[navin]

Tempesta Extreme courtesy the wonderful and patient Rick Craig of Selah Audio.

[navin]

Selah's RC4 without subwoofer (2 external subwoofers were used in this system - a TC Sounds 15" in the front and a SEAS ROY in the rear).

[navin]

Guys this is the first time I am sharing my build pics in public. I have been a member of another DIY AUDIO forum for many years but feared i was wasting server space. A special thanks to Bob in St. Louis and Charmerci to helping me do this.

[mykyll2727]

Cool! Thanks for sharing. I'm looking forward to following your build!

[Bob in St. Louis]

Very cool Navin!
I can't help but to think of cedar when I see that wood color.

The plywood in the first design looks like 3/4? Did you bent it to the curve, or are those thinner layers of play that you laminated yourself around the arc?

Again, nice build Sir. Well done.

Bob

p.s. Thanks for the pictures. 

[navin]

The plywood in the first design looks like 3/4? Did you bent it to the curve, or are those thinner layers of play that you laminated yourself around the arc?
p.s. Thanks for the pictures. 

Thank you mykyll2727 and Bob.

Bob, you are right it is thinner layers of ply bent around an arc. If you look closely at the first picture of the Tempesta you will see a pattern in the top left corner behind the speaker (covered in plastic sheet). I used this pattern to bend layers of 6mm ply to the shape. This is not my first pair of bent sides speakers. I have used the same pattern for some of my earlier speakers.

The wall thickness includes 3 layers of 6mm ply, 1 layer of 3mm resin bonded fiberglass and 1 layer of 3mm lead sheet so yes the total thickness is about 24mm. Once I add 4mm of veneer to the sides it would be about 28mm. BTW because we live in Mumbai, India (think hot and humid) all ply and veneer we use is capable of surviving this climate.

For the outer layer of ply I prefer to use a better quality of ply so as to get the best possible finish.
http://www.truwoodply.com/royale.html

To attach the grill I embed small 10mm dia x 6mm thick NdFeB in the baffle. The grill then has a matching steel plate at that location. I have attached some pictures of the center speaker

You can see the NdFeB magnets in this close up


This is the full front view, the speaker is 48" wide, 16" high and tapered from 4-6" in depth (including veneer thickness).


side view of speaker showing taper


Close up right woofer, mid and tweeter cavity - that little hump you see on the bottom left is a depression made to accomodate some wall deviation against which the speaker will be kept.


Close up of woofer, mid and tweeter crossovers. Woofer and tweeter share a board.


View of center speaker without front baffle (pre veneer, polish, etc..).

[kip_]

Looking good Navin. Are you using the Xtremes as fronts or the RC4s?

[Bob in St. Louis]

Wow, that's an impressive build Navin.
The way you're building those side layers, it almost sounds like you could use these as small canoes! 

Bob

[navin]

Looking good Navin. Are you using the Xtremes as fronts or the RC4s?

The living room will have the RC4 (with 15" and 10" subwoofers) as front (10 ft apart) and the matching center and 4 smaller 15cm 2way (Seas) speakers for the rear. 

The bedroom will have the Tempesta Extreme (and a 12" TC sounds subwoofer) in the front and a on-wall version of the S6 in the rear (phantom center since the front speakers are only 6.5 ft apart (c-c) and the TV itself is 4 ft wide I have not used a center speaker.

Bob this picture is for you...it shows 3mm Lead sheet and 3mm resin bonded fiberglass layered between 3 layers of 6mm marine grade ply. That is the cross section of the Tempesta side walls. oh and BTW I do NOT think using lead in a canoe's side wall will help. 

[Bob in St. Louis]

Very cool Navin, thank you for the photo. I'd love to give a tap on that side panel, I'll bet that's as dead as a hundred year old oak tree!

Regarding lead for use in a canoe, how about concrete? http://www.concretecanoe.org/ 

[navin]

Regarding lead for use in a canoe, how about concrete? http://www.concretecanoe.org/ 

OMG Bob you are bringing back memories. Many many years ago (1987-88) a friend of mine and myself built a MTM using a pair of Focal 8N515 and MDT33 (purchased from Dennis Oullet at Solen). The cabinet was built of 1.5" (40mm) concrete panel and the baffle was a full 2" (50mm) thick.

I dont know if you guys remember the Rauna Balder and Tyr? The Balder was a MTM using a pair of 6.5" and a dome tweeter and the Tyr was a small bookshelf that weighed, I think, 20kgs (twice other speakers it's size). Later they had a larger speaker called the Njord (I hope I spelt that right).

[Bob in St. Louis]

For another crazy idea, you could use premade, steel mesh impregnated concrete panels and use a RTV silicone to adhere a layer of lead shot on the back side of it.

That should be 'dead'. 

[mykyll2727]

Navin,

Very impressive work indeed!! Man, talk about bomb proof! I'll be following this thread closely. Thanks again for sharing it with us and I'm loving the job you're doing!

[navin]

For another crazy idea, you could use premade, steel mesh impregnated concrete panels and use a RTV silicone to adhere a layer of lead shot on the back side of it.

Actually Bob it is not that mad.  I have experimented with lead shot. The idea first came to me in the mid 90s. I think it was 93 or 94 when a company called Pro Kennex (it was called just Kennex before that) that produced a tennis racket using lead shot.

My first attempt was to take a PVC pipe fill it with 0.177 shot and seal both ends. The pipe was cut to the depth of the speaker and was lodged from the front baffle to the rear using rubber isolation between the MDF baffle and reat panels. The idea was to convert kinetic energy into heat (inside the box).

It did not work too well; maybe it was the execution.

Next idea was to takes long strings of fiberglass yarn (or loose mat) and stick one end of the mat to the internal bracing letting the rest of the mat hang like a curtain. For sealed boxes this works pretty nice but over use can deaded the sound so one has to be very judicious. For ported boxes it is a no-no. I should have tried in the TLs I have built but when I was building TLs I did not have this idea.

As far as the "steel mesh impregnated concrete panels" is not a new idea. Using either shotcreting or hand packed polymer concrete (in a wood pattern) one can make panels of this type. The problem i faced was handling the panels. I used C channels to brace the box but it became unwieldy and after some time started to develop cracks (the woofer used was a JBL2245) so I dropped that idea. If I remember right the box weighed 200-300kgs when done. I needed 8 men to lift and push finally I had to import an "Airsled" to move it. I still have the Airsled.   

http://www.airsled.com/standard.htm

Bob/mykyll2727, where I live no one take audio seriously. I have developed a reputaion of being hmm how do we put this nicely.... a bit mad. In the US or Europe I am sure there are more people who are serious about building loudspeakers (much more serious than me). For many many years (pre internet) i used to be on my own in left field doing my own thing. Fortunately now I can see other's designs and ideas. I dont feel as mad now.

[Bob in St. Louis]

Navin, I like you. You sound my my kinda guy! 
Good information though, most informative.
Although finding more 'mad' people on the internet doesn't make you less mad, it just means you're in good company. 

You are correct, there aren't very many "audio guys" where you live. I can only think of two and they're both open baffle guys.

Bob

[navin]

Navin, I like you. You sound my my kinda guy! 

Then you must  absolutely check this Aussie bloke called Bon out.
http://www.diyaudio.com/forums/multi-way/218437-3-way-active-time-aligned-constrained-layer-construction-2.html

In Mumbai (formerly known as Bombay) we live in small (Tokyo priced) NY style pigoen holes that masquerade as apartments. The advantage of living in a house is really useful for speaker DIYers. Bon has built a good workshop on his property.

Yes there are a few OB guys in India (maybe 1 in Mumbai). One of them has a GR research (Sigfried Linkwitz Orion style) OB, another has a pair of Jamo 909 and a third has a pair of Audio Artistry Beethoven (I think) and there are at least 2 pairs of AV123 x-statiks floating around.
http://www.hifivision.com/av-lounge/25930-beauty-open-baffle-speaker-5.html

I too was originally thinking of building a Hawthorne Trio using a pair of 10" Iris Augies and a 10" Sterling Silver Iris. Trouble was that WAF dictated the speakers not be 2-3m from all walls. Amplification was to be a Carver M1.0t for the Augies, a EL34 P-P UL for the mid and a triode strapped EL34 for the tweeter.

The maddest of all Indian audio guys must be Mazher Jaffar of Schwinn Audio (it is more a hobby than a business for him). He goes by the name of 'Bhagwan' (indian word for God).
http://www.schwinnaudio.com/

[Bob in St. Louis]

I like that guy Bon, too. That's a level of lunacy I have yet to reach. 
Good thread though, I enjoined it. Thank you for the link. I bumped his thread and gave him my thoughts.

I am fortunate to have a shop in the house as well. Very small, but useful enough to allow me to create and build things in a climate controlled area without having to go outside in inclimate weather.

Someday, I hope you're able to build a pair of HawthorneAudio OBs. I'd love to see what you could do with them.
Regarding your "neighbors", there's a fellow on the Hawthorne forum, "Sanjivs" that lives in New Delhi. He's a great guy.

Bob

[navin]

Someday, I hope you're able to build a pair of HawthorneAudio OBs. I'd love to see what you could do with them.

I have not met Sanjiv but I have heard about him via Hawthorne's forum. We live about 2000 km apart but in Sanjiv's neck of the woods lives another audio 'wild child'. Goes by the name of Viren Bakshi and he makes some lovely tube amps.

Sure there are many options. Concrete (or even "RCC" style mesh based cement), Marble/Graanite/Engineered Quartz and other Stone, Glass and Plexi glass (the later often used in car audio), Lumber (MDF, Birch ply, Solid wood etc..), and various Metals (usually with damping).

About 3 decades ago I heard Dave Wilson talk about enclosures and he identified 3 qualities all loudspeaker cabinets need to have to qualify as good cabnets "A loudspeaker enclosure must be highly rigid, highly damped, and monotonic". To that I add one more quality: the weight of a cabinet must also serve either to make the cabinet more rigid, better damped, and/or reduce resonances (monotonic) and preferably this resonance should be where materials like Dacron, Foam, etc.. can virtually eliminate them (300Hz+).

For Damping you need some viscoelastic material. Rigidity should be accompanied by a very high Young's modulus. and making a cabinet monotonic can be achieved by bracing and sandwich layers.

Sure Dave Wilson and his friends would love to have Material X, Y or Z and be called X-men or Y-men but I believe good old fashioned common sense and some good old fashioned "rolling up the sleeve, and getting the finger nails dirty" can achieve the same results and we can laugh that the Voodoo (I prefer to call it Buffalo poo) expoused by those who put them selves on a pedestial and shout it out.

I come from the old school. We believe that there is only one way to bake good bread, dont take the sugar and caffiene out of Coke, a good hamburger needs to have 400 calories, and loudspeaker cabinets will weigh something, will be "this" big, and will move "this much" air.

If I were to go OB (OB needs only one nice baffle so you need 25% of the material you need for a typical closed/ported box and even less if you are looking a TLs or horns), I would most definitely use a sandwich of at least 5 materials (9-10 layers). The front would be highly polished engineered quartz (routed for the basket of the woofer), then a layer of foam rubber (shore hardness about 40), 3 layers of resin bonded  fiberglass mat strenghtened with rovings, lead sheet embedded inside 2 layers of buytl rubber damping a la Dynamat, and good old fashioned marine grade ply and open cell foam

The Baffle would be about 80-90mm in total. What say?

[Bob in St. Louis]

Your description of the ideal baffle sounds like a dream, I like it very much.
But, back to the subject at hand....the Tempestas....

Bob
(I'm worried you're losing your audience because of me). 

[navin]

Your description of the ideal baffle sounds like a dream, I like it very much.
But, back to the subject at hand....the Tempestas....

Sorry for be a Scheherazade. I will post pictures as soon as I get the speakers back.

The Tempestas and RC4 (and matching center) have gone for veneering. I cannot do the veneering as it requires a humidity controlled room and hot glue so that it looks professional. A friend of mine sells ply (Truwood) so he hooked me up with a professional service that usually does 100s of sheets at a go.

With a little pleading and cajoling they have agreed to do the 2 towers and center speaker. Meanwhile I will cut and build the rear speakers. These will be coated in zinc silicate to match the walls they are going to placed against. See "Guideline for Application of IZS" in the link below
http://www.asianpaints.com/industrial/protective_coatings/protect_tech_paint_appln.aspx

After building speakers for almost 30 years this is the first time I am attempting to finish the speakers in a manner that makes them look professional. Since the polish in the rooms has been coated with melamine (60% matt) the same finish (and same veneer) will be used for the speakers. I know that usually expensive speakers are polished in a high gloss polyurathene coat but my wife wants to speakers to blend into the room so we are not using a high gloss finish.

Amplification for both systems is being discussed here
http://www.audiocircle.com/index.php?topic=107170.new#new

Sorry again about the digression.