide was used ?
2- When trying to find info about Synergy/Unity Horn type of designs ... thought about possible physical configurations of the drivers/horns assembly
and was wondering why i never saw anything that would have a similar arrangement to the following drawing ( don't laugh at my photoshop skillz ok ? ahah )
( ouch way to large sorry )
Hopefully the simplistic drawing makes sense ..so the HF horn/driver unit would be inside the wooder horn assembly
3- Lastly, what are the drawbacks of dipole/cardioid arrangement for mid woofer to control the directivity ? ( open baffle i think is one way )
I can think of having to deal with the rear wave and probably lower output of lower frequencies
how is the directivity controlled? width of the baffle ?
Have a great day all of you 🙂
Trying to understand relationship between beamwidth an driver size.,... found some very neat excel format ( thanks Csaba Horvath !! )
from here : http://www.tonestack.net/software/speaker-directivity-simulators.html
That kind of explain i think why the use of larger woofers by Dr. Earl Geddes ( much respect! ).
1- So i was wondering why i never saw any type of " waveguides " for woofers ?? Surely a similar waveguide that is normally used for HF could be used partially for Mids ??
Wouldn't a smaller driver like let's say a 6" have the same type of directivity behavior as a larger one if a waveguide was used ?
2- When trying to find info about Synergy/Unity Horn type of designs ... thought about possible physical configurations of the drivers/horns assembly
and was wondering why i never saw anything that would have a similar arrangement to the following drawing ( don't laugh at my photoshop skillz ok ? ahah )
( ouch way to large sorry )
Hopefully the simplistic drawing makes sense ..so the HF horn/driver unit would be inside the wooder horn assembly
3- Lastly, what are the drawbacks of dipole/cardioid arrangement for mid woofer to control the directivity ? ( open baffle i think is one way )
I can think of having to deal with the rear wave and probably lower output of lower frequencies
how is the directivity controlled? width of the baffle ?
Have a great day all of you 🙂
"Waveguide" has almost become a useless term, but horns for woofers have been common for about 100 years.
Here is an example from late last century:
Multiple entrant horns built like the Synergy/Unity don't require delay compensation to time align the driver output, lending that format more useful for passive crossovers. The single horn also reduces diffraction and reflection problems that need to be addressed in nested horn within horn designs.
Basically, a dipole or cardioid arrangement uses destructive interference to "control", or affect directivity.
More power, or more drivers, and often both are needed for the same on axis level- a drawback in terms of $ to SPL ratio.
Ah you guys discussed this recently i see. ok so obviously internal reflections would be a problem, but the KF750 one is for quite narrow coverage ?
Wouldn't using a less aggressive curve lessen the problems with internal reflections ?
" Nested horns" is the term i was missing..thanks for the precision 🙂
As for the dipole/cardi .. ok yes that is what i vaguely understood as far as mechanism goes. and we are then loosing SPL as the tradeoff , good point.
If i can take it back to " horns for woofer ", let's assume a typical 2-3 way vertical stack , would there be any benefit in using some form of "horn " for the woofer section ?
When i look at directivity in the 1khz and lower region with the simulator, anything under a ~12" will never achieve a desirable directivity without help ?
Wouldn't using a less aggressive curve lessen the problems with internal reflections ?
" Nested horns" is the term i was missing..thanks for the precision 🙂
As for the dipole/cardi .. ok yes that is what i vaguely understood as far as mechanism goes. and we are then loosing SPL as the tradeoff , good point.
If i can take it back to " horns for woofer ", let's assume a typical 2-3 way vertical stack , would there be any benefit in using some form of "horn " for the woofer section ?
When i look at directivity in the 1khz and lower region with the simulator, anything under a ~12" will never achieve a desirable directivity without help ?
Yes. Some do this.
Some control directivity all the way down and some choose to make the break at the Schroeder frequency. First decide what you want to do and then find a way to do it.
Isn't Schroeder like ~200hz in most rooms ? that's quite deep for directivity control isn't it ?
Also, i'm learning for now .... not currently in designing mode for anything particular.
But good advice , thanks 🙂
Also, i'm learning for now .... not currently in designing mode for anything particular.
But good advice , thanks 🙂
Take a look at this thread. No waveguide for woofers, ha?
https://www.diyaudio.com/community/...l-low-distortion-with-a-2-way.334757/page-528
https://www.diyaudio.com/community/...l-low-distortion-with-a-2-way.334757/page-528
It's not as easy to hear issues in the hundreds so waveguiding there meets diminishing returns, just as long as you do something to manage the modes.
You'd have to be enthusiastic to take it further but the results can be good. People even talk about something as simple as making a regular box large enough to handle Schroeder, and avoiding the baffle step as being worth it.
You'd have to be enthusiastic to take it further but the results can be good. People even talk about something as simple as making a regular box large enough to handle Schroeder, and avoiding the baffle step as being worth it.
AHAHAH that is so awesome !!!
i'm an enthousiast alright, if it was what was required, that's ^^^ something i would put in display in my rather large living room 🙂
Remember my " quasi inifite baffle " subwoofer with the concrete port that leads to the garage thing with holes in the concrete wall for 16X 15" subs ??
still haven't done it ( life don't ask .. ) but that's still in my HT room project for the coming years 🙂 ( nobody prob remember lol , i'lll try and find some pics )
"People even talk about something as simple as making a regular box large enough to handle Schroeder, and avoiding the baffle step as being worth it."
Could you please elaborate, i have difficulties tying stuff together here .
The baffle step sends a lot of lower/mid energy behind the speaker, and this comes back from the walls in modes which cause a rough response. Now, right down low the room takes over, that can be dealt with in other ways. One thing to do is make the baffle large enough to get down to where the room takes over.
Allen : thanks for the clarification
@GM ahah i just noticed your prof pic LOL
I quickly looked up nested horns and compound horns and seems like this stuff is/was quite popular in PA.
So if i may proceed with more noobite questions ....
What determines the frequency where the guide/horn stops working? ( assuming that the angle is enough to support the wavefront all the way to the mouth )
Like in the pic i linked above, the giant wood decoration wall horn thing 😎 ( imagine having those pieces in ur living room ..ouff )
The dimensions are pretty big but the angle seems rather steep at the mouth and into the flare.
Would it be right to assume that this should provide support quite low ? ( again assuming proper angles/loading )
Then how do we link the directivity ( angle ) and the diff measurements/design of horns ?
At some point the wavefront just leaves the mouth because the flare are getting to large to keep it pressurized ?
Does this mean that horns with different angle will automatically provide different coverage ?
@GM ahah i just noticed your prof pic LOL
I quickly looked up nested horns and compound horns and seems like this stuff is/was quite popular in PA.
So if i may proceed with more noobite questions ....
What determines the frequency where the guide/horn stops working? ( assuming that the angle is enough to support the wavefront all the way to the mouth )
Like in the pic i linked above, the giant wood decoration wall horn thing 😎 ( imagine having those pieces in ur living room ..ouff )
The dimensions are pretty big but the angle seems rather steep at the mouth and into the flare.
Would it be right to assume that this should provide support quite low ? ( again assuming proper angles/loading )
Then how do we link the directivity ( angle ) and the diff measurements/design of horns ?
At some point the wavefront just leaves the mouth because the flare are getting to large to keep it pressurized ?
Does this mean that horns with different angle will automatically provide different coverage ?
It must be at least an acoustical 1/4 WL axial length and 1/2 WL to load to the desired mouth cutoff. For waveguides it's 1 WL.
It's a truncated tractrix flare IIRC, so doesn't load very low, i.e. mid-bass/lower mids same as Altec's truncated expo horns, so as asked, no; the rest of the flat surfaces is for baffle loading down to the speaker's Fb, i.e. no BSC required.
Combined wall angle, i.e. its flair frequency (Hz), flare factor (expo, etc..) along its axial length. For a specific point:
-6dB Hz = 10^6/(wall angle*mouth width)
No, the horn's sound 'bubble' vibrates at 'x' Hz BW, energizing the air around it, creating a pulse 'train' of sound 'bubbles', i.e. the simple minded way I understand this complex bit of physics is to view a single Hz as a child's bubble ring where the ring is the fundamental and when the bubble is blown forward (+/compression) the infinitely small center of the bubble is its highest harmonic, harmonically expanding exponentially back in time to the fundamental and ditto in reverse (-/rarefaction) to complete 1 WL.
Correct, as the math clearly shows. 😉
It's a truncated tractrix flare IIRC, so doesn't load very low, i.e. mid-bass/lower mids same as Altec's truncated expo horns, so as asked, no; the rest of the flat surfaces is for baffle loading down to the speaker's Fb, i.e. no BSC required.
Combined wall angle, i.e. its flair frequency (Hz), flare factor (expo, etc..) along its axial length. For a specific point:
-6dB Hz = 10^6/(wall angle*mouth width)
No, the horn's sound 'bubble' vibrates at 'x' Hz BW, energizing the air around it, creating a pulse 'train' of sound 'bubbles', i.e. the simple minded way I understand this complex bit of physics is to view a single Hz as a child's bubble ring where the ring is the fundamental and when the bubble is blown forward (+/compression) the infinitely small center of the bubble is its highest harmonic, harmonically expanding exponentially back in time to the fundamental and ditto in reverse (-/rarefaction) to complete 1 WL.
Correct, as the math clearly shows. 😉
GM: hnmm you loose me in almost every answer there ...man i feel like i understand nothing in this audio world 🙄
1- So for example, a waveguide would need to be of a minimum of 35cm to be able to keep load/directing down to 1khz ?
Would that means that a waveguide of at least 70cm deep is required to have any effect down to 500hz out of a woofer ?
How do you differentiate between waveguide and horn in this instance ? ( loading VS directivity control as per Earl Geddes ? )
2- ""is for baffle loading down to the speaker's Fb, i.e. no BSC required. "" i have no idea what you mean here
3- trying to figure out the units here : "-6dB Hz = 10^6/(wall angle*mouth width) "
wall angle is both sides of the horn or just 1 side refered to axial axis ?
mouth width in cm ? mm ?
4- the sound bubble thing .... hmmm . ... i guess i'd need some drawings to understand it or something lol
thanks again for your time 🙂
appreciated !
1- So for example, a waveguide would need to be of a minimum of 35cm to be able to keep load/directing down to 1khz ?
Would that means that a waveguide of at least 70cm deep is required to have any effect down to 500hz out of a woofer ?
How do you differentiate between waveguide and horn in this instance ? ( loading VS directivity control as per Earl Geddes ? )
2- ""is for baffle loading down to the speaker's Fb, i.e. no BSC required. "" i have no idea what you mean here
3- trying to figure out the units here : "-6dB Hz = 10^6/(wall angle*mouth width) "
wall angle is both sides of the horn or just 1 side refered to axial axis ?
mouth width in cm ? mm ?
4- the sound bubble thing .... hmmm . ... i guess i'd need some drawings to understand it or something lol
thanks again for your time 🙂
appreciated !
Sometimes it's ready and sometimes it isn't. You have to keep that in mind when you design. It is quite involved. Do you have hornresp?
Yes and no. Making one narrow pushes the boundaries and the horn world is all about compromises.
Oh well, took a 'shot'. 🙁
Right.
WG = conical/parabolic expansion. Seems there's a technical moniker for it, but don't remember ATM.
Oops! Inches, I don't 'think' in metric, so -6dB Hz (cm) = (2.54*10^6)/(wall angle*mouth width)
Right, one pair of opposing walls.
BSC = baffle step compensation
Sorry, simple as I can get as to how a spherical phenomena can create what measures as a (often chopped up) sine wave.
You're welcome!
Right.
WG = conical/parabolic expansion. Seems there's a technical moniker for it, but don't remember ATM.
Oops! Inches, I don't 'think' in metric, so -6dB Hz (cm) = (2.54*10^6)/(wall angle*mouth width)
Right, one pair of opposing walls.
BSC = baffle step compensation
Sorry, simple as I can get as to how a spherical phenomena can create what measures as a (often chopped up) sine wave.
You're welcome!
JimMTVT, Its all got to do with wavelength, physical size of sound and how it interacts with physical objects. If you have a question try to think it through wavelength.
Controlling sound needs equally sizable objects, low frequencies have long wavelength and big objects are needed to control the sound. Lowest frequencies are longer than average listening room so you need room sized speaker system to have some control over, for example multisub stuff.
Other way to control is interference of multiple sources and this happens on any transducer by themselves as wavelegth gets short enough, roughly shorter than the transducer dimension and now the interference to various directions (path length difference between any two points on the transducer to observation angle) makes beaming.
Waveguides are kind of a way to cheat some on this, so is cardioid and also dipole stuff. Cardioid variety can have kind of narrower response like a bigger driver (or baffle) would and waveguide can somewhat too, basically these provide a way to juggle a speaker system directivity and size which are important aspects in many ways. In the end we listen to pressure variations in a room so, tailor fit the speakers to listening situation and personal preference.
Controlling sound needs equally sizable objects, low frequencies have long wavelength and big objects are needed to control the sound. Lowest frequencies are longer than average listening room so you need room sized speaker system to have some control over, for example multisub stuff.
Other way to control is interference of multiple sources and this happens on any transducer by themselves as wavelegth gets short enough, roughly shorter than the transducer dimension and now the interference to various directions (path length difference between any two points on the transducer to observation angle) makes beaming.
Waveguides are kind of a way to cheat some on this, so is cardioid and also dipole stuff. Cardioid variety can have kind of narrower response like a bigger driver (or baffle) would and waveguide can somewhat too, basically these provide a way to juggle a speaker system directivity and size which are important aspects in many ways. In the end we listen to pressure variations in a room so, tailor fit the speakers to listening situation and personal preference.
AllenB: ok yes makes sense 🙂 I do have Hornresp installed although i still don't understand how to use it, specifically how to see directivity with it ?
pretty sure i saw a pic of someone here that had the FR at an angle out of it and i can't find that.
GM: don't worry i'm canadian so quite fine with both metric and imperial .. i'll try that equation later on thanks for the precision in the units 🙂
Baffle step compensation , this is something that can be tweaked with active equ/crossover and really only needs to be taken into account when using pasive crossover right ? 🤔
" spherical phenomena can create what measures as a (often chopped up) sine wave. "
I will try and read your last paragraph until i can make sense of it then .
thanks again
pretty sure i saw a pic of someone here that had the FR at an angle out of it and i can't find that.
GM: don't worry i'm canadian so quite fine with both metric and imperial .. i'll try that equation later on thanks for the precision in the units 🙂
Baffle step compensation , this is something that can be tweaked with active equ/crossover and really only needs to be taken into account when using pasive crossover right ? 🤔
" spherical phenomena can create what measures as a (often chopped up) sine wave. "
I will try and read your last paragraph until i can make sense of it then .
thanks again
tmuikku: Thanks for the good info! appreciated !
Evident that larger WV are only influenced by object or a certain size, the problem is the repsective size VS the WL is often misleading.
Like with spacing, 1/4 WL is often mention and i can partly understand why , kinda obvious when thinking about waves.
It gets a bit less obvious with horn/baffles/driver size .
Evident that larger WV are only influenced by object or a certain size, the problem is the repsective size VS the WL is often misleading.
Like with spacing, 1/4 WL is often mention and i can partly understand why , kinda obvious when thinking about waves.
It gets a bit less obvious with horn/baffles/driver size .
