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Two way synergy Horn
Two way synergy Horn
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Old 13th February 2021, 07:57 PM   #1
de45dd is offline de45dd
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Join Date: Jan 2013
Default Two way synergy Horn

From another Project which I did not finish I have two 5 inch midrange drivers, PHL 950Nd, here.

As I am still looking for a speaker for my home cinema I came to the idea to build an prototyp of an two-way
synergy-horn based on them combining with the HF10AK which am currently using in my Coax-Speaker.
Two 12 inch woofers in D'appolito configuration around the horn will complete them to an three way speaker.

So the plan is to run the 12 inch woofers to about 300-400Hz and then the horn should take over, where the
two midrange drivers should run to about 1,5khz - 2khz and then HF10AK will complete to 20khz.

At first of all I took ath4 (which is a really great piece of software, thanks to mabat!) to generate a horn contour as startup for the synergy horn.
My plan is to have 90° horizontal coverage and 50° vertical coverage. The horn should be about 12 inch wide to match the woofers width. After trying a lot of different configs I came out with the following ath4-configuration:


Code:
   Throat.Profile = 1
  Throat.Diameter = 25.4             ; [mm]
  ; half of HF10AK Exit angel (21 degree)
  Throat.Angle = 10.5                  ; [deg]
  Length = 112                                ; [mm]
  
  ; -------------------------------------------------------
  
  ; Horizontal analysis
  Coverage.Angle = 45 - 20*sin(p)^2
  Term.s = 0.7 - 0.2*sin(p)^2
  Term.n = 4.0 - 1.4*sin(p)^2
  Term.q = 0.996 - 0.003*sin(p)^2
  
  ; -------------------------------------------------------
  Morph.TargetShape = 1
  Morph.FixedPart = 0.0
  Morph.Rate = 3
  Morph.CornerRadius = 12 ; [mm]
  
  ; -------------------------------------------------------
  Mesh.AngularSegments = 80
  Mesh.LengthSegments = 30
  
  Mesh.ThroatResolution = 4.0     ; [mm]
  Mesh.InterfaceResolution = 8.0  ; [mm]
  Mesh.InterfaceOffset = 5.0      ; [mm]
  
  ; -------------------------------------------------------
  ABEC.SimType = 1
  ABEC.f1 = 800 ; [Hz]
  ABEC.f2 = 20000 ; [Hz]
  ABEC.NumFrequencies = 20
  ABEC.MeshFrequency = 1000 ; [Hz]
  
  ABEC.Polars:SPL = {
    MapAngleRange = 0,90,19
    NormAngle = 0    ; [deg]
    Distance = 3      ; [m]
    Offset = 113       ; [mm]
  }
  
  ; -------------------------------------------------------
  Output.STL = 1
  Output.ABECProject = 1
I came out with the following simulated polar pattern:

Horizonal:
horizontal — ImgBB

Vertical:
vertikal — ImgBB

Then I imported the STL into sketchup to build the horn around the contour and together with hornresp I came up with the following result:
File-Upload.net - Synergy-Horn.skp

File-Upload.net - SynergyHorn.stl


To simulate the midrange frequency response in hornresp I will now descripe what I did and If I did something wrong please tell me.

At first I ran through the Input Wizard with the following settings:
Quarter Space --> Horn loaded --> Multiple Entry --> 3 segments --> Conical (S1) --> Conical (S2) --> Conical (S3) --> Entry Point at S2 --> No acoustical lining --> Throat Chamber --> Throad adapter --> Conical (Throad adapter)

On side one in hornresp (attached screenshot) I did the following settings (see my comments in attached screenshot).
On hornresp side two (attached screenshot) I did the following settings (see also my comments in attached screenshot).
Then I openend the Multiple Entry Horn wizard (to find under tools) and honfresp simulated me the following frequency response (see attachment) which looks good to make an crossover at about 1,5-1,8khz to the HF10HAK.

Is the calculation I did correct?
Do you have a recommendations about the horn? What I can do better? What I did wrong? I want to optimize the horn as far as possible before making a 3d-print-prototyp
Attached Images
File Type: jpg honresp_side1.jpg (435.7 KB, 714 views)
File Type: jpg honresp_side2.jpg (412.0 KB, 703 views)
File Type: png calculated frequency response.png (15.6 KB, 699 views)

Last edited by de45dd; 13th February 2021 at 08:41 PM.
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Old 13th February 2021, 11:07 PM   #2
tmuikku is online now tmuikku  Finland
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Hi, from the renderings it looks like you have the mids on the sides of the horn. Are they within 1/4wl at crossover from each other? If not you could get them a little bit closer if they were at the top and bottom.
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Old 14th February 2021, 01:45 AM   #3
soho54 is offline soho54  United States
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Join Date: Nov 2005
Location: Georgia
Quote:
Originally Posted by de45dd View Post
[FONT=Arial]Is the calculation I did correct?
Do you have a recommendations about the horn? What I can do better? What I did wrong? I want to optimize the horn as far as possible before making a 3d-print-prototyp
Ok I think you can make this work, but the odds of getting it right the first time is very low. Don't let this discourage you, this just means you will have to design and test a few before you can get it right.

Running with that I would suggest the first print be a test bed.

Design the first horn to have the two mids ports in different positions, and test them separately covering the untested side with duct tape. Have one side close together and closer to the throat, and position the other side ~10cm farther from the throat and taps placed farther apart from one another. With luck one of the two will work, and if not you will have a really good idea what you need them to do on the next version.

In your horn there isn't much play space on the sides of the horn, so I would adjust port size. Pull one side further from the throat and remove the latter half of the ports area on that side.

FWIW, for me ~1500hz ends up with a port opening starting 32-40mm from the throat measured along the center of the horn. Horn coverage, flair type, and CD driver depth all play a part. You can also adjust this somewhat with mid chamber volume.

Do not model the mid plug on the test run. Use a flat base, and make some different volume plugs to stick in and test. You will find that the mid taps length and volume under the cone are not cut and dry, and are affected by each other. You will have to dial them in by changing the volume and shape of the volume under the mid.

You can sorta see this effect in Hornresp by using the wizard and changing the Throat Chamber Volume and the Throat Chamber Port Length. You can get the same FR with different inputs, and you can also get a feel for how to adjust your real chamber volume to get the real world FR you are after.

Hornresp can get you close, but there are so many interconnected small parameters that interact. I will say you may want to really pay attention to the large spike there over 1K in the HR sim. Learn how to dampen it in hornresp, so that if it is in the real FR you will know what you have to alter to get rid of it.

As a fellow SketchUp user remember to go back in and remove all the stray interior faces, and the dreaded surface multi faces. They aren't always an issue, but sometimes they give slicers the hickups.

Have fun!

EDIT: that is yellow play-doh used in volume testing years before I got my 3d printer in the real life pics.
Attached Images
File Type: png one.PNG (134.7 KB, 673 views)
File Type: png two.PNG (211.4 KB, 665 views)
File Type: png three.PNG (27.7 KB, 87 views)
File Type: png four.PNG (7.4 KB, 85 views)
File Type: jpg 0608191326.jpg (408.2 KB, 118 views)
File Type: jpg 0608191328.jpg (370.7 KB, 164 views)
File Type: jpg 0608191329.jpg (401.3 KB, 150 views)

Last edited by soho54; 14th February 2021 at 01:48 AM.
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Old 14th February 2021, 02:45 AM   #4
soho54 is offline soho54  United States
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Location: Georgia
It's easier for me to convert the hornresp ME1 to an OD horn in order to play with the loudspeaker wizard and adjust mid volume to tap length and size.

Of course, I use an old version of HR... maybe things are easier now.

I'm not sure quarter space is the way to go. I normally use half space and assume a low corner will be a little bit better, and the upper corner is pretty close.
Attached Images
File Type: png five.PNG (45.8 KB, 114 views)
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Old 14th February 2021, 07:36 AM   #5
de45dd is offline de45dd
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Join Date: Jan 2013
Quote:
Originally Posted by tmuikku View Post
Hi, from the renderings it looks like you have the mids on the sides of the horn. Are they within 1/4wl at crossover from each other? If not you could get them a little bit closer if they were at the top and bottom.
Because of my horn contour with wide horiztonal coverage I donīt think that I can keep them in this range. For me the question also for the 1/4-Wavelength rule is still unclear. Which postion of the opening is important? The start of the openening, the middle or the end? Attached are my measured distances. If the start of the opening is important I can keep them into this range.

Also the 1/4 wavelength rule regarding the distance along the middle of the horn to the input slots is still unclear. What is the starting point for measurment? The diagraphm inside compression driver or the horn throat? Same for end of measurement. Should I chosse the start, the middle or the end of the input ports?
I tried to make it more clear with the attached sketch.
Attached Images
File Type: jpg Distance_To_Each_Other.jpg (328.7 KB, 62 views)
File Type: jpg 1-4_Wavelength_rule.jpg (129.0 KB, 114 views)

Last edited by de45dd; 14th February 2021 at 08:04 AM.
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Old 14th February 2021, 07:44 AM   #6
de45dd is offline de45dd
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Join Date: Jan 2013
Quote:
Originally Posted by soho54 View Post
Design the first horn to have the two mids ports in different positions, and test them separately covering the untested side with duct tape. Have one side close together and closer to the throat, and position the other side ~10cm farther from the throat and taps placed farther apart from one another. With luck one of the two will work, and if not you will have a really good idea what you need them to do on the next version.
ok that means you put one driver on the left side and only measure with one driver active. Then you only measure the other side with only other side active?

Quote:
Originally Posted by soho54 View Post
In your horn there isn't much play space on the sides of the horn, so I would adjust port size. Pull one side further from the throat and remove the latter half of the ports area on that side.
Yes that is a problem. I tried different settings with reducing the input area but then I got an abrubt downfall at about 1,5khz.
So reducing the input area does not model very well in hornresp but is maybe better for the compression driver because it "see's" more horn surface.

Quote:
Originally Posted by soho54 View Post
I will say you may want to really pay attention to the large spike there over 1K in the HR sim. Learn how to dampen it in hornresp, so that if it is in the real FR you will know what you have to alter to get rid of it.
Tried differnt settings but the spike is always there. Do you have an idea how to get rid of it?

Last edited by de45dd; 14th February 2021 at 07:47 AM.
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Old 14th February 2021, 08:24 AM   #7
de45dd is offline de45dd
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Join Date: Jan 2013
Quote:
Originally Posted by tmuikku View Post
Hi, from the renderings it looks like you have the mids on the sides of the horn. Are they within 1/4wl at crossover from each other? If not you could get them a little bit closer if they were at the top and bottom.
putting them on top and buttom is physically not possbible because then I do not have the length to put the 5 inch drivers there. I then need either a bigger horn (what I do not want beacause of match the 12 inch woofer size and keep veritcal coverage low) or use smaller drivers.
Also I want to keep the 12 inch woofers as low as possible together because of D'Appolito configuration. That was the main reason putting them on the side.
What is the effect when not keeping 1/4-Wavelength rule for the input ports to each other?
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Old 14th February 2021, 02:47 PM   #8
de45dd is offline de45dd
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Join Date: Jan 2013
another topic which is unclear to me. Normally the surround is known to only produce "waste" and distortion and is only there to "hold" the cone. In my design (and in a lot of other synergy design I have also seen) I have put the input slots as near as possible to the horn throat (1/4 wavelength rule) which results in, that the input slots is maybe have in the surround and other half over the membran surface. Does this matter in this case? Or is better to trying to put the input slots in front of the cone only?
Attached Images
File Type: jpg surround.jpg (189.0 KB, 100 views)
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Old 14th February 2021, 04:38 PM   #9
tmuikku is online now tmuikku  Finland
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Hi, I haven't built synergy yet but that seems to be the rule of thumb, distance of the taps from the throat dictates the crossover point. I guess if the distance between the opposing mid drivers is more than distance from throat it could add some anomalies in the frequency response.

Tap location relative to the speaker cone: I've got no other info than I remember mark100 and some other member commented sound or measurements were best when the tap is middle of the cone. I don't know how holes are located in Danley synergies, but I suspect that there is problems getting drivers close enough and the hole position is a natural place to balance different properties of the system. Best chance for success would be to start copying what others are doing and then trying to improve on that with ideas emerging from prototypes.

You will learn a lot from the first print and measurements, have fun!

Last edited by tmuikku; 14th February 2021 at 04:40 PM.
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Old 14th February 2021, 05:46 PM   #10
soho54 is offline soho54  United States
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First off the Ap1 in my hornresp pic should have been 17.5. It was late... It is useful for trends only as the cd isnt accounted for.

Quarter wavelength along the horn starts inside the cd, and until approximately the port center. Quarter length across the horn is also approximated at the port center. The more oblong the port the more reality will round things off and differ from the sim.

Ports placed greater than 1/4 wl apart will start producing combfiltering as you move around as the distance from you to each port changes, and it can be seen in polar measurement.. 1/2 wl is a real killer here as things cancel out.

Yes, just do one mid at a time. Run a sim for a single mid for both positions as well. Then compare reality to them. Check polars for deal breakers as well.

If you shrink the ports as they are you have to remove more mid chamber volume, or move the port further from the throat.... the cd seeing more horn face is always a good thing to a point.

The spike will always be there as the drivers motor to sprung weight is tight in this horn profile. I just meant that if you see a +6db spike in reality you can lower it by changing things in the horn.

As for ports on the top or bottom if you pulled the mids closer to the horn inside surface while leaving them on the sides you might just be able to place a short port tube on the top and bottom right over your corners. 6-7mm horn thickness is enough with 2.4-3mm thick walls and medium in fill. With all the extra mid support material there as well I wouldn't be afraid of 4mm horn thickness. This would push them closer to the surrounds.

Surrounds. Ports at the center of the driver would be best, but isnt going to happen most of the time. I think the time difference from the port to the other points along the driver is more an issue than the surround itself in the mids. The chambers and plug shapes help with this though.
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