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Multi-Way Conventional loudspeakers with crossovers

synergy.....Take #7
synergy.....Take #7
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Old 25th March 2020, 06:25 PM   #1
mark100 is online now mark100  United States
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synergy.....Take #7
Default synergy.....Take #7

Or at least I'm calling it Take 7.
It's really the 3rd completely different cabinet.
Other 'takes' were trying out different size ports or different drivers, etc.

They've all been desinged to go with subs at 100Hz like my previous synergy thread 100Hz two-way synergy project.

That thread ended up turning into this 60x40
syn5 with 18fh500s 400R.jpg
I've truly enjoyed this speaker, to the point I wanted to build another for stereo, but it's too damn big and heavy to move around. About 100 lbs.
One of the biggest joys in audio for me, is being able to move gear around, listen outside, swap stuff around, always making comparisons and learning.
So I've spent a few months researching how to get the synergy goodness, but shed alot of weight.

Anyway here's the outcome.
syn 7 dcx.jpg
It's a 90x60, that has very close to the same primary horn width and height, but of course less depth due to its wider pattern.
It weighs in at a glorious 45 lbs !!!
Uses two dirt cheap faital 10FE200's as mids, and one not so cheap b&c dcx 464 coax cd, ...but getting the CD down to 500Hz is what lets it work.

I did a few things different from my previous attempts that all tried to adhere to the conventional synergy wisdom.
Biggest change was putting the mid ports in the center of the horn instead of in the corners.
I made a test horn where I could block ports easily and experimented a bit. I couldn't find a compelling case for corner ports, in terms of how the HF and VHF were effected.
That was a peasant surprise really, because I wanted the ports in the horn center as part of a weight reduction design. It allowed the mid drivers to go on the top and bottom in small cavities, and the horn side walls be all the cabinent there is.
Like this
syn 7 constr.jpg
Plus, ports in the center of the horn are just plain easier to make

Also made a simple box to test port sizes and shapes, port thickness, and how much port frustrum matters. Picture a sealed box where you just lay a plate with various port tries on top, and move it around over the cone.
I used plates out of 12mm BB and thin steel sheet, and ended up choosing a 10:1 compression ratio in terms of hole size.
Surprisingly, I could not find anything to beat a simple round hole aligned with the center of the cone.
Neither could i find a reason to use thin ports, or even do anything to the wood hole other than a little roundover smoothing.

The port holes' center is 7.5" from the throat. Basically, the 10" drivers sit as close to the horn apex as possible, which also puts the port nearly under the center of the cone.

I always have to give sincere thanks to BWaslo for his speadsheet....I simply could not make a synergy without it.
Also need to thank Makita for my track saw Lol. It makes the bevel/miter cuts so easy and true...much better than i can do by table saw and sleds.
Oh, I've found I like to make the horn start at 1.4" square, and not have to round out the walls to mate the CD. It's been easier to add museum wax to the horn corners in the mouth.

Syn7 may or may not get a secondary flare depending on outdoor testing.
I should be able to make a detachable flare like in the first pic fairly easily.
What I really want to do is add a tractrix flare as the secondary flare.
Ala the K-402. I figure the K-402 first 2/3's from the throat is pretty much straight sided conical, and the last 1/3 tractrix. A conatrix or a tractical, depending on which end you look from haha

Last edited by AllenB; 25th March 2020 at 09:58 PM. Reason: Typos.. requested edit
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Old 25th March 2020, 10:57 PM   #2
kipman725 is offline kipman725  United Kingdom
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Cool horn!

Perhaps the problem with center ports occurs off axis?
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Old 25th March 2020, 11:47 PM   #3
tmuikku is offline tmuikku  Finland
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Very cool! Is it easy to get (tune?) the throat area right with this design principle? Main thing preventing me to try one has been how to make the throat. Makita track saw surely is accurate! Very good tool for speaker builder.
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Old 26th March 2020, 12:21 AM   #4
mark100 is online now mark100  United States
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synergy.....Take #7
Quote:
Originally Posted by kipman725 View Post
Cool horn!

Perhaps the problem with center ports occurs off axis?
Thx kipman725,

Great you asked that...because that was the test i used to evaluate the different port placement sizes, shapes, thicknesses, frustrum, etc.
The test being, how consistent was on-axis with off-axis.
If on-ax and off-ax vary consistently, response is totally fixable ime.

I'm confused why convention says put the ports in the corners .......
my measurements say why?
On-ax vs off-ax for Hf and VHf were about the same, corner vs middle...so why corners????

What seemed to matter the most for Mid, but definitely after port distance from throat, was getting the mid port under the middle of the mid driver.


All i know is i'm hearing truly glorious, and loud, sound from a 45lb speaker
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Old 26th March 2020, 12:29 AM   #5
mark100 is online now mark100  United States
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synergy.....Take #7
Quote:
Originally Posted by tmuikku View Post
Very cool! Is it easy to get (tune?) the throat area right with this design principle? Main thing preventing me to try one has been how to make the throat. Makita track saw surely is accurate! Very good tool for speaker builder.
Thx Tmuikku,

Yep, the Makita rocks ! It's crazy how much better my wood working has increased because of it.

I'm still digesting your super program....I'll try to tune this 'syn 7 'with it when i get proficient.
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Old 26th March 2020, 12:52 AM   #6
mark100 is online now mark100  United States
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synergy.....Take #7
Thank you for the edit changes AllenB
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Old 26th March 2020, 03:19 AM   #7
fluid is offline fluid  Australia
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Quote:
Originally Posted by mark100 View Post

I'm confused why convention says put the ports in the corners .......
my measurements say why?
On-ax vs off-ax for Hf and VHf were about the same, corner vs middle...so why corners????

What seemed to matter the most for Mid, but definitely after port distance from throat, was getting the mid port under the middle of the mid driver.
Hiding the ports in the corners and making them smaller had effects on the tweeters output, in that that when the ports are closer for midrange drivers the effects are greater. When you move them out further they have less effect. Pushing the tweeter lower like with your DCX makes a lot of the other compromises less important.

The depth, frustrumming and needing to use a cone plug comes down to trying to push the midrange low pass frequency higher. Horn resp sims shows the interaction of the volume of air in the throat chamber, port length and size. When you move the target down to 500Hz that is easier too. The 10FE200 also has a pretty shallow cone and not that much trapped air, a deeper cone might well present differently.

Centering the port over the driver will minimize path length differences and seems like a no brainer but it is not always possible when trying to juggle the physical size of midranges close enough to the throat.

Last edited by fluid; 26th March 2020 at 03:22 AM.
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Old 26th March 2020, 04:24 AM   #8
Patrick Bateman is offline Patrick Bateman  United States
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Quote:
Originally Posted by mark100 View Post
Thx kipman725,

Great you asked that...because that was the test i used to evaluate the different port placement sizes, shapes, thicknesses, frustrum, etc.
The test being, how consistent was on-axis with off-axis.
If on-ax and off-ax vary consistently, response is totally fixable ime.

I'm confused why convention says put the ports in the corners .......
my measurements say why?
On-ax vs off-ax for Hf and VHf were about the same, corner vs middle...so why corners????

What seemed to matter the most for Mid, but definitely after port distance from throat, was getting the mid port under the middle of the mid driver.


All i know is i'm hearing truly glorious, and loud, sound from a 45lb speaker
Click the image to open in full size.

The closer that you get to the throat, the more that the shape needs to be perfect.

IE, if you have some discontinuities in a horn and they're located three inches from the throat, it probably won't screw things up too much.

But as you get closer and closer, the shape of the horn becomes more and more critical.

Augerpro has some great examples of this in his 3D printed waveguide thread. He's got graphs that demonstrate that a change of just 2-4mm make a difference at the throat.

And the really depressing thing, is that if the throat is off, there's almost nothing you can do to fix it.

So, that's part of the reason why you want to 'hide' the midrange taps in a Unity horn. Particularly if the mids are close to the throat.
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Old 26th March 2020, 06:07 AM   #9
jjasniew is offline jjasniew  United States
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Why not 3D print the throat part, and mount it as a component to the wood part? That would make the critical small dimensions consistent and easier to realize.
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Old 26th March 2020, 06:08 AM   #10
camplo is offline camplo
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Impressive! I've got a cordless Makita drill and plans to add to the collection lol.
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