Presenting the Trynergy - a full range tractrix synergy. - diyAudio
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Old 2nd September 2014, 06:42 PM   #1
xrk971 is online now xrk971  United States
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Default Presenting the Trynergy - a full range tractrix synergy.

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Presenting the Trynergy - a full range tractrix synergy.

This speaker spun-off from the PRV 5MR450-NDY thread here: PRV 5MR450-NDY for FAST applications
and is sufficiently OT from the main thread which deals with the PRV driver and a FAST implementation that I think it deserves its own thread. The 1.0x scale tractrix horn design was calculated using Volvotreter's tractrix spreadsheet using a 2.78in square throat and a 175Hz flare frequency. http://volvotreter.de/downloads/Tractrix_v1.4b.zip

The spreadsheet as I used it to build my horns is on post 90 here http://www.diyaudio.com/forums/full-...ml#post4049422

I then took the dimensions from every inch of axial distance and plotted the curve for the horn profile. I then fitted the curve with a two-point spline in Solidworks, then made a 3d model using the lofting tool, then I unrolled the curved shape to a flat 2d pattern using the sheet metal "flatten" tool. This pattern, once cut onto foam core (scored with parallel cuts every 3 to 5 mm on on the concave side) self-formed into the tractrix profile when enforcing the mechanical mates of the mouth, throat, and edge boundary conditions via hot melt glue to the top and bottom panels. For the 0.70x case, the throat is 2.0 in square and the mouth is 20 in wide and horn is 15.3 in deep. Glue the throat section first, then the mouth, then the middle.

Cut plan for 2d panel on post 94 here http://www.diyaudio.com/forums/full-...ml#post4049533

Here is the cut/glue plan for the flat top and bottom panels on post 175:
Presenting the Trynergy - a full range tractrix synergy.

The idea for this speaker came from a large 300Hz 28in wide x 17in tall x 22in deep tractrix horn driven by a full range driver. I then scaled that horn down to 0.70x for a 400Hz 20in wide x 12in tall x 15in deep tractrix. Originally designed with the Faital Pro 3FE25 in mid, I stuck a Vifa TC9FD in it for grins. With some DSP EQ'ing I was able to get the following response from the little Vifa:

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With semi-decent polars:

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And the Impulse response isn't too shabby either:

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Here is a closeup of the horn driver throat flange fitted with the TC9FD (note that a FC spacer with a cutout had to be made to prevent the surround from rubbing the flange plate):

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Here is the rear sealed chamber (6in x 6in x 4in and lined with open cell grey foam):

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Here is the horn before I put the woofers on (note the black panels on top of the white panels - those are the constrained layer damping (CLD) layers used to reduce panel resonances using latex caulking in between the white horn walls and the black foam sheets):

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I normally model stuff before building, but in this case, I had some buyout PE 6.5in woofers lying around. There is only so many ways to fit these drivers into the tractrix so I went for the build it as you go approach sans modeling and got this after 90 minutes of cutting foam core/cardboard and hot glue:

Click the image to open in full size.

After building it, I then modeled it and saw that it needs a rear sealed chamber on the woofers otherwise there is no bass to speak of due to proximity of the backside of woofers and the mouth causing cancellation. Here is the predicted response with the woofers and the TC9FD:

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With 3.5 mm xmax being reached at 21 volts:

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Giving a corresponding max SPL capability of about 113dB at 1m and 21v:

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With the corresponding electrical power input predicted to be 30 watts per 6.5 in driver, which is OK per the manufacturer's rating:

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The $40 cost break down is as follows:

- Qnty 4 Parts Express buyout 6.5 in polycone woofers (same driver as used in ther well-regarded B652 speakers) $5 ea x 4 = $20

- Qnty 1 Vifa TC9FD driver $12

- 4 sheets of foam core $4

- 1 tube of latex caulking for the constrained layer damping $2 (n.b., DO NOT use Liquid Nails - as the solvent vapors will melt the foam in the foam core!)

- 1 dual banana post binding terminal $1 ( Edit: technically $3 now with qnty 3 binding posts)

- Hot melt glue sticks $1

Note that you will need active EQ and bi-amping to make this work. It is not a passive speaker. If you have a miniDSP 2x4 and a couple of amps you are set. If you need tips on how to do this, check out the "Cheap and FAST OB, Literally" thread.

I still need to install the rear sealed chamber and get a measurement with the woofers on.

Let's see if a point source synergy speaker can be built for $40 and if it sounds good. Stay tuned!

Measurements and sound clips to follow.

Update Sept 3, 2014: the tractrix fullrange Synergy is completed and it sounds wonderful! See post 13.

Click the image to open in full size.

Click the image to open in full size.

Edit Sept 4, 2014: New tweaks on EQ provide linear phase from 600Hz to 5kHz and cleaner impulse response. Note all data smoothed at 1/12th octave.

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Click the image to open in full size.

Edit: Sept 7, 2014 - Faital Pro 3FE22 driver with 4-way miniDSP XO and bass horn sub.
Click the image to open in full size.

Edit: Sept 12, 2014 - How to adjust and optimize time alignment between HF and mid woofers - Presenting the Trynergy - a full range tractrix synergy.

Last edited by xrk971; 12th September 2014 at 02:20 PM.
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Old 2nd September 2014, 07:59 PM   #2
kees52 is offline kees52  Netherlands
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Nice

you for shure the script for it? so I can try it with phillips and frs8m.

I do not like high qts woofers in a horn.

I use analog filters so I am curieus about it.

And this horn is more home friendly, as for second winter program.

regards

kees
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Old 2nd September 2014, 08:16 PM   #3
xrk971 is online now xrk971  United States
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Let me clean up the code a bit and then I will post it. High Qts drivers are not necessarily bad for horn loading. This is a myth from the days of high impedance amps of past. The low mechanical damping may pose issues with oacillations in freq response but that is more of a high Qms. For the woofer injection ports those really are not horn loaded but rather convenient entry points into horn mouth. For the fullrange driver I admit the Vifa is not the best choice and I am waiting for the Faital Pro 3FE25 or 3FE22 to arrive. Even there, the high Qts was not so bad to make it sound bad. In fact, I thought it rather nice sounding. Of course not as good as the $105 5MR450NDY but I can't complain for a $20 horn (before 6.5 in woofers).
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Old 2nd September 2014, 09:21 PM   #4
kees52 is offline kees52  Netherlands
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Oke, I await it.

I have play some with the Xmax, and have in akabak the ports adjusted so that I have 120 dB 5mm Xmax (speaker is max 8 mm), the implemention of the reflex ports is very nice for this.

the FRS8M from visaton is also very good for you it is a small fullrange who go to 20 Khz.

I have change your script a little, like the power to them, high has now 1.5 and not 1.95.
chamber is smaller because it is little woofer, but handle 40 watts.

I get 120 +dB with 20 volts on it xmax 4mm that is small, wauw.

second photo are the phillips woofers in normal conic horn.

regards

kees
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File Type: jpg ScreenHunter_218 Sep. 01 23.22.jpg (98.9 KB, 141 views)
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File Type: zip 5mr450-2.zip (4.3 KB, 5 views)

Last edited by kees52; 2nd September 2014 at 09:24 PM.
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Old 2nd September 2014, 09:32 PM   #5
xrk971 is online now xrk971  United States
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Kees,
That is some impressive bass you are getting out of the Phillips and it would appear seamless integration with the Visaton. 120dB+ is very good without hitting xmax.
You should build it based on how good the sim is coming out. My quad 6.5 in woofers can get lower bass but then the box volume has to be very big because they are rather large Vas drivers.
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Old 2nd September 2014, 09:35 PM   #6
xrk971 is online now xrk971  United States
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Default Akabak script for 0.7x Synergy Horn

Here is the code for this speaker.

Version TRCTX4X.txt

Have fun and let me know if you find any bugs or typos.
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File Type: txt TRCTX4X-Script.txt (11.7 KB, 48 views)
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Old 2nd September 2014, 10:10 PM   #7
BYRTT is offline BYRTT  Denmark
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Well done, looking at pictures build now gets a very technical and functions combined look. Did read some post by Danley his version in a fair broad band was capable produce acoustic squarewaves does this have chance here.
Ever
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Old 2nd September 2014, 11:11 PM   #8
xrk971 is online now xrk971  United States
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I wonder if I can see a square wave recorded with the REW raw signal? Square waves are hard but doable if you have a clean impulse response function. Right now there is ringing due to cone breakup from
7k on up to 12khz. If I can smooth those out with EQ then there might be cleaner square waves.
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Old 3rd September 2014, 02:06 AM   #9
unaHm is offline unaHm  United States
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Quote:
Originally Posted by xrk971 View Post
My quad 6.5 in woofers can get lower bass but then the box volume has to be very big because they are rather large Vas drivers.
How big do you estimate it would need to be? Would it be feasible to make an enclosure for the whole unit, that doubles as the sealed rear chamber for the combined woofers?
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Old 3rd September 2014, 02:21 AM   #10
xrk971 is online now xrk971  United States
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Quote:
Originally Posted by unaHm View Post
How big do you estimate it would need to be? Would it be feasible to make an enclosure for the whole unit, that doubles as the sealed rear chamber for the combined woofers?
That is normally what is done and this provides sufficient volume for a bass reflex. For a sealed system I only need 11 liters per two drivers. Or a 8x14x6 in box per side with two drivers. I am going sealed to get clean bass transients. If I made the total volume 2 cu ft for all four drivers with bass reflex ports I can reach 60Hz.
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