Desktop TL template audio discussion

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#141
wchang said:
Let's call this general type folded "stepped TL".
Click to expand...

May I call this particular implementation "flatwounds" 🙂

Hello guys
I now have the final stage of this shell. Thank you all for helping me understand how to work a box or two for these Pioneer coaxials. I feel I have ended up with a viable option, but to be completely honest, I do not have any idea if this is any better than the previous tower like iteration. I have rounded the leading edge of the face on this model, but this is only to give a clue to the finished look. This would be changeable in the 3D file

I would enjoy giving this back to the community as an easy box option for any similar sized driver. I have impressed myself with how the planning for build has worked out! Hoping justifiably. Please let me know if this is worth sharing to the community

My reasons for saying other drivers:
I have managed to make it a highly modular jig system that ends up being the trim
This can work with all sorts of panel materials
can be easily scaled
provides unreal access to a very well fitting together box
makes all sorts of ruler and angle implements unnecessary
removes most of the post assembly trim, fit and finish work
Finished panels can be used
Using precut and finished panels, only a bunch of small clamps are needed. No need for long across the box clamps
Driver, vent, all the rounding and step work is already taken care of by this stage
If raw material panels are used for the sides, they will only need surface finish for the box to not require any further finish
Baffle is designed to layer on a face. This can be done with this same method or something like a pretty wood
Box can tuned in all areas including fill, tunnel taper inserts tunnel length changes
If what I have learned is correct, this shell can be scaled down to smaller drivers with all tunnels and openings keeping ratio and pipe keeping basic tune

How does everyone who provided input feel, is the able to be presented as an open source resource for users?

These speakers or whatever ends up being the keepers will be the start of a one room studio and workshop renovation. I would enjoy logging this process and maybe have mistakes caught out along the way

Thank you all, let's see how these build and test and sound

Thanks and regards
Randy

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#142
I couldn't leave it alone 😀. I have now optimised to be totally universal system that will allow a build process using semi or finished sheet material. This will only need to be cut to size and surfaces finished to personal taste. Only equipment needed will be a screwdriver, screws, glue, optional clamps, any finish if using unfinished material

The objective is to remove all the messy construction methods involving edge blending, hole cutting, routing, major sanding, paint and varnish. The design requires either making or ordering a printed or CNC'ed jig and getting your timber shop to cut the sheet material part sizes

This system enables new manufactured woods like resin impregnated plant fibre products like pre-finished flooring planks, bamboo boards, foam and foam core, hex core, composites to be used for the panels as well as the usual ply and MDF

The system is also configurable for a full 3d print or CNC at any scale (will work well for smaller drivers like the 2-4" stuff) to a tower floor stander monster. All dimensions, holes, tunnels are configurable with an easy-to-use template
 
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#144
planet10 said:
being able to tune whatever you build is GOOD.........

dave
Click to expand...

Dave
Would you be able to change the thread title to "Desktop TL template audio discussion" please? I have a FreeCAD template and a tutorial for that which I would like to share in a new thread and have that thread as discussion for construction and this one as discussion for audio. Promise this will be well worth it to folks with difficulties with advanced wood working and open up messing around with TL's to more people in the community

Thanks and regards
Randy
 
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#146
Hi Greg,

thank you for your reply in post 140.

However, I am still not understanding your explanation. Since I do not want to pollute the thread with unrelated issue, I was trying to cantact you via PM or e-mail, but none appears to be enabled in your profile.

If you do not want to be bothered in this manner, please ignore this post.

Kindest regards,

M
 
#149
Do you mean HR should instead show a change in tuning frequency if I scaled down the pipe to a smaller opening while keeping the ratio? I ran simulations for various volumes at the same ratio and the tuning frequency remained consistent. What am I doing wrong to get that result?
 
#151
I think I get what you are trying to say. Have a look at the table I created for 6 segments. The volume changes due to all the opening surface areas changing. But the tunnel lengths remain the same to keep the tune. The angled line is lifted or dropped while keeping the angle. The resulting uprights depict opening surface area. The total length of the line remains the same as seen by the horizontal line. Altering the angle changes the apparent line length and alters tune, altering length changes angle and tune. I thought I got the grasp of pulling numbers out of such a table. Let me how far off I am please
 
#152
Here’s a TL design I made for a 6.5in driver - the Purifi in this case but I have also used it successfully with other 6.5in drivers like an OEM XBL motor by Dan Wiggins. The woofer goes where the turn is located. The other cutout was for the tweeter and waveguide.

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https://www.diyaudio.com/community/...using-ptt6-5-and-rs28f-in-a-waveguide.354778/

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Predicted response:
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You can listen to it here, I have a it playing with the Wiggins XBL and an OEM custom ribbon tweeter:


 
#154
How does this look for a 4" driver?

Rated power: 40W
Maximum power: 80W
Impedance: 4 Ohm, 8 Ohm
Frequency: 69-2KHz
Sensitivity: 88db±3db
Equivalent volume: 8L
Qts: 0.49
Fo: 69Hz
Voice coil: 25mm
Net weight: 1.05kg
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I wonder if this would be a good candidate to test a scaled full print and the tunnel shortening functions in the template and post print. Looking for recommendations on other drivers to try in the 2-4" range
 
#157
That is a tapered TL simulation with variable stuffing at strategically placed locations to extend the bass rolloff and smooth the mid bass resonances. The impedance plot of a bass reflex and TL can look very similar. They are both vented and have a double peak with a saddle at the cabinet Fs. The TL has the resonance frequency based on 1/4 wave theory, whereas the BR is based on a Helmholtz resonator volume with a vent.
 
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#158
planet10 said:
Looks like it is 20 dB down above 2kHz.

dave
Click to expand...
You are right, I did notice that. Would this be a good choice with a 2" full range or a tweeter as a two-way? This is not my 4" full range. I went to shop for a 4" last night and realised that they actually aren't full range. Most only have a response to 100hz or so, and I am guessing my ones wouldn't be any different. Then I started looking for a 4" sub that could be used as a woofer for a lower tuned system. I asked for recommendations for a good driver but no responses so far on that

I couldn't find any other than the 4" peerless that showed much bass extension. Then I looked to car audio and found one 4" coax that says down to 35hz and one dual cone down to 50hz. They are $50 AUD a pair and are available in the local shop. What would make a good test driver for a smaller test run?

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