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New project-TL towers, using Bob Brines plans

Wharfedale Diamond 11.1 & 11.2 Speakers

GeorgeO

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OK, so I am now in the planing stages of my latest speaker-this is a tower speaker, 92 db, detail/pictures of the plans are available here:

FT-1600 MKII

For details about his construction techniques-this is also an interesting read, see:

Construction Techniques

The list of materials is drivers, inductors and resistors, terminals(MX), port tubes(pvc), wire, fibreglass, and I need to decide what is the exterior finish. In case anyone would like to follow this thread, I suggest a quick reading of the info that Brines has put on the link that I posted is good for anyone who wants to follow this project-that way you will know the background. I willpost photographs as I go along. The inductors are being custom hand wound for me by a friend.

My thinking at this time is to go for MDF(Nuwud)-18mm thick for the raw carcass, since keeping costs as low as possible is a very important consideration. Nuwud offers two densities 700 and 750, I'm planning to use the 700, it is about Rs 40 per sft. I need about 1 1/2 sheets of it. The plywood shop that I went to a couple of days ago, to enquire about materials offers veneer of two types-either reconstituted stuff at around 20/sft or real veneer for a little more-this is 3.5-3.6 mm thick.If not veneer, I can also use commercial plywood and paint it.

I'm planning to use low cost pine wood for the baffle and corners, and while I dont know the exact cost, this is available quite cheap from used packing crates. Pine is not as hard as some of the other species of timber, but I have used it successfully in earlier projects and am happy with the results.

Outside dimensions are 43 X 10 1/2 X 10 1/2 inches.

I will be talking to a carpenter tomorrow, since i have some carpentry work in my new house, will try and get a quote for labour only, and buy the materials myself. If any one has any suggestions, please send them to me soon.

Thanks

George
 

quad

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You may find the Tritrix assembly video useful.

YouTube - DIY TriTrix Speaker Cabinet Assembly

For the trademark Bob Brines style supra baffle, it would
be best cut on a CNC.

If you plan to use T-nuts, the Fostex (going by my
FE206E) needs size 10-24, which I could not get locally.
M6 T-nuts (known here as Tiger Nuts) are easy to find,
but the M6 bolt is a bit larger than the driver holes.

Do you plan to line the MDF with Bison panel or something
similar, following Brine's construction tips?
 

GeorgeO

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Thanks for the quick response.

You may find the Tritrix assembly video useful.

YouTube - DIY TriTrix Speaker Cabinet Assembly

For the trademark Bob Brines style supra baffle, it would
be best cut on a CNC.

Havent decided on the supra baffle yet. Also I generally dont use grills, on my projects, forgot to mention that in my earlier post.

If you plan to use T-nuts, the Fostex (going by my
FE206E) needs size 10-24, which I could not get locally.
M6 T-nuts (known here as Tiger Nuts) are easy to find,
but the M6 bolt is a bit larger than the driver holes.

Do you plan to line the MDF with Bison panel or something
similar, following Brine's construction tips?

Is Bison a possible drop fit for the "Hardi Backer" that he mentions in his plans? I need to research it a bit. I wasnt sure if there was anthing similar locally, so I had planned to avoid it-but if I can use it , I will.. Also, in my view polyfill is easier to handle than fibreglass, so my preference is towards poly.

I havent made up my mid towards T nuts-I may use something available locally for now, and get hold f T nuts when I go to the US in Sept-assuming that the project is completed by then!

George
 

GeorgeO

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Also, in earlier projects I haven used grills-drivers have been exposed. I havent made up my mind on this one-though I note that Fostex grills( metal mesh grills that can be screwed on using the driver mounting hopes) or locally available look alikes can do the trick.

Does anyone here know how much 6mm Bison Board costs per sft? I checked it out and looks interesting.Their website has a link to the price list, but looks like the page is not available now.
 

soundsgreat

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Hi,

George Nice to see the latest project here ! Am sure many budding DIYers will benefit from this :D!!

Anything from my end you know you are always welcome ! Hope to see the progression pics and such soon.

Regards.
 

GeorgeO

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Thanks.

I had a word with the carpenter today, and showed him my other speakers-stand mounted monitors. He felt we could consider two options- a deluxe version, using 3-4mm decorative plywood, front timber and eight corners with rounded timber, or a lower cost version using plywood for all surfaces with 45 degree joints, and the option of suing a supra baffle.Based on the earlier input on this thread,

I plan to source Bison board for the inside, make an MDF raw carcass, and use plywood on the exteriors.My estimate is that the materils may cost around 3500+/-, and await his quote tomorrow morning for labour-maybe 2500 =/-

George
 

keith_correa

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Hi George:

Are you planning to glue the edges or nail them or do both?
Is there any particular reason why you plan on building this using MDF+Plywood BOTH?
I think cement fibre boards are available in India which can be used instead of the HardiBacker boards. Masonite boards too. I think Bison board constitutes wood bonded with cement which is not the same as the HardiBacker but may serve the purpose of adding mass. I think if you speak to an interior designer he/she will be able to suggest various options depending on application needs. Maybe someone on our forum is an interior designer and knows what stuff can be used exactly instead of the HardiBacker boards.
About the damping with polyfill instead of fibreglass, Bob uses the fibreglass to line the walls/HardiBacker - how do you intend to achieve this using polyfill - or do you intend not lining them for damping at all but stuff them with the polyfill instead?
Also Bob says "Use of an elastic cement to laminate the HardiBacker and MDF forms a constrained layer effect that further damps any vibration entering the walls". Is the "elastic cement" the same as "Liquid nails" that he refers to at the beginning of his "Construction Techniques"? What do you intend using for this?
 

GeorgeO

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Keith

Let me try and answer your questions:

I will glue and use fasteners for the edges.

I use both MDF and ply to get the benefit of a sandwich construction, as well as build up the thickness to about 25mm and for the looks. Re Bison Board, it looks like a good, low cost option to me, so I will plan to use it as specified-instead of Hardibacker.

I dont plan to stuff the enclosure, only plan to line the insides, as specified in the plans so I will check Brines forum before taking a decision.

I dont have access to Liquid Nails, so will use some locally available glue.

My final test is the "knuckle test"-if you rap the encl with your knuckles it should sound dead.

George
 

sasmit

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you could also look at something called a "solid board" it already has a sandwich construction.It is different from normal board in the way that it has 4 layers bonder together instead of two layers with pine strips in between...which is what bison board will be. you can get this solid variety in Century ,green ply etc.
 
Last edited:

keith_correa

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I think what Bob means when he says this - "Use of an elastic cement to laminate the HardiBacker and MDF forms a constrained layer effect that further damps any vibration entering the walls" - is that he is coating the inner walls with some sort of elastic cement [whatever that means].

Know the glue that our cobblers use to "stick" shoe soles etc? It's liquidy and rubbery. How about using that as the coating?
 

GeorgeO

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This is not what is called "Block board", is it? BB has batons of solid timber inside with plies on either side, and comes in 19/25 and 30 mm thickness. I dont think BB is suitable-it is not as dense as MDF.
 

GeorgeO

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I think what Bob means when he says this - "Use of an elastic cement to laminate the HardiBacker and MDF forms a constrained layer effect that further damps any vibration entering the walls" - is that he is coating the inner walls with some sort of elastic cement [whatever that means].

Know the glue that our cobblers use to "stick" shoe soles etc? It's liquidy and rubbery. How about using that as the coating?

You mean "Dendrite" kind fo rubbery stuff? I suspect that the kind of choices that we have now in India may be closer to "Fevicol" type yellow or white glues. I will research this a bit more.
 

keith_correa

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George, can you ask Bob about your idea of the plywood over a MDF carcass? I'm thinking that it would be a bit of overkill to do this both. Increases cost/work too.
 

GeorgeO

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Keith

I am rethinking this myself-I had in my earlier projects used 2 layers-no cement board on the inside. I havent yet costed the project with the three layers, and may also consider the option of using 0.3mm thick decorative veneer if it doesnt cost too much.

I have a friend here in Bangalore who has built a 3 way with active crossovers(usign Vifa drivers) using MDF and then polished it, plan to go and have a look at his enclosure this week and make up my mind. The carpenter has 2 more days work at my house, so I will discuss this with him probably in the next day or so.

George
 
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