Full Range TC9 Line Array CNC Cabinet

Hi Guys,

I have had this project in the pipeline for a long time and finally getting some progress made on it. It will still take a while for the project to be completed but I thought I would start to post some information as a build log.

I really like the tall and thin format and think that it will fit in very well as a living room system. Inspiration came from Wesayso’s Two Towers build and the feedback on that design has given me new motivation to get going with mine. Other designs from OPC, Koldby, Halair and one I found on a Scandinavian site have all provided a wealth of information and different strategies to use.

Parts Express had a sale on TC9 drivers and after somewhat of an impulse purchase I had more than fifty of them so I had no choice but to build a line array!

I weighed up all the pros and cons and decided to keep it simple because my other speaker projects have had a habit of dragging on for years. The design I have gone for is most closely related to OPC’s in that it is a rectangular box with five separate sealed enclosures to keep the possibility of pipe resonances down and to allow the series and parallel speakers to have separate volumes.

To make my life easier I designed a cabinet in MDF that could be cut by CNC and would enable me to assemble it fairly easily. I settled on MDF because it is cheap and relatively stable after it has been cut. Plywood would need to have been assembled almost straight away to avoid warping. Birch ply is almost unobtainium in Western Australia, the only place that has it is AUD$300 per 8x4 sheet. I have used Hoop pine ply before which is also very high quality but still $200 a sheet and because it is a softer wood it warps even more unless weighed down.

I also live in a more remote part of WA almost 1200KM from the capital city so transporting sheets of wood is either difficult or costly sometimes both.

I was in Perth for the birth of my son so I was able to get the CAD design done and I had my car to take the cabinet pieces back in so the plan started to come together.

The CNC Company wanted a 2D DXF so the plans were drawn up in AutoCAD, I later created a 3D model from the 2D sketches to verify that it all fitted together and luckily it did. This is the basic design and some shots and animations from Fusion 360.

Here is a link to where the impedance comparisons started as that was useful information

Full Range TC9 Line Array CNC Cabinet

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The CNC fairy paid me a visit and dropped off my cabinets.

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The drivers fit in the cutout, which is a relief.

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I have some strategically placed 6mm holes to allow the base to mate with the top and bottom plates so it lines up without needing to measure.

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The base will be made out of 19mm Oak Hardwood flooring; the MDF will be used as a router template. I bought some pyramid spikes and washer feet so they can be used on carpet or hard floors.

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I tried two ways to seal and mount the drivers.

First is an idea from Troels Gravesen to use thin packing foam as a gasket. It works nicely but compresses too much and leaves a slight gap.

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Second is to use foam weather stripping, this works better and lines the driver basket up perfectly. In the test I mounted it to the back of the driver but I think I will mount it to the baffle recess for the finished baffle.

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The screws I bought have turned out to be a little short and don’t have the best thread for holding in MDF. New stainless steel chipboard screws of the right length are on the way. A little superglue in the pilot hole should harden up the MDF and provide sufficient holding power.
 
The cabinet is well braced and holds together without clamps due to the accuracy of the CNC cuts. The cabinet is quite stiff and has a high-pitched ring with a knock test. To damp that down some I have a sheet of 3mm rubber, which will attach to the side panels of the cabinet. I looked into all sorts of different compounds, which were too expensive, but I already had the rubber so decision made.

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I also had a roll of leather look vinyl with a fabric backing. I bought this when I thought I might use a finish similar to Sonus Faber (Leather and Teak) as I think it looks amazing on the little bookshelf speakers I have (Concertino Domus).

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The plan now is to wrap the outside of the cabinet; it will be easier than painting a tower over 2m in length. I also think that this will help with damping as well.
 
I am still undecided on the audibility of cabinet edge diffraction as according to some it falls into the realm of something the ear ignores. But to make sure I have a foot on either side I plan to make an attempt to reduce it where I can. I have recessed the drivers into the baffle so they sit flush reducing any sharp edges near the driver.

I am going to use a ½” roundover on the edges front and back as I have used 16mm MDF and I don’t want to compromise the structure in favour of a bigger roundover.

The other strategy is to use pressed wool felt around the edges of the front baffle in a Dunlavy style. I have seen some experiments where this has had quite a significant reduction on measured edge diffraction so the jury is still out as to whether it will work.

I am going to wrap the finished cabinet in a black fabric sock in the same way that OPC did with his. The secondary benefit to the felt is that it will act as a spacer to allow the drivers excursion without hitting the fabric. Test sock is working!

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For wiring I am going so use some knock off Wago lever clamps.

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The plan is to run a length of wire the length of the cabinet in small sections according to this schematic from Roger Russell.

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Where there is a need to branch to the driver the middle wire will go to the driver, the upper to the rest of the cabinet. I will use glue or another fastener to mount them to the the solid baffle bracing.

Quick Disconnect terminals will be crimped to the end to allow the drivers to be easily mounted and removed if necessary. The series drivers will just go from terminal to terminal with short wires and crimps.
 
Looks fantastic! And those Wago clamps look nice! Very clean and easy. I'll have to find a source here. Not to cross-contaminate threads, but what volume did you end up with per driver?

You can get them from ebay.

20 Pcs 3 Way 3 Port Lever Clamp Lock Terminal Block AC 250V 32A PCT-213 | eBay

Or search for terminal block lever clamp.

They are hard to tell apart from the genuine article except QC isn't so good as I had one that had no actual clamp inside, the levers just flapped. Just buy more than you need.

You can can get genuine wago ones product code 222-413 from most of the distributers, newark, RS, Farnell.

My cabinet comes out at about 2L not taking into account bracing but allowing for the effects of damping.

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I have some comments for your thread but they will have to wait as I don't have any more time right now :xeye:
 
Cool!

A norwegian team made a LA aswell but used only rubbery kind of glue to secure the drivers to baffle. (No rigid/fixed fixing so the drivers are not directly coupled to the baffle)

Thanks!

I would really like to isolate the drivers from the baffle but I haven't been able to come up with a workable way to do it. Do you have a link to the Norwegian array?

I have glued small tweeters in place with silicone before, but they weighed next to nothing. I have also used magnet mounts but for 25 drivers it was too much for me to contemplate.
 
Sure :)

DTP Line Source - Side 2

Post #31

They dont list what kind of glue they used but its a red liquid gasket (that cure to a rubbery solid).
The screws were used to hold in place while curing, removed afterwards.

Interesting, looks like they have made a sandwich of an outer baffle with roundover which maybe holds the driver down and the glue acts as a gasket. How do you then isolate the face baffle from everything else? This is why I couldn't find something simple.

Not sure about the NS3 drivers and the tweeter in the middle, he mentions the SEAS full range used in LXmini but not the TC9 even though Wesayso's thread is mentioned. I also really don't understand all the spaghetti wiring, that cannot be good.

Huge amount of work to make the cabinet like that on the inside, hats of to him for the effort.

Are you thinking about a Line array Mark 2 like you mention in that thread? ;)
 
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