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New project - TG’s Faital 3 way classic 15”


Janus77

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Using 18mm ply for the bracings, i've arrived at the following calculation on dimensions:

image.png.f4e2ca07d5e1eb0745a68194e8f38122.png

 

 

43.7mm deep instead of the 44mm Troels advised if using 24mm braces.  It's only 0.19cbl difference, being slightly larger volume than the OG design.

 

I don't think i need to check this with Troels, have looked at the numbers for long enough to be confident i'm maintaining internal dimensions. (famous last words)

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To do list:

 

1. source black wood vinyl - have found a few supply options which look good.  

This looks forgiving: https://www.amazon.com.au/VViViD-Black-Textured-Air-release-Adhesive/dp/B01BNT5DBW/ref=pd_sbs_201_1/355-1826262-5218520?_encoding=UTF8&pd_rd_i=B01BNT5DBW&pd_rd_r=4f3af288-d867-475f-9fa9-df708a08fbc9&pd_rd_w=aW5GV&pd_rd_wg=tdl5n&pf_rd_p=50c53f88-de65-41cf-869b-e0a249ae05bb&pf_rd_r=ZSHH3Q8JBXPZSMX1Y3G8&psc=1&refRID=ZSHH3Q8JBXPZSMX1Y3G8

 

2. buy castor wheels

 

3. Probably overkill, but seeing as i'm 190cbml over Troels design, thinking about gluing a sheet of this into each cabinet to further reduce vibration:

https://www.ebay.com.au/itm/223549385116

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Our couch sits quite low, these castors are as low loading height as i've found at 38mm.  Troels had 49mm feet on his speakers. 

25mm wheels might make them stick a bit on our carpet, but the height is excellent and i reckon i can muscle them around ok:

 

https://www.australianwheelandcastors.com.au/products/Ø25mm-1-Nylon-Polyamide-p157719527

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21 minutes ago, Janus77 said:

bottom looks like

 

Life expectancy of 5-7 years? That's a worry, even in these days of built-in obsolescence. DIY is (should be) a cut above all that. I had a terrible time replacing some stick-on stuff once, and swore against it. You can sand paint off later, (or paint over varnish), and do whatever suits at the time.

 

With your feet, I'd suggest you get an accurate-ish measurement of your collective ear heights when seated, and work from there. Tilting (forward, anyway) is much better than fussing with stands. Bass response will benefit from the bottom of the baffle joining the floor - no "baffle step loss".

 

I think castors would be a nuisance, especially on carpet - they are really cantankerous to move in fine increments, which you will need. 25 mm diameter wheels will be "up to the axles" in carpet!

 

Sliders (large - at least 50 mm square or round) would be much easier, and kinder to carpet.

 

Just throwing in some thoughts here. Don't let me dampen your enthusiasm; you are obviously giving this a lot of thinking time, and might be asking for some external influence.

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Thanks Brian, any input is appreciated.

 

I figured 5-7 years was the life expectancy on a car - hoped the wrap would last much longer on speakers inside.  Worth checking further with the supplier though.

 

I'll look into the sliders, have done some rough calculations on height and our ears are generally going to be slightly below where the tweeter will be.  Might be time for a new couch.

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I'm guessing the ear height thing will be fine. If you look at people's sketches of lobing, at a 3 m listening distance, it won't matter if you're within 6" or so. Same with a measuring mike. But of course we want to know the ideal, so we can be comfortable in knowing the reality of the situation.

 

Priority is really important. I'd be weighing up the difference between a level of crossover cost, and the cost of a new couch. More important might be avoiding leather as a couch material, as the reflections forwards to your ears can badly damage the sound. And that depends on the height of the couch back, etc.

 

Also appropriate springs to mind. You were writing about Sorbothane sheets as lining yesterday, at $1750 per square metre. This is not what you need for speaker lining - it's designed to go between 2 surfaces as part of CLD. You need mass and good adhesion. I haven't come across the bitumen pads that Troels uses in this country, but Dynamat Extreme has some similarity - needs a shiny surface to stick well to, ideally, so a coat of varnish internally would do. It certainly deadens boxes, according to the venerated knuckle test.

 

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Our current couch is a big bass trap, fabric. 

I wouldn't buy a leather couch, nothing worse than sitting on a leather couch on a hot summer day with shorts on.

To be honest, part of the agreement with my wife to build speakers was that she gets a new couch for the living room, so i'll keep in mind ear height when shopping and will stick away from leather at all cost.

 

I know what you mean about the small castors being difficult to move, however i think they'll be easier to move than sliders.  Will give it some more thought - i had it in my head that i'm better off with a lower profile castor even if more difficult to roll as it'll bring the tweeter closer to ear level.  Angling the speakers as you mentioned might be a better solution, i can just put some plastic floor savers under the rear castors.

 

Will take a look at the Dynamat Extreme material, thank you.  Would this material be best applied to the internal face of the front baffle (around the drivers)?

 

Crossover components scheduled to arrive tomorrow, will get started over the weekend if i can find some board to mount them on - it's happening!! :D

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Don't worry about not having the exact enclosure volume that Troels has, it's the relationship between port length and volume that is key to meet a specified tuning frequency, so if you end up with 110 L you will need to change the port length to meet desired 38.5hz, use winsd to model different volumes and then see how the port length and graph changes. (the difference of 10L will not change the graph much)

Small volume changes will not make much difference to frequency graph curve - this also you can test using the Faital driver parameters.

 

And, if later on you go active DSP, you can force the driver to go lower and extend the range, given you are using this in a domestic environment you can trade maximum output for extension. 

 

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Tweeters and crossover kit from Jantzen is with the Fedex driver for delivery today, exciting!

 

Wondering if i try to get a coat of varnish onto the ply a few days before the first class, so i'm ready to cut during the first class?  Troels recommends a layer to reduce tearing when cutting the panels.  Added benefit is the vinyl will stick to a varnished surface better than an unfinished porous wood surface i believe.

 

Regarding the additional damping material, i think i'm getting ahead of myself with this idea.  I wanted to stay true to Troels design, he doesn't use any dynamat or asphalt matting in this design, so i think i'll forget the idea.  I can always go back and do it later too which is the great thing about DIY :) i'll be able to move up to the Be dome tweeter if i want in a few years, and can upgrade crossovers easily too if/when i want..

 

Castors, rather than trying to keep the height down, i'll go something slightly higher (60-70mm) which has a larger wheel diameter with proper bearings to make moving them around easier.  I can put some plastic caps under the rear castors to angle the speaker down slightly if needed.  Sliders are a good idea too, however i might want to move them in and out of rooms occasionally, I think wheels give more flexibility.

 

 

 

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Wife just signed for the FedEx delivery. 

 

Thinking through the clearcoat idea, might have to plan it a little as i don't want any clearcoat on the front baffles as i plan to stain these before doing a varnish or polyurethane finish, guess i just mark out the cuts and leave a little extra room for the 2 front baffles so i can leave them unfinished.

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Having just completed a build of these speakers, a few comments that may help you avoid my pitfalls!

 

- Plywood is quite brittle so varnish coating is recommended or just be very careful (but expect some damage in handling).

- Drill holes for speaker wire into speaker cavities before you add the felt. Otherwise the drill will destroy the felt. 
- Similarly for holes for castors.

- Add the castors before you close the speaker up. 
- If using feet, use Super Strength Araldite as it has a working time of 1h. The other versions cure too quickly for applying with an injection.

- Add 1mm to the diameter of drivers when you rebate the baffle. Measure drivers with a caliper!

- Same for BR tubes and sand down from the front baffle for a smooth finish. 
- Careful where placing the BR tubes as bolts for castors may impact. 30mm bolts should be ok to leave headroom between bolts and BR tubes. 
- Using 24mm BP means that each speaker is very heavy and hence difficult to manoeuvre. Make sure you have a buddy to help move. 
- Cut the felt with a Stanley Knife whilst positioned on the internal speaker panels. Then glue. Make sure you leave room so that felt doesn’t impede clamping the front and back. 
- Order more of the glue for crossover fixing than you think you need. The stuff that TG uses is wonderful. 
- Titebond 3 is really nice. You need about 1litre.

- Same for the tile glue - 1litre is about right. Definitely use gloves and a stiff brush. 

I’ll publish a complete build story on 3 Sad Bastards and it’s a topic on an upcoming podcast :)

 

Have fun - they are a cracking speaker!!!

 

Aris

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Thanks Aris, i'll look forward to your build story on the podcast. 

Which of the kit options did you purchase, and did you use 24mm birch, 18mm birch, or MDF in the construction?

I'd considered having the panels cut to spec, however i've always wanted to learn some woodworking skills, so construction in the Makerspace course is a nice way to kill 2 birds with 1 stone.

For the tile glue, did you use any particular brand for a reason, or any generic Bunnings product will do?

I'll order the Titebond 3 for the cabinet construction.

I have many questions, however i'll wait until having listened to the upcoming podcast! :)

Your comments having built these are invaluable, thanks for posting.

 

I'm a little concerned that my low end DAC and amp will become weak links even though i think they sound excellent with my Paradigm 9se, i imagine the 3wc will be more revealing.  Wait and see..

The kit has arrived today, so no opportunity to source more of the crossover glue.

Mid and Bass drivers have not shipped from lean Uk yet, the 18 sound were out of stock, should be back in stock next week.

 

Listening to your podcast right now, good fun.

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I actually got the Tweeter (Be version) and Woofer locally. I think the Mid I got from Germany Thomann as the UK was out of stock at the time. The link below is to the UK site.

 

I opted for the upscale x-over, who knows if it's that much better than the standard.

 

Satori TW29BN-B-8

$499 [ $1,007.91 ]

https://www.wagneronline.com.au/satori-1-dome-tweeter-beryllium-neo/speaker-drivers/audio-speakers-pa/tw29bn-b-8-81676/999531/pd/

 

18 SOUND 8NMB420/8

£126 ($230) [ $595.69 ]

https://www.thomann.de/gb/eighteensound_8nmb420_8_ohm.htm

 

Faital 15PR400

$369 [ $738.00 ]

https://djcity.com.au/product/faital-pro-fa-15pr400-15-inch-lf-driver/


 

For tile glue I used Dunlop Vinyl Adhesive from Bunnings. Works really well.

 

Dunlop 1L Vinyl Adhesive

https://www.bunnings.com.au/dunlop-1l-vinyl-adhesive_p6820002

 

Finally, in terms of cutting etc, I opted to design and get the whole lot done via CNC at Plyco (Melbourne). They were awesome to deal with. If you go that route I can share my designs.

 

I opted for 24mm Premium Birch Plywood.

 

Aris

 

 

Edited by aris
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Purchased a piece of 12mm MDF from Bunnings, and cut the crossover boards with a jigsaw.  Also purchased 1L of Vinyl glue (thanks Aris), and a coil of 50/50 resin core solder.

Started assembling the crossovers as a dry run, positioning quite tight on the boards, i guess it doesn't matter if the components sit close to one another as long as wires aren't touching the outside of the caps.

Will complete the tweeter crossovers tonight, and possibly the bass crossovers.

I need to get some copper wire to use for bridging some of the tabs where i need more than 2 connections on the 1 tab, hopefully one of the electrical engineers at work can assist.

10 days until my first woodwork class.

 

Still undecided on:

1. Which vinyl to use for the cabinets - thinking a black brushed aluminium finish for the sides, top and bottom, and just spray the rear black, and where to source.

2. What stain/finish to use on the front baffle - thinking a fairly red stain with maybe a matte polyurethane finish.  It's probably going to depend a bit on time, if i'm close to finishing the cabinets after 3 weeks, I might get more creative with the front baffle.

3. Need to work out exactly how to construct the front grills, it's a large area to have only a rectangle of wood with speaker cloth over it.  Thinking the woodworking instructor can give me some ideas on how to ensure this is strong, whether it's biscuits in the joints, or even corner braces.

I have an idea that i construct the rectangles of wood, then clamp them down on the front baffle and just drill through to the depth i need the plug hole in the front baffle, then i can glue in the little clip thing they'll be held on by, and putty over the hole before stretching the fabric over.  Should allow me to ensure they fit well.  Does this sound like a decent approach?

4. I need to buy some varnish/laquer to treat the birch before cutting.  I will need to receive the wood on the Tuesday before the class starts on the Thursday, thinking i might check if i can do a quick lacquer that afternoon so they're dry by the Thursday for cutting.  Probably just buy something from Mitre 10 up the road for this.

5. Castors/sliders. Troels calls for 30-40mm feet, i can get castors that low but they wont roll on carpet as the rollers are tiny.  If i go to a larger ball bearing castor they'll sit 70-80mm off the ground minimum.  If i use a castor trolley i still need to lift on and off when i want to move them.  Maybe sliders and i just make up some trolley's separately for moving the speakers around, that will allow me to get them home easily and the sliders will be adequate for moving them in and out for listening sessions..

 

Aris, pity we're not both in the same city, it'd be interesting to do a side by side of the Be vs fabric tweeters with the higher and lower spec caps.  I'd also like to hear what different quality amps do for these.

 

Listening to Ben Harper on the Paradigm mk1 9se last night, they sound excellent to my ears.  I'll be sad to let them go once this build is completed..

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We have an oscilloscope at work, the electrical engineers offered to test the crossovers out after i've soldered them together.  Should be in interesting exercise, good to ensure they work before putting them in the cabinets.

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Regarding the crossover, it is better if the components are spaced a little to reduce interaction between components. Most important are the inductors.

 

Inductors should be spaced away from each other by several inches (if possible), and also mounted so that they are not in the same plane - mount them at 90 degrees to the other coils whenever possible to reduce the magnetic field’s effect on the other coils. Also, make sure  when looking through the middle of any coil that you cannot see any other coil - this will also help to reduce interaction.

 

Cheers,

 

Matt.

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Thanks Matt, 

The inductors on the bass crossover are at either end of the board (about 15cm apart), i'll mount one of them on its side and ensure through the hole it is not pointing at another coil..  I'll ensure none of the components (apart from capacitor groups) are touching.

 

The crossovers are mounted in fairly close proximity, (pic below from Troels' website), inductors are all spaced fairly well apart though:

1951055554_Crossoverphoto.jpg.c6cc9a18652359d220bc0281f1f5485d.jpg

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The feet work really well. 
 

https://www.bunnings.com.au/richmond-60mm-x-m12-ball-jointed-levelling-foot_p0078253


In terms of drivers and crossover, I reckon that the Be dome may be overkill. Troels says as much. 


I have a couple of mates (the other 2 Sad Bastards) about to arrive at my house to have a listen to my 3WC-15’s. I’m sure they will say what they think soon enough!

I’m terms of crossover layout, follow Troels. Other than in the midrange where the resistors can be spaced better his layout is pretty good and doable with some care. I’m not a great solderer but I would say to make sure you heat the wire and then apply solder not use solder as glue :)

Edited by aris
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